Investigating hnRNPA2B1 as a Modulator of TERT Splicing in the Vascular Endothelium

Background: Cardiovascular disease and cancer, together account for 50% of the deaths in the U.S. Chemotherapy (CTx) regimens containing doxorubicin (Dox), lead to cardiotoxic consequences for cancer patients, with major adverse cardiovascular events being 6-18% more likely. Dox is known to suppress the activity of telomerase reverse transcriptase (TERT) the catalytic subunit of telomerase. Our group has shown that TERT is critical in preserving microcirculation homeostasis and protecting against mitochondrial damage. Alternative splicing of TERT generates a catalytically inactive variant, β-del TERT, that is linked to the progression of coronary heart disease and resistance to chemotherapy. Preliminary data suggests that Dox negatively shifts the splicing towards β-del TERT and that silencing β-del TERT protects against Dox-induced endothelial dysfunction. hnRNPA2B1, an RNA binding protein with roles in pre-mRNA splicing and gene regulation, has been identified as a promoter of the FL-TERT isoform in iPSCs. The goal of this study is to investigate the role of hnRNPA2B1 as a modulator of TERT splicing in the endothelium and ultimately identify the regulators of TERT splicing in the microvasculature. Hypothesis: We hypothesize that hnRNPA2B1 binds to TERT mRNA and acts as a FL-TERT splice switch in the vascular endothelium. Inhibiting hnRNPA2B1 could lead to endothelial dysfunction. Methods: RBPmap was used to predict binding sites for RNA-binding proteins (RBPs) in the TERT RNA sequence. RT-qPCR was used to measure the change in mRNA expression of select RBPs after treatment of primary endothelial cells (HUVECs) with Dox (100 nM, 24h). Arterioles isolated from surgical discard adipose from healthy patients were incubated for 48h with si-hnRNPA2B1 and used for video-microscopy. Endothelial dependent flow-mediated-dilation (FMD) and endothelial independent dilatation (papaverine) were evaluated. Results: hnRNPA2B1 was identified by RBPmap as binding within the TERT RNA sequence and was downregulated after treatment with Dox. FMD was markedly reduced in si-hnRNPA2B1 vessels (23±10, n=2) vs. control vessels (83±8, n=2). Smooth muscle dependent dilation to papaverine was not impaired in the si-hnRNPA2B1 or control vessels. Conclusion: Preliminary results in our lab show that Dox decreases the expression of FL-TERT. hnRNPA2B1 is downregulated after treatment with Dox. Vessels treated with si-hnRNPA2B1 had markedly reduced FMD when compared with control vessels. Characterizing splicing regulators of TERT in the vasculature will potentially provide alternative therapeutic strategies for cancer patients receiving CTx. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.