Pathology Grand Rounds February 23, 2023 - Jason Mills, MD, PhD
February 23, 2023Information
Common Features of Metaplasia and Tumorigenesis in the GI Tract – by Jason Mills, MD, PhD
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- 00:00Thank you everyone for joining
- 00:03our grand rounds today.
- 00:05It is my honor and great pleasure
- 00:09to introduce Doctor Jason Mills.
- 00:12He is a Herman Brown endowed professor
- 00:15at Baylor College of Medicine,
- 00:17Chief of Research in the section
- 00:20of gastroenterology and Hepatology,
- 00:22and the Co director of Digestive Disease
- 00:25Center at the Texas Medical Center.
- 00:28So he graduated summa *** laude from
- 00:31Washington University in Saint Louis with
- 00:33double major in Russian and biology, right?
- 00:38Then he received the MD and PhD
- 00:41from University of Pennsylvania and
- 00:43went back to Washu for his anatomic
- 00:46pathology residency and postdoctoral.
- 00:50Fellowship there.
- 00:51And he mentioned that he had a
- 00:55traumatizing experience with Doctor
- 00:57Peter Humphrey as pathologist here at Yale.
- 01:01Now when they were, you know,
- 01:03signing out a big stack of the
- 01:05Hershey Springs case in the middle,
- 01:08they had a, you know,
- 01:09frozen section and had to leave.
- 01:11And then when they came back and they
- 01:13didn't remember which stack half stack
- 01:15they have reviewed versus they have not.
- 01:18So they had to go over again the.
- 01:20Except that's the entire case again.
- 01:23So they will have a reunion
- 01:25in the afternoon today.
- 01:27So you can have some conversation on that,
- 01:30right?
- 01:31And actually Jason was my PhD thesis
- 01:34mentor at Washu and so I have known
- 01:37him for 18 years now and all my
- 01:40interest in the GI research came
- 01:42from him and and he was a positive
- 01:46influence for me to pursue my career
- 01:49in pathology on the first day.
- 01:51When I joined this laboratory,
- 01:53we sit down on the double headed
- 01:56microscope and he went over mouse
- 01:58and human stomach Histology and
- 02:01encouraged me to become a pathologist.
- 02:03And at that time I was very negative
- 02:07because I never thought about becoming a
- 02:10pathologist during my entire medical school.
- 02:12But see now I'm a I became a pathologist.
- 02:16That's how influence influential
- 02:18he is and as pathologists.
- 02:21And some researchers here,
- 02:23we know well what metaplasia looks like,
- 02:27but we do not know.
- 02:28Well, you know, how it happens.
- 02:30What's the process mechanism on the line?
- 02:33So Doctor Miller says,
- 02:35focused on his research in the
- 02:38cellular and molecular process
- 02:40changes during the metaplasia.
- 02:42And published more than,
- 02:44you know,
- 02:45hundred papers on the metaplasia and in
- 02:49addition to the seminal scientific works,
- 02:52he is very talented as he told
- 02:54you that he majored in Russian,
- 02:55he is very fluent in Russian and French
- 02:59and also he can speak some Chinese
- 03:02and he knows many words in Korean.
- 03:04So with his talents in language,
- 03:09he recently coined terminology collagenosis.
- 03:14Which describes a universal program
- 03:17how mature cells reenter and change
- 03:21their subcellular structure and
- 03:24re-enter cell cycle and becoming a.
- 03:28The regenerative cells which
- 03:31happens during the metaplasia,
- 03:33so he's on the title of his talk today
- 03:36is the common features of metaplasia
- 03:39and tumorigenesis in the GI track which
- 03:42implies the polygenesis basically.
- 03:44So please join me in welcoming Dr.
- 03:47Mills.
- 03:50That's.
- 03:53Thanks. Thanks so much for the
- 03:55invitation and thanks to Juan Jay.
- 03:57I mean it's it's fantastic growth
- 03:59obviously to come here and and see
- 04:01people again and meet and meet
- 04:03new people and but it it's really
- 04:05fantastic to see you know somebody
- 04:07that you saw kind of come immediately
- 04:09can just over from in fact I picked
- 04:12you up at the airport I think
- 04:13when you were interviewing for a
- 04:15Graduate School at Washington St.
- 04:18Louis and then to have him come
- 04:19to my lab and then not even be
- 04:21interested in pathology and coming
- 04:23to do a PhD and then to wind up.
- 04:24A pathologist and then here is an
- 04:26assistant professor and Andre is
- 04:28the first out of my group to to
- 04:29become an assistant professor.
- 04:31So it's just you know it's fantastic
- 04:34honor and and fun to see see how
- 04:36things are things grow and and
- 04:38it was a fantastic introduction
- 04:39because you know essentially I just
- 04:41want to I usually don't do a lot
- 04:44of introduction for how I organize
- 04:45the talk but because you know I am
- 04:47a pathologist but also a cell and
- 04:49developmental biologist my talk
- 04:51kind of it will go back and forth.
- 04:53The first part is all going to be sort
- 04:54of human. Well, it's your background.
- 04:56And then the middle part is gonna go
- 04:58all the way down into ribosomes and,
- 05:00you know, very cell biological.
- 05:03But if you're interested in human pathology,
- 05:05don't give up there because it'll
- 05:06come back also to human pathology.
- 05:08So that's on the sort of that organization.
- 05:10And then just as one day said,
- 05:12as a resident,
- 05:14I became fascinated with metaplasia.
- 05:16And, you know,
- 05:17how do these cells that are sort of
- 05:20normal cells show up in the wrong
- 05:22place and how does that happen
- 05:23at a cell biological?
- 05:25Point of view,
- 05:26so that's my clinical interest.
- 05:27So we we're always doing sort of
- 05:29translational work on that side,
- 05:31but then on the research side,
- 05:33my cell biologist always side says.
- 05:38You know what what how does cells do that?
- 05:40How can cells like make this happen?
- 05:42So what are the mechanisms?
- 05:43So that's what the talk is about.
- 05:44So yes the cell biological
- 05:47changes are the cell,
- 05:49biological processes polygenesis and
- 05:51then you know the the context for the.
- 05:56Pathology is metaplasia.
- 05:58So.
- 06:01One just said why don't you put
- 06:03prognosis in your title so I
- 06:04I added it last night so.
- 06:08OK. So you know as far
- 06:09as I said it's like the,
- 06:11the clinical drive for this is
- 06:12how do these metaplasia happen,
- 06:14how do precancerous lesions arise
- 06:16along the GI tract and and how
- 06:18do they progress to tumors.
- 06:19So that's kind of what drives and
- 06:22funds our work and lately you know
- 06:25it's not just us but with the advent
- 06:28of of single cell RNA seek in in
- 06:31multiple organs I think you know
- 06:33we're beginning to realize that
- 06:35there's a lot more commonality
- 06:37in metaplasia across multiple.
- 06:38The Oregon.
- 06:39So there might be commonality in in
- 06:41these precancerous lesions that that
- 06:43you know I was trained when I was an,
- 06:46you know an AP resident to think it was.
- 06:51Sort of process.
- 06:52Interest on metaplasia in the stomach
- 06:54and and certainly has nothing to
- 06:55do with how colon cancer starts
- 06:57or how pancreatic cancer starts.
- 06:59On the other hand it's kind of like you
- 07:01know it's kind of becoming clear that
- 07:03that there's a lot of similarities.
- 07:05So let's talk about that.
- 07:07So you know with with Jim
- 07:08Golden Ring at Vanderbilt,
- 07:09we had this review recently
- 07:11in gastroenterology talking
- 07:13about some of these concepts.
- 07:15In this one in particular we
- 07:17focused on the similarities
- 07:19between Barrett's metaplasia and
- 07:21gastric and intestinal metaplasia.
- 07:23And basically you know,
- 07:24if you think of Barretts,
- 07:25the ideology there is obviously
- 07:27quite different from the way you
- 07:29get intestinal metaplasia in the
- 07:31stomach and and that's because,
- 07:33you know, we know that.
- 07:35Had a thing of of reflux of acid and
- 07:38and probably also importantly bile as well.
- 07:41And then that takes your squamous
- 07:43epithelium right and turns it into
- 07:45this what in Barretts is called,
- 07:47you know,
- 07:48a columnar mucosa at least at first,
- 07:51which is basically organized
- 07:53a pyloric gastric unit is.
- 07:56So it's essentially just a
- 07:57pyloric metaplasia or a pseudo
- 07:58pyloric metaplasia from squamous,
- 08:00although nobody ever calls it
- 08:01that in the esophagus,
- 08:03I want to point out that to researchers.
- 08:05Jim being the one on golden Ring that
- 08:08coined this term at Vanderbilt that
- 08:10that that what that means is that
- 08:12that the cells at the bottom are stem cells,
- 08:15spasmolytic polypeptide
- 08:16expressing metaplasia.
- 08:17And so that's a term that was coined in,
- 08:20in the stomach actually originally in
- 08:23humans because spasmolytic polypeptide
- 08:25is trefoil factor 2 and that shows
- 08:27up only in these pyloric sort of
- 08:29lesions in the body of the stomach.
- 08:31So a lot of what we'll talk about
- 08:33involves this transition into this.
- 08:36Mucus secreting deep, antral,
- 08:38deep pyloric TF2 positive
- 08:41muck 6 positive lineage.
- 08:42OK,
- 08:43so in the stomach,
- 08:44when H pylori get tired of being
- 08:45in the Antrim,
- 08:46they want to expand their knee and they
- 08:48want to go into the body of the stomach.
- 08:49And it turns out that the way they do this,
- 08:51or we can model this with drugs.
- 08:54And in fact Juan Jade pioneered this.
- 08:56And there are hundreds of papers now
- 08:58in the world using this technique,
- 08:59which is using high doses of tamoxifen can
- 09:03completely reprogram the stomach of a mouse.
- 09:06The same way that H pylori can in
- 09:08humans and actually H pylori and mouse
- 09:10over a longer time course and what
- 09:12happens during that reprogramming is
- 09:14essentially what we talk about as
- 09:17pathologist as chronic atrophic gastritis,
- 09:19but is actually also a metaplasia
- 09:21because it turns the corpus units away
- 09:24from being oxyntic units with gas with
- 09:27the parietal cells and chief cells into
- 09:29basically a pyloric like structure
- 09:31with MUC 5 AC positive foveolar cells,
- 09:34a lower ismal.
- 09:35Proliferative center and again these
- 09:38deep antral like cells which are
- 09:41characterized in the stomach as
- 09:44spasmolytic polypeptide expressing
- 09:46metaplasia. So.
- 09:46You know,
- 09:47the first step basically of H pylori
- 09:49is to turn normal oxyntic glands into
- 09:52these pseudo pyloric metaplasia glands,
- 09:54which is much more what they're
- 09:55accustomed to in the antrum,
- 09:56and that's how they spread from the stomach.
- 10:00So basically what that means is
- 10:02that that you know as we kind of
- 10:04learn more and more about Barretts
- 10:06and we do the single cell RNA seek
- 10:07and we do the genome studies and we
- 10:09try to look at the clonal origin,
- 10:12origin of the Barrett's lesions.
- 10:14And you know the best consensus
- 10:17is that these kind of columnar
- 10:20lesions that look gastric are the
- 10:21first ones that appear in Barretts.
- 10:23But even these can be traced back
- 10:26to roots in in oxyntic mucosa,
- 10:28in other words, if you do clonal.
- 10:31Genomic analysis,
- 10:32you see that these often can be found in
- 10:34a patient near where they're you know,
- 10:37most proximal eccentric glands are.
- 10:40So the idea then is that bile or
- 10:42acid can turn these oxyntic glands
- 10:44into these pyloric glands.
- 10:46And then pretty clearly what happens
- 10:48then is they become intestinal used.
- 10:50And why do I say it's pretty clear?
- 10:52It's because if you look at all Barrett
- 10:54specimens, especially if you have,
- 10:55you know, full thickness,
- 10:56they almost always have bases that
- 10:58are muck 6 positive or trefoil.
- 11:00Factor 2 positive or look just like these,
- 11:03you know spasmolytic polypeptide
- 11:04expressing metaplasia cells and it's
- 11:06only the surface at least until you
- 11:08get a high grade dysplasia that
- 11:10has a lot of intestinal lization
- 11:12and of course then the progression
- 11:14progression from here is into dysplasia.
- 11:16So our research really is into you know,
- 11:20how do you get from here to here,
- 11:21how do you get from here to here
- 11:22and how do you get from here to
- 11:24here from a pathology standpoint,
- 11:25you know then that gives you cancer.
- 11:27One thing just as a take home
- 11:29is that we think.
- 11:31Critical event in all of these
- 11:33transitions very early on is 53
- 11:35mutation and we're going to dig right
- 11:37into the cell biology as we we you
- 11:39know why we think that now clinically
- 11:41and Barretts and molecularly we're
- 11:43finding that that basically as soon as
- 11:45you have a loss of heterozygosity for
- 11:47people 53 and and and patients have
- 11:50loss of function for PD3 then those
- 11:53Barretts lesions behave differently.
- 11:55They're almost always become
- 11:56dysplastic and the rate of conversion
- 11:59to neoplasms much higher. So.
- 12:02What I'm saying is that I think,
- 12:04you know, basically based on
- 12:06the the lineage tracing and all
- 12:07these sort of parallels and the
- 12:09molecular work that we're doing
- 12:10that what we think happens is,
- 12:12you know, violent acid comes in,
- 12:13Barretts and it.
- 12:15Takes out the squamous epithelium
- 12:18and then in the in the that sort
- 12:22of damaged bedding and in that
- 12:24reflex setting you get migration
- 12:26of this kind of gastric epithelium.
- 12:30And then the gastric epithelium
- 12:33becomes intestinalis.
- 12:34And so you can kind of see some of
- 12:36these examples from and a lot of
- 12:37the work that I was telling you,
- 12:38the molecular work showing the origins
- 12:41of the Barretts lesions in in,
- 12:43you know,
- 12:44way back at some point in a patient
- 12:46in oxyntic mucosa is from Stuart
- 12:48McDonald and Marnick Sanson and
- 12:50Nick Wright who've been doing this
- 12:52for a decade or two in in London.
- 12:54So you can see like these oxyntic
- 12:57lesions in in sometimes distal
- 12:59Barretts and then you can see this
- 13:01is just from their paper actually
- 13:02and you see these more pyloric.
- 13:04Regions where you have the spam
- 13:06mucous cells at the bottom and then
- 13:08you see spam mucous cells at the
- 13:10bottom as the tops become intestinalis
- 13:12used with goblet cells, so.
- 13:16So we've been working,
- 13:17we started working on Barretts five
- 13:19or six years ago and started seeing
- 13:21that all come together with our stomach work.
- 13:24And then you know when you kind of
- 13:26do this sort of thing then you go
- 13:27back to the stomach and you think again,
- 13:29well do we really understand how
- 13:31the stomach metaplasia happens.
- 13:33And so we started really kind of
- 13:35digging into the different types
- 13:37of stomach metaplasia.
- 13:39You know that from a research side
- 13:41and and actually in in Asia it's a
- 13:43diagnostic thing where you really
- 13:44make a distinction between.
- 13:46Incomplete and test on that ablation,
- 13:47complete and test on metaplasia.
- 13:49In fact,
- 13:50you know they're type ones and type
- 13:52twos based on use and patterns.
- 13:53But what does all that mean?
- 13:55Well,
- 13:56it turns out that really if you
- 13:57go back in the in the stomach and
- 13:59especially look at the borders of
- 14:01patches of intestinal metaplasia,
- 14:02a lot of the times they're they're
- 14:04incomplete and they have the same
- 14:06kind of organizations Barretts with
- 14:08spasmolytic polypeptide expressing
- 14:09metaplasia type deep pyloric cells at
- 14:12the bottom and then internalization
- 14:14of of goblet cells.
- 14:16At the top and during COVID when
- 14:18I had more time to kind of mess
- 14:20around and and look into history of
- 14:22stuff and I was trying to go back
- 14:25and and try to figure out where
- 14:27it was that everybody in the in
- 14:30the stomach became obsessed with
- 14:31intestinal metaplasia.
- 14:32You know is this something that's
- 14:34always happened because pretty
- 14:35clearly the first thing that
- 14:37happens in atrophy is this
- 14:38more pyloric metaplasia.
- 14:39Yet we never signed that out.
- 14:41We never diagnosed that.
- 14:42I started going back in history and
- 14:44and you find that people you know.
- 14:46Have been talking about pyloric
- 14:48metaplasia actually since like the
- 14:511890s and it was only in the sort of
- 14:531960s or 70s that people became so
- 14:56interested in intestinal medication.
- 14:58It was about the time that endoscopic
- 15:00biopsies came around and and
- 15:02pathologists got only little snippets.
- 15:04And you couldn't sort of tell the
- 15:06orientation to tell whether there was basil,
- 15:08you know, pyloric glands or not.
- 15:10But even, you know in the 1890s
- 15:12they kind of had this concept that
- 15:14there were these sort of pyloric or.
- 15:16Or acid or mucin cell like glance
- 15:18at the bottom that these then might
- 15:20have might be feeding these kind of
- 15:22incomplete intestinal metaplasia.
- 15:24This is from a textbook on gastric
- 15:27pathology in 1897 just to kind
- 15:30of show this diagram with sort of
- 15:32spam metaplasia on the bottom and
- 15:35then internalization on the top.
- 15:37And then just you know,
- 15:38I as I do a lot of sort of translational
- 15:40work and I have slides about my
- 15:42desk that I look at all the time
- 15:44and you know bring people in like
- 15:46Juan J and and sit and look.
- 15:47You can actually see this pretty
- 15:49frequently if you look for it where
- 15:51you can see these kind of deep
- 15:53pyloric glands erupting into more
- 15:55superficial transitioning into this
- 15:56kind of incomplete metaplasia.
- 15:59OK, so that's stomach and esophagus.
- 16:02But it turns out now with single
- 16:04cell or in a site where you can
- 16:07take apart each one of these cells
- 16:09during progression to pan in lesions
- 16:11again for some reason in you know
- 16:13pathology we only talk about panning,
- 16:14but in in the mouse where we
- 16:16can sort of look at each step,
- 16:18there's an intermediate step called
- 16:21acinar ductal metaplasia where
- 16:23the acinar cells shrink and become
- 16:26more cuboidal columnar cells and
- 16:29and proliferative.
- 16:30In an acute or chronic pancreatitis
- 16:32setting and when you start to
- 16:34profile those cells by single cell
- 16:36RNA seek what's interesting and
- 16:37this was work done at Vanderbilt.
- 16:40With a from Kathy Delgiorno's group
- 16:42and and a number of collaborators
- 16:45including Ken Lau.
- 16:46I don't think you were on this paper
- 16:48though on J while you were there, but.
- 16:51But what you see in these early pancreatic
- 16:54lesions is the same sorts of gastric cells.
- 16:57Now of course,
- 16:58they're not organized into a gland,
- 16:59you know, they're all on these asinine.
- 17:01But by single cell RNA seek,
- 17:02you see cells that look
- 17:04like foveolar pit cells.
- 17:05You see cells that look like
- 17:08these spasmolytic polypeptide
- 17:09pyloric metaplasia cells.
- 17:11So and you see the same kinds
- 17:13of cytokines that are starting
- 17:14to emerge as being universal.
- 17:16So I'm not going to talk about this,
- 17:18but aisle 13,
- 17:20aisle 33 shows up as mediating
- 17:23these metaplasia as in the esophagus
- 17:26and the stomach and even as we're
- 17:28going to say now in the intestines.
- 17:30And so the other thing I think
- 17:32it's been really kind of exploding
- 17:34in in from the pathology side.
- 17:36Is that the right sided,
- 17:38you know serrated sessile.
- 17:40You know, polyps,
- 17:42we used to call them serrated
- 17:44sessile lesions also had this
- 17:46same kind of basic format.
- 17:48So in this case you're taking
- 17:50things that were 100% intestinal
- 17:52and then now they're moving towards
- 17:53the gastric side and they wind up
- 17:55somewhere in the middle with this kind
- 17:57of pyloric morphology where again
- 17:59single cell RNA seek shows that.
- 18:00But then you know,
- 18:01as I've been collecting these lesions
- 18:04and we've been looking at them
- 18:07morphologically and immunohistochemically,
- 18:09you again see you know and.
- 18:11And it's been described before too by
- 18:13others that there's muck 6 positive,
- 18:15which is exactly the same expression
- 18:17pattern as spam cells that
- 18:18emerge that are gastric,
- 18:20you know,
- 18:21that are characteristic deep sort
- 18:23of acinar lesions within these SSL.
- 18:25And then there's an ad mix sort
- 18:27of muck 5 AC full Viola and
- 18:30goblet cell surface lesions.
- 18:31So at least on the right sided.
- 18:35SSL type of lesion there seems to be
- 18:37the same kind of metaplasia but sort of
- 18:39coming from intestine back towards gastric.
- 18:42Now that polyps and tubular adenoma
- 18:43seem to take a different course that's
- 18:45kind of more traditionally stem cell
- 18:47based and doesn't fall within that category.
- 18:50But still now we got four different organs
- 18:53all converging towards this sort of,
- 18:55you know pyloric like which is actually
- 18:58probably maybe one of the primordial
- 19:00embryonic states of the stomach and
- 19:02that's probably why and repair the stomach.
- 19:05Kind of chooses to go back
- 19:07to this sort of lesion.
- 19:08But once you have an established
- 19:11lesion that's mixed lineage where it's,
- 19:13you know, making both intestinal
- 19:15and gastric cells at the same time,
- 19:16you could see at least you know,
- 19:18reason why that might be a risk
- 19:21for progressing to cancer.
- 19:23And so part of that,
- 19:24you know,
- 19:25manifest itself when you do genome
- 19:27sequencing and you look for mutations.
- 19:29And that's why this is kind of
- 19:30some of the clinical data for why
- 19:32people do 3 mutations so important,
- 19:34which is that,
- 19:34you know,
- 19:34in these Barretts glands as they
- 19:36start to progress and clones
- 19:37emerge and they start to get the
- 19:39ones that are mixed intestinal,
- 19:40it seems like those are the ones that
- 19:42are prone to developing P53 mutation.
- 19:44It's those clones that then very rapidly,
- 19:47you know, from a heterozygote,
- 19:48once there's a loss of heterozygosity,
- 19:50they almost immediately go into dysplasia.
- 19:53And and neoplasia and then and
- 19:56metastatic and metastasis.
- 19:58OK.
- 19:58So that's the like if my talks at sandwich,
- 20:01that's this is the path introduction
- 20:03that we're going to delve into what
- 20:05we think some of the mechanisms are
- 20:06for how we get these metaplasia and
- 20:08then we'll come back out again to
- 20:09see some of the clinical trial work
- 20:11that we're doing to try to address it.
- 20:13So the question is to where are all these?
- 20:18Lesions coming from, you know,
- 20:19in these four different organs and
- 20:21you know the knee jerk response that I
- 20:24would have given you 15 years ago when
- 20:26Juan Jason the lab was the stem cell.
- 20:28Everybody thinks stem cells are
- 20:29what gives rise to, you know,
- 20:31lesions and and that are proliferative
- 20:33and gives rise to cancer.
- 20:34Well, but it turns out, you know,
- 20:36the stem cells are kind of tricky and
- 20:38in the pyloric versus oxyntic mucosa.
- 20:40So the, the professional stem cells
- 20:42and the oxyntic costs are way up
- 20:44here close to the surface and
- 20:45then when you get this you know,
- 20:47change into this more pyloric.
- 20:48They're kind of down here.
- 20:50So there's a change there
- 20:52already work towards the base.
- 20:54But then there's another thing that we,
- 20:56you know,
- 20:56have to think about which is
- 20:58that say in the pancreas there
- 20:59aren't any stem cells at all.
- 21:00So where are those proliferative
- 21:02cells coming from?
- 21:03And and there's been a long strain,
- 21:05relatively long for this kind of
- 21:07cell plasticity field of maybe 10-15
- 21:09years of good mouse work with human
- 21:11correlation showing that most of the
- 21:14reparative metaplastic proliferating
- 21:15proliferating cells in the pancreas
- 21:17that come about during pancreatitis.
- 21:19And pancreatic injuries actually
- 21:20all come from the acinar cells that
- 21:22are doing their digestive enzyme
- 21:24secretion that that reprogram.
- 21:25Well,
- 21:25it turns out we have a ton of evidence
- 21:28now that actually similar things
- 21:29are happening down at the base.
- 21:31And the reason probably why you get
- 21:33this change from an oxyntic mucosa,
- 21:35this kind of organization with
- 21:37proliferative cells at the base
- 21:39is because the,
- 21:40the fuel for these changes in in
- 21:42these lesions is actually at the
- 21:44base and the differentiated cells
- 21:45just as it happens in the pancreas,
- 21:48in the acinar cells,
- 21:49it's in the digestive enzymes.
- 21:50Recruiting chief cells at the base.
- 21:52So that brings up this concept
- 21:55that how do you get from a,
- 21:58a, a differentiated cell,
- 22:00massive secretory cell like the
- 22:02pancreatic acinar solar chief cell
- 22:04to a much smaller proliferating cell.
- 22:06And you know that actually,
- 22:08you know stirred us to begin to
- 22:10explore the idea of cell plasticity,
- 22:12which is where this fits.
- 22:14And you know this,
- 22:15this concept has exploded in the last
- 22:18five to 10 years and we had the first,
- 22:20I think the first ever meeting that I helped.
- 22:23Organized,
- 22:23which is a keystone meeting in 2019 on it,
- 22:27but then there was a follow up
- 22:28and now there are a number of
- 22:29meetings that are scheduled.
- 22:30We had a paper on nomenclature,
- 22:32but just to kind of put us all in the
- 22:34same cell and developmental biology
- 22:36page when we're talking about this lesions,
- 22:38you know the canonical stem
- 22:40cell idea of how you get.
- 22:42Differentiation in a tissue is
- 22:44that you have these stem cells
- 22:46that make faith choices, right.
- 22:48And as they differentiate and
- 22:49they're basically like marbles
- 22:51rolling down this Waddington,
- 22:52this Conrad Waddington was
- 22:54the person who came up with
- 22:56this concept of a landscape of sort
- 22:59of differentiation choices and then
- 23:01the ball sort of slowly roll down
- 23:03and then you get your chief cells and
- 23:04parietal cells and acinar cells at the
- 23:06base and then they just sit there.
- 23:07You know, the idea inherent to this
- 23:09concept is that it's a unidirectional
- 23:10flow of the balls roll down the hill.
- 23:12And so then if you need to get repair,
- 23:14any kind of repair done,
- 23:15then you need to take one of
- 23:16these progenitors to repair.
- 23:17But it's pretty clearly not the
- 23:19case because now we all know that.
- 23:22The balls can kind of go back up
- 23:23the hill and you can get just
- 23:25in the setting like I told you.
- 23:26If acinar cells they can
- 23:28become proliferative.
- 23:29You can get sort of the balls going
- 23:31over the grooves and being becoming
- 23:33other cells like beta cells in the
- 23:35pancreatic islets can become alpha cells.
- 23:36So these are trans differentiation
- 23:39and dedifferentiation events.
- 23:41And in fact when you really think
- 23:43where we care is pathologists and
- 23:45and pathology researchers about the
- 23:47injury and inflammation standpoint.
- 23:49You know it's quite possible that
- 23:51none of these grooves even stay the
- 23:53same during inflammation in the
- 23:54entire niches changing and all the
- 23:55groups are changing the identities
- 23:57may change you know and as we do
- 23:59more single cell RNA seek we see that
- 24:01you know I cell identities are all
- 24:03kind of overlapping you know and and
- 24:05these groups may not be so so clear.
- 24:09So there's a lot of interest in
- 24:12collagenosis and or in itself by in
- 24:14plasticity and differentiation and in
- 24:16fact that kind of got I was tickled
- 24:19to see that there was a last month
- 24:20the call for in scientific reports
- 24:22for papers on on plasticity and
- 24:24specifically specifically pathogenesis.
- 24:26OK.
- 24:27So the why do we have this term
- 24:30pathogenesis and the reason is because
- 24:32all of those balls are rolling around
- 24:35on the hill that that I was showing
- 24:38you had to do sort of with the.
- 24:40That, that tissue and developmental biology,
- 24:43the idea that every cell has got its
- 24:46own identity and that in plasticity
- 24:48events the cells, you know,
- 24:49change identity and it matters if
- 24:51they become less differentiated
- 24:52than they're rolling up.
- 24:53And if they're trans differentiated,
- 24:55they're, you know,
- 24:56becoming another cell type.
- 24:57But what if we're actually interested
- 24:59in the process of how you take a
- 25:02differentiated cell and convert
- 25:03it to a proliferating cell?
- 25:05You know,
- 25:05that is not likely to be different
- 25:08in every single organ, just like.
- 25:10If you need a program cell death,
- 25:12you have the apoptotic program and you
- 25:14have apoptosis and that's the same.
- 25:15And nobody thinks that apoptosis
- 25:17is different in every cell type.
- 25:20So this change in identity,
- 25:22these dedifferentiation events are
- 25:23likely to be similar across tissue types.
- 25:26So there must be a cell biological process
- 25:29or an osis that dictates these events.
- 25:32And so we came up with this idea that if
- 25:35we wanted to look at the cell biology
- 25:38of how these cells rearrange then.
- 25:40We should have a term
- 25:41so we can talk about it.
- 25:42And Paola is the Greek return,
- 25:44like in palindromes, you know,
- 25:45a site that goes back and forth.
- 25:50Can be read both ways right.
- 25:52And and and Jen is the general,
- 25:55you know, generative.
- 25:56So Palingenesis is the return to the
- 25:58generative state, regenerative state.
- 26:00So but when we're talking about this then
- 26:03what we're talking about is basically.
- 26:05How do you take these chief cells and make
- 26:07these metaplastic proliferative cells?
- 26:09So these are very Long live
- 26:11cells that don't proliferate.
- 26:12How do they become proliferative?
- 26:15So the take home is that it?
- 26:18It's a the.
- 26:19Basic.
- 26:20Like so biological change that
- 26:22has to happen here is a change
- 26:25in the way the cell uses energy.
- 26:28When the cell is in the base
- 26:30of a gastric unit,
- 26:32then it uses energy to produce
- 26:34digestive enzymes and secrete.
- 26:35When it's in the base of a of
- 26:37a reparative metaplastic unit,
- 26:39then it uses energy to divide.
- 26:41So all of the in between.
- 26:43The Collagenosis part is how the
- 26:46cell adapts itself to go from
- 26:48a digestive enzyme secreting
- 26:50energetic cell to a proliferating.
- 26:53Non energetic but but non secretory.
- 26:57So and basically this is the basic
- 26:59scheme which seems to be conserved across,
- 27:02you know, from fly guts to, you know,
- 27:05pancreas to stomach to lung.
- 27:06Every time you are calling
- 27:08differentiated cells back into
- 27:09the cell cycle and that is that
- 27:12there's a massive upregulation of
- 27:13autophagy and lysosome as the cell
- 27:15reprograms its internal organs.
- 27:17Followed by a second stage where
- 27:19the genes that we recognize it
- 27:22as being metaplastic.
- 27:24And those are a lot of different
- 27:26genes like trefoil factor or
- 27:27spasmolytic polypeptide or some
- 27:29of the socks genes like Sox 9.
- 27:31Followed by this very important one,
- 27:33which is the stage when the cell
- 27:35decides whether to actually
- 27:36enter the cell cycle or not.
- 27:38And this is the key stage for cancer
- 27:40because you're taking these old
- 27:41long lived cells and you're bringing
- 27:43them back into the cell cycle.
- 27:45And so this is a checkpoint that
- 27:47we'll talk about as being important.
- 27:48And just to kind of put us on
- 27:50an ultrastructural footing,
- 27:51what we're talking about is a very
- 27:53large pancreatic acinar cell or
- 27:55digestive enzyme secreting chief cell
- 27:56with layer after layer of rough ER,
- 27:58all these secretory granules becoming
- 28:01this much smaller proliferative
- 28:03stem like cell.
- 28:04And this can happen in the mouse and
- 28:06you know about 42 hours basically.
- 28:10So the kinds of things that are
- 28:12going to happen and we're going
- 28:13to talk about are modeled in this
- 28:15little video that Jeff Brown is a
- 28:18gastroenterologist and assistant
- 28:19professor at Washu now.
- 28:21Um,
- 28:21basically all this rough ER turns
- 28:24into autophagosomes and then starts
- 28:27to digest all the secretory
- 28:29apparatus and also gets rid of all
- 28:32that extra ER itself.
- 28:33The cell reshapes like
- 28:35this and then the next step
- 28:37is that's going to enter the the cell cycle.
- 28:40So how do we study this?
- 28:43So what we've taken to do doing is to
- 28:46looking at these metaplasia models,
- 28:49both of which involve collagenosis,
- 28:50both of which are drug induced and
- 28:53relatively short term like within days
- 28:55we can get these changes in both the
- 28:57stomach and the pancreas at the same time.
- 29:00That way we can look at all
- 29:01the conserved features,
- 29:01not just what happens in the stomach.
- 29:04And so we use two systems for the most part,
- 29:06one of which.
- 29:08Juan Jay invented which is our discovery,
- 29:11which is that if you treat mice
- 29:13with high doses of tamoxifen,
- 29:14it has an estrogen and sex independent
- 29:17toxicity effect on the stomach,
- 29:19which kills all the parietal cells
- 29:21within a couple of days basically,
- 29:23and reprograms the chief cells
- 29:25and the entire oxyntic mucosa
- 29:27into this pyloric like mucosa.
- 29:29And the other is an established
- 29:31model of of Cerulean,
- 29:33which is a CCK hormone analog treatment
- 29:36that turns the pancreas into this.
- 29:38Kind of duck like,
- 29:40but it's really just more again
- 29:43metaplastic proliferative phenotype.
- 29:45So this is the dosing scheme for
- 29:47high dose tamoxifen and this is
- 29:49what it looks like pathologically.
- 29:50Here's a normal mouse stomach
- 29:51with parietal cells up here,
- 29:53digestive enzyme secreting chief
- 29:54cells here and within three days of
- 29:57those tamoxifen injections the cells,
- 29:58the units become like tubes with
- 30:00just mucus cells on top and
- 30:02mucous cells in the bottom and
- 30:04then proliferation throughout,
- 30:05whereas normally proliferation
- 30:06is confined to this top area in.
- 30:09The normal stomach and pancreas,
- 30:12all of these acinar acini open up
- 30:14and you get these kind of cuboidal
- 30:17cyst like proliferative cells also
- 30:19if we do the cerulean treatment
- 30:22there just to give him a plug.
- 30:25To embarrass him a little bit.
- 30:28So with this system then we've been
- 30:30able to and I'm just going to show
- 30:32you some highlights but you know
- 30:33because a lot of this is published
- 30:35because it the the stomach system
- 30:37is so synchronous and then we can
- 30:40transmit translate that into lesions
- 30:42in humans and and and then confirm
- 30:45with the the pancreatic system we've
- 30:47been really able to kind of pretty
- 30:50quickly delineate us and others
- 30:52the the the program that happens in
- 30:55polygenesis and basically you take an.
- 30:58A uninjured secretory cell and you
- 31:00cause some kind of injury that's
- 31:02going to induce some metaplasia.
- 31:04And of course you know as we know
- 31:06the whole point of that is to induce
- 31:07proliferation so that it repairs the damage.
- 31:09But the other thing that happens
- 31:11is about this kind of time course
- 31:13all the different the organelles
- 31:14that are specifically tied to the
- 31:16differentiated function are decreased.
- 31:18You know,
- 31:18so things like the rough ER and and
- 31:20and and this is focused on the stomach,
- 31:22but they're equivalents in in
- 31:24pancreas and other organs,
- 31:25but things like pepsinogen and and so on.
- 31:29And that occurs across these three stages.
- 31:32The first stage is this massive autophagy,
- 31:34which is of course what's helping to
- 31:36get rid of these differentiated organs.
- 31:38The second stage is that METAPLASTIC
- 31:40gene expression where you start to see
- 31:43that the cells have rearranged how they.
- 31:45Actually Mark and label and
- 31:48then the final stage is this.
- 31:50Mtorc increase, which is critical for
- 31:53entering into the cell cycle and that is
- 31:57immediately after a stage of induction
- 32:00and then suppression of people 53.
- 32:01So this crossing point is very important
- 32:03because the main thing that P53 does
- 32:05is I'll show you is suppress mtorc.
- 32:07So CP3 has to decrease for these cells to
- 32:10be licensed to read into the cell cycle.
- 32:13So you know we're going to head
- 32:14on this theme several times,
- 32:15but I already hinted at it from
- 32:17what we know about Barretts and
- 32:19why this kind of reprogramming.
- 32:21Is so important in NYPD.
- 32:22Three is important.
- 32:24It's important for this licensing step.
- 32:26You don't let differentiated cells
- 32:28back into the cell cycle unless
- 32:31they've cleared up 53 checkpoint.
- 32:33So thinking about mtorc one,
- 32:35it's the central energy regulator and
- 32:36this is a super simplistic version of it.
- 32:38But just so that we're on the same page,
- 32:41you know it's pretty much integrates
- 32:43the vast majority of the cells
- 32:45energetic inputs and outputs with
- 32:47the two main wings being related,
- 32:49wings being protein translation
- 32:51and of course driving the cell
- 32:53cycle via phosphorylation of the
- 32:55small ribosomal subunit 6.
- 32:57So this is going to be important
- 32:59because this is a great marker for
- 33:01Mturk activity by immunostaining.
- 33:03Works great or an IF you can tell
- 33:05how much import there is by how
- 33:07much phosphorylated S6 there is,
- 33:09so Amtrak increases.
- 33:10This in itself is stimulated by
- 33:12low energy and by autophagy and
- 33:15all of the breakdown products
- 33:17in in the lysosomes and a key.
- 33:19Inhibitor of mtorc is this gene called before
- 33:22or red one which we'll talk about also.
- 33:25So let's look at some of how
- 33:27what this looks like in actual
- 33:30ultrastructure and you can see
- 33:31that within 24 hours down now we're
- 33:34looking in chief cells that we have
- 33:36all these massive autophagosomes,
- 33:38auto lysosomes,
- 33:39all this auto degraded machinery
- 33:41that these cells start to rearrange
- 33:43their their entire architecture
- 33:45and you can see just here this is
- 33:48quantified by how much lysosomes there.
- 33:50And then we use this 3D electron
- 33:53microscopic tactic called focused
- 33:55IMDb scanning electron microscopy
- 33:58to kind of look at it more detail.
- 34:00And you can see as we kind of
- 34:02spin this around,
- 34:03this is a single chief cell as this
- 34:05polygenesis process that's happening early.
- 34:07This is a capillary loop and
- 34:09these are the secretory granules,
- 34:11this is the nucleus and these are
- 34:12all lysosomes and autophagosomes.
- 34:13So like half the cell becomes
- 34:16auto degradative as the.
- 34:19As this early stage in Polygenesis happens,
- 34:23so that's what's happening to
- 34:27autophagosomes and and lysosomes.
- 34:29For that to happen Mturk has to decrease
- 34:31and here we're looking at mtorc
- 34:33activity using this phosphorus 6 and
- 34:35here we focus on the chief cells.
- 34:37And here within 12 hours all all of this
- 34:40phosphorus 6 or M torc activity is lost
- 34:42in the chief cells and then by maximum
- 34:44metaplasia it all comes back again.
- 34:46So here it's working for secretion
- 34:48and not for proliferation,
- 34:49here it's working for proliferation.
- 34:51And in between is when all that autophagy
- 34:53is happening and you can see even on
- 34:56Western blots of mouse stomach you can
- 34:57see it happening on the other hand.
- 34:59We knock out this suppressive ddit 4,
- 35:02which I showed you in that cartoon with
- 35:04it gets induced early to suppress network.
- 35:07You don't have the same decrease
- 35:10in mtorc activity and you don't
- 35:13have the same autophagy.
- 35:14So if you look at mtorc,
- 35:15basically it's much, you know.
- 35:17Normally it's like that and in
- 35:19the four knockout it's like that.
- 35:21So that leads to actually more,
- 35:24more proliferation,
- 35:25more metaplasia downstream.
- 35:27And conversely,
- 35:29when you inhibit mtorc.
- 35:32That's how we know that the cell cycle
- 35:35reentry is critical because taking rapamycin,
- 35:38an M TORC inhibitor,
- 35:39and treating mice with it does not block
- 35:42the the metaplasia or the autophagy
- 35:44or those first couple of steps,
- 35:46but it it blocks the
- 35:49proliferation completely.
- 35:51So early on did it 4 suppresses mtorc.
- 35:54We have all that autophagy but on
- 35:56that last slide we also see that
- 35:58did it four goes away within the
- 36:00first couple of stages and that's
- 36:02when 53 comes on and P53 continues
- 36:04to suppress M torque until or
- 36:06unless the cell then decides to
- 36:08come back and the cell cycle.
- 36:10So that part of the way we know that
- 36:12is that in P53 knockouts we also don't
- 36:15have this mtorc loss early on we
- 36:18have more proliferation both in the.
- 36:20The stomach and the pancreas and
- 36:22then what we know that the critical
- 36:25regulator of P53 that tells the cell
- 36:28whether the cell should increase
- 36:30M Turk and go back into the cell
- 36:32cycle is a protein called ifrd one.
- 36:34And we'll show you how that works
- 36:36and how that P3 I 41 access works.
- 36:39But you can see it's massively
- 36:42upregulated during collagenosis
- 36:43and then as the cells we enter
- 36:45the cell cycle it goes away.
- 36:47And in the absence of in the
- 36:49absence of ID 11,
- 36:50all the cells wind up dying and
- 36:52not completing the process.
- 36:54But if you knock out paid 53,
- 36:56then they're rescued and
- 36:57they reenter the cell cycle.
- 36:59So that's how we know I pretty
- 37:00when it's upstream of 53.
- 37:01So we'll talk about how RD1
- 37:03dictates to P3 to dictate M torque.
- 37:05A lot of this work was done by Max Yao,
- 37:08who's in China now as an assistant professor.
- 37:12So let's talk now about some of the
- 37:15machinery that executes this process
- 37:17and the way that we've started to do this.
- 37:20Stepping back,
- 37:21right,
- 37:21like if this process of taking
- 37:23a differentiated cell and bring
- 37:25it back into the cell cycle is,
- 37:28you know,
- 37:29a conserve process across
- 37:31multiple tissues just
- 37:32like apoptosis, then there should be
- 37:34genes that are dedicated to the process,
- 37:37just as there are genes dedicated to
- 37:39apoptosis like BCL's and caspases and so on.
- 37:41So we started doing screens in
- 37:45these regenerative metaplastic.
- 37:47Organs after after you know during
- 37:51the regenerative phase and look for
- 37:53genes that are all ex Co expressed
- 37:54and and from these I FD one indeed it
- 37:56four came out I've already told you
- 37:58about them need it for suppressing
- 38:00mtorc I-41 suppressing P53 but we have
- 38:02other targets that we've been working
- 38:04on another really strong one is ATF
- 38:06three which I want to talk about and
- 38:08we're starting to piece together then
- 38:09this architecture but this is what
- 38:11we've learned so far in in this talk
- 38:13do you injury happens the cell starts
- 38:15to undergo a topology did it for.
- 38:18Suppresses mtorc to turn it off
- 38:19to allow the autophagy to happen.
- 38:21I have heard one is induced that
- 38:24eventually accumulates and suppresses
- 38:25P53 which allows cell cycle entry.
- 38:30So. Why then is mtorc so important?
- 38:33Because, you know,
- 38:34when we think about why Barretts
- 38:36becomes cancer,
- 38:37why gastric intestinal metaplasia
- 38:38or you know,
- 38:40pseudo pyloric metaplasia gives
- 38:42rise to cancer and we think about
- 38:45this pathogenesis process,
- 38:46this conversion,
- 38:47you know,
- 38:47being critical for that and mtorc being
- 38:50critical for that cell cycle reentry
- 38:52because that's what you need for cancer.
- 38:54Why is it so important?
- 38:55Well,
- 38:56here's what we delve like the deepest
- 38:57into the structure and organelles
- 38:59before we kind of come back out again.
- 39:01Our thinking now is that it's all about
- 39:05ribosomes when you're a chief cell.
- 39:06I showed you that electron microscope
- 39:09micrograph where it's just layer after
- 39:11layer after layer of rough ER and all
- 39:14that roughly RISER line by ribosomes.
- 39:17That are making digestive enzymes to go into,
- 39:20you know,
- 39:20the lumen of the R and then to be secreted.
- 39:23When you become a proliferative cell,
- 39:25you don't need all that secretory
- 39:26roufi R you need ribosomes in the
- 39:28cytosol to make more ribosomes than
- 39:30histones to make a copy of the cell.
- 39:32And the key driver for ribosome
- 39:35Biogenesis is M torque OK,
- 39:38and the reason why ribosome Biogenesis
- 39:40needs so much energy is because it's
- 39:43an incredibly complex process of
- 39:45assembling all of these ribosomal
- 39:47proteins and ribosomal RNA's that
- 39:49require all three RNA polymerases
- 39:52and translation into these.
- 39:53Large and small 1640 subunits which
- 39:57come together as a single subunit,
- 40:00multiple modifications happen and all
- 40:01of its sort of starts in the nucleolus.
- 40:03So that's our basic ribosome review.
- 40:06And then as I talked about,
- 40:07there's a big difference between this
- 40:09pool and this side of solid pool,
- 40:11right,
- 40:11because this is for secretion and this
- 40:13is more for division and housekeeping.
- 40:16So to get from the ribosome to translation,
- 40:20we have to realize that the M
- 40:22RNA is going to be loaded up
- 40:24the preinitiation complexes.
- 40:25That's going to bring the two
- 40:27subunits together.
- 40:27So the two subunits only
- 40:29come together with M RNA
- 40:30normally, OK. So they're kept together
- 40:33with M RNA as they translate.
- 40:35And then the way most of our
- 40:37translation happens is not with
- 40:38single ribosomes but multiple ones
- 40:40like pearls on a string, line up,
- 40:42line up and those are called polysomes.
- 40:44We're not going to go too much into this,
- 40:45but you can tell the difference.
- 40:47Between Monisms and polysomes by
- 40:48spinning them down and the longer
- 40:50you know ones or polysomes so they
- 40:52take lower longer to spin spin out.
- 40:54So the last review slide here on ribosomes.
- 40:57The reason why they require so much,
- 40:59they require 80% of the cells energy.
- 41:02So that's why it's so important how you,
- 41:03you know, regulate ribosome Biogenesis and
- 41:0660% of your RNA in each cell is ribosomes.
- 41:10So there's huge proportions of the
- 41:12transcription and translation that
- 41:14goes into ribosome Biogenesis.
- 41:15So what happens to ribosomes
- 41:17during palingenesis?
- 41:18So we knew already that they had to
- 41:20be coming off the rough ER and we saw
- 41:23that's what all the autophagy was doing.
- 41:25But you can also just document it,
- 41:26there's many ways.
- 41:27To to show that you're losing
- 41:29both large and small.
- 41:31Subunits of ribosomes are just Western
- 41:33blots early on in the process and
- 41:35then they come back on again later.
- 41:37So there's a loss and then
- 41:39regeneration process.
- 41:39But you can also see some of the
- 41:42ribosomes getting taken up into
- 41:44the the rough ER and you can also
- 41:46see them kind of spinning off the
- 41:47ER here into the sideshow.
- 41:49And in fact Juan J was one of the first
- 41:51to show this by knocking out a gene
- 41:53that that regulates all that rough
- 41:55ER when he was a graduate student.
- 41:57So this is kind of what we think
- 41:58is happening.
- 41:59In terms of stages of of pathogenesis,
- 42:02normally you have all these rough ER.
- 42:06Ribosomes making peptides and then,
- 42:08you know,
- 42:09there's an injury and these autophagosomes
- 42:11start to take up the raffia and the
- 42:13ribosomes all come off OK what's the
- 42:15problem with the ribosomes coming off?
- 42:16As soon as they come off the M RNA,
- 42:17then they fall apart into their
- 42:20subunits and into ribosomal proteins,
- 42:22and those can stimulate P53.
- 42:24I'm going to show you that again
- 42:25a couple of different times,
- 42:26but that's probably why this whole ribosome
- 42:29is the center of this mtorc P53 axis.
- 42:31But this is just to show you that we
- 42:33also get a lot of ribosome Biogenesis,
- 42:35so we're losing.
- 42:36Have some and then later we see
- 42:38huge increases in nucleolar size,
- 42:40which you can see here in quantify
- 42:42in both the stomach and the pancreas.
- 42:44So what that means is we're losing
- 42:46ribosomes here and then the nucleoli
- 42:48are getting turned on or making
- 42:50more ribosomes here.
- 42:51But that's not the entire story as we see,
- 42:54because I 41's going to play an important
- 42:56part in between those two things.
- 42:58So to be able to study these things,
- 43:00we already have one tool which
- 43:02is the ID one
- 43:03knockout. But Charles Chow in the lab,
- 43:06who's an instructor looking for a job soon,
- 43:09also made a knockout of ribosome
- 43:11Biogenesis for the first time,
- 43:12surprisingly that he can.
- 43:14Reduced ribosome Biogenesis knockout by
- 43:16knocking out this key modifier that's
- 43:18critical for the small subunit of ribosomes.
- 43:20And when he does that you that you
- 43:22can no longer make ribosomes and
- 43:24when you do that and you induce
- 43:26collagenosis all the cells die unless
- 43:28you also put them on a P53 knockout.
- 43:31So again PD3 knockout is critical
- 43:33that's sensing the death of of cells
- 43:37that don't make ribosomes anymore.
- 43:39So this particular gene which is
- 43:41involved in the ribosome Biogenesis.
- 43:44Suppresses P53 presumably because
- 43:46it makes both subunits.
- 43:47So they're both subunits are there.
- 43:49It stops the people to three
- 43:50induction that happens with
- 43:52ribosome will breakdown products,
- 43:53but I have 41 is occurring here
- 43:56earlier I showed you and it's also
- 43:59responsible for suppressing P53.
- 44:00How does that work?
- 44:02Well, it turns out that it's in between.
- 44:04That's just to remind you of
- 44:05that and that NAP 10 is there,
- 44:07but I heard you once turning on
- 44:08earlier and doing the suppression.
- 44:09So how does it work?
- 44:12So it turns on it, you know,
- 44:13it turns on here.
- 44:14And what it does,
- 44:16it turns out.
- 44:17Is that I 41 fits right here right where the
- 44:20M RNA would go between the two subunits.
- 44:23So when I offered you one
- 44:24attaches just like M RNA,
- 44:26it can keep the two ribosomal
- 44:27subunits together as a whole.
- 44:29So instead of having this happen
- 44:31during those early stages,
- 44:32which then leads to breakdown
- 44:34in P53 activation,
- 44:35I 41 can come right there in that pocket.
- 44:40And as they come off the ribosomes,
- 44:41they're preserved.
- 44:42So essentially 53 is blocked because
- 44:44you don't get breakdown of all the
- 44:47ribosomes during the first stage.
- 44:49So on the one hand you could have this,
- 44:52but when you have ribosome Biogenesis
- 44:54you can stop P53 by making new ribosomes,
- 44:57and if you have 41 then you salvage
- 44:59the existing ribosomes so both
- 45:01of those then converge on P53.
- 45:03OK, so that is the ********.
- 45:06Organellar and molecular stuff.
- 45:08So now let's come kind of back out to
- 45:10how this all comes out in tumors and
- 45:12and come back out towards the pathology.
- 45:15So with all this background
- 45:16then it's pretty clear,
- 45:18you know that the cells spent a lot
- 45:20of time trying to regulate them to
- 45:22work via PD3 and via this protein deed
- 45:24at 4:00 to be able to ensure that
- 45:26the there's no tumors that come out
- 45:28of this taking these old cells and
- 45:30driving them back into the cell cycle.
- 45:32So what if we get rid of the ability to
- 45:35stop mtorc and regulate this process so.
- 45:38You know what if we take out them
- 45:40torque regulation and then in
- 45:42in a system where we can induce
- 45:43metaplasia multiple times and the
- 45:45thinking would be then that what's
- 45:47going to happen is we kind of
- 45:49injure each time and we don't
- 45:51have much error checking.
- 45:52Then you go through collagenosis,
- 45:54then you heal, then you go through
- 45:55pathogenesis and you heal.
- 45:56But each time you can accumulate
- 45:58mutations until finally you get to
- 46:00the mutations like Karas or something
- 46:02like that that drives a tumor and
- 46:04then you know you no longer go
- 46:06back to being a chief seller and.
- 46:08Lesson or so.
- 46:09So I already showed you how we kind
- 46:11of we do these screens and coming
- 46:13back to dead at 4 so that you know
- 46:16knocks out the ability of the cell
- 46:17to decrease M torque and it knocks
- 46:19out its ability to be able to
- 46:21sense the P53 damage and to be able
- 46:23to stop cells from coming back.
- 46:25And cell cycle basically just kind of
- 46:27skips past all this error checking
- 46:29right into the proliferation.
- 46:30So you see a lot more proliferation
- 46:32when you knock out deed it for.
- 46:33And So what happens is essentially
- 46:35you can take mutations and carry
- 46:37them right into these dysplasias.
- 46:38And so functionally what Max did
- 46:40in the lab was do multiple rounds
- 46:43of Immunogen which causes gastric
- 46:45tumors kind of slowly in the stomach
- 46:48in these cells that could no longer
- 46:50in these mice that could no longer
- 46:52regulate the the collagenosis and
- 46:54that mtor checkpoint versus control
- 46:56cells that could still did multiple
- 46:58rounds of tamoxifen to do multiple
- 47:00rounds of metaplasia and repair.
- 47:01And what he saw as we predicted was
- 47:03a lot more tumors in the deed at 4
- 47:06knockouts and a lot bigger tumors
- 47:08in fact just for the pathology.
- 47:10This is one that arose as a huge
- 47:12sort of polypoid tumor that was
- 47:14more intestinal type between the
- 47:16Antrim and the corpus,
- 47:17but then had a had a focus of the diffuse
- 47:21signet ring cells that you can see.
- 47:23And it's rare in the mouse to get
- 47:25such an obviously metastatic tumor.
- 47:26You can see them kind of in this
- 47:28PAS stain going right through the
- 47:30muscle area and into this aerosan
- 47:32intelink vascular space.
- 47:34So in other words, if you can't do this,
- 47:36check here to make sure these
- 47:38cells are OK and send them back,
- 47:40you know, to repair them.
- 47:41They come back to repair with mutations
- 47:44and then eventually they form tumors.
- 47:46OK, so last thing, the human thing.
- 47:50You coming back all the way back to human,
- 47:53the human part of the talk.
- 47:56Again,
- 47:56we've been again going back to
- 47:59Barretts and trying to study this,
- 48:01how these processes happen and how
- 48:03people heal from these processes.
- 48:05Unfortunately,
- 48:05this great mouse models that we
- 48:07can use for tumorigenesis and
- 48:09metaplasia and stomach don't apply
- 48:11because mice don't get variants,
- 48:13they don't reflux at all,
- 48:14they don't have any bile or
- 48:15acid ever in their esophagus.
- 48:17So there's no really good rodent
- 48:19models for this.
- 48:20So you know, you have to study the human.
- 48:22And so I've been collaborating in
- 48:24this amazing collaboration with.
- 48:26Rhonda Souza and Stu Spechler's
- 48:28group and Rob odds.
- 48:30Also, you know, pathologist,
- 48:31yeah, pathologist.
- 48:32To look at, at their models of
- 48:34Barretts and some clinical trials,
- 48:36I'll just show you.
- 48:37Here's where I had them down to Houston.
- 48:38There's Rob and and me.
- 48:41And there's actually, there's my.
- 48:42There's the same microscope that Wanj
- 48:45learned on, taken down to down to Houston.
- 48:48And Rhonda like is fond of saying
- 48:50that humans are the best model system.
- 48:52So it with Barretts we have to do that.
- 48:54So, So what in this model what
- 48:57they've done is they you know with
- 49:00the dysplastic Barretts you can treat
- 49:02it by radiofrequency ablation just to
- 49:04basically take out all the Barretts
- 49:06and take it down to the ulcer bed and
- 49:09granulation tissue and then for some
- 49:11reason it heals back as squamous.
- 49:13So basically what you're doing
- 49:14is radiofrequency ablation,
- 49:15the Barretts,
- 49:16and it goes to this just ulcer bed basically.
- 49:18What's leftover?
- 49:21And then you know what happens though,
- 49:23you know after this ulceration is it
- 49:25comes back as a squamous and what
- 49:27they did was they they took a bunch
- 49:28of patients and enrolled them should
- 49:30also say for the this study and
- 49:32then did the pre and then one week,
- 49:34two week and four week biopsies
- 49:35all the way proximal to distal
- 49:37from before the margin of RFA to
- 49:39the gastric margin after the RFA.
- 49:41And you know try to look at how
- 49:42the healing process, how all this,
- 49:45you know mucosa became squamous again.
- 49:49So that's kind of what it looks like.
- 49:52You know, the question is where
- 49:53does all that squamous come from?
- 49:54And the only source of squamous or even
- 49:56epithelial cells that you could think of
- 49:57would be at this proximal margin, right.
- 49:59But it turns out that's
- 50:00actually not what happens.
- 50:01What happens is it comes
- 50:03back as squamous throughout.
- 50:05So there's some source of squamous
- 50:07epithelium that's obviously trans or D or
- 50:10some kind of differentiating, you know,
- 50:12that's that's feeding the squamous.
- 50:14And you know we have a couple of clues,
- 50:17one of which well we talked about.
- 50:20But one of which I'll show you
- 50:22evidence for here, you know,
- 50:23so the idea is that coming from
- 50:24the proximal squamous, you know,
- 50:25there's a come from the distal gastric,
- 50:27but then why would that be squamous?
- 50:28But it turns out it just comes in
- 50:30all these little islands like this.
- 50:31And so if you focus,
- 50:32here's one of these islands of this
- 50:35NEO squamous healing epithelium.
- 50:37And, you know,
- 50:38where does this come from on either side?
- 50:40Basically it's going to go down
- 50:41to like a single cell.
- 50:43It turns out that there's pretty good
- 50:45evidence both morphologically and also
- 50:47with their advanced endoscopy that
- 50:48if you look under each of these new.
- 50:51Kind of ulcerated surface as a single
- 50:53cell layer of squamous is forming.
- 50:55They're all underneath ducts
- 50:57from submucosal glands.
- 50:59So you know,
- 50:59just for those of you don't remember
- 51:02your human esophageal theology.
- 51:04These are the 70 coastal glands,
- 51:05and they have ducts that reach
- 51:07up to the squamous epithelium.
- 51:09And normally like if you blade
- 51:10all this with RFA,
- 51:11then there's still a source of epithelium.
- 51:13At least you know distally for
- 51:15some of these squamous islands.
- 51:18But the other source is probably some of
- 51:19these deeper Barretts that escapes the.
- 51:21RFA as we have a lot of work showing
- 51:23that there's transitions in there.
- 51:26So like in fact that's what we're doing now.
- 51:27We're doing spatial transcriptomics,
- 51:29we're growing organoids and we're doing
- 51:31a lot of IHC and Multiplex IFF to kind
- 51:33of show how these transitions happen.
- 51:36So that's that. So summarizing.
- 51:39Take homes.
- 51:41This kind of pyloric metaplasia
- 51:43is some kind of like maybe
- 51:45or metaplasia that you see,
- 51:47you know,
- 51:47intestine in the cases of SL going
- 51:50towards that you see the body of.
- 51:52I don't mean gastritis and H
- 51:55pylori induced atrophic gastritis,
- 51:57it's the what seems to be
- 52:00happening in Barretts.
- 52:02And the root of this and although we
- 52:04don't know this yet in the SL how
- 52:07that happens but but at least in the
- 52:09pancreas and the stomach for sure
- 52:11and probably in Barretts is the cell
- 52:13biological process that's driving this,
- 52:15the palingenesis process.
- 52:16And that basically is about cells converting
- 52:19energy from one state to the other.
- 52:21Now you know this is a pathology grand
- 52:24rounds and I'll tell you that when
- 52:26I was doing a lot of this looking
- 52:28at where this metaplasia happened
- 52:30and where what people thought about
- 52:32it 100 years ago.
- 52:34Well, over 100 years ago,
- 52:35George Adami was a famous pathologist
- 52:37who at the time was at McGill said,
- 52:39you know, it looks like in tissues
- 52:41that are going to become cancerous,
- 52:43there's all this reprogram,
- 52:45you didn't use that term of cells
- 52:48from mature cells to dividing cells,
- 52:51and that seems to fuel the cancer.
- 52:52So he kind of anticipated all of this.
- 52:54And he said that what must happen
- 52:56is the cell converts its energy
- 52:58use from secretion to division.
- 53:00So, you know, it's kind of funny.
- 53:02Then we forgot that for like 9000.
- 53:03Years.
- 53:04And then, you know,
- 53:05we've come back to that old
- 53:06pathologists who just by looking
- 53:08at a bunch of tissues made the
- 53:10same kind of analysis that it
- 53:11was the same in multiple tissues,
- 53:13you know,
- 53:14even as a picture of a liver cell with
- 53:16its kind of autophagy before they
- 53:17even knew what the organelles were.
- 53:19So a lot of that depends on ribosomes
- 53:21and and so the metaplasia depends on
- 53:23this collagenosis which depends on ribosome.
- 53:26So these are all areas where you
- 53:28could target potentially both to.
- 53:30First metaplasia,
- 53:31but also if cancers emerge from
- 53:34those this aberrant checking
- 53:36of pathogenesis or P53,
- 53:38then maybe with they proliferate
- 53:39by going through that.
- 53:48The city. Ohh, it's all the eye.
- 53:53And where we got some of the
- 53:55mice and this is our group down
- 53:58in Texas with my wife's lab,
- 54:00she's mysorekar and on the mills,
- 54:02so we're the M&M labs together, so.
- 54:11Yes, you know. And then.
- 54:14So, so I don't know,
- 54:16but I think there are papers already too.
- 54:19But I'm, I I bet you it's the same aisle 13,
- 54:21aisle 33 access which drives it
- 54:24seemingly in in Barretts and
- 54:27in pancreas and and in stomach.
- 54:30The, the very idea Polygenist
- 54:33is absolutely reversible.
- 54:34Yeah, 100% it's,
- 54:35it's a normal way to recruit stem cells,
- 54:38especially for organs that don't
- 54:39have stem cells like the pancreas.
- 54:41That's the only way the pancreas
- 54:42can kind of repair itself is by
- 54:44recruiting the acinar cells.
- 54:45And then normally they come right back.
- 54:47It's only when you know they acquire
- 54:49enough mutations that they don't read,
- 54:51differentiate and they think
- 54:52it's an idea to keep growing.
- 54:53You know, that it becomes irreversible.
- 54:55And that's why we think,
- 54:57you know, chronic inflammation,
- 54:58which is the first question you had,
- 55:00is so important.
- 55:01Because it keeps stimulating
- 55:03this collagenosis until of these
- 55:05kind of old cells.
- 55:06You know, if you think about it,
- 55:07they don't really do much error
- 55:09checking of their chromatin under
- 55:10normal circumstances because
- 55:11they're just making a handful of,
- 55:13you know,
- 55:14digestive enzymes over and over again.
- 55:15And most of their ribosomes
- 55:17are already taken care of,
- 55:18so they're most of their chromatin is inert.
- 55:20So then you ask them to rearrange everything,
- 55:22come back into cell cycle and
- 55:23expose a bunch of cell cycle genes,
- 55:25which is very dangerous.
- 55:26So they need this error checking and it
- 55:29just seems like we've evolved only one.
- 55:30Protein which is P53 to do all
- 55:32that error checking.
- 55:33So each time you go through that cycle of
- 55:36you're asking people to three to work.
- 55:39And the more you do it the more chances
- 55:40you're taking until you get a you
- 55:42know clone that doesn't have it work.
- 55:43And then you start having more
- 55:46errors in each replication.
- 55:47And then when that happens then
- 55:49eventually you'll get a make or
- 55:51a rass or you know something else
- 55:52that drives it outside the geotrack.
- 55:54Yeah.
- 55:55Actually you know I 41 is conserved
- 55:57all the way through plants.
- 55:58It's the the the the it's.
- 56:01Amazing protein.
- 56:01It goes right between the ribosomes.
- 56:03That's why it's so conserved.
- 56:04And it has 0 phenotype in any Organism,
- 56:07from plants to flies to yeast.
- 56:12Even if it's not in all yeast.
- 56:13Because I think it's more multicellular
- 56:15thing when you knock it out until
- 56:17you injure and ask them to kind of
- 56:20reprogram and respond to injury.
- 56:21So there's flying effort you want and
- 56:23if you knock it out then you can't
- 56:25recruit stem cells and the fly gut.
- 56:29Deliver after partial hepatectomy
- 56:31of you knockout I31 you screw up
- 56:34the ability to to get all that GI
- 56:37tract again and parasites kidney.
- 56:40That's a non GI Oregon also and in
- 56:42fact all this is tied to aging in
- 56:44the sense that as you get older
- 56:45you seem to be able to lose.
- 56:47You lose these markers in these
- 56:48genes and in in the bladder we
- 56:50know that actually where each time
- 56:52you go through UTI of shedding you
- 56:53need to recruit new stem cells.
- 56:55As you age you lose I 41 and
- 56:59you're less able to do this.
- 57:00That's work from the My wife side actually
- 57:03because she's a a bladder expert.
- 57:15Yeah, right. So, yeah,
- 57:16the question is why are some metaplasia
- 57:18is dangerous and some not, right?
- 57:20You know, I have no idea because that's
- 57:22the same thing with stomach, right?
- 57:25I mean, autoimmune gastritis
- 57:26causes massive metaplasia.
- 57:27And you know, there's a huge controversy
- 57:30about whether it increases risk of
- 57:32gastric cancer or not in the absence
- 57:34of Co infection with H pylori.
- 57:35And I think probably the
- 57:37consensus is it doesn't.
- 57:38So even the very same metaplasia
- 57:40and H pylori context.
- 57:42You know it's risky, but but it's not in
- 57:44the autoimmune gastritis context, so.
- 57:49I, I, I don't know, uh, I, you know,
- 57:52I think 1 aspect would be the
- 57:54repetitive nature and the chronicity.
- 57:57Another aspect, you know,
- 57:58in the stomach,
- 58:00I've always thought of that H pylori is
- 58:01also got oncogenes that it, you know,
- 58:03pretty much injects into cells.
- 58:05And also there's this sense of kind
- 58:09of progression and that that that
- 58:12that glands on the border between
- 58:14the Antrim and the corpus going to go
- 58:16through this more and more and more
- 58:17as autoimmune gastritis, I think.
- 58:19You know,
- 58:20kind of happens sporadically,
- 58:21hits an area,
- 58:22then comes back and it's kind of back and
- 58:24forth in different areas as opposed to
- 58:25the same area going over and over again,
- 58:27but.
- 58:29I've never been asked that question.
- 58:30It's a really good about the cervix,
- 58:32you know like in areas where you
- 58:34get metaplasia that don't that
- 58:36may even be protective.
- 58:37I mean you know in the stomach a
- 58:39complete intestinal metaplasia seems
- 58:40almost protective against gastric cancer.
- 58:42So that's another interesting fact.
- 58:46And and I think in autoimmune
- 58:48gastritis there's more complete
- 58:50than there is incomplete.
- 58:51But I think it's definitely risky
- 58:53to have the kind of metaplasia where
- 58:55you have a mixed phenotype where it's
- 58:57both gastric and intestinal and it keeps.
- 59:00Happening it almost, you know,
- 59:02is asking for trouble.
- 59:03So maybe pure metaplasia are better.
- 59:05I don't know.
- 59:06It's a good question.
- 59:08Haven't.
- 59:11Haven't asked.
- 59:13OK. Question on the.
- 59:18Building. And you describe.
- 59:23But when you look at.
- 59:26Or the before.
- 59:31Yeah, yeah. He.
- 59:37Your life experiences that are known
- 59:40to alters. So the question is, drew,
- 59:43are there germline variants of genes
- 59:45like D at 4 the AG is the autophagy
- 59:49genes that affect susceptibility?
- 59:51I. That's a good question.
- 59:54I don't know did it.
- 59:55Four is very controversial also
- 59:57from the cancer standpoint,
- 59:58it seems like half the literature
- 60:00says that mutations are variants or
- 01:00:02pro tumorigenic and half are anti.
- 01:00:04But the issue with pathogenesis
- 01:00:06and tumorigenesis is you know it's
- 01:00:09a cycle normally so umm and it's
- 01:00:11sort of aberration in the cycling
- 01:00:12that we think is giving the tumors.
- 01:00:14So just kind of completely knocking
- 01:00:17it down might not would probably
- 01:00:19give you a premature aging thing
- 01:00:20if in fact that's what I said,
- 01:00:22I pretty one has no phenotype
- 01:00:23but actually it has an aging.
- 01:00:24Genotype so as you age then and
- 01:00:28you get inability to regenerate
- 01:00:30the that tends to be where you
- 01:00:33manifest your pathogenesis defects
- 01:00:35because you probably wouldn't be
- 01:00:37able to necessarily you've never
- 01:00:39traced people that don't get tumors
- 01:00:41based on you know lacking that but
- 01:00:43obviously people do three is a key
- 01:00:46checkpoint and that is the you know
- 01:00:48incredibly tight the tumor genesis
- 01:00:50the in terms I'll be a little bit
- 01:00:53more specific though about autophagy.
- 01:00:55Which is that we have tried with a
- 01:00:58G57 and 1601 variant to show effects
- 01:01:01and haven't really been successful.
- 01:01:04Where we have genetically been able
- 01:01:06to completely shut palingenesis
- 01:01:07down both in the pancreas and the
- 01:01:09stomach is by affecting lysosomes.
- 01:01:10So if you want to really get dive
- 01:01:12into the autophagy aspect of it,
- 01:01:13we actually think it.
- 01:01:14It's from the EPG 5 which is the
- 01:01:16fusion of autophagosomes and
- 01:01:18lysosome steps down there are the
- 01:01:19most important and a lot of it
- 01:01:21maybe non canonical autophagy.
- 01:01:22So a knockout the the best knockout.
- 01:01:25They had to stop.
- 01:01:26The whole process is as in the
- 01:01:29phosphorylation that phosphorylase that puts
- 01:01:31phosphate phosphate groups on Mano six,
- 01:01:34you know to make Manor 6 phosphate.
- 01:01:36So none of the digestive,
- 01:01:37the license only enzymes go to the lysosome.
- 01:01:39Those mice are completely resistant
- 01:01:41to you know which is not necessarily
- 01:01:43a good thing because it means
- 01:01:45they can't repair in the pancreas
- 01:01:46is kind of if you keep forcing
- 01:01:48pancreatitis or pancreas is turned
- 01:01:50to snot basically because they can't
- 01:01:53you know repair the damage so.
- 01:01:55In our experience,
- 01:01:56it's really lysosomes I you know,
- 01:01:58it's massive autophagy.
- 01:01:59Clearly LC3,
- 01:02:00it's all the classic but the the main.
- 01:02:03The thing seems to be required is
- 01:02:05the flux through the lysosomes.
- 01:02:09Short question.
- 01:02:12Cheap.
- 01:02:18Yeah. So, so the question is whether
- 01:02:20parietal cells can do the same thing.
- 01:02:22And in fact, as part of the more general
- 01:02:24question of is it like universal and
- 01:02:26the parietal cells are great test case
- 01:02:27of the only cell that we've never seen
- 01:02:30couldn't do any kind of plasticity.
- 01:02:32And actually Juan Jay also did
- 01:02:34the that the experiment early on.
- 01:02:35So if he did when he was doing
- 01:02:37the the tamoxifen to be marked,
- 01:02:40all the parietal cells,
- 01:02:41they all died basically and they they didn't,
- 01:02:45they never seem to. D differentiate.
- 01:02:48Actually we have a pretty good idea
- 01:02:49because some of our work is just on
- 01:02:51the regular differentiation parietal
- 01:02:52cells and there seems to be a
- 01:02:54checkpoint and their differentiation,
- 01:02:55after which they are no longer
- 01:02:57plastic at all, but up to about
- 01:02:59halfway into becoming a parietal,
- 01:03:01so then they can take detours.
- 01:03:03And in fact,
- 01:03:05working with Shilpa Jane at Baylor,
- 01:03:08we've been collecting some of the
- 01:03:09interesting sort of parietal hyperplasia
- 01:03:11that happen in a neuroendocrine setting
- 01:03:12or an autoimmune gastritis setting,
- 01:03:14and you can definitely see some pretty
- 01:03:16odd using markers that we know of.
- 01:03:18Pre parietal cells some odd
- 01:03:19sort of parietal cell variance,
- 01:03:21but I don't think those are coming backwards.
- 01:03:23I think those are actually coming
- 01:03:25from the stem cell and then in
- 01:03:27the setting bottom you gastritis.
- 01:03:28They take a detour because they're
- 01:03:30going to be destroyed basically by
- 01:03:32the anti parietal cell antibodies.
- 01:03:34So yeah, not all cells can do it.
- 01:03:36Seems like protocells are quite resistant.
- 01:03:40A lot of questions.
- 01:03:45Yeah.
- 01:03:51He said great. It's great to like,
- 01:03:54you know, don't present that often,
- 01:03:56but before a bunch of pathologists, so.
- 01:04:01Yeah, is the neuroendocrine proliferation,
- 01:04:04you know those little tumors or little
- 01:04:06growths or you know that you get with
- 01:04:08chronic bridal cell loss or chronic,
- 01:04:10you know, PPI's and.
- 01:04:11You know, is are those metaplastic?
- 01:04:13They sure look funny, right?
- 01:04:15I mean, you know,
- 01:04:16they don't look like they're normal
- 01:04:19endocrine cells sitting lining up
- 01:04:21with the rest of the epithelium,
- 01:04:23because normally integrins
- 01:04:25cells are always surrounded by.
- 01:04:28Other non neuroendocrine epithelial
- 01:04:29cells and then you know in these
- 01:04:31lesions you get these little,
- 01:04:33you know, expansions.
- 01:04:36And I yeah great great question.
- 01:04:40How would they you know the the
- 01:04:41only the one thing that that might
- 01:04:43speak to that is one of the detours
- 01:04:46it seems like those riddles can
- 01:04:48make but I just said is towards
- 01:04:50more of an endocrine lineage.
- 01:04:51So you know maybe maybe that's why
- 01:04:53I never really thought about it.
- 01:04:56We had a mouse model where we drove
- 01:04:58large tea energen you know to drive
- 01:05:00proliferation and to to try to get
- 01:05:02a bunch of pre parietal cells but
- 01:05:03what happened with time this is
- 01:05:05when I was in Jeff Gordon's lab.
- 01:05:06What happened with time was they all
- 01:05:09turned into endocrine tumors in the stomach.
- 01:05:11So they actually went through.
- 01:05:13So it's like they hit a certain wall
- 01:05:15of parietal cell differentiation and
- 01:05:17then took a detour towards endocrine.
- 01:05:20Then it became endocrine proliferations,
- 01:05:21and then they became metastatic
- 01:05:24neuroendocrine tumors.
- 01:05:24So I don't know,
- 01:05:26maybe we just solved a mystery.
- 01:05:28Maybe it's because the reason why they
- 01:05:30happen so much is not just because of
- 01:05:32hypergastrinemia and the G cell stimulation,
- 01:05:35but also because.
- 01:05:36The pre parietal cells themselves can
- 01:05:39fuel endocrine cells in that setting.
- 01:05:42Yeah, and take a detour.
- 01:05:44They clearly can in the mouse we showed.
- 01:05:46That means it's hard,
- 01:05:47it's artificial because we're
- 01:05:48expressing large T but but still,
- 01:05:50they start off as pre parietal cells and
- 01:05:52then you could watch them even become,
- 01:05:53you know,
- 01:05:54through EM and and staining become endocrine.
- 01:05:57So yeah,
- 01:05:57maybe,
- 01:05:58maybe that's maybe your two
- 01:06:00questions are linked.
- 01:06:06All right. Thank you, everybody. Yeah.