Gerald Alter (Committee Member), Scott Baird (Committee Member), Paula Bubulya (Advisor), David Cool (Committee Member), Mark Mamrack (Committee Chair)
Doctor of Philosophy (PhD)
Transcription of protein-coding genes is coordinated with pre-mRNA processing as well as mRNP assembly and nuclear export in mammalian cells. In this dissertation, I examined the functions of two homologous non-classical serine-arginine-rich (SR) proteins, Btf (BCLAF1) and TRAP150 in these steps of gene regulation. Since Btf and TRAP150 share 39% sequence identity and 66% sequence similarity, I also examined whether Btf and TRAP150 have overlapping or distinct functions in pre-mRNA processing. Using two different reporter loci, I showed in-situ recruitment of Btf and TRAP150 at reporter transcription sites, and I identified both Btf and TRAP150 being associated with a core EJC component Magoh. However, my data indicate that these proteins have different roles in maintaining the cellular mRNA distribution in HeLa cells. My data demonstrate that Btf depletion, but not compensatory TRAP150 up-regulation, leads to a global change in cellular distribution of mRNA. Thus, my data reveal that modulating the expression of a single protein, Btf, has global impact upon the nuclear/cytoplasmic distribution of mRNAs. In addition, HeLa cells depleted of Btf and TRAP150 showed chromosomal misalignment at metaphase. This suggests that both proteins regulate the mitotic progression of HeLa cells. My exon microarray data show cell cycle and mitosis as the major processes being affected in Btf or TRAP150 depleted HeLa cells. In all, my results suggest that both Btf and TRAP150 have distinct but important roles in maintaining mRNA distribution in cells, but they are both important for mitotic progression. Future studies will determine if absence of Btf or TRAP150 leads to altered processing of endogenous transcripts encoding cell cycle regulator proteins, thereby affecting the cellular distribution of these mRNAs and providing a mechanism for mitotic regulation by Btf and TRAP150.
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