The Regulation Of Endothelial Function Through Hmgcr/Mevalonate Pathway Mediated Yap Activity

Background: Cardiovascular diseases (CVD) are the leading cause of death in the United States. Statins, a class of hydroxy-methylglutaryl-coenzyme A reductase (HMGCR) inhibitors, have been proven to be effectively prevent and treat CVD by improving vascular functions independent of their cholesterol-lowering effect. However, the molecular mechanisms by which statins improve cardiovascular functions remain elusive. In this study, we used human induced pluripotent stem cells-derived endothelial cells (hiPSC-ECs) to explore the protective role of statins in the vascular system. Methods and Results: hiPSCs were generated from 3 healthy individuals and differentiated into endothelial cells using two different iPSC clones and two batches (4 biological replicates for each individual). hiPSC-ECs of each individual were treated with simvastatin or a vehicle control. The RNA-sequencing analysis was performed on 12 control and 12 statin-treated hiPSC-ECs. A total number of 2,580 differentially expressed genes (DEGs) were found in simvastatin-treated hiPSC-ECs. Gene enrichment analysis revealed that statin-upregulated DEGs were highly enriched in angiogenesis and anti-inflammation pathways. Interestingly, statin-downregulated DEGs were significantly enriched in epigenetic regulation and nucleosome assembly pathways, suggesting an epigenetic regulatory role of stains in vascular gene expression. To test this hypothesis, we further performed the Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analysis on vehicle or simvastatin treated hiPSC-ECs. Transcription factor (TF) binding motif analyses of ATAC-seq peaks using HOMER revealed that YAP/TEAD binding was the most significantly downregulated TF after statin treatment. Furthermore, we observed that statin can improve endothelial functions (e.g., angiogenesis and nitric oxide production) after the YAP activity was inhibited. The ChIP-seq analysis showed that statin downregulated the expression levels of genes associated with the endothelial-to-mesenchymal transition (EndoMT) by attenuating the binding capacity of YAP. As such, simvastatin effectively rescued diabetic vascular dysfunction mainly through inhibiting EndoMT. Conclusion: We found that statins can improve endothelial functions through attenuating the chromatin accessibility of EndoMT-related genes, a process tightly regulated by the activity of YAP. These findings will provide novel insights into the protective mechanisms of statins in the cardiovascular system beyond their cholesterol-lowering effects.