Abstract 12338: Promotion of Arteriolar Differentiation of Vascular Endothelial Cells by PKD-1/CD36 Signaling-Mediated Chromatin Remodeling

Abstract

Vessel narrowing and occlusions reduce blood supply to end tissues, leading to myocardial infarction in the heart or tissue loss in the peripheral vasculature. Effective approaches are needed to establish de novo arteriogenesis to treat these conditions. An essential first step is to understand mechanisms of arteriolar differentiation, in which transcriptional reprogramming of vascular endothelial cells (ECs) may be critical. Our previous studies indicate that protein kinase D (PKD-1) is required for arterial differentiation and plays an essential role in proarteriogenic reprogramming via transcriptional inhibition of antiangiogenic receptor CD36 via histone deacetylase HDAC7. We hypothesize that PKD-1/CD36 signaling initiates an epigenetic reprogramming of ECs for arteriolar differentiation via chromatin remodeling. To test this hypothesis, we isolated primary heart and lung ECs from wild-type control, EC-specific cd36 KO or pkd-1 KO mice. Total RNA was extracted for expression of arteriogenic genes by RT-qPCR. The proteins were collected for Western blotting and ChIP assays. Our results showed that when CD36 was downregulated in primary ECs from hearts and lungs, the expression levels of PKD-1 and arteriogenic genes EphB2 and DLL4 were significantly elevated compared to controls (p < 0.05). Intriguingly, we observed a significant increase in protein expression of neuropilin1. In contrast, in heart ECs from the EC-specific pkd-1 KO mice, arteriogenic gene expressions were downregulated whereas CD36 expression was significantly upregulated. Using the ChIP assay, we measured the interactions between H3K9 on the CD36, DLL4, or EphB2 promoters using ECs from EC-specific cd36 and pkd-1 KO mice. In conclusion, our results indicate that an epigenetic reprogramming regulates arteriolar differentiation at a transcriptional level by chromatin remodeling. PKD-1 signaling may dictate CD36 transcriptional levels, thereby reprogramming ECs for arteriolar differentiation by inducing an arteriogenic gene signature, which may contribute to de novo arteriogenesis under ischemic conditions.