Poster #076, University of California, San Diego
The Effect of LARP1 Phospho-mutants on mRNA Translation and Gene Expression
Mentors: Farnaz Mansouri-Noori B.Sc, Ph.D, Karen Pu BCompSc; Gene W. Yeo Ph.D., MBA
RNA-binding proteins (RPBs) are integral to several cellular processes, including splicing, mRNA translation, and decay, which together regulate gene expression. The process of mRNA translation involves the production of all proteins through a highly regulated network of RBPs. Among these, the La-related protein 1 (LARP1), which belongs to a conserved family of RBPs with important functions in RNA metabolism, is involved with regulating the translation and stability of 5’Terminal Oligo Pyrimidinene (5’TOP) mRNAs. These mRNAs code for ribosomal proteins, the machinery that makes mRNA translation possible, and have a special sequence motif that recruits LARP1. The overexpression of LARP1 has been found in different types of cancer and is suggested to contribute to tumor growth and survival. Post-translational modifications (PTMs) such as phosphorylation are proposed to modulate LARP1 function, especially in disease contexts, yet this remains poorly understood. Using site-directed mutagenesis and STAMP (Surveying Targets by APOBEC-Mediated Profiling) technology in human cells (HEK293T), we will investigate how specific phosphorylation marks influence the RNA-binding capacity of LARP1. We hypothesize that preventing phosphorylation at defined regions of LARP1 would alter its binding to previously known mRNA targets and, therefore, the regulation the protein exerts on gene expression during mRNA translation. By characterizing the functional importance of seven phosphorylation sites, this work will reveal how distinct phospho-mutants of LARP1 could modulate its interaction with certain mRNA targets. Ultimately, this strategy will help determine whether preventing or inducing phosphorylation at specific sites of LARP1 could be beneficial in a therapeutic context, particularly in cancer and tumor progression.