Mir-342-5p Downstream to Notch Enhances Arterialization of Endothelial Cells in Response to Shear Stress by Repressing MYC

During vascular development, endothelial cells (ECs) undergo arterialization in response to genetic programs and shear stress-triggered mechanotransduction, forming a stable vascu-lature. Although the Notch receptor is known to sense shear stress and promote EC arterialization, its downstream mecha-nisms remain unclear. In this study, the Notch downstream miR-342-5p was found to respond to shear stress and promote EC arterialization. Shear stress upregulated miR-342-5p in a Notch-dependent manner in human umbilical vein endothelial cells (HUVECs). miR-342-5p overexpression upregulated the shear stress-associated transcriptomic signature. Moreover, miR-342-5p upregulated arterial markers and promoted EC ar-terialization in a Matrigel plug assay and retinal angiogenesis model. In contrast, miR-342-5p knockdown downregulated arterial markers, compromised retinal arterialization, and partially abrogated shear stress and Notch activation-induced arterial marker upregulation. Mechanistically, miR-342-5p overexpression suppressed MYC to repress EC proliferation and promote arterialization, achieved by promoting MYC pro-tein degradation by targeting the EYA3. Consistently, EYA3 overexpression rescued miR-342-5p-mediated MYC downre-gulation and EC arterialization. In vivo, miR-342-5p expres-sion was notably decreased in the ligated artery in a hindlimb ischemia model, and an intramuscular injection of miR-342-5p promoted EC arterialization and improved perfusion. In summary, miR-342-5p, a mechano-miR, mediates the effects of shear stress-activated Notch on EC arterialization and is a potential therapeutic target for ischemic diseases.