Abstract 196: Poly (rC)-binding Protein-1 (Pcbp1) Is Essential For Vascular Development

Abstract

The formation of the heart and the connecting vessels is essential for the function of the vertebrates, as vascular deficiency during embryonic development often leads to embryonic lethality. The vasculature forms as a branching network of endothelial cells (ECs) that becomes specified and assembles into vessels. the formation of new blood vessels from the existing vasculatures, or angiogenesis, is fundamental during development and pathological processes. Critical factors in governing vascular development are often required for organismal survival. Hence, gaining a complete understanding of the developmental process requires unique approaches to study tissue or cell-type specific functions. Poly(rC)-Binding Protein 1 (Pcbp1) is an evolutionarily conserved RNA binding protein that is not well understood in vivo . Pcbp1 is abundantly expressed in the angiogenic endothelium. However, little is known about the function and mechanism of Pcbp1 in the context of angiogenesis and vascular development. Germline deletion of Pcbp1 results in peri-implantation lethality, which limits its potential for studying the role of Pcbp1 in development. To address this deficit, we had generated an inducible endothelial deletion of Pcbp1 with Cdh5-Cre ERT2 (Pcbp1-ieKO) to study its role in vascular development. When the EC deletion was induced at embryonic day (E) 9.5, Pcbp1-ieKO exhibited inadequate angiogenesis in the hindbrain at E12.5. Furthermore, when the EC deletion was induced at postnatal day (P) 1, Pcbp1-ieKO displayed reduced coronary and brain vascular density, as well as blunted retinal angiogenesis at P6. Single-cell RNA sequencing of Pcbp1-ieKO retina at P6 revealed a significant reduction in EC population and expression of genes critical for angiogenesis downstream of VEGF signaling and NOTCH activation. Notably, knockdown of Pcbp1 in human colony-forming endothelial cells (hCFEC) blunts the VEGFR2 and NOTCH activation upon VEGFA treatment. Our preliminary results suggest Pcbp1 is a critical regulator for angiogenesis, future studies will be directed at identifying the mechanism of Pcbp1 in regulating VEGF and NOTCH signaling, ultimately to provide insights for novel therapeutic strategies to control angiogenesis in cardiovascular disease.