Fang Fang Zhang1, Yu Hong Liu1, Dan Wei Wang1, Ting Sheng Liu1, Yue Yang1, Jia Min Guo1, Yi Pan1, Yan Feng Zhang1, Hong Du2, Ling Li3, Liang Jin4. 1. State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, 24 Tongjiaxiang Avenue, Nanjing, Jiangsu, People's Republic of China. 2. Department of Endocrinology, Nanjing Jinling Hospital, 305 Zhongshan East Road, Nanjing, People's Republic of China. 3. Department of Endocrinology, School of Medicine, Zhongda Hospital, Southeast University, Nanjing, People's Republic of China. 4. State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, 24 Tongjiaxiang Avenue, Nanjing, Jiangsu, People's Republic of China. ljstemcell@cpu.edu.cn.
Abstract
AIMS/HYPOTHESIS: Although obesity is a predisposing factor for pancreatic beta cell dysfunction, the mechanisms underlying its negative effect on insulin-secreting cells is still poorly understood. The aim of this study was to identify islet long non-coding RNAs (lncRNAs) involved in obesity-mediated beta cell dysfunction. METHODS: RNA sequencing was performed to analyse the islets of high-fat diet (HFD)-fed mice and those of normal chow-fed mice (NCD). The function in beta cells of the selected lncRNA 1810019D21Rik (referred to in this paper as ROIT [regulator of insulin transcription]) was assessed after its overexpression or knockdown in MIN6 cells and primary islet cells, as well as in siRNA-treated mice. Then, RNA pull-down, RNA immunoprecipitation, coimmunoprecipitation and bisulphite sequencing were performed to investigate the mechanism of ROIT regulation of islet function. RESULTS: ROIT was dramatically downregulated in the islets of the obese mice, as well as in the sera of obese donors with type 2 diabetes, and was suppressed by HNF1B. Overexpression of ROIT in MIN6 cells and islets led to improved glucose homeostasis and insulin transcription. Investigation of the mechanism involved showed that ROIT bound to DNA methyltransferase 3a and caused its degradation through the ubiquitin proteasome pathway, which blocked the methylation of the Nkx6.1 promoter. CONCLUSIONS/ INTERPRETATION: These findings functionally suggest a novel link between obesity and beta cell dysfunction via ROIT. Elucidating a precise mechanism for the effect of obesity on lncRNA expression will broaden our understanding of the pathophysiological development of diabetes and facilitate the design of better tools for diabetes prevention and treatment. DATA AVAILABILITY: The raw RNA sequencing data are available from the NCBI Gene Expression Omnibus (GEO series accession number GSE139991).
AIMS/HYPOTHESIS: Although obesity is a predisposing factor for pancreatic beta cell dysfunction, the mechanisms underlying its negative effect on insulin-secreting cells is still poorly understood. The aim of this study was to identify islet long non-coding RNAs (lncRNAs) involved in obesity-mediated beta cell dysfunction. METHODS: RNA sequencing was performed to analyse the islets of high-fat diet (HFD)-fed mice and those of normal chow-fed mice (NCD). The function in beta cells of the selected lncRNA 1810019D21Rik (referred to in this paper as ROIT [regulator of insulin transcription]) was assessed after its overexpression or knockdown in MIN6 cells and primary islet cells, as well as in siRNA-treated mice. Then, RNA pull-down, RNA immunoprecipitation, coimmunoprecipitation and bisulphite sequencing were performed to investigate the mechanism of ROIT regulation of islet function. RESULTS: ROIT was dramatically downregulated in the islets of the obesemice, as well as in the sera of obese donors with type 2 diabetes, and was suppressed by HNF1B. Overexpression of ROIT in MIN6 cells and islets led to improved glucose homeostasis and insulin transcription. Investigation of the mechanism involved showed that ROIT bound to DNA methyltransferase 3a and caused its degradation through the ubiquitin proteasome pathway, which blocked the methylation of the Nkx6.1 promoter. CONCLUSIONS/ INTERPRETATION: These findings functionally suggest a novel link between obesity and beta cell dysfunction via ROIT. Elucidating a precise mechanism for the effect of obesity on lncRNA expression will broaden our understanding of the pathophysiological development of diabetes and facilitate the design of better tools for diabetes prevention and treatment. DATA AVAILABILITY: The raw RNA sequencing data are available from the NCBI Gene Expression Omnibus (GEO series accession number GSE139991).
Entities:
Keywords:
DNA methyltransferase; DNMT3A; LncRNA; Nkx6.1; Obesity; ROIT
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