RNA-binding proteins as regulators of transcription and axial patterning during Xenopus embryogenesis

RNA-binding proteins as regulators of transcription and axial patterning during Xenopus embryogenesisby Caitlin Suzanne DeJongDoctor of Philosophy in Molecular and Cell BiologyUniversity of California, BerkeleyProfessor Richard M. Harland, ChairThe over-arching goal of this thesis is to expand our knowledge of the mechanisms by which one cell, a fertilized egg, develops into an organism composed of multiple cell types, each with different functions and behaviors. RNA-binding proteins have been identified as potent regulators of development and embryogenesis. The studies presented in this thesis illustrate the pleiotropic effects of RNA-binding proteins in Xenopus development and will focus specifically on two RNA-binding proteins that are maternally deposited and zygotically transcribed: TAF15 and DGCR8.TATA-binding protein-associated factor 15 (TAF15) belongs to the FET family of atypical RNA-binding proteins, which also includes Fused in sarcoma (Fus) and Ewing’s sarcoma (EWS). FET proteins were originally discovered as components of fusion oncogenes and are most noted for their implication in various cancers and neuromuscular degenerative diseases. However, little is known of the endogenous function of FET proteins. The diverse biological activities of the FET family proteins can be likened to a biological Swiss army knife; as these proteins contain domains for transcriptional activation, RNA-binding, DNA-binding, and function in both RNA Polymerase II-mediated transcription and pre-mRNA splicing. An exciting possibility is that the FET proteins may function to connect transcription and splicing. By employing the bioinformatics approach of RNA-sequencing, I generated a list of significant genes that are differentially expressed between uninjected and taf15 depleted embryos. From this analysis I found that TAF15 regulates target genes at both the transcriptional and post-transcriptional level. The studies that focus on the role of TAF15 in Xenopus development are