Microrna-217 modulates human skin fibroblast senescence by directly targeting DNA methyltransferase 1

Abstract

// Ben Wang 1, 4, * , Rui Du 1, * , Xiao Xiao 2 , Zhi-Li Deng 1 , Dan Jian 1 , Hong-Fu Xie 1 and Ji Li 1, 3, 4 1 Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China 2 Department of Dermatology, Hunan Provincial People’s Hospital, Changsha, China 3 Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province, Changsha, China 4 Center for Molecular Medicine, Xiangya Hospital, Central South University, Changsha, China * These authors have contributed equally to this work Correspondence to: Hong-Fu Xie, email: xiehongfu1964@aliyun.com Ji Li, email: liji_xy@csu.edu.cn Keywords: DNMT1, miR-217, senescence, skin aging Received: January 10, 2017 Accepted: February 28, 2017 Published: March 23, 2017 ABSTRACT DNA methyltransferase 1 (DNMT1) is a major epigenetic regulator associated with many biological processes. However, the roles and mechanisms of DNMT1 in skin aging are incompletely understood. Here we explored the role of DNMT1 in human skin fibroblasts senescence and its related regulatory mechanisms. DNMT1 expression decreased in passage-aged fibroblasts and DNMT1 silencing in young fibroblasts induced the senescence phenotype. MiR-217 is predicted to target DNMT1 mRNA and miR-217 expression increased in passage-aged fibroblasts. MiR-217 directly targeted the 3′-untranslated region (3′-UTR) of DNMT1 in HEK 293T cells and inhibited DNMT1 expression in fibroblasts. MiR-217 overexpression induced a senescence phenotype in young fibroblasts, and miR-217 downregulation in old HSFs partially reversed the senescence phenotype. However, these effects could be significantly rescued by regulating DNMT1 expression in fibroblasts. After regulating miR-217 levels, we analyzed changes in the promoter methylation levels of 24 senescent-associated genes, finding that 6 genes were significantly altered, and verified p16 and phosphorylated retinoblastoma (pRb) protein levels. Finally, an inverse correlation between DNMT1 and miR-217 expression was observed in skin tissues and different-aged fibroblasts. Together, these findings revealed that miR-217 promotes fibroblasts senescence by suppressing DNMT1-mediated methylation of p16 and pRb by targeting the DNMT1 3’-UTR.