MiR-497∼195 cluster regulates angiogenesis during coupling with osteogenesis by maintaining endothelial Notch and HIF-1α activity

A specific bone vessel subtype, strongly positive for CD31 and endomucin (CD31(hi)Emcn(hi)), is identified as coupling angiogenesis and osteogenesis. The abundance of type CD31(hi)Emcn(hi) vessels decrease during ageing. Here we show that expression of the miR-497 similar to 195 cluster is high in CD31(hi)Emcn(hi) endothelium but gradually decreases during ageing. Mice with depletion of miR-497 similar to 195 in endothelial cells show fewer CD31(hi)Emcn(hi) vessels and lower bone mass. Conversely, transgenic overexpression of miR-497 similar to 195 in murine endothelium alleviates age-related reduction of type CD31(hi)Emcn(hi) vessels and bone loss. miR-497 similar to 195 cluster maintains the endothelial Notch activity and HIF-1a stability via targeting F-box and WD-40 domain protein (Fbxw7) and Prolyl 4-hydroxylase possessing a transmembrane domain (P4HTM) respectively. Notably, endothelialium-specific activation of miR-195 by intravenous injection of aptamer-agomiR-195 stimulates CD31(hi)Emcn(hi) vessel and bone formation in aged mice. Together, our study indicates that miR-497 similar to 195 regulates angiogenesis coupled with osteogenesis and may represent a potential therapeutic target for age-related osteoporosis.