Dataset Information

MiR-204 is associated with an endocrine phenotype in human pancreatic islets but does not regulate the insulin mRNA through MAFA.

ABSTRACT: miR-204 has been proposed to modulate insulin expression in human pancreatic islets by regulating the expression of the MAFA transcript, and in turn insulin transcription. We investigated miR-204 expression in pancreatic endocrine tumors (PET), a panel of human tissues, tissues derived from pancreatic islet purification, and in induced pluripotent stem cells (iPSCs) differentiated towards a pancreatic endocrine phenotype by quantitative real time RT-PCR or droplet digital PCR (ddPCR). In addition, we evaluated the effect of miR-204 up- or down-regulation in purified human islets and in the EndoC-?H1 cell line, as an experimental model of human pancreatic ? cells. Our results confirm that miR-204 was enriched in insulin producing PET, in ? cells within healthy pancreatic islets, and highly expressed in EndoC-?H1 cells. Moreover, in iPSCs miR-204 increased stepwise upon stimulated differentiation to insulin producing cells. However, up- or down-regulation of miR-204 in human islets and in EndoC-?H1 cells resulted in modest and not significant changes of the MAFA and INS mRNAs measured by ddPCR or c-peptide release. Our data confirm the association of miR-204 with a ? cell endocrine phenotype in human pancreatic islets, but do not support its direct role in regulating the levels of insulin mRNA through MAFA.

SUBMITTER: Marzinotto I

PROVIDER: S-EPMC5656581 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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miR-204 is associated with an endocrine phenotype in human pancreatic islets but does not regulate the insulin mRNA through MAFA.

Marzinotto Ilaria I Pellegrini Silvia S Brigatti Cristina C Nano Rita R Melzi Raffaella R Mercalli Alessia A Liberati Daniela D Sordi Valeria V Ferrari Maurizio M Falconi Massimo M Doglioni Claudio C Ravassard Philippe P Piemonti Lorenzo L Lampasona Vito V

Scientific reports 20171025 1

miR-204 has been proposed to modulate insulin expression in human pancreatic islets by regulating the expression of the MAFA transcript, and in turn insulin transcription. We investigated miR-204 expression in pancreatic endocrine tumors (PET), a panel of human tissues, tissues derived from pancreatic islet purification, and in induced pluripotent stem cells (iPSCs) differentiated towards a pancreatic endocrine phenotype by quantitative real time RT-PCR or droplet digital PCR (ddPCR). In additio ...[more]

PMID: 29070792

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Project description:RNA-binding proteins and microRNAs are potent post-transcriptional regulators of gene expression. Human transformer 2β (Tra2β) is a serine/arginine-rich-like protein splicing factor and is now implicated to have wide-ranging roles in gene expression as an RNA-binding protein. RNA immunoprecipitation (RIP) with an anti-Tra2β antibody and microarray analysis identified a subset of Tra2β-associated mRNAs in HCT116 human colon cancer cells, many of which encoded cell death-related proteins including Bcl-2 (B-cell CLL/lymphoma 2). Tra2β knockdown in HCT116 cells decreased Bcl-2 expression and induced apoptosis. Tra2β knockdown accelerated the decay of BCL2α mRNA that encodes Bcl-2 and full-length 3' UTR, while it did not affect the stability of BCL2β mRNA having a short, alternatively spliced 3' UTR different from BCL2α 3' UTR. RIP assays with anti-Tra2β and anti-Argonaute 2 antibodies, respectively, showed that Tra2β bound to BCL2α 3' UTR, and that Tra2β knockdown facilitated association of miR-204 with BCL2α 3' UTR. The consensus sequence (GAA) for Tra2β-binding lies within the miR-204-binding site of BCL2 3' UTR. Mutation of the consensus sequence canceled the binding of Tra2β to BCL2 3' UTR without disrupting miR-204-binding to BCL2 3' UTR. Transfection of an anti-miR-204 or introduction of three-point mutations into the miR-204-binding site increased BCL2 mRNA and Bcl-2 protein levels. Inversely, transfection of precursor miR-204 reduced their levels. Experiments with Tra2β-silenced or overexpressed cells revealed that Tra2β antagonized the effects of miR-204 and upregulated Bcl-2 expression. Furthermore, TRA2β mRNA expression was significantly upregulated in 22 colon cancer tissues compared with paired normal tissues and positively correlated with BCL2 mRNA expression. Tra2β knockdown in human lung adenocarcinoma cells (A549) increased their sensitivity to anticancer drugs. Taken together, our findings suggest that Tra2β regulates apoptosis by modulating Bcl-2 expression through its competition with miR-204. This novel function may have a crucial role in tumor growth.

Project description:Genetic and epigenetic mechanisms may interact and together affect biological processes and disease development. However, most previous studies have investigated genetic and epigenetic mechanisms independently, and studies examining their interactions throughout the human genome are lacking. To identify genetic loci that interact with the epigenome, we performed the first genome-wide DNA methylation quantitative trait locus (mQTL) analysis in human pancreatic islets. We related 574,553 single nucleotide polymorphisms (SNPs) with genome-wide DNA methylation data of 468,787 CpG sites targeting 99% of RefSeq genes in islets from 89 donors. We identified 67,438 SNP-CpG pairs in cis, corresponding to 36,783 SNPs (6.4% of tested SNPs) and 11,735 CpG sites (2.5% of tested CpGs), and 2,562 significant SNP-CpG pairs in trans, corresponding to 1,465 SNPs (0.3% of tested SNPs) and 383 CpG sites (0.08% of tested CpGs), showing significant associations after correction for multiple testing. These include reported diabetes loci, e.g. ADCY5, KCNJ11, HLA-DQA1, INS, PDX1 and GRB10. CpGs of significant cis-mQTLs were overrepresented in the gene body and outside of CpG islands. Follow-up analyses further identified mQTLs associated with gene expression and insulin secretion in human islets. Causal inference test (CIT) identified SNP-CpG pairs where DNA methylation in human islets is the potential mediator of the genetic association with gene expression or insulin secretion. Functional analyses further demonstrated that identified candidate genes (GPX7, GSTT1 and SNX19) directly affect key biological processes such as proliferation and apoptosis in pancreatic β-cells. Finally, we found direct correlations between DNA methylation of 22,773 (4.9%) CpGs with mRNA expression of 4,876 genes, where 90% of the correlations were negative when CpGs were located in the region surrounding transcription start site. Our study demonstrates for the first time how genome-wide genetic and epigenetic variation interacts to influence gene expression, islet function and potential diabetes risk in humans.

Dataset Information

MiR-204 is associated with an endocrine phenotype in human pancreatic islets but does not regulate the insulin mRNA through MAFA.

Publications

miR-204 is associated with an endocrine phenotype in human pancreatic islets but does not regulate the insulin mRNA through MAFA.

Similar Datasets

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