Endothelial cytochrome P450 -derived cholesterol limits angiogenesis [ext631_RNA-seq]

Mechanistically, POR deletion activated the Sterol Regulatory Element Binding Transcription Factor (SREBP2) regulatory pathway, as shown by increased nuclear translocation of cleaved SREBP2 in EC and in en face-stained mouse aortae. Overexpression of nuclear SREBP2 in endothelial cells mimicked the angiogenic phenotype observed upon POR deletion. Conversely, double deletion of POR and SREBP2 normalized angiogenesis to levels of control cells.

RNAseq of POR-deficient EC revealed an upregulation of PI3K-related signaling pathways and genes involved in cholesterol homeostasis, including enhanced expression of pro-angiogenic factors. In line with these findings, knockout of POR increased cellular PIP3 levels, AKT phosphorylation, and activation of downstream targets such as p70 S6 kinase. These findings demonstrate that inhibition of the endothelial POR/CYP51A1 axis impairs endogenous cholesterol synthesis, activates SREBP2, and enhances angiogenesis via PI3K/AKT/mTOR signaling, highlighting a critical and novel link between intracellular cholesterol metabolism and vascular growth.