Pancreatic islet enhancer clusters enriched in type 2 diabetes risk-associated variants

Area of Science:

• Genomics
• Endocrinology
• Molecular Biology

Background:

• Type 2 diabetes impacts over 300 million globally, with significant mortality and morbidity.
• Pancreatic islet dysfunction is a key factor in type 2 diabetes development.
• The molecular mechanisms driving type 2 diabetes pathogenesis remain largely unknown.

Purpose of the Study:

• To map and functionally characterize human islet cis-regulatory networks.
• To investigate the role of islet enhancers in gene regulation and type 2 diabetes.
• To identify how genetic variants associated with type 2 diabetes affect islet function.

Main Methods:

• Mapping of human islet cis-regulatory networks.
• Identification of genomic sequences targeted by islet transcription factors.
• Analysis of clustered enhancers and three-dimensional chromatin domains.
• Enrichment analysis of type 2 diabetes and fasting glycemia-associated variants in islet enhancers.
• Assessment of trait-associated variants' impact on DNA binding and enhancer activity.

Main Results:

• Identification of genomic sequences driving islet-specific gene activity through transcription factor binding.
• Discovery that most regulatory sequences are clustered enhancers within three-dimensional chromatin domains.
• Significant enrichment of type 2 diabetes and fasting glycemia risk variants within these clustered islet enhancers.
• Identification of specific variants disrupting DNA binding and islet enhancer function.

Conclusions:

• Human islet cis-regulatory networks, particularly clustered enhancers, play a critical role in type 2 diabetes pathogenesis.
• Dysregulation of these islet enhancers by genetic variants contributes to the molecular mechanisms underlying type 2 diabetes.
• Understanding islet epigenome regulation offers valuable mechanistic insights into type 2 diabetes.