CHD4 and NKX2.2 Cooperate to Regulate Beta Cell Function by Repressing Non-Beta Cell Gene Programs

Area of Science:

• Endocrinology
• Molecular Biology
• Genetics

Background:

• NKX2.2 is a key transcription factor for pancreatic islet beta (β) cell identity and function.
• Cofactor proteins modulating NKX2.2 activity in β cells remain largely uncharacterized.
• Chromodomain helicase DNA-binding protein 4 (CHD4) is a nucleosome remodeler involved in gene regulation across various cell types.

Purpose of the Study:

• To identify NKX2.2 interacting partners in pancreatic β cells.
• To investigate the roles of CHD4 in β cell maturation and function, both dependent and independent of NKX2.2.
• To generate and analyze conditional knockout mice lacking Chd4 specifically in β cells (Chd4 βKO).

Main Methods:

• Unbiased proteomics screen to identify NKX2.2 interacting proteins.
• Generation of Chd4 βKO mice for conditional gene deletion in β cells.
• Assessment of β cell morphology, function, glucose homeostasis, insulin secretion, and calcium signaling in Chd4 βKO mice.

Main Results:

• Proteomics identified CHD4 as an NKX2.2 interacting partner.
• Chd4 deletion in β cells led to impaired islet integrity, maturation, and function.
• Chd4 βKO mice exhibited early-onset diabetes, characterized by disrupted glucose-stimulated insulin secretion and calcium signaling.
• Downregulation of essential β cell regulatory genes was observed in Chd4-deficient β cells.

Conclusions:

• CHD4 acts as an essential transcriptional cofactor for NKX2.2 in pancreatic β cells.
• CHD4 is indispensable for the proper maturation and sustained function of pancreatic β cells.
• Disruption of CHD4 function in β cells leads to a diabetic phenotype.