[Knockdown of RUNX3 inhibits hypoxia-induced endothelial-to-mesenchymal transition of human cardiac microvascular endothelial cells]

Abstract

Objective To investigate the effects of Runt-related transcription factor 3 (RUNX3) knockdown on hypoxia-induced endothelial-to-mesenchymal transition (EndoMT) of human cardiac microvascular endothelial cells (HCMECs), and elucidate the underlying molecular mechanism. Methods HCMECs were cultured in hypoxic conditions and infected with RUNX3-RNAi lentivirus to knock-down the expression of RUNX3. Reverse transcription PCR was performed to detect the mRNA expressions of RUNX3 and EndoMT related genes such as CD31, vascular endothelial cadherin (VE-cadherin), α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1); Western blotting was used to determine the protein expressions of RUNX3, CD31, α-SMA and another molecules involved in EndoMT; and immunofluorescence cytochemistry was applied to observe the colocalization of CD31 and α-SMA. Results Hypoxia induced the transition of HCMECs to mesenchymal cells. Hypoxia up-regulated the expression of TGF-β2, Smad2/3, phosphorylation of Smad2/3 (p-Smad2/3), Notch-1, Hes1, and Hey1; knockdown of RUNX3 down-regulated the levels of Smad2/3, p-Smad2/3, Hes1, and Hey1 to different extents, and raised the levels of TGF-β2 and Notch-1. Conclusion Knockdown of RUNX3 in HCMECs attenuates hypoxia-induced EndoMT via partially inhibiting TGF-β and Notch signaling pathway.