Project description:Vascular remodeling is the process of structural alteration and cell rearrangement of blood vessels in response to injury and is the cause of many of the world's most afflicted cardiovascular conditions, including pulmonary arterial hypertension(PAH). Many studies have focused on the effects of vascular endothelial cells and smooth muscle cells(SMCs) during vascular remodeling, but pericytes, an indispensable cell population residing largely in capillaries, are ignored in this maladaptive process. Here we report that hypoxia-inducible factor 2α(HIF2α) expression is increased in human PAH patient lung tissues and HIF2α overexpressed pericytes result in greater contractility and an impaired endothelial-pericyte interaction. Using single-cell RNAseq and hypoxia-induced pulmonary hypertension(PH) models, we show HIF2α as a major molecular regulator for pericytes’ transformation into SMC-like cells. HIF2α overexpression in pericyte-selective mice exacerbate PH and right ventricular hypertrophy. Temporal cellular lineage tracing shows that HIF2α overexpressing reporter NG2+ cells (pericyte-selective) relocate from capillaries to arterioles and co-express SMA. This novel insight into the potential role of NG2+ pericytes in pulmonary vascular remodeling via HIF2α signaling suggests a potential drug target for PH.
Project description:Using a combination of single-cell RNAseq methods and murine pulmonary hypertension models, we show HIF2α overexpressing pericytes’ transformation into SMC-like cells, confirming HIF2α as a major molecular regulator in hypoxia-induced pulmonary hypertension (PH) and vascular remodeling. We demonstrate that HIF2α overexpression in pericyte-dominant transgenic mice exacerbates PH and right ventricular hypertrophy (RVH), whereas disruption of HIF2α expression attenuates the development of PH.
Project description:Circadian disruption enhances cancer risk, and many tumors exhibit disordered circadian gene expression. We show rhythmic gene expression is unexpectedly robust in clear cell renal cell carcinoma (ccRCC). Furthermore, the clock gene BMAL1 is higher in ccRCC than in healthy kidneys, unlike in other tumor types. BMAL1 is closely related to ARNT and we show that BMAL1-HIF2α regulates a subset of HIF2α target genes in ccRCC cells. Depletion of BMAL1 reprograms HIF2α chromatin association and target gene expression and reduces ccRCC growth in culture and in xenografts. Analysis of pre-existing data reveals higher BMAL1 in patient-derived xenografts that are sensitive to growth suppression by HIF2α antagonists. We show that increasing BMAL1 sensitizes ccRCC-derived A498 cells to growth inhibition by PT2399. Together, these findings indicate that an alternate HIF2α heterodimer containing the circadian partner BMAL1 contributes to HIF2α activity, growth, and sensitivity to HIF2α antagonist drugs in ccRCC cells.