Deciphering the Molecular Basis of Trophoblast Stem Cell Differentiation and Function
The work described in this thesis profiled the transcriptome of undifferentiated (TSCs) and 4-days differentiated (TGCs) cells through RNA-seq and identified ~7,800 differentially expressed genes which include regulators of the cell cycle, apoptosis, cytoskeleton, cell mobility, embryo implantation, metabolism and various signaling pathways. We revealed that several mitotic proteins, including Aurora A kinase, were downregulated in TGCs and that the activity of Aurora A kinase is required for the maintenance of TSCs. We also identified hitherto undiscovered, cell-type-specific alternative splicing events in 31 genes and expression of 19 novel exons in 12 genes in TSCs and TGCs. Similarly, we discovered that the expression of Cyclin-dependent Kinase 1 (Cdk1) was downregulated in fused BeWo cells and its inhibition through small-molecule inhibitor induced fusion in these cells. The role of Caspase3 downregulation in conferring resistance to genotoxic stress-induced apoptosis in developmentally programmed polyploid cells was also investigated. Finally, we discovered that the polyploid nuclei in fused BeWo cells result from nuclear fusion following the fusion of the cells. Overall, results described in this dissertation uncover several potential regulators of TSC differentiation and TGC function, thereby providing a valuable resource for developmental and molecular biologists interested in the study of stem cell differentiation and embryonic development. Moreover, these results will help in understanding the role and regulation of apoptosis in differentiated TGCs.