All ETDs from UAB

Advisory Committee Chair

Anita Hjelmeland

Advisory Committee Members

William J Placzek

Erin Ahn

Brittany Lasseigne

Louis B Nabors

Eddy Yang

Document Type

Dissertation

Date of Award

2023

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

RNA binding proteins (RBPs) are critical regulators of gene expression as they are responsible for the chaperoning and processing of every nascent RNA transcript. Many studies have investigated mechanisms of specificity of RBP function and have identified factors such as cell-specific expression of RBPs and differential preferences for RNA secondary structure. However, RBPs are often multi-domain proteins that contain repeats of various RNA binding domains (e.g., RNA recognition motif) and little work in the genomic era of transcriptomic interrogation has been done to define the contribution of individual domains to the overall protein function. Polypyrimidine tract binding protein 1 (PTBP1) is an RBP that contains four repeats of the most common RNA binding domain, the RNA recognition motif (RRM). PTBP1 is a particularly important RBP, as it has roles in nearly all aspects of RNA processing from its nascent transcription to its ultimate utilization in downstream biological processes. There has been extensive work characterizing PTBP1’s biological roles, and PTBP1 is even considered the model system for alternative splicing as its role in regulation of exons in many different transcripts has been thoroughly described. However, little work has begun to tackle the overarching biochemical question of how each of PTBP1’s four RRMs contribute to its overall function. Here we have described in detail the structural heterogeneity between the four RRMs of PTBP1, with the global hypothesis that the individual RRMs of PTBP1 have unique and context-specific roles in coordinating the overall function of PTBP1 and can be indeiv pendently regulated by protein-protein interactions. We report that RRM1 impacts transcriptional programs involved in Wnt signaling, nervous system development, regulation of immune function, and cell-cell adhesion through regulation of gene- and exon-level expression of distinct RNA targets. Importantly, we have described a mechanism by which RRM1 can be specifically regulated by the pro-survival protein MCL1. This particularly biologically relevant as loss of function of RRM1 (in this work, by deletion) phenotypically drives a pro-migratory state. In summary, we have demonstrated that RRM1 has an independent contribution to overall PTBP1 function and can be specifically regulated by a protein-protein interaction with the pro-survival protein MCL1.

Share

COinS