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Comprehensive Search for GPCR Compounds which Can Enhance MafA and/or PDX-1 Expression Levels Using a Small Molecule
Hideaki Kaneto1, Atsushi Obata1, Masashi Shimoda1
1Department of Diabetes, Endocrinology and Metabolism, Kawasaki Medical School, Japan.
Abstract:
It has been shown that chronic hyperglycemia gradually decreases insulin biosynthesis and secretion which is accompanied by reduced expression of very important insulin gene transcription factors MafA and PDX-1. Such phenomena are well known as β-cell glucose toxicity. It has been shown that the downregulation of MafA and/or PDX-1 expression considerably explains the molecular mechanism for glucose toxicity. However, it remained unknown which molecules can enhance MafA and/or PDX-1 expression levels. In this study, we comprehensively searched for G protein-coupled receptor (GPCR) compounds which can enhance MafA and/or PDX-1 expression levels using a small molecule compound library in pancreatic β-cell line MIN6 cells and islets isolated from nondiabetic C57BL/6 J mice and obese type 2 diabetic C57BL/KsJ-db/db mice. We found that fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in MIN6 cells. We confirmed that fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in islets from nondiabetic mice as well. Furthermore, these reagents more clearly enhanced MafA, PDX-1, or insulin expression levels in islets from obese type 2 diabetic db/db mice in which MafA and PDX-1 expression levels are reduced due to glucose toxicity. In conclusion, fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in MIN6 cells and islets from nondiabetic mice and obese type 2 diabetic db/db mice. To the best of our knowledge, this is the first report showing some molecule which can enhance MafA and/or PDX-1 expression levels. Therefore, although further extensive study is necessary, we think that the information in this study could be, at least in part, useful at some point such as in the development of new antidiabetes medicine based on the molecular mechanism of β-cell glucose toxicity in the future.
Insights
Researchers identified fulvestrant and dexmedetomidine hydrochloride as compounds that can increase MafA and PDX-1 expression. These key insulin gene transcription factors are reduced in beta-cell glucose toxicity, offering potential new diabetes treatments.
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.
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