MC4R Variants Modulate α-MSH and Setmelanotide Induced Cellular Signaling at Multiple Levels

Area of Science:

• Endocrinology and Metabolism
• Molecular Biology
• Genetics

Background:

• The melanocortin-4 receptor (MC4R) is crucial for regulating body weight.
• Mutations in MC4R are the primary genetic cause of monogenic obesity.

Purpose of the Study:

• To functionally characterize 17 MC4R variants identified in obese patients.
• To assess the impact of setmelanotide, a potent MC4R agonist, on these variants.

Main Methods:

• Assessed cell surface expression, cAMP response, β-arrestin-2 recruitment, and ERK activation for wild-type and variant MC4R.
• Utilized α-melanocyte stimulating hormone (α-MSH) and setmelanotide as agonists.

Main Results:

• Observed significant heterogeneity in MC4R variant function, affecting signaling pathways differently.
• Setmelanotide demonstrated higher potency than α-MSH, enhancing cAMP responses in several variants.
• Despite functional diversity, no clear correlation was found between variant function and obesity phenotype severity.

Conclusions:

• Obesity-associated MC4R variants exhibit varied effects on MC4R signaling pathways.
• Comprehensive functional analysis is vital for understanding MC4R variant-associated obesity.
• These findings support personalized treatment approaches for obesity based on MC4R genotype and signaling characteristics.