Post-transcriptional Regulation of Gene Expression by Rod1

Abstract

The process of gene expression consists of several interconnected steps which ensure proper protein production from a specific gene. However, an extensive amount of transcripts containing premature termination codons (PTCs) are generated in cells, mainly through alternative splicing events. If translated, these transcripts could generate truncated proteins which are potentially deleterious to the cell. Nonsense-Mediated mRNA Decay (NMD) is a mechanism of mRNA degradation which eliminates these faulty transcripts, thus protecting the cell against abnormal protein functions. Chapter 2 of this thesis describes experiments aimed at finding new protein factors involved in NMD. Rod1 is found to be required for NMD in HEK293 cells and to regulate several potential NMD targets. In chapter 3, the role of Rod1 in erythroid cells, where it is highly expressed, is addressed. Rod1 is found to regulate Alternative Splicing (AS) together with Ptbp1 and Raver1. AS is a mechanism that regulates inclusion or skipping of thousands of exons and is therefore an important generator of protein diversity in metazoans. AS is regulated by a large number of factors, including core spliceosomal proteins and proteins that activate or repress specific exons. AS is regulated in a tissue-specific manner, and some AS factors, like Rod1, are expressed in restricted tissues as well. Chapter 3 also contains experiments aimed at finding RNAs associated with Rod1 and Ptbp1 in differentiated MEL (murine erythroleukemia) cells. In chapter 4, results from chapters 2 and 3 are discussed, as well as its implications. Future directions are also presented.