title: Promoter hypermethylation of let-7a-3 is relevant to its down-expression in diabetic nephropathy by targeting UHRF1.
abstract: Diabetic nephropathy (DN) is one of the most serious complications of diabetes mellitus (DM). Recent researches show that DNA methylation plays a role in DN. However, the exact mechanism is not fully understood. MicroRNAs (miRNAs) are a group of endogenous non-coding small RNAs that are involved in the regulation of the development of DN. We have previously demonstrated that let-7a was down-expressed in DN by microarray, but the mechanism is unclear. In this study, let-7a-3 was found to be the only gene with the CpG island in the promoter region among the three let-7a members (let-7a-1, let-7a-2 and let-7a-3) by bioinformatic methods. Also, the expression levels of three homologues of let-7a were tested by real-time PCR, and DNA methylation of the let-7a-3 gene in the promoter region was analyzed by quantitative methylation-specific PCR (qMSP) in 60 individuals, with 20 cases in the control (CON), DM and DN groups respectively. Additionally, the target gene of let-7a-UHRF1 was proved by bioinformatic analysis and dual-luciferase reporter assay. Results showed that let-7a-3 was down-regulated in DN patients. Moreover, qMSP data showed that the average methylation ratio of the let-7a-3 promoter in the DN group was significantly higher than that in the CON and DM groups (P<0.05). Data also showed that let-7a negatively regulated the mRNA and protein expressions of methylation-related gene-UHRF1 through UHRF1 3'UTR. And the expressions of UHRF1 and DNMT1 were increased in DN patients. Therefore, we concluded that promoter hypermethylation and down-expression of let-7a-3 may play a role in DN by targeting UHRF1.
authors.affiliation: Department of Bioinformatics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Peng
authors.affiliation: Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Handeng
authors.initials: H
authors.lastname: Liu
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Peng
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: He
authors.initials: H
authors.lastname: Zha
authors.affiliation: Department of Endocrinology, The First Affiliated Hospital, Chongqing Medical University, No. 1, Youyi Road, Chongqing 400010, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Luyu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Pin
authors.initials: P
authors.lastname: Yin
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wen
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China.
authors.forename: Tianhui
authors.initials: T
authors.lastname: Wu
authors.affiliation: Molecular Medicine and Cancer Research Center, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China; Department of Cell Biology and Medical Genetics, Chongqing Medical University, No. 1, Medical College Road, Chongqing 400016, China. Electronic address: zhangzheng92@163.com.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000328:Adult; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D016022:Case-Control Studies; D018899:CpG Islands; D019175:DNA Methylation; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D003928:Diabetic Nephropathies / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D044767:Ubiquitin-Protein Ligases
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D035683:MicroRNAs; C487931:mirnlet7 microRNA, human; C406364:UHRF1 protein, human; D044767:Ubiquitin-Protein Ligases
keywords: Diabetic nephropathy; Methylation; MicroRNA