miR-146a-5p mediates inflammation-induced β cell mitochondrial dysfunction and apoptosis

Area of Science:

• Endocrinology
• Molecular Biology
• Immunology

Background:

• Pro-inflammatory cytokines upregulate miR-146a-5p in pancreatic islets.
• miR-146a-5p overexpression is linked to beta cell apoptosis and impaired insulin secretion.
• The precise molecular mechanisms remain unclear.

Purpose of the Study:

• To investigate the role of miR-146a-5p in beta cell function under inflammatory conditions.
• To elucidate the molecular mechanisms by which miR-146a-5p affects beta cell survival and function.

Main Methods:

• Developed stable MIN6 cell lines with miR-146a-5p overexpression or inhibition.
• Treated cell lines with pro-inflammatory cytokines (IL-1β, IFNγ, TNFα) to model type 1 diabetes in vitro.
• Analyzed cell death, mitochondrial function (membrane potential, DNA copy number, respiration, ATP production), insulin secretion, and gene expression via RNA sequencing.
• Examined miR-146a-5p expression and mitochondrial markers in islets from NOD mice.

Main Results:

• miR-146a-5p overexpression increased beta cell death and mitochondrial depolarization under inflammatory stress.
• Inhibition of miR-146a-5p reversed these detrimental effects, enhancing insulin secretion, mitochondrial DNA copy number, respiration, and ATP production.
• RNA sequencing revealed altered pathways related to insulin secretion, apoptosis, and mitochondrial function.
• NOD mouse islets showed increased miR-146a-5p and decreased mitochondrial function markers over time.

Conclusions:

• miR-146a-5p promotes beta cell dysfunction and apoptosis during inflammatory stress.
• The mechanism involves the suppression of mitochondrial function.
• Targeting miR-146a-5p may offer a therapeutic strategy for type 1 diabetes by preserving beta cell function.