Slight up‐regulation of Kir2.1 channel promotes endothelial progenitor cells to transdifferentiate into a pericyte phenotype by Akt/mTOR/Snail pathway

Xiaodong Cui,Xiaoxia Li,Naijun Dong,Robert Chunhua Zhao,Yanting He,Jie Yu

doi:10.1111/jcmm.16944

Abstract

It was shown that endothelial progenitor cells (EPCs) have bidirectional differentiation potential and thus perform different biological functions. The purpose of this study was to investigate the effects of slight up‐regulation of the Kir2.1 channel on EPC transdifferentiation and the potential mechanism on cell function and transformed cell type. First, we found that the slight up‐regulation of Kir2.1 expression promoted the expression of the stem cell stemness factors ZFX and NS and inhibited the expression of senescence‐associated β‐galactosidase. Further studies showed the slightly increased expression of Kir2.1 could also improve the expression of pericyte molecular markers NG2, PDGFRβ and Desmin. Moreover, adenovirus‐mediated Kir2.1 overexpression had an enhanced contractile response to norepinephrine of EPCs. These results suggest that the up‐regulated expression of the Kir2.1 channel promotes EPC transdifferentiation into a pericyte phenotype. Furthermore, the mechanism of EPC transdifferentiation to mesenchymal cells (pericytes) was found to be closely related to the channel functional activity of Kir2.1 and revealed that this channel could promote EPC EndoMT by activating the Akt/mTOR/Snail signalling pathway. Overall, this study suggested that in the early stage of inflammatory response, regulating the Kir2.1 channel expression affects the biological function of EPCs, thereby determining the maturation and stability of neovascularization.

Highlights

Bone marrow–derived endothelial progenitor cells (EPCs) can be mobilized, homed to the site of local vascular injury and differentiated into vascular endothelial cells in vascular repair
The results showed that MK2206, RAD001 and Snail siRNA could attenuate the up-regulated expression of NG2, PDGFRβ, NS and ZFX promoted by Kir2.1 (Figure 5B), suggesting that Akt/mTOR/ Snail plays a central role in the endothelial- mesenchymal transition (EndoMT) of Kir2.1-induced EPCs
It was surprising to find that the slightly up-regulated expression of Kir2.1, which was achieved by taking advantage of transfection with adenovirus at different medium containing viral particles at different titres (MOIs) values, could promote the maintenance of stemness and reduce the senescence of EPCs

Summary

| INTRODUCTION

Bone marrow–derived endothelial progenitor cells (EPCs) can be mobilized, homed to the site of local vascular injury and differentiated into vascular endothelial cells in vascular repair. The recent literature has shown that under certain physiological or pathophysiological conditions, EPCs can undergo an endothelial- mesenchymal transition (EndoMT); their function will presumably be altered.[5,6] the underlying mechanism of this transformation process has not yet been clarified. According to their functional characteristics and amino acid sequences, channels in the inward rectifier potassium channels (Kir) family can be divided into the following seven subfamilies into four functional groups: Kir1.x, Kir4.x, Kir5.x and Kir7.x (K+ transport channels); Kir2.x (classic K+ channels); Kir3.x (G-protein-gated K+ channels); and Kir6.x (ATP-sensitive K+ channels).[7] The channels in this family conduct more inward current under a negative voltage/ balanced potential than under a negative current/outward voltage. Transfection with siRNA or scramble siRNA was carried out using Lipofectamine 3000 according to the manufacturer's recommended instructions

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION