Date of Graduation
School of Medicine
RNA splicing is an important component of gene expression that contributes immensely to the biological complexity of higher eukaryotes. The regulation of splicing by external stimuli, such as nutrients, is poorly understood, however. The experiments contained herein sought to understand how the activity of splicing factors called SR proteins is regulated by insulin and polyunsaturated fatty acids in the liver using the model mRNA glucose-6-phosphate dehydrogenase (G6PD). RNA affinity and chromatin immunoprecipitation experiments demonstrated that refeeding of rodents stimulates the binding of SR proteins to the splicing regulatory element of G6PD; and this was especially relevant for SRp20. In vitro and in vivo splicing assays demonstrated that SRp20 is relevant for the splicing of G6PD. Additionally, analysis of SR proteins in hepatocytes determined that insulin stimulates the amount of phosphorylated SRp20 in the nucleus by 13-fold while the polyunsaturated fatty acid, arachidonic acid, attenuated this by 80%. A similar pattern was observed for SRp30 a/b and SRp40. These data suggest that the increase in binding activity of SRp20 during refeeding is stimulated by the increase in phosphorylation via insulin. These findings demonstrate that the activity of SR proteins changes in response to nutritional status and can ultimately impact the splicing of target mRNAs.
Walsh, Callee McConnell, "The effect of nutrients upon the activity of SR proteins" (2009). Graduate Theses, Dissertations, and Problem Reports. 4548.