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Updated: Jun 13, 2025
High-resolution Respirometry to Measure Mitochondrial Function of Intact Beta Cells in the Presence of Natural Compounds
Published on: January 23, 2018
miR-146a-5p mediates inflammation-induced β cell mitochondrial dysfunction and apoptosis
Preethi Krishnan1, Renato Chaves Souto Branco2, Staci A Weaver3
1Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA; Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA; Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Abstract:
We previously showed that miR-146a-5p is upregulated in pancreatic islets treated with proinflammatory cytokines. Others have reported that miR-146a-5p overexpression is associated with β cell apoptosis and impaired insulin secretion. However, the molecular mechanisms mediating these effects remain elusive. To investigate the role of miR-146a-5p in β cell function, we developed stable MIN6 cell lines to either overexpress or inhibit the expression of miR-146a-5p. Monoclonal cell populations were treated with proinflammatory cytokines (interleukin-1β, interferonγ, and tumor necrosis factor α) to model type 1 diabetes in vitro. We found that overexpression of miR-146a-5p increased cell death under conditions of inflammatory stress and led to mitochondrial membrane depolarization, whereas inhibition of miR-146a-5p reversed these effects. Additionally, inhibition of miR-146a-5p increased insulin secretion, mitochondrial DNA copy number, respiration rate, and ATP production. Further, RNA-seq data showed enrichment of pathways related to insulin secretion, apoptosis, and mitochondrial function when the expression levels of miR-146a-5p were altered. Finally, a temporal increase in miR-146a-5p expression levels and a decrease in mitochondria function markers were observed in islets derived from nonobese diabetic mice. Collectively, these data suggest that miR-146a-5p may promote β cell dysfunction and death during inflammatory stress by suppressing mitochondrial function.
Insights
MicroRNA-146a-5p promotes pancreatic beta cell death and dysfunction by impairing mitochondrial function during inflammatory stress, a key factor in type 1 diabetes.
Area of Science:
- Endocrinology
- Molecular Biology
- Immunology
Background:
- MicroRNA-146a-5p (miR-146a-5p) is upregulated in pancreatic islets during inflammation.
- Overexpression of miR-146a-5p is linked to beta cell apoptosis and reduced insulin secretion.
- The precise molecular mechanisms remain unclear.
Purpose of the Study:
- To investigate the role of miR-146a-5p in pancreatic beta cell function and survival under inflammatory conditions.
- To elucidate the molecular pathways affected by miR-146a-5p in beta cells.
Main Methods:
- Developed stable MIN6 cell lines with miR-146a-5p overexpression or inhibition.
- Treated cells with proinflammatory cytokines (IL-1β, IFNγ, TNFα) to mimic type 1 diabetes in vitro.
- Analyzed cell death, mitochondrial function (membrane potential, DNA copy number, respiration, ATP), insulin secretion, and gene expression (RNA-seq).
- Examined miR-146a-5p levels and mitochondrial markers in islets from nonobese diabetic mice.
Main Results:
- miR-146a-5p overexpression increased beta cell death and mitochondrial depolarization under inflammatory stress.
- Inhibition of miR-146a-5p improved insulin secretion, mitochondrial DNA copy number, respiration, and ATP production.
- RNA-seq revealed altered pathways in insulin secretion, apoptosis, and mitochondrial function.
- Islets from nonobese diabetic mice showed increased miR-146a-5p and decreased mitochondrial function markers.
Conclusions:
- miR-146a-5p promotes pancreatic beta cell dysfunction and apoptosis during inflammatory stress.
- Suppression of mitochondrial function is a key mechanism by which miR-146a-5p exerts its effects.
- miR-146a-5p is a potential therapeutic target for type 1 diabetes.
