Comprehensive Search for GPCR Compounds which Can Enhance MafA and/or PDX-1 Expression Levels Using a Small Molecule...

Area of Science:

• Endocrinology
• Molecular Biology
• Pharmacology

Background:

• Chronic hyperglycemia causes beta-cell glucose toxicity, reducing insulin biosynthesis and secretion.
• This toxicity is linked to decreased expression of key insulin gene transcription factors, MafA and PDX-1.
• The molecular mechanisms underlying glucose toxicity and potential therapeutic targets remain under investigation.

Purpose of the Study:

• To identify G protein-coupled receptor (GPCR) compounds that enhance MafA and/or PDX-1 expression.
• To investigate the effects of identified compounds on insulin gene expression in pancreatic beta-cells and islets.
• To evaluate therapeutic potential for type 2 diabetes by targeting beta-cell glucose toxicity.

Main Methods:

• Screening of a small molecule compound library in MIN6 pancreatic beta-cell line.
• Testing identified compounds in islets isolated from non-diabetic C57BL/6J mice and obese type 2 diabetic C57BL/KsJ-db/db mice.
• Quantification of MafA, PDX-1, and insulin expression levels.

Main Results:

• Fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression in MIN6 cells.
• These compounds also enhanced expression in islets from non-diabetic mice.
• Significantly greater enhancement of MafA, PDX-1, or insulin expression was observed in islets from db/db mice, where these factors are reduced due to glucose toxicity.

Conclusions:

• Fulvestrant and dexmedetomidine hydrochloride effectively increase MafA, PDX-1, and insulin expression in various models, including those mimicking type 2 diabetes.
• This study provides the first evidence of molecules that can enhance MafA and/or PDX-1 expression.
• These findings may contribute to the development of novel anti-diabetic medications targeting the molecular mechanisms of beta-cell glucose toxicity.