Poster abstracts
Poster number 28 submitted by Anthony Caputo
Investigating the mechanisms of cell-type-specific alternative polyadenylation
Anthony Caputo (Case Western Genetics and Genome Sciences), Ashleigh Schaffer (Case Western Genetics and Genome Sciences), Jingyi Liu (Case Western Genetics and Genome Sciences), Eric Wagner (Dept. of Biochemistry and Biophysics, Univ. of Rochester Sch. of Med. and Dentistry)
Abstract:
A necessary step for the functional maturity of nearly all eukaryotic pre-mRNAs is 3’ cleavage and polyadenylation. Interestingly, over 70% of human transcripts have more than one site at which polyadenylation can occur, a phenomenon known as alternative polyadenylation (APA). APA produces mRNA isoforms that differ in stability, subcellular localization, translational efficiency, or even the encoded protein sequence. Poly(a) sites (PASs) are selected and processed by dynamic interactions of proteins known as the cleavage and polyadenylation (CPA) complex. Mutations in these proteins cause neurological disorders and are associated with poor cancer prognosis. Because PASs are present throughout gene bodies, aberrant APA caused by mutations of the CPA complex is thought to produce functionally diverse outcomes at the cellular level. Indeed, specialized RNA sequencing technologies have revealed dramatic alterations in PAS usage and significant impacts on cell viability when CPA complex proteins are perturbed.
Interestingly, PAS patterns across identical gene sets vary widely by cell type. Exploring the link between cell-type specific APA and CPA complex activity, we have identified distinct, cell-type-specific responses to genetic knockout of the canonical CPA constituent, CLP1. CLP1 is dispensable for human embryonic stem cell (hESC) viability but is essential for the viability of hESC-derived motor neurons. A potential explanation for these observations is that the composition of the CPA complex varies between cell types. To test this hypothesis, we will first identify differences in CPA complex composition between three isogenic cell types: hESCs, motor neurons, and skeletal muscle. Next, we will determine whether APA differences observed between cell types are due to variation in CPA complex composition. To supplement these findings, we will also explore the connection between selective vulnerability of neurons to CLP1 depletion and the composition of the CPA complex across different cell types.
Keywords: Alternative polyadenylation, stem cells, differentiation