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[Various molecular mechanisms involved in the pathogenesis of type II diabetes and their potential therapeutic
1Département de médecine interne B, Centre hospitalier universitaire vaudois, Lausanne.
Abstract:
The pancreatic beta cell presents functional abnormalities in the early stages of development of non-insulin dependent diabetes mellitus (NIDDM). The disappearance of the first phase of insulin secretion induced by a glucose load is a early marker of NIDDM. This abnormality could be secondary to the low expression of the pancreatic glucose transporter GLUT2. Together with the glucokinase enzyme, GLUT2 is responsible for proper beta cell sensing of the extracellular glucose levels. In NIDDM, the GLUT2 mRNA levels are low, a fact which suggests a transcriptional defect of the GLUT2 gene. The first phase of glucose-induced insulin secretion by the beta pancreatic cell can be partly restored by the administration of a peptide discovered by a molecular approach, the glucagon-like peptide 1 (GLP-1). The gene encoding for the glucagon is expressed in a cell-specific manner in the A cells of the pancreatic islet and the L cells of the intestinal tract. The maturation process of the propeptide encoded by the glucagon gene is different in the two cells: the glucagon is the main hormone produced by the A cells whereas the glucagon-like peptide 1 (GLP-1) is the major peptide synthesized by the L cells of the intestine. GLP-1 is an incretin hormone and is at present the most potent insulinotropic peptide. The first results of the administration of GLP-1 to normal volunteers and diabetic patients are promising and may be a new therapeutic approach to treating diabetic patients.
Insights
Non-insulin dependent diabetes mellitus (NIDDM) involves pancreatic beta cell dysfunction, marked by reduced glucose transporter GLUT2 expression. Glucagon-like peptide 1 (GLP-1) shows promise in restoring insulin secretion, offering a potential NIDDM therapeutic strategy.
Area of Science:
- Endocrinology
- Molecular Biology
- Diabetes Research
Background:
- Pancreatic beta cell dysfunction, specifically reduced glucose transporter 2 (GLUT2) expression, is an early indicator of non-insulin dependent diabetes mellitus (NIDDM).
- Impaired GLUT2 function affects glucose sensing and insulin secretion in beta cells, potentially stemming from transcriptional defects.
- The first phase of glucose-induced insulin secretion is a critical marker affected in early NIDDM.
Purpose of the Study:
- To investigate the role of GLUT2 expression in NIDDM pathogenesis.
- To explore the potential of glucagon-like peptide 1 (GLP-1) in restoring beta cell function and insulin secretion.
Main Methods:
- Analysis of GLUT2 mRNA levels in pancreatic beta cells from NIDDM models.
- Administration of GLP-1 to assess its effect on glucose-induced insulin secretion.
Main Results:
- Low GLUT2 mRNA levels were observed in NIDDM, suggesting a transcriptional defect.
- Administration of GLP-1 partially restored the first phase of glucose-induced insulin secretion.
Conclusions:
- Reduced GLUT2 expression is implicated in early NIDDM pathophysiology.
- GLP-1 demonstrates therapeutic potential for NIDDM by improving insulin secretion, representing a promising new treatment avenue.