title: Demethylation of the MafB promoter in a compromised β-cell model.
abstract: Recent studies suggest that dedifferentiation of pancreatic β-cells is involved in compromised β-cell function in diabetes mellitus. We have previously shown that the promoter activity of MafB, which is expressed in α-cells of adult islets and immature β-cells in embryonic pancreas but not in mature β-cells in mice, is increased in compromised β-cells of diabetic model mice. Here, we investigated a rat β-cell line of INS1 cells with late-passage numbers, which showed extremely low expression of MafA and insulin, as an in vitro model of compromised β-cells. In these INS1 cells, the mRNA expression and the promoter activity of MafB were upregulated compared with the early-passage ('conventional') INS1 cells. Analysis of the MafB promoter in these late-passage INS1 cells revealed that specific CpG sites in the MafB promoter were partially demethylated. The reporter assay revealed that the unmethylated promoter activity of the 373 bp region containing these CpG sites was higher than the in vitro methylated promoter activity. These results suggest that the chronic culture of the rat β-cell line resulted in partial DNA demethylation of the MafB promoter, which may have a role in MafB promoter activation and possible dedifferentiation in our compromised β-cell model.
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan wnishimura@jichi.ac.jp ynoda@jichi.ac.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nishimura
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ishibashi
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Eto
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Funahashi
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Haruhide
authors.initials: H
authors.lastname: Udagawa
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Harukata
authors.initials: H
authors.lastname: Miki
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Souichi
authors.initials: S
authors.lastname: Oe
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan wnishimura@jichi.ac.jp ynoda@jichi.ac.jp.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Noda
authors.affiliation: Department of Metabolic DisordersDiabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, JapanDivision of AnatomyBio-imaging and Neuro-cell Science, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007328:Insulin / Q000235:genetics; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051258:MafB Transcription Factor / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015854:Up-Regulation / Q000235:genetics
chemical_list: D007328:Insulin; D051258:MafB Transcription Factor; C490405:Mafb protein, rat; D015513:Oncogene Proteins; D012333:RNA, Messenger
keywords: MafB; dedifferentiation; demethylation; diabetes mellitus; β-cells