Involvement of microRNAs in the cytotoxic effects exerted by proinflammatory cytokines on pancreatic beta-cells.
OBJECTIVE
Pancreatic beta-cells exposed to proinflammatory cytokines display alterations in gene expression resulting in defective insulin secretion and apoptosis. MicroRNAs are small noncoding RNAs emerging as key regulators of gene expression. Here, we evaluated the contribution of microRNAs to cytokine-mediated beta-cell cytotoxicity.


METHODS
We used global microarray profiling and real-time PCR analysis to detect changes in microRNA expression in beta-cells exposed to cytokines and in islets of pre-diabetic NOD mice. We assessed the involvement of the microRNAs affected in cytokine-mediated beta-cell failure by modifying their expression in insulin-secreting MIN6 cells.


RESULTS
We found that IL-1beta and TNF-alpha induce the expression of miR-21, miR-34a, and miR-146a both in MIN6 cells and human pancreatic islets. We further show an increase of these microRNAs in islets of NOD mice during development of pre-diabetic insulitis. Blocking miR-21, miR-34a, or miR-146a function using antisense molecules did not restore insulin-promoter activity but prevented the reduction in glucose-induced insulin secretion observed upon IL-1beta exposure. Moreover, anti-miR-34a and anti-miR-146a treatment protected MIN6 cells from cytokine-triggered cell death.


CONCLUSIONS
Our data identify miR-21, miR-34a, and miR-146a as novel players in beta-cell failure elicited in vitro and in vivo by proinflammatory cytokines, notably during the development of peri-insulitis that precedes overt diabetes in NOD mice.
Roggli
Elodie
E
Department of Cell Biology and Morphology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
Britan
Aurore
A
Gattesco
Sonia
S
Lin-Marq
Nathalie
N
Abderrahmani
Amar
A
Meda
Paolo
P
Regazzi
Romano
R
D000818:Animals; D016923:Cell Death; D002460:Cell Line; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D017930:Genes, Reporter; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000503:physiopathology; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000502:physiology*; D008156:Luciferases / Q000235:genetics; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology; D051379:Mice; D016688:Mice, Inbred NOD; D035683:MicroRNAs / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016207:Cytokines; D035683:MicroRNAs; D008156:Luciferases