Connexin-36 contributes to control function of insulin-producing cells

Area of Science:

• Endocrinology
• Cell Biology
• Molecular Biology

Background:

• Connexin-36 (Cx36) is a gap junction protein found in insulin-producing beta cells.
• Cx36 plays a role in regulating beta-cell function and insulin secretion.

Purpose of the Study:

• To investigate the role of Cx36 in beta-cell function using viral gene transfer.
• To determine how altering Cx36 levels affects insulin release and content in INS-1E cells and rat pancreatic islets.

Main Methods:

• Viral gene transfer (sense and antisense vectors) to manipulate Cx36 expression in INS-1E cells and rat pancreatic islets.
• Reverse transcriptase-PCR to detect connexin transcripts.
• Western blot, immunofluorescence, and freeze-fracture analysis to assess Cx36 levels.
• Measurement of insulin content and glucose-induced insulin release.

Main Results:

• Viral vectors successfully altered Cx36 expression in INS-1E cells and rat islets, with sense vectors increasing and antisense vectors decreasing Cx36 levels.
• Both increased and decreased Cx36 levels led to reduced glucose-induced insulin release and insulin content in INS-1E cells.
• Basal insulin secretion remained unaffected by changes in Cx36 levels.
• Similar effects on insulin content and basal secretion were observed in rat pancreatic islets.

Conclusions:

• Cx36 plays a critical role in regulating insulin content in pancreatic beta cells.
• Significant alterations in Cx36 levels can impair glucose-induced insulin release, particularly in INS-1E cells.
• Cx36's function in beta cells is sensitive to its expression levels, suggesting a narrow optimal range for normal function.