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Stearoyl‐CoA desaturase 1 determines pancreatic β‐cell fate through regulation of DNA methylation pattern
Author(s) -
Dobosz Aneta Maria,
Janikiewicz Justyna,
Borkowska Anna Maria,
Kwiatek Wojciech Maria,
Dobrzyn Agnieszka
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.09301
Subject(s) - pdx1 , dna methylation , lipotoxicity , methylation , biology , pancreatic islets , downregulation and upregulation , proinsulin , gene expression , endocrinology , chemistry , microbiology and biotechnology , insulin , medicine , islet , gene , insulin resistance , biochemistry
Study objective Stearoyl CoA desaturase 1 (SCD1) is a pivotal enzyme involved in saturated fatty acids metabolism that exhibits a protective role against lipotoxicity in pancreatic β‐cells. It has been shown that SCD1 deficiency contributes to impaired insulin secretion, β‐cell failure and development of type 2 diabetes (T2D). In the present study we investigated the involvement of SCD1 in regulation of DNA methylation and expression of transcription factors (TFs) responsible for maintenance of mature β‐cells function and identity. Methods The experiments were carried out ex vivo on pancreatic islets isolated from wild type (WT) and SCD1 knock‐out (SCD1 KO) mice, and in vitro on INS‐1E pancreatic β‐cell line, where lipotoxicity was induced by palmitic acid treatment. Morphological and functional characteristics of islets was evaluated by ELISA assays, immunofluorescence labeling and transmission electron microscopy techniques. DNA methylation and gene expression levels were assessed by bisulfite sequencing and real‐time quantitative PCR analyses, respectively. Results Our data demonstrated that pancreatic islets of SCD1 KO mice are characterized by different microarchitecture, secretory granules content and functional abnormalities manifested by diminished insulin secretion and greater proinsulin secretion in comparison to WT islets. On both ex vivo and in vitro models we observed significantly reduced expression of TFs crucial to maintenance of β‐cell identity such as Pdx1 , MafA , Nkx6.1 and Neurod1 . Interestingly, transcriptional repression of Pdx1 and MafA was related to excessive methylation of promoter regions of those TFs. In addition, we showed that downregulation of SCD1 activity/gene expression affects global DNA methylation pattern and changes methyl groups distribution within chromosomes in pancreatic β‐cells. DNA hypomethylation which occurred in SCD1‐deficient β‐cells was followed by decreased expression of DNA methyltransferase 1 (Dnmt1). We indicated that activation of AMP‐activated protein kinase (AMPK) axis influences post‐translational regulation of Dnmt1, thereby mediating the effect of SCD1 inhibition on global DNA methylation profile in β‐cells. Conclusions Together, our findings suggest that SCD1 is a gatekeeper that preserves epigenetic inheritance of DNA methylation pattern in β‐cells. Thus, SCD1 protects β‐cells from lipid‐derived loss of identity in methylation‐dependent manner through regulation of expression of TFs responsible for maintenance of β‐cell identity. Our results provide additional mechanistic insights toward understanding the role of SCD1 in T2D pathogenesis. Support or Funding Information This work was supported by grants from the National Science Center, Poland, grants no UMO‐2017/27/N/NZ3/01987 (AMD) and UMO‐2015/19/D/NZ4/03705 (JJ), and by The National Centre for Research and Development, grant no STRATEGMED 3/305813/2/NCBR/2017 (AD).