Stress-Induced MicroRNA-708 Impairs β-Cell Function and Growth

Area of Science:

• Endocrinology
• Molecular Biology
• Cell Biology

Background:

• Pancreatic beta-cell function is sensitive to glucose and stress.
• MicroRNAs (miRNAs) are crucial regulators of gene expression.
• Identifying glucose-modulated miRNAs in islets is important for understanding beta-cell regulation.

Purpose of the Study:

• To identify miRNAs regulated by glucose in mouse pancreatic islets.
• To investigate the role of glucose-induced miRNAs in beta-cell function and stress response.

Main Methods:

• Mouse pancreatic islet culture under varying glucose concentrations.
• Induction of endoplasmic reticulum (ER) stress using thapsigargin.
• miRNA and gene expression analysis (e.g., Nnat).
• Overexpression and inhibition of miR-708 and NNAT.
• Assessment of glucose-stimulated insulin secretion (GSIS), beta-cell proliferation, and apoptosis.

Main Results:

• miR-708 was identified as the most upregulated miRNA in low glucose and ER stress conditions.
• Low glucose induction of miR-708 was dependent on ER stress.
• Neuronatin (Nnat) was identified as a direct target of miR-708.
• miR-708 overexpression impaired GSIS and beta-cell proliferation while inducing apoptosis.
• miR-708 inhibition or NNAT overexpression rescued GSIS.

Conclusions:

• A novel mechanism of glucose regulation involving stress-induced miR-708 in pancreatic islets was uncovered.
• miR-708 acts as a repressor of beta-cell function and growth under stress conditions.
• Targeting miR-708 may offer therapeutic potential for beta-cell dysfunction.