The Polycomb-Dependent Epigenome Controls β Cell Dysfunction, Dedifferentiation, and Diabetes

Area of Science:

• Epigenetics and Molecular Biology
• Endocrinology and Metabolism
• Genomics and Computational Biology

Background:

• The role of chromatin machinery in complex diseases like type 2 diabetes is not well understood.
• Investigating epigenetic mechanisms offers potential insights into disease pathogenesis.

Purpose of the Study:

• To investigate the contribution of chromatin dysregulation to type 2 diabetes (T2D) pathogenesis.
• To identify specific epigenetic signatures associated with pancreatic beta cell dysfunction.

Main Methods:

• Deep epigenome mapping and single-cell transcriptomics were employed to analyze chromatin states in T2D.
• Functional studies involved assessing the impact of Polycomb Repressive Complex 2 (PRC2) loss of function in mouse models.

Main Results:

• Two distinct chromatin-state signatures were identified, correlating with beta cell dysfunction in both mice and humans.
• Ectopic activation of Polycomb-silenced domains and loss of lineage-defining genes were observed.
• Loss of PRC2 in beta cells led to diabetes-mimicking transcriptional changes and beta cell dedifferentiation, independent of hyperglycemia.

Conclusions:

• PRC2 is essential for maintaining pancreatic beta cell identity and function.
• Chromatin dysregulation, particularly PRC2 dysfunction, is a significant contributor to T2D.
• A two-hit model, involving both chromatin alterations and hyperglycemia, is proposed for beta cell failure in diabetes.