RAP1 protects from obesity through its extratelomeric role regulating gene expression

Area of Science:

• Molecular Biology
• Genetics
• Metabolism

Background:

• RAP1 (Repressor/activator protein 1) is a component of shelterin, a complex that protects telomeres.
• RAP1 also binds to chromosome arms, suggesting roles in gene regulation beyond telomere maintenance.
• The in vivo function of nontelomeric RAP1, particularly in metabolic regulation, remains largely unexplored.

Purpose of the Study:

• To investigate the nontelomeric functions of RAP1 in vivo.
• To determine the role of RAP1 in the regulation of metabolism and obesity.

Main Methods:

• Generation of a whole-body RAP1 knockout mouse model.
• Phenotypic analysis including body weight, fat accumulation, and plasma metabolic markers.
• Gene expression analysis in liver and visceral white fat.
• Chromatin immunoprecipitation to assess RAP1 binding to target gene loci.

Main Results:

• RAP1 knockout mice exhibit early-onset obesity, more severe in females, with increased abdominal fat and hepatic steatosis.
• Rap1-deficient mice display elevated fasting plasma levels of insulin, glucose, cholesterol, and alanine aminotransferase.
• Gene expression profiling reveals deregulation of metabolic pathways, including fatty acid and glucose metabolism, and PPARα signaling.
• RAP1 directly binds to Pparα and Pgc1α gene loci, modulating their transcription in the liver.

Conclusions:

• The telomere-binding protein RAP1 plays a significant role in the regulation of mammalian metabolism.
• RAP1 deficiency leads to metabolic syndrome-like phenotypes, suggesting its involvement in preventing obesity and related disorders.
• These findings uncover a novel function for a telomere-associated protein in metabolic control, impacting pathways like PPARα signaling.