title: High glucose-induced cytoplasmic translocation of Dnmt3a contributes to CTGF hypo-methylation in mesangial cells.
abstract: Connective tissue growth factor (CTGF) plays an essential role in the pathogenesis of diabetic nephropathy and we have previously identified that high glucose induced the expression of CTGF by decreasing DNA methylation. The aim of the present study was to investigate the underlying mechanisms of the high glucose-induced CTGF hypo-methylation. Human glomerular mesangial cells (hMSCs) were treated with low glucose (5 mM), mannitol (30 mM) or high glucose (30 mM) respectively. Immunofluorescence staining, real-time quantitative PCR and western blotting were performed to determine the subcellular distribution and expression of CTGF and Dnmt3a. ChIP-PCR assay was applied to investigate the capability of Dnmt3a to bind the CpG island of CTGF. Our results showed that high glucose induced both mRNA and protein expressions of CTGF, and led to increased cytoplasmic translocation of Dnmt3a in cultured hMSCs. The nuclear Dnmt3a protein was significantly reduced after high glucose treatment, although the expression of total Dnmt3a protein was not altered. We further discovered that ERK/MAPK signalling contributed to the high glucose-induced cytoplasmic translocation of Dnmt3a. Consequently, less Dnmt3a protein was bound to the CpG island of CTGF promoter, which induced an increase in CTGF expression by epigenetic regulation in the presence of high glucose. In conclusion, high glucose induces cytoplasmic translocation of Dnmt3a, possibly through activating ERK/MAPK signalling pathway, which contributes to the decreased binding of Dnmt3a on CTGF promoter and the subsequent CTGF hypo-methylation in diabetic nephropathy.
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China.
authors.forename: Aimei
authors.initials: A
authors.lastname: Li
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Nephrology, The Third Xiangya Hospital, Central South University, Changsha 410013, Hunan, China yibin_yb@163.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Yi
mesh_terms: D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000235:genetics* / Q000378:metabolism; D018899:CpG Islands; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D044127:Epigenesis, Genetic; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D008353:Mannitol / Q000494:pharmacology; D050527:Mesangial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: C526317:CCN2 protein, human; C000717967:DNMT3A protein, human; D055513:Connective Tissue Growth Factor; D008353:Mannitol; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D005947:Glucose
keywords: CTGF; Dnmt; high glucose; human glomerular mesangial cell; methylation