Mengmeng Wang,Ying Bai,Haitao Chi,Ping Lin,Yu Wu,Jiahui Cui,Yi Wang,Jing Sun,Ming-Fei Lang
Ischemic stroke still remains a therapeutic challenge due to its complex pathogenesis and implications. By screening biomarkers in the peripheral blood of ischemic stroke patients , miR-451 was identified as a differentially expressed miRNA along the disease course of ischemic stroke. To investigate the role of miR-451, middle cerebral artery occlusion (MCAO) was performed as an ischemic stroke model in mice. Intracerebroventricular administration of miR-451 mimic in the MCAO mice significantly decreased infarct size, while miR-451 inhibitor significantly increased infarct size. To understand the molecular mechanism of the protective effect of miR-451, Phd3 (also Egln3) was validated as a new miR-451 target. Either fewer or more Phd3-positive cells were observed in brain sections from mice receiving miR-451 mimic or inhibitor, respectively. In addition, the levels of p53 (a known Phd3 target) were significantly downregulated when the levels of Phd3 were reduced, suggesting its participation in reducing apoptosis after the miR-451 administration. Indeed, reduced apoptosis upon miR-451 mimic administration was detected by TUNEL staining . In conclusion, this study demonstrated a new protective role of miR-451 in cerebral ischemia and identified Phd3 as a novel miR-451 target, linking the mechanism to the involvement of p53 in the regulation of apoptosis during the pathogenesis of ischemic stroke.
Vascular calcification (VC) is a common complication of chronic kidney disease (CKD). VC is a gene-regulated process similar to osteogenic differentiation. There are still no convincing schemes to prevent and reduce the development of VC. It has been reported that hypoxia-inducing factor 1α (HIF-1α) and endothelin-1(ET-1) are related to VC. In this study, we found that the expression of ET-1 and HIF-1α was enhanced after VC, the interaction between HIF-1α and ET-1 was confirmed by CO-IP and luciferase experiments. We found that ET-1 was an upregulated differential gene of calcified vascular smooth muscle cells (VSMCs) through gene sequencing. However, hypoxia-inducing factor 2α (HIF-2α) and HIF-1α have antagonistic effects on each other. HIF-1α is a pro-inflammatory cytokine, and HIF-2α can improve inflammation and fibrosis. Roxadustat, as a selective PHD3 inhibitor, preferentially activates HIF-2α. It is still unclear whether roxadustat improves VC in CKD by regulating the expression of HIF-2α/HIF-1α. Alizarin red staining and western blot as well as immunohistochemical results showed that roxadustat could significantly reduce the degree of vascular and VSMCs calcification in CKD rats. Serum HIF-1α and ET-1 were significantly decreased after roxadustat treatment. In addition, western blot results showed that roxadustat could decrease the expression of HIF-1α and ET-1 in vascular tissues and calcified VSMC, but HIF-2α expression significantly increased. Interestingly, our study confirmed that activation of HIF-1α or inhibition of HIF-2α reversed the ameliorating effect of roxadustat on VC, proving that the effect mediated by roxadustat is HIF-2α/HIF-1α dependent. We have demonstrated for the first time that roxadustat improves VC in CKD rats by regulating HIF-2α/HIF-1α, thus providing a new idea for the application of roxadustat in VC of CKD.
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