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Control of insulin gene expression by glucose
S Goodison1, S Kenna, S J Ashcroft
1Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Headington, Oxford, U.K.
The Biochemical Journal
|July 15, 1992
Summary
High glucose levels increase insulin gene expression in beta cells, mediated by the 5' upstream region. This effect is influenced by various metabolites and signaling pathways, highlighting glucose
Area of Science:
- Molecular Endocrinology
- Gene Regulation
- Pancreatic Beta Cell Function
Background:
- Glucose metabolism is crucial for insulin secretion and synthesis in pancreatic beta cells.
- Understanding the transcriptional regulation of the insulin gene is key to metabolic research.
Purpose of the Study:
- To investigate how extracellular glucose concentration affects preproinsulin mRNA levels.
- To identify the role of the 5' upstream region of the insulin gene in mediating glucose-induced transcription.
Main Methods:
- Northern-blot analysis to quantify preproinsulin mRNA levels.
- Bacterial reporter gene assay (chloramphenicol acetyltransferase) to study insulin gene promoter activity.
- Transfection of HIT T15 beta-cell line with reporter gene constructs.
Main Results:
- Increased extracellular glucose significantly elevated preproinsulin mRNA and reporter gene expression.
- Mannoheptulose, a glucose metabolism inhibitor, blocked the glucose effect.
- Specific metabolites (mannose, 4-methyl-2-oxopentanoate) stimulated expression, while others (galactose, arginine) did not.
- The 5' upstream region of the insulin gene was confirmed to mediate glucose-induced transcriptional effects, modulated by calcium and protein kinase C pathways.
Conclusions:
- The 5' upstream region of the insulin gene contains regulatory elements responsive to glucose.
- Glucose-stimulated insulin gene transcription involves complex signaling pathways influenced by cellular metabolism.