Abstract 2074: De Novo Nucleotide Synthesis Is Necessary For DNA Damage And Repair In Atheroprone Endothelial Cells

Abstract

Aims: Endothelial cell (EC) metabolism is tightly regulated by hemodynamic changes to protect them from atherogenic injury induced by disturbed flow (d-flow) and other atherogenic risk factors. Therefore, characterizing the role of flow-induced metabolic reprogramming is important to develop new treatments for atherosclerosis and similar diseases. Currently, the effect of proatherogenic d-flow on EC nucleotide metabolism, including de novo purine and pyrimidine synthesis, remains under explored. ATIC and CAD are critical enzymes for de novo purine synthesis and pyrimidine synthesis, respectively. We investigated in the role of ATIC and CAD-mediated de novo nucleotide metabolism in atheroprone ECs. Methods and Results: (i) scRNA-Seq analysis results showed that DNA damage response was increased in ECs exposed to d-flow, this was accompanied by increased ATIC-mediated de novo purine synthesis and CAD-mediated de novo pyrimidine synthesis; (ii) Knockdown of ATIC or CAD with siRNA aggravated EC DNA damage, apoptosis and EC permeability induced by d-flow or other atherogenic factors; (iii) Supplement of nucleobases can rescue ATIC KD-mediated DNA damage and apoptosis in ECs; (iv) MYC, predicted high stringency binding with ATIC promoter, was highly expressed in d-flow induced ECs and MYC knockdown reduced the increased ATIC expression in d-flow induced ECs; (v) The atherosclerotic lesion size was markedly increased in EC-specific Atic deficient mice in atherosclerosis. Conclusion: ATIC and CAD-mediated de novo nucleotide synthesis in ECs supply nucleotides to repair DNA damage and preserve EC barrier integrity in vulnerable atheroprone regions and ultimately protect against the development and progression of atherosclerosis.