PAX6 maintains β cell identity by repressing genes of alternative islet cell types

Area of Science:

• Endocrinology
• Molecular Biology
• Diabetes Research

Background:

• Type 2 diabetes is characterized by impaired pancreatic beta cell function.
• The precise molecular mechanisms driving beta cell dysfunction in diabetes are not fully understood.

Purpose of the Study:

• To investigate the role of the transcription factor PAX6 in maintaining adult beta cell identity and function.
• To elucidate the mechanisms by which PAX6 regulates beta cell gene expression and identity.

Main Methods:

• Analysis of PAX6 expression in diabetic mouse models and insulin receptor antagonist-treated mice.
• Conditional deletion of Pax6 in adult mouse beta cells.
• Lineage tracing, transcriptome, and chromatin analyses.
• shRNA-mediated gene suppression in human beta cells.

Main Results:

• PAX6 expression is downregulated in beta cells under diabetic conditions and metabolic stress.
• Loss of PAX6 in adult beta cells leads to severe hyperglycemia, ketosis, beta cell dysfunction, and alpha cell expansion.
• PAX6 directly activates beta cell-specific genes and represses alternative islet cell genes (ghrelin, glucagon, somatostatin).
• PAX6 exhibits a similar regulatory function in human beta cells.

Conclusions:

• PAX6 is essential for maintaining mature beta cell function and identity.
• Reduced PAX6 expression in metabolically stressed beta cells may be a contributing factor to beta cell failure and alpha cell dysfunction in type 2 diabetes.