MELANOCORTIN-4 RECEPTOR (MC4-R): A Comprehensive Review
Introduction
The melanocortin-4 receptor (MC4-R) is a G-protein coupled receptor (GPCR) that is expressed in the hypothalamus and is involved in a variety of physiological processes such as energy homeostasis, food intake, and hormone release. It plays a pivotal role in the regulation of energy balance and body weight, and its dysfunction has been implicated in obesity and related metabolic disorders. In this review, we aim to provide an overview of the current understanding of MC4-R and its role in energy metabolism.
Structure and Function
The MC4-R is a transmembrane receptor composed of seven transmembrane helices and is part of the melanocortin receptor family. It binds to the melanocortin agonists α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotropic hormone (ACTH), which are produced by the hypothalamus. Binding of the agonists to MC4-R results in the activation of G proteins, which in turn activate intracellular signaling pathways. These pathways lead to the regulation of energy balance, food intake, and hormone release.
Role in Energy Balance and Obesity
MC4-R is a major regulator of energy balance and body weight. In rodents, activation of MC4-R in the hypothalamus increases energy expenditure and reduces food intake, leading to weight loss. MC4-R knockout mice have been shown to be hyperphagic and obese. In humans, loss-of-function mutations in the MC4-R gene have been linked to obesity and metabolic disorders such as type 2 diabetes.
Conclusion
In conclusion, the MC4-R is a G-protein coupled receptor that plays a critical role in energy balance and body weight regulation. Its dysfunction has been linked to obesity and metabolic disorders. Further research is needed to understand the role of MC4-R in energy metabolism.
References
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