Research & Publications
My laboratory is deeply engaged in system biology by combining functional genomics, epigenetics, transcriptomics, proteomics and gene editing in vivoand in vitroto understand the molecular mechanisms underlying metabolic syndrome, its traits obesity, hyperlipidemia and hypertension and its complications coronary artery disease (CAD), and type2 diabetes (T2D). We have recruited more than one thousand kindreds with early onset CAD and multiple metabolic risk factors for genetics and metabolic studies. Our work involves high throughput sequencing to identify disease genes, followed by characterization of the disease genes in vivoand in vitro. My group has mapped and identified a number of human disease genes for coronary artery disease and metabolic syndrome, and has published the findings in leading journals Nat Genet, Science, NEJM, Cell Metab, PNAS, etc. These achievements have made us to one of the leading laboratories in investigation of metabolic syndrome. Subsequent molecular and physiological studies in human subjects and animal models have allowed us to unravel many functions of the identified genes and to discover novel targets for pharmaceutical intervention. In addition, I have funded The Program for Cardiovascular Genetics at Yale, which is equipped with most modern techniques of genotyping, including whole exome sequencing, clinical phenotyping and computational biology. This effort has provided us with the opportunity to have access to most extreme inherited cardiovascular disorders and identify disease genes for rare disorders. Other key discoveries of our laboratory are identification of novel gain of function mutations in DYRK1B(NEJM 2014) and loss of function mutations in the gene encoding serine protease CELA2A (Nat Genet 2019) which we have shown are associated with early-onset CAD, T2D and metabolic traits including fatty liver disease (NAFLD). Through careful molecular characterization of Dyrk1B in mice and human we have shown that it increases DNL by AKT-independent activation of mTORC2 via removal of FKBP12 from the complex and increased uptake of FFA by upregulating FABP1(manuscript under review by Nature). These molecular interactions are focus of intense investigation in my lab with the ultimate goal of generating drugs to treat NAFLD. We have patented CELA2A for the treatment of DMII and are in process of patenting Dyrk1B for NAFLD. Over last 3 years we have established techniques of gene editing in my laboratory and with the help of my talented postdoctoral fellows have successfully characterized a number of disease genes in vivo and invitro. I have trained more than 30 undergraduate, PhD, MD/PhD, and postdoctoral fellows over last 10 years. Ten of these trainees have joined academia.
a. (Recommended by F1000Prime)(AHA Young Investigator Award Finalist) Keramati AR, Fathzadeh M, Singh R, Lin A, Faramarzi S, Choi M, Mane S, KasaeM,BabaeeBigi, MalekzadehR, Hosseinian Babaie M, Lifton RP, and Mani A.A formof the metabolicsyndromeassociatedwith mutationsin DYRK1B. NEJM,2014 ;370(20):1909-19, PMID: 24827035 (Keramati was selected as a finalist at AHA early investigator award 2014 for this work)
- (AHA Young Investigator award Finalist) Fatemehsadat Esteghamat, James Samuel Broughton, Emily Smith, Rebecca Cardone, Tarun Tyagi, Mateus Guerra, András Szabó, , Nelson Ugwu, Mitra Mani, Bani Azari, Gerald Kayingo, Sunny Chung, Mohsen Fathzadeh, Ephraim Weiss, Jeffrey Bender, Shrikant Mane5, Richard Lifton, Adebowale Adeniran, Michael Nathanson, Fred Gorelick, John Hwa, Miklós Sahin-Tóth, Renata Belfort-DeAguiar, Richard Kibbey, Arya Mani,.CELA2A mutations predispose to early-onset atherosclerosis and metabolic syndrome and affect plasma insulin and platelet activation. Nat Genet,2019,1233-1243. Epub 2019 Jul 29. PMID:31358993
- (Editors’ choice) Mani A (co-corresponding author), Radhakrishnan J, Wang H, Mani A, Mani MA, Nelson-Williams C, Carew KS, Mane S, Najmabadi H, Wu D, Lifton RP. LRP6 Mutation in a Family with Early Coronary Disease and Metabolic Risk Factors. Science2007;315:1278-82. PMC2945222
Specialized Terms: Identification of cardiovascular disorders that have strong familial pattern
Extensive Research Description
1. By identification of mutation in Wnt coreceptor LDL receptor-related protein 6 (LRP6) my lab has identified one of the first disease genes for early onset coronary artery disease (OMIM: ADCAD2) and metabolic syndrome (Science 2007). Genotype phenotype correlation showed that the mutations impact a number of metabolic phenotypes, raising the possibility of complex downstream effects of the mutation. This discovery caused a paradigm shift by establishing a causal link between impaired LRP6 /Wnt signaling and CAD and its associated metabolic traits. Through a broad range of investigations in humans and animal models generated in our lab we have been able to delineate the role of Wnt signaling in regulation of plasma lipids and glucose, body weight and appetite, fatty liver disease and atherosclerosis.
Our genetic studies in primary human cells, and in animal models implicated LRP6 in clearance of LDL-C elevation. Having unique access to the study populations, we have had the opportunity to investigate the role of LRP6 in regulation of cholesterol synthesis and uptake in primary human cells and tissues.These studies implicated LRP6 in cellular LDL binding and uptake, findings which were soon replicated by other labs (Fabian Bartz et al, Cell Metabolism 2009). We were also the first group to demonstrate that LDLR and clathrin internalizations are LRP6-dependent. These studies identified LRP6 as a critical modulator of receptor-mediated LDL endocytosis.
Familial combined hyperlipidemia is the most common atherogenic lipid disorder. The underpinning genetic causes of this inherited disorder remain vastly unknown. Mice with LRP6mutation (LRP6R611C) generated in our lab exhibited elevated plasma LDL and TG levels and fatty liver, inflammation and fibrosis. The molecular dissection of disease pathway showed that LRP6mutation triggers hepatic de-novo lipogenesis (DNL), cholesterol biosynthesis, VLDL and apoB secretion via TCF7L2-dependent activation of IGF/TOR nutrient sensing pathway. These traits were normalized in vivoby administration of rmWnt3a. These findings identified Wnt signaling as a regulator of TOR pathway and a target for treatment of combined hyperlipidemia. Our ongoing studies focus on investigating the role of Wnt antagonist DKK1 in plasma lipid and mechanisms by which neutralizing antibodies can be used as treatment for hyperlipidemia.
- Liu W, Mani S, Davis NR, Sarrafzadegan N, Kavathas PB, Mani A. Mutation In EGFP Domain of LDL Receptor-Related Protein 6 Impairs Cellular LDL Clearance. Circulation Research2008;103(11):1280-1288. PMID:18948618
- Carmen J, Booth CJ, he Combined Hyperlipidemia Caused by Impaired Wnt-LRP6 signaling is reversed by Wnt3a Rescue. Cell Metab. 2014;19(2):209-220. PMID: 24506864
- Ye ZJ, Go GW, Singh R, Liu W, Keramati AR, Mani A. Lrp6 protein regulates low density lipoprotein (ldl) receptor-mediated ldl uptake. J Biol Chem. 2012;287:1335-1344,PMC3256876
2. The molecular mechanisms underlying insulin resistance are poorly understood. Our studies have established a causal link between altered Wnt signaling/LRP6 and type 2 diabetes. Common genetic variations in Wnt effector TCF7L2 were later found by GWAS to be the strongest predictor for type 2 diabetes in practically every population and ethnic group in the world by mechanisms that were previously not understood. Examination of the skeletal muscle tissues of LRP6 mutation carriers revealed significantly reduced insulin receptor expression compared to unaffected relatives. Further investigations unraveled Wnt transcriptional regulation of the insulin receptor, findings that replicated by Ron Kahn laboratory at Harvard, and Cagan group at Mount Sinai. We also demonstrated for the first time the role of Wnt signaling in regulation of the TOR nutrient sensing pathways in in the skeletal muscle and provided novel insights into mechanisms that underlie skeletal muscle insulin resistance.
LRP6 mutation carriers are affected by nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease. Mice with the human LRP6 (R611C) mutation exhibited both steatohepatitis and steatofibrosis. Using this mouse model, we were able to demonstrate that the activation of the noncanonical Wnt pathways underlie a spectrum of NASH-related liver diseases and are important potential therapeutic targets against NASH.
- (featured article) Singh R, De Aguiar RB, Naik S, Mani S, Ostadsharif K, Wencker D, Sotoudeh M, Malekzadeh R, Sherwin RS, Mani A. Lrp6 enhances glucose metabolism by promoting tcf7l2-dependent insulin receptor expression and igf receptor stabilization in humans. Cell Metab. 2013;17:197-209 PMC3589523
- Wang S, Song K, Srivastava R, Dong C, Go GW, Li N1, Iwakiri Y, Mani A.Nonalcoholic fatty liver disease induced by noncanonical Wnt and its rescue by Wnt3a.FASEB2015 PMID: 25917329
- Liu W, Singh R, Choi CS, Lee HY, Keramati AR, Samuel VT, Lifton RP, Shulman GI, Mani A. Low density lipoprotein (ldl) receptor-related protein 6 (lrp6) regulates body fat and glucose homeostasis by modulating nutrient sensing pathways and mitochondrial energy expenditure. J Biol Chem. 2012;287:7213-7223PMC3293520
3. In collaboration with a team of cardiothoracic surgeons at Yale we were the first group to show the dramatic increase in expression of Wnt coreceptor LRP6 in human atherosclerotic coronary arteries. By dissecting the molecular pathways in human VSMCs, we were able to show that LRP6 forms a complex with PDGFR-β, enhances its lysosomal degradation, increase VSMC differentiation and prevents excessive proliferation. These functions were severely impaired by LRP6 mutations. Our findings implicated LRP6 as a critical modulator of PDGF-dependent regulation of cell cycle in VSMC and showed that loss of this function contributes to development of early onset atherosclerosis in humans. These findings also suggested that increased expression of LRP6 in atherosclerotic lesion functions as a compensatory mechanism to reduce VSMC proliferation.
One of the most exciting developments in our labwas the generation of a novel coronary artery disease mouse model. In these mice we showed that reduced LRP6 activity promotes loss of vascular smooth muscle cell (VSMC) differentiation, leading to aortic medial hyperplasia. Carotid injury augmented these effects and led to subtotal vascular occlusion. LRP6R611Cmice on high fat diet displayed dramatic obstructive CAD and exhibited an accelerated atherosclerotic burden on LDLR knockout background. It is noteworthy that mice, including those with sever hyperlipidemia develop atherosclerosis of the aorta but are resistant against coronary artery disease. We demonstrated that impaired LRP6 activity leads to enhanced non-canonical Wnt signaling, culminating in diminished TCF7L2 and increased activation of PDGF signaling. Strikingly, Wnt3a administration to LRP6R611Cmice improved the activity of LRP6 and its downstream signaling pathway, led to TCF7L2-dependent VSMC differentiation and rescued post carotid injury neointima formation. These findings underscored the critical role of intact Wnt signaling in maintaining the normal structure of the vessel wall, established a causal link between impaired LRP6/TCF7L2 activities and arterial disease and identified Wnt signaling as a therapeutic target against CAD. Motivated by this remarkable finding, we are currently working with the industry to generate small molecule against Wnt inhibitors for treatment of atherosclerosis.
- Keramati AR, Singh R, Lin A, Faramarzi S, Ye Z, Mane S, Tellides G, Lifton RP, and Mani A. Wild-type LRP6 inhibits, whereas atherosclerosis-linked LRP6R611C increases PDGF-dependent vascular smooth muscle cell proliferation. Proc Natl Acad Sci U S A2011,108(5):1914-8, PMC3033290.
- Srivastava R, Zhang J, Go GW, Narayanan A, Nottoli TP,Mani A. Impaired LRP6-TCF7L2 activity enhances smooth muscle cell plasticity and causes coronary artery disease. Cell Reports,2015.13(4):746-59PMID: 26489464
- Srivastava R, Rolyan H, Xie Y, Li N, Bhat N, Hong L, Esteghamat F, Adeniran A, Geirsson A, Zhang J, Ge G, Nobrega M, Martin KA, Mani A.TCF7L (Transcription Factor 7-Like ) Regulation of GATA6 (GATA-Binding Protein 6)-Dependent and -Independent Vascular Smooth Muscle Cell Plasticity and Intimal Hyperplasia Arterioscler Thromb Vasc Biol.2019 Feb;39(2):250-262PMID:30567484
4. My laboratory investigates the genetic causes of adult congenital heart disease. As a director of Cardiovascular Genetics program, I have access to outlier kindreds with rare familial cardiovascular disorders and unknown disease gene. We have mapped and identified disease genes for syndromic and nonsyndromic, autosomal dominant and recessive patent ductus arteriosus, bicuspid aortic valve. The identified disease genes have been functionally characterized in vivoand in vitroand their roles in disease development have been dissected. The function of these genes ranges from epigenetic regulation to determination of the telomere length. These investigations have led to discovery of genetic networks that are involved . We have also currently a number of manuscripts under review by top tier journals.
a. Li N, Subrahmanyan L, Smith E, Yu X, Zaidi,S, Choi M, Mane S, Nelson-Williams C, Bahjati M, Kazemi M, Hashemi M, Fathzadeh M, Narayanan A, Tian L, Montazeri F Mani M, Begleiter ML, Coon BG, Lynch HT, Olson EN, Zhao Ho, Ruland J, Lifton RP, and Mani A. Mutations in the histone modifier PRDM6 are associated with isolated nonsyndromic patent ductus arteriosus. Am J Hum Genet.2016; 98(6):1082-91PMID: 27181681
- Mani A, Radhakrishnan J, Farhi A, Carew KS, Warne CA, Nelson-Williams C, Day RW, Pober B, State MW, Lifton RP. Syndromic patent ductus arteriosus: evidence for haplo insufficient TFAP2B mutations and identification of a linked sleep disorder. Proc Natl Acad Sci U S A2005;102: 2975-2979. PMC549488
- Mani A, Meraji SM, Houshyar R, Radhakrishnan J, Mani A, Ahangar M Rezaie TM, Taghavinejad MA, Broumand B, Zhao H, C. Nelson-Williams C, Lifton R. Finding genetic contributions to sporadic disease: A recessive locus at 12q24 commonly contributes to patent ductus arteriosus. Proc Natl Acad Sci U S A 2002;99:15054-15059. PMC137543
- Seidelmann SB, Smith E, Subrahmanyan L, Dykas D, Abou Ziki MD, Azari B, Hannah-Shmouni F, Jiang Y, Akar JG, Marieb M, Jacoby D, Bale AE, Lifton RP, Arya Mani. The Application of Whole Exome Sequencing in the Clinical Diagnosis and Management of Inherited Cardiovascular Diseases in Adults. Circ: Cardiovasc Genet 2017Feb; PMID: 28087566
- A.Annotated Samples of Scholarship
-Building strong national and international ties with major cardiovascular centers.
- -Identification of a number of genetic mutations that underlie cardiovascular diseases.
- -Publication in many prestigious journals including Science, Cell Metabolism, Proceedings of the National Academy of Sciences, Circulation Research and Journal of Biological Chemistry.
- -Recipient of prestigious awards like Interurban Club Sir William Osler Young Investigator Award.
- -Member of editorial boards: Journal of Circulation Genetics, the Journal of Geriatric Cardiology.
- -Invited speaker at important national and international meetings: Keystone Symposia, Gordon Conferences and seminars at more than 20 prestigious universities.
- -Advisory boards of the Journal of Genetics, Journal of Iranian National Academy of Medical Sciences and Journal Iranian Cardiovascular Research Journal.
-Establishing the Cardiovascular Genetics Program at Yale, the first clinical program that uses state of the art whole exome sequencing for diagnostic purposes.
C. Role in collaborative projects within the Medical Center and with other institutions.
At the international level I collaborate with physicians from Iran, India and Germany. This collaboration is for recruitment of patients with CAD, DNA collection, genetic and physiological studies to identify the underlying causes of CAD. I collaborate with scientists at the Teheran, Isfahan and Shiraz Universities to recruit patients with inherited cardiovascular disease, to perform human clinical studies, and to obtain primary cells and tissues. Several publications have resulted from these collaborations.
Cardiology; Genetics; Heart; Heart Defects, Congenital; Metabolic Syndrome; Lipid Metabolism Disorders; Hyperlactatemia