Histone Arginine Methylation-Mediated Epigenetic Regulation of Discoidin Domain Receptor 2 Controls the Senescence of Human Bone Marrow Mesenchymal Stem Cells.

Zhenyu Xu,Yue Wang,Fang Shen,Charlie Xiang,Yue Yu,Wenming Wu

doi:10.1155/2019/7670316

Abstract

The application of human bone marrow mesenchymal stem cells (hBM-MSCs) in cell-based clinical therapies is hindered by the limited number of cells remaining after the initial isolation process and by cellular senescence following in vitro expansion. Understanding the process of in vitro senescence in hBM-MSCs would enable the development of strategies to maintain their vitality after cell culture. Herein, we compared the gene expression profiles of human embryonic stem cells and human BM-MSCs from donors of different ages. We first found that the expression of discoidin domain receptor 2 (DDR2) in adult donor-derived hBM-MSCs was lower than it was in the young donor-derived hBM-MSCs. Moreover, in vitro cultured late-passage hBM-MSCs showed significant downregulation of DDR2 compared to their early-passage counterparts, and siRNA inhibition of DDR2 expression recapitulated features of senescence in early-passage hBM-MSCs. Further, we found through knockdown and overexpression approaches that coactivator-associated arginine methyltransferase 1 (CARM1) regulated the expression level of DDR2 and the senescence of hBM-MSCs. Finally, chromatin immunoprecipitation analysis confirmed direct binding of CARM1 to the DDR2 promoter region with a high level of H3R17 methylation in early-passage hBM-MSCs, and inhibition of CARM1-mediated histone arginine methylation decreased DDR2 expression and led to cellular senescence. Taken together, our findings suggest that DDR2 plays a major role in regulating the in vitro senescence of hBM-MSCs and that CARM1-mediated histone H3 methylation might be the upstream regulatory mechanism controlling this function of DDR2.

Highlights

Mesenchymal stem cells (MSCs) are multipotent adult stem cells with self-renewal capacity, multilineage differentiation potential, and immunomodulatory properties [1]
We discovered that coactivator-associated arginine methyltransferase 1 (CARM1) upregulates both total and phosphorylated discoidin domain receptor 2 (DDR2) expression in hBM-MSCs via increased methylation of histone H3 in the DDR2 promoter region and can contribute to the rejuvenation of latepassage hBM-MSCs
We first identified DDR2 as a gene differentially expressed among hBM-MSCs, Y-hBM-MSCs, and human embryonic stem cells (hESCs) using microarray and bioinformatics technologies

Summary

Introduction

Mesenchymal stem cells (MSCs) are multipotent adult stem cells with self-renewal capacity, multilineage differentiation potential, and immunomodulatory properties [1]. Young donor-derived hBM-MSCs have different proliferative abilities and senescence characteristics during the in vitro passaging process compared to adult hBM-MSCs [14,15,16]. The in vitro senescence potential of young donor-derived hBMMSCs lies somewhere between those of human embryonic stem cells (hESCs) and hBM-MSCs. Discoidin domain receptor 2 (DDR2) has recently been shown to play an essential role in skeletal development and the differentiation of marrow progenitor cells to osteoblasts while suppressing marrow adipogenesis [17]. DDR2 was first identified as differentially expressed among hBM-MSCs with different senescence characteristics. Previous studies have shown that hMSCs acquire specific epigenetic changes during ex vivo expansion [18, 19] and that those DNA methylations are associated with the promoter regions of genes involved in cell differentiation [20]. We discovered that CARM1 upregulates both total and phosphorylated DDR2 expression in hBM-MSCs via increased methylation of histone H3 in the DDR2 promoter region and can contribute to the rejuvenation of latepassage hBM-MSCs

Materials and Methods

Results

Discussion

Findings

Conflicts of Interest