Identification of Dragon, a Novel Member of the Sma/mab Tgf Beta Signaling Pathway in Caenorhabditis Elegans

The C. elegans postembryonic lineage, the M lineage, gives rise to mesodermal cell types: body wall muscles, sex muscles and coelomocytes. Past research in the Liu lab has shown that SMA-9, the C. elegans homolog of Drosophila Schnurri, is required for establishing dorsoventral asymmetry in the M lineage, and that it does so by antagonizing the Sma/Mab TGF-β signaling pathway. To identify additional factors involved in regulating dorsoventral asymmetry, our lab has screened for mutations that suppress the M lineage defects of sma-9 mutants. Using snip-SNP mapping, I have mapped one of these suppressor mutations, jj4, and identified it to be a mutation in Y71G12B.16, the hitherto uncharacterized C. elegans homolog of DRAGON. DRAGON belongs to the well-conserved RGM family of proteins, members of which have been shown to act as coreceptors for BMP signaling in mouse and Xenopus. Furthermore, I have conducted epistasis studies to place dragon in the context of the Sma/Mab TGF-β signaling pathway, as well as designed constructs that would help shed light on the temporal and spatial expression patterns of dragon. Additionally, I have designed and made fusion protein expression constructs, which can be used to generate antibodies against DRAGON. India. His early interest in science was fueled by his parents, and this manifested itself in his winning several scientific competitions and quizzes while in middle and high school. He then went on to complete his undergraduate Bachelor of Technology as a graduate student. As a teaching assistant at Cornell University, Debjeet discovered a new-found love in teaching. His passion for teaching, together with his wish to work for the improvement of the developing world shaped the next phase of his career, as he is headed to the Maxwell School of Public Affairs at Syracuse University for his Master of Public Administration degree. Outside academics, he is interested in writing stories, dramatics, quizzing, current affairs, playing the slide guitar and drums, playing word games, English literature, skiing, cooking and traveling. iii 15 To my parents, who have always stood by me… iv 16 ACKNOWLEDGEMENTS