INVESTIGATING THE ROLE OF PI4KA IN ANGIOGENESIS

Abstract

Angiogenesis, the formation of new blood vessels, is a critical cellular process towards establishing a functional circulatory system capable of delivering oxygen and nutrients to tissues. Abnormal angiogenesis regulation leads to defects in a vascular network structure that could contribute to the pathogenesis of diseases such as ischemic vascular disease, diabetes, and cancer. Angiogenesis is a multistep cellular process including sprouting initiation, tubulogenesis, branching, lumen formation and vascular stabilization. PI4KA, a lipid kinase, produces the primary source of the PI4P content of plasma membrane that converts into the signalling lipids PI(4,5)P2 and PI(3,4,5)P3. Both signalling lipids are vital for many cell functions, including cell growth, endocytosis, metabolism, ion channel regulation and cell motility. However, the role of PI4KA in endothelial cell biology and angiogenesis remains unknown. The current study aimed to investigate the role of PI4KA in angiogenesis using the siRNA knockdown approach in combination with relevant phenotypic cell-based assays. We showed that PI4KA knockdown by siRNA inhibits endothelial tubulogenesis as assessed by two in vitro angiogenesis assays. In addition, we found that PI4KA inhibition led to decrease endothelial cell migration and proliferation, which are essential for angiogenesis. Single-cell morphology analysis demonstrated that PI4KA downregulated endothelial cells increased their size and width-to-length ratio. In contrast, the actin content is decreased when PI4KA knockdown cells are grown under high density. Using 39 phospho-kinase antibody array, we found that PI4KA inhibition led to decreased phosphorylation of several kinases involved in angiogenesis, including ERK, EGFR and PDGFR. In conclusion, our findings suggest that PI4KA is required for proper endothelial tube formation. This study opens an avenue for potential therapeutic targeting of PI4KA as an anti-cancer therapy by controlling tumor angiogenesis.

Date of Award	2023
Original language	American English
Awarding Institution	HBKU College of Health & Life Sciences