Abstract P507: Comprehensive Characterization Of Poly(a)-clickseq Data Sets Reveal Novel Polyadenylation Signals In Human Right Ventricle Failure

Abstract

Background: Many human genes hold more than 1 poly(A) site, and polyadenylation gives rise to transcripts with different 3′ untranslated regions (3’UTR) lengths, and this process known as alternative polyadenylation (APA). It plays a significant role in many cellular processes and dysregulation of APA leads to many human diseases. However, the functional consequences of APA events in the right ventricle (RV) failure in humans remain unexplored. Objective: To understand whether a global APA event is presented in the progression of RV failure by using the novel algorithm PolyA miner in the RV of healthy donors and patients with RV failure. Methods and Results: RV tissue samples were obtained from failing human hearts at the time of cardiac transplantation at the Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital. The RV tissues were immediately frozen in liquid nitrogen and stored at –80°C until use. Normal tissue samples were obtained from donor hearts that were not used for transplantation and were collected and stored in the same manner. We characterized the APA profiles of RV failing patients and compared them to healthy RV specimens by using Poly(A)-ClickSeq (PAC-seq) RNA sequencing and the PolyA-miner algorithm. We determined shortening versus lengthening of 3′UTRs based on the PolyA index, a metric unit that determines the length of 3′UTR. Based on these scores, we identified 435 transcripts with a significant shift in cleavage site usage. Further, we discovered 3'UTR shortening and lengthening of many genes in failing RV compared to healthy RV specimens. By examining polyadenylation events in these hearts, we identified disease-specific APA signatures in many genes. In addition, differential APA events in RV failure regulate many pathways important for the progression of the RV failure. Conclusions: Our study highlights the important roles for APA in human RV failure, including reforming multiple pathways and regulating specific gene expression, representing the complex interplay between APA and other biological processes in the RV failure.