PhD, University of Cincinnati, 2020, Medicine: Molecular and Developmental Biology

The formation of a functional vascular system is required for proper embryonic development in all vertebrates. Being one of the first organ systems to form during embryogenesis, ¬the cardiovascular system, comprising the heart, arteries, veins and capillaries, transports nutrients, oxygen, metabolites, waste, immune cells and hormones throughout the body. Thus, the formation of organ systems during development and subsequent maintenance throughout life is reliant upon a normal functional vascular system. This dissertation focuses on the molecular mechanisms that govern vascular development in zebrafish embryos. We utilize zebrafish embryos due to their rapid development, optical transparency and high amenability to genetic manipulation.

Committee: Saulius Sumanas Ph.D. (Committee Chair); Elisa Boscolo Ph.D. (Committee Member); Brian Gebelein Ph.D. (Committee Member); Joshua Waxman Ph.D. (Committee Member); Katherine Yutzey Ph.D. (Committee Member) Subjects: Cognitive Psychology; Developmental Biology

Doctor of Philosophy, The Ohio State University, 2004, Molecular, Cellular, and Developmental Biology

Ets transcription factors have been implicated in the development, regulation, and survival of numerous hematopoietic derived cells, including B and T-lymphocytes. E26 avian leukemia oncogene-2 (Ets-2) is an Ets family member transcription factor. Strong expression of Ets-2 is observed in developing thymocytes from the DN1 stage and in B-cells from the pro-B stage. A conserved sequence within the Ets-2 pointed domain amino acids 69 to 73 PLLTP is able to interact with the Map kinase ERK. Threonine seventy-two is phosphorylated by ERK1, and permits transactivation by Ets-2. Mutation of this residue from a threonine to an alanine, Ets-2 T72A, abrogates Ras mediated transactivation of Ets-2. Based on this evidence, we hypothesized that Ets-2 was important in T- and B-cell development, activation, and function. To test this hypothesis we analyzed Ets-2 activation in T-cell lines, and created two transgenic mice lines that express Ets-2 T72A in either developing T-cells or B-cells. Transactivation of Ets-2 can be induced by both Ras activation and by phorbol 12-myristate 13-acetate and ionomycin stimulation in the Jurkat T-cell line. In-vitro analysis of Ets-2 activation by ionomycin results in a rapid, but transient Ets-2 band shift as evidenced by western blot analysis of protein extracts from thymocytes. Transgenic mice that over-express Ets-2 T72A in the thymus displayed a dramatic reduction in thymus size associated with hypocellularity. This reduction was associated with a partial developmental block at the double negative 2 and double negative 3 stage of development, a twenty-fold increase in c-Kit+ expression, and a five-fold increase the CD5low population. Further, thymocytes from the transgenic mice have increased apoptosis both in-vitro and in-vivo compared to non-transgenic littermates. Transgenic mice that over-express Ets-2 T72A in B-lymphocytes revealed a loss of the B220Hi population of B-cells in the bone marrow. This population consists of mature B-cell (open full item for complete abstract)

Committee: Natarajan Muthusamy (Advisor) Subjects: Biology, Cell