Christian Tschudi, PhD
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Research Summary
Unraveling the biology of pathogens is fundamental toward understanding mechanisms of pathogenesis and identifying genes essential for survival in the host. Our research focuses on the protozoan parasite Trypanosoma brucei, which causes devastating diseases in humans and animals in sub-Saharan Africa. We are applying RNA interference (RNAi), namely down-regulation of gene expression by homologous double-stranded RNA, to identify genes essential for survival within the insect vector and mammalian host. In addition, high-throughput next-generation sequencing technologies (RNA-Seq) are used to analyze gene expression patterns (the transcriptome) during the developmental cycle. Lastly, we are interested in understanding gene silencing by RNAi in African trypanosomes with the objective to uncover its biological function.
Specialized Terms: African trypanosomiasis; Gene expression profiling; Gene discovery; Next-generation sequencing; RNA interference
Extensive Research Description
Professor Tschudi’s studies focus on the biology of trypanosomes the causative agents of devastating diseases in Africa and South America. Most projects in the laboratory utilize bioinformatics and modern genetic techniques to identify and dissect parasite-specific functions. The laboratory has developed several methodologies for creating mutants and has been instrumental in establishing a number of techniques to study processes at the biochemical level. These approaches will lead to a better understanding of the infectious cycle of the parasite, which involves a mammalian as well as an insect host. The long term goal is to identify candidate molecules that can be targets for chemotherapy.
Most recently, we have established and used RNA-sequencing (RNA-Seq), a novel high-throughput sequencing technology, to interrogate the transcriptome of the parasitic protozoa Trypanosoma brucei, the agent of African sleeping sickness in man and nagana in cattle.
In the course of this work, we have optimized the RNA-Seq protocol for use with trypanosomatids, built our own server, implemented a stream-lined bioinformatics pipeline and generated one of the most comprehensive genome-wide transcript maps at single-nucleotide resolution. Such information is central to the identification of functional elements, to determine the timing and regulation of gene expression in different developmental stages and to identify novel drug targets. Indeed, this work has dramatically expanded the repertoire of known genes to include over 1,000 novel genes with many displaying features suggesting that they are secreted or modulate the characteristics of membranes and thus play a role in the response of T. brucei to the changing environment during its complex life cycle. We expanded the transcriptome studies to developmental stages of T. brucei in the tsetse fly vector (in collaboration with Dr. Aksoy) and to the life cycle of Leishmania (Viannia) panamensis (in collaboration with Dr. McMahon-Pratt).
- Profiling the transcriptome of the parasitic protozoa Trypanosoma brucei, the agent of African sleeping sickness in man and nagana in cattle, by next-generation high-throughput sequencing.
- Characterization of molecular mechanisms Involved in RNA metabolism with special emphasis on RNA interference and the role of small RNAs in trypanosome biology.
- Developmental biology of African trypanosomes in its Invertebrate Host, a collaborative effort with Professor Serap Aksoy in the Department of Epidemiology of Microbial Diseases
- Characterization of enzymes involved in RNA modification, a collaboration with Professor Shulamit Michaeli at Bar Ilan University in Tel Aviv, Israel
Coauthors
Research Interests
Parasitic Diseases; Tropical Medicine; Trypanosomiasis, African; Genomics; RNA Interference
Public Health Interests
Genetics, Genomics, Epigenetics; Infectious Diseases; Parasitology
Selected Publications
- Two cold shock domain containing proteins trigger the development of infectious Trypanosoma bruceiToh J, Nkouawa A, Dong G, Kolev N, Tschudi C. Two cold shock domain containing proteins trigger the development of infectious Trypanosoma brucei. PLOS Pathogens 2023, 19: e1011438. PMID: 37276216, PMCID: PMC10270622, DOI: 10.1371/journal.ppat.1011438.
- A single-point mutation in the RNA-binding protein 6 generates Trypanosoma brucei metacyclics that are able to progress to bloodstream forms in vitroShi H, Butler K, Tschudi C. A single-point mutation in the RNA-binding protein 6 generates Trypanosoma brucei metacyclics that are able to progress to bloodstream forms in vitro. Molecular And Biochemical Parasitology 2018, 224: 50-56. PMID: 30055184, PMCID: PMC6147148, DOI: 10.1016/j.molbiopara.2018.07.011.
- The proteome and transcriptome of the infectious metacyclic form of Trypanosoma brucei define quiescent cells primed for mammalian invasionChristiano R, Kolev NG, Shi H, Ullu E, Walther TC, Tschudi C. The proteome and transcriptome of the infectious metacyclic form of Trypanosoma brucei define quiescent cells primed for mammalian invasion. Molecular Microbiology 2017, 106: 74-92. PMID: 28742275, PMCID: PMC5607103, DOI: 10.1111/mmi.13754.
- Transcriptome Profiling of Trypanosoma brucei Development in the Tsetse Fly Vector Glossina morsitansSavage AF, Kolev NG, Franklin JB, Vigneron A, Aksoy S, Tschudi C. Transcriptome Profiling of Trypanosoma brucei Development in the Tsetse Fly Vector Glossina morsitans. PLOS ONE 2016, 11: e0168877. PMID: 28002435, PMCID: PMC5176191, DOI: 10.1371/journal.pone.0168877.
- Developmental Progression to Infectivity in Trypanosoma brucei Triggered by an RNA-Binding ProteinKolev NG, Ramey-Butler K, Cross GA, Ullu E, Tschudi C. Developmental Progression to Infectivity in Trypanosoma brucei Triggered by an RNA-Binding Protein. Science 2012, 338: 1352-1353. PMID: 23224556, PMCID: PMC3664091, DOI: 10.1126/science.1229641.
- The RNA Interference Pathway in Trypanosoma bruceiUllu E, Kolev N, Barnes R, Tschudi C. The RNA Interference Pathway in Trypanosoma brucei. 2011, 28: 167-185. DOI: 10.1007/978-3-642-28687-2_8.
- The Transcriptome of the Human Pathogen Trypanosoma brucei at Single-Nucleotide ResolutionKolev NG, Franklin JB, Carmi S, Shi H, Michaeli S, Tschudi C. The Transcriptome of the Human Pathogen Trypanosoma brucei at Single-Nucleotide Resolution. PLOS Pathogens 2010, 6: e1001090. PMID: 20838601, PMCID: PMC2936537, DOI: 10.1371/journal.ppat.1001090.
- Distinct and overlapping roles for two Dicer-like proteins in the RNA interference pathways of the ancient eukaryote Trypanosoma bruceiPatrick KL, Shi H, Kolev NG, Ersfeld K, Tschudi C, Ullu E. Distinct and overlapping roles for two Dicer-like proteins in the RNA interference pathways of the ancient eukaryote Trypanosoma brucei. Proceedings Of The National Academy Of Sciences Of The United States Of America 2009, 106: 17933-17938. PMID: 19815526, PMCID: PMC2764927, DOI: 10.1073/pnas.0907766106.
- A PCR-Based Method for Gene Deletion and Protein Tagging in Trypanosoma bruceiArhin G, Shen S, Ullu E, Tschudi C. A PCR-Based Method for Gene Deletion and Protein Tagging in Trypanosoma brucei. 2004, 270: 277-286. DOI: 10.1385/1-59259-793-9:277.
- Analysis of Gene Function in Trypanosoma brucei Using RNA InterferenceDjikeng A, Shen S, Tschudi C, Ullu E. Analysis of Gene Function in Trypanosoma brucei Using RNA Interference. 2004, 73-83. DOI: 10.1385/1-59259-775-0:073.
- RNA interference in Trypanosoma brucei: cloning of small interfering RNAs provides evidence for retroposon-derived 24-26-nucleotide RNAs.Djikeng A, Shi H, Tschudi C, Ullu E. RNA interference in Trypanosoma brucei: cloning of small interfering RNAs provides evidence for retroposon-derived 24-26-nucleotide RNAs. RNA 2001, 7: 1522-30. PMID: 11720282, PMCID: PMC1370195.
- Unusual diversity in α-amanitin sensitivity of RNA polymerases in trichomonadsVaňáčová Š, Tachezy J, Ullu E, Tschudi C. Unusual diversity in α-amanitin sensitivity of RNA polymerases in trichomonads. Molecular And Biochemical Parasitology 2001, 115: 239-247. PMID: 11420110, DOI: 10.1016/s0166-6851(01)00294-8.
- In vivo epitope tagging of Trypanosoma brucei genes using a one step PCR-based strategyShen S, Arhin G, Ullu E, Tschudi C. In vivo epitope tagging of Trypanosoma brucei genes using a one step PCR-based strategy. Molecular And Biochemical Parasitology 2001, 113: 171-173. PMID: 11254965, DOI: 10.1016/s0166-6851(00)00383-2.
- Characterization of a candidate Trypanosoma brucei U1 small nuclear RNA geneDjikeng A, Ferreira L, D'Angelo M, Dolezal P, Lamb T, Murta S, Triggs V, Ulbert S, Villarino A, Renzi S, Ullu E, Tschudi C. Characterization of a candidate Trypanosoma brucei U1 small nuclear RNA gene. Molecular And Biochemical Parasitology 2001, 113: 109-115. PMID: 11254959, DOI: 10.1016/s0166-6851(00)00384-4.
- Determinants for cap trimethylation of the U2 small nuclear RNA are not conserved between Trypanosoma brucei and higher eukaryotic organismsGünzl A, Bindereif A, Ullu E, Tschudi C. Determinants for cap trimethylation of the U2 small nuclear RNA are not conserved between Trypanosoma brucei and higher eukaryotic organisms. Nucleic Acids Research 2000, 28: 3702-3709. PMID: 11000261, PMCID: PMC110770, DOI: 10.1093/nar/28.19.3702.
- New Turns in Trypanosome RNA MetabolismTschudi C. New Turns in Trypanosome RNA Metabolism. Biochemical Society Transactions 2000, 28: a472-a472. DOI: 10.1042/bst028a472c.
- Cotranscriptional Cap 4 Formation on the Trypanosoma brucei Spliced Leader RNA*Mair G, Ullu E, Tschudi C. Cotranscriptional Cap 4 Formation on the Trypanosoma brucei Spliced Leader RNA*. Journal Of Biological Chemistry 2000, 275: 28994-28999. PMID: 10880518, DOI: 10.1074/jbc.m004193200.
- Genetic interference in Trypanosoma brucei by heritable and inducible double-stranded RNA.Shi H, Djikeng A, Mark T, Wirtz E, Tschudi C, Ullu E. Genetic interference in Trypanosoma brucei by heritable and inducible double-stranded RNA. RNA 2000, 6: 1069-76. PMID: 10917601, PMCID: PMC1369981, DOI: 10.1017/s1355838200000297.
- Import of proteins into the trypanosome nucleus and their distribution at karyokinesis.Marchetti M, Tschudi C, Kwon H, Wolin S, Ullu E. Import of proteins into the trypanosome nucleus and their distribution at karyokinesis. Journal Of Cell Science 2000, 113 ( Pt 5): 899-906. PMID: 10671379, DOI: 10.1242/jcs.113.5.899.
- A new twist in trypanosome RNA metabolism: cis-splicing of pre-mRNA.Mair G, Shi H, Li H, Djikeng A, Aviles H, Bishop J, Falcone F, Gavrilescu C, Montgomery J, Santori M, Stern L, Wang Z, Ullu E, Tschudi C. A new twist in trypanosome RNA metabolism: cis-splicing of pre-mRNA. RNA 2000, 6: 163-9. PMID: 10688355, PMCID: PMC1369902, DOI: 10.1017/s135583820099229x.
- RNA Metabolism in Trypanosomes: Approaches to Unravel pre-mRNA Signals Required for Intron RemovalTschudi C, Ullu E. RNA Metabolism in Trypanosomes: Approaches to Unravel pre-mRNA Signals Required for Intron Removal. 2000, 19-42. DOI: 10.1007/978-1-4757-4622-8_2.
- Double-stranded RNA induces mRNA degradation in Trypanosoma bruceiNgô H, Tschudi C, Gull K, Ullu E. Double-stranded RNA induces mRNA degradation in Trypanosoma brucei. Proceedings Of The National Academy Of Sciences Of The United States Of America 1998, 95: 14687-14692. PMID: 9843950, PMCID: PMC24510, DOI: 10.1073/pnas.95.25.14687.
- Exonic Sequences in the 5′ Untranslated Region of α-Tubulin mRNA Modulate trans Splicing in Trypanosoma bruceiLópez-Estraño C, Tschudi C, Ullu E. Exonic Sequences in the 5′ Untranslated Region of α-Tubulin mRNA Modulate trans Splicing in Trypanosoma brucei. Molecular And Cellular Biology 1998, 18: 4620-4628. PMID: 9671472, PMCID: PMC109048, DOI: 10.1128/mcb.18.8.4620.
- Trypanosome Capping Enzymes Display a Novel Two-Domain StructureSilva E, Ullu E, Kobayashi R, Tschudi C. Trypanosome Capping Enzymes Display a Novel Two-Domain Structure. Molecular And Cellular Biology 1998, 18: 4612-4619. PMID: 9671471, PMCID: PMC109047, DOI: 10.1128/mcb.18.8.4612.
- Physical and transcriptional analysis of the Trypanosoma brucei genome reveals a typical eukaryotic arrangement with close interspersionof RNA polymerase II- and III-transcribed genesMarchetti M, Tschudi C, Silva E, Ullu E. Physical and transcriptional analysis of the Trypanosoma brucei genome reveals a typical eukaryotic arrangement with close interspersionof RNA polymerase II- and III-transcribed genes. Nucleic Acids Research 1998, 26: 3591-3598. PMID: 9671824, PMCID: PMC147737, DOI: 10.1093/nar/26.15.3591.
- Structure of the Trypanosoma brucei U6 snRNA gene promoterNakaar V, Günzl A, Ullu E, Tschudi C. Structure of the Trypanosoma brucei U6 snRNA gene promoter. Molecular And Biochemical Parasitology 1997, 88: 13-23. PMID: 9274863, DOI: 10.1016/s0166-6851(97)00078-9.
- Transcription of the Trypanosoma brucei spliced leader RNA gene is dependent only on the presence of upstream regulatory elementsGünzl A, Ullu E, Dörner M, Fragoso S, Hoffmann K, Milner J, Morita Y, Nguu E, Vanacova S, Wünsch S, Dare A, Kwon H, Tschudi C. Transcription of the Trypanosoma brucei spliced leader RNA gene is dependent only on the presence of upstream regulatory elements. Molecular And Biochemical Parasitology 1997, 85: 67-76. PMID: 9108549, DOI: 10.1016/s0166-6851(96)02816-2.
- Accurate Modification of the Trypanosome Spliced Leader Cap Structure in a Homologous Cell-free System (∗)Ullu E, Tschudi C. Accurate Modification of the Trypanosome Spliced Leader Cap Structure in a Homologous Cell-free System (∗). Journal Of Biological Chemistry 1995, 270: 20365-20369. PMID: 7657609, DOI: 10.1074/jbc.270.35.20365.
- Accurate Transcription of the Trypanosoma brucei U2 Small Nuclear RNA Gene in a Homologous Extract *Günzl A, Tschudi C, Nakaar V, Ullu E. Accurate Transcription of the Trypanosoma brucei U2 Small Nuclear RNA Gene in a Homologous Extract *. Journal Of Biological Chemistry 1995, 270: 17287-17291. PMID: 7542235, DOI: 10.1074/jbc.270.29.17287.
- An unusual liaison: Small nuclear and cytoplasmis RNA genes team up with tRNA genes in trypanosomatid protozoaNakaar V, Tschudi C, Ullu E. An unusual liaison: Small nuclear and cytoplasmis RNA genes team up with tRNA genes in trypanosomatid protozoa. Trends In Parasitology 1995, 11: 225-228. DOI: 10.1016/0169-4758(95)80085-9.
- Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomes.Nakaar V, Dare A, Hong D, Ullu E, Tschudi C. Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomes. Molecular And Cellular Biology 1994, 14: 6736-6742. PMID: 7523857, PMCID: PMC359204, DOI: 10.1128/mcb.14.10.6736.
- Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomesNakaar V, Dare A, Hong D, Ullu E, Tschudi C. Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomes. Molecular And Cellular Biology 1994, 14: 6736-6742. DOI: 10.1128/mcb.14.10.6736-6742.1994.
- Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomesNakaar V, Dare A, Hong D, Ullu E, Tschudi C. Upstream tRNA genes are essential for expression of small nuclear and cytoplasmic RNA genes in trypanosomes. Molecular And Cellular Biology 1994, 14: 6736-6742. DOI: 10.1128/mcb.14.10.6736-6742.1994.
- Trypanosomatid protozoa provide paradigms of eukaryotic biology.Tschudi C, Ullu E. Trypanosomatid protozoa provide paradigms of eukaryotic biology. Infectious Agents And Disease 1994, 3: 181-6. PMID: 7827786.
- RNA polymerase III-mediated transcription of the trypanosome U2 small nuclear RNA gene is controlled by both intragenic and extragenic regulatory elements.Fantoni A, Dare A, Tschudi C. RNA polymerase III-mediated transcription of the trypanosome U2 small nuclear RNA gene is controlled by both intragenic and extragenic regulatory elements. Molecular And Cellular Biology 1994, 14: 2021-2028. PMID: 8114733, PMCID: PMC358562, DOI: 10.1128/mcb.14.3.2021.
- RNA Polymerase III-Mediated Transcription of the Trypanosome U2 Small Nuclear RNA Gene Is Controlled by both Intragenic and Extragenic Regulatory ElementsFantoni A, Dare A, Tschudi C. RNA Polymerase III-Mediated Transcription of the Trypanosome U2 Small Nuclear RNA Gene Is Controlled by both Intragenic and Extragenic Regulatory Elements. Molecular And Cellular Biology 1994, 14: 2021-2028. DOI: 10.1128/mcb.14.3.2021-2028.1994.
- RNA Polymerase III-Mediated Transcription of the Trypanosome U2 Small Nuclear RNA Gene Is Controlled by both Intragenic and Extragenic Regulatory ElementsFantoni A, Dare A, Tschudi C. RNA Polymerase III-Mediated Transcription of the Trypanosome U2 Small Nuclear RNA Gene Is Controlled by both Intragenic and Extragenic Regulatory Elements. Molecular And Cellular Biology 1994, 14: 2021-2028. DOI: 10.1128/mcb.14.3.2021-2028.1994.
- A common pyrimidine-rich motif governs trans-splicing and polyadenylation of tubulin polycistronic pre-mRNA in trypanosomes.Matthews K, Tschudi C, Ullu E. A common pyrimidine-rich motif governs trans-splicing and polyadenylation of tubulin polycistronic pre-mRNA in trypanosomes. Genes & Development 1994, 8: 491-501. PMID: 7907303, DOI: 10.1101/gad.8.4.491.
- 2'-O-methyl RNA oligonucleotides identify two functional elements in the trypanosome spliced leader ribonucleoprotein particleUllu E, Tschudi C. 2'-O-methyl RNA oligonucleotides identify two functional elements in the trypanosome spliced leader ribonucleoprotein particle. Journal Of Biological Chemistry 1993, 268: 13068-13073. PMID: 8514747, DOI: 10.1016/s0021-9258(19)38620-x.
- Temporal order of RNA-processing reactions in trypanosomes: rapid trans splicing precedes polyadenylation of newly synthesized tubulin transcripts.Ullu E, Matthews K, Tschudi C. Temporal order of RNA-processing reactions in trypanosomes: rapid trans splicing precedes polyadenylation of newly synthesized tubulin transcripts. Molecular And Cellular Biology 1993, 13: 720-725. PMID: 8417363, PMCID: PMC358950, DOI: 10.1128/mcb.13.1.720.
- Temporal Order of RNA-Processing Reactions in Trypanosomes: Rapid trans Splicing Precedes Polyadenylation of Newly Synthesized Tubulin TranscriptsUllu E, Matthews K, Tschudi C. Temporal Order of RNA-Processing Reactions in Trypanosomes: Rapid trans Splicing Precedes Polyadenylation of Newly Synthesized Tubulin Transcripts. Molecular And Cellular Biology 1993, 13: 720-725. DOI: 10.1128/mcb.13.1.720-725.1993.
- Temporal Order of RNA-Processing Reactions in Trypanosomes: Rapid trans Splicing Precedes Polyadenylation of Newly Synthesized Tubulin TranscriptsUllu E, Matthews K, Tschudi C. Temporal Order of RNA-Processing Reactions in Trypanosomes: Rapid trans Splicing Precedes Polyadenylation of Newly Synthesized Tubulin Transcripts. Molecular And Cellular Biology 1993, 13: 720-725. DOI: 10.1128/mcb.13.1.720-725.1993.
- Trans splicing in trypanosomes requires methylation of the 5' end of the spliced leader RNA.Ullu E, Tschudi C. Trans splicing in trypanosomes requires methylation of the 5' end of the spliced leader RNA. Proceedings Of The National Academy Of Sciences Of The United States Of America 1991, 88: 10074-10078. PMID: 1719544, PMCID: PMC52870, DOI: 10.1073/pnas.88.22.10074.
- Destruction of U2, U4, or U6 small nuclear RNA blocks Trans splicing in trypanosome cellsTschudi C, Ullu E. Destruction of U2, U4, or U6 small nuclear RNA blocks Trans splicing in trypanosome cells. Cell 1990, 61: 459-466. PMID: 1692263, DOI: 10.1016/0092-8674(90)90527-l.
- Conserved sequences in the U2 snRNA-encoding genes of Kinetoplastida do not include the putative branchpoint recognition regionTschudi C, Williams S, Ullu E. Conserved sequences in the U2 snRNA-encoding genes of Kinetoplastida do not include the putative branchpoint recognition region. Gene 1990, 91: 71-77. PMID: 2401409, DOI: 10.1016/0378-1119(90)90164-m.
- Permeable trypanosome cells as a model system for transceiption and trans-splicingUllu E, Tschudi C. Permeable trypanosome cells as a model system for transceiption and trans-splicing. Nucleic Acids Research 1990, 18: 3319-3326. PMID: 2356121, PMCID: PMC330939, DOI: 10.1093/nar/18.11.3319.
- Polygene transcripts are precursors to calmodulin mRNAs in trypanosomes.Tschudi C, Ullu E. Polygene transcripts are precursors to calmodulin mRNAs in trypanosomes. The EMBO Journal 1988, 7: 455-63. PMID: 3366120, PMCID: PMC454342, DOI: 10.1002/j.1460-2075.1988.tb02833.x.
- The U6 small nuclear RNA from Trypanosoma bruceiTschudi C, Krainer A, Ullu E. The U6 small nuclear RNA from Trypanosoma brucei. Nucleic Acids Research 1988, 16: 11375-11375. PMID: 3060859, PMCID: PMC339025, DOI: 10.1093/nar/16.23.11375.
- The U2 RNA analogue of Trypanosoma brucei gambiense: implications for a splicing mechanism in trypanosomesTschudi C, Richards F, Ullu E. The U2 RNA analogue of Trypanosoma brucei gambiense: implications for a splicing mechanism in trypanosomes. Nucleic Acids Research 1986, 14: 8893-8903. PMID: 3786140, PMCID: PMC311918, DOI: 10.1093/nar/14.22.8893.
- Calmodulin genes in trypanosomes are tandemly repeated and produce multiple mRNAs with a common 5' leader sequence.Tschudi C, Young A, Ruben L, Patton C, Richards F. Calmodulin genes in trypanosomes are tandemly repeated and produce multiple mRNAs with a common 5' leader sequence. Proceedings Of The National Academy Of Sciences Of The United States Of America 1985, 82: 3998-4002. PMID: 3858856, PMCID: PMC397921, DOI: 10.1073/pnas.82.12.3998.
- Alu sequences are processed 7SL RNA genesUllu E, Tschudi C. Alu sequences are processed 7SL RNA genes. Nature 1984, 312: 171-172. PMID: 6209580, DOI: 10.1038/312171a0.
- Reverse transcription of trypanosome variable antigen mRNAs initiated by a specific oligonucleotide primer.Merritt S, Tschudi C, Konigsberg W, Richards F. Reverse transcription of trypanosome variable antigen mRNAs initiated by a specific oligonucleotide primer. Proceedings Of The National Academy Of Sciences Of The United States Of America 1983, 80: 1536-1540. PMID: 6188156, PMCID: PMC393636, DOI: 10.1073/pnas.80.6.1536.