Genetic screening for MC4R gene identifies three novel mutations associated with severe familiar obesity in a cohort of Spanish individuals

MC4R Deficiency Causes Dysregulation of Postsynaptic Excitatory Synaptic Transmission as a Crucial Culprit for Obesity

Melanocortin 4 receptor (MC4R) in the paraventricular nucleus of the hypothalamus (PVH) shows bidirectional characterization in modulating food intake and energy homeostasis. We demonstrate that MC4R knockdown (KD) in the PVH can attenuate AMPA receptor (AMPAR)-mediated postsynaptic responses by altering the phosphorylation of AMPAR GluA1 subunit through the protein kinase A (PKA)-dependent signaling cascade and simultaneously lead to rapid body weight gain. Furthermore, PKA KD in the PVH engendered similar electrophysiological and behavioral phenotypes as in MC4R KD mice. Importantly, we observed that the reduction of AMPAR GluA1 expression not only led to attenuated synaptic responses but also caused body weight gain, suggesting that the aberration of synaptic responses may be one of the crucial pathogeny of obesity. Our study provides the synaptic and molecular explanations of how body weight is regulated by MC4R in the PVH.

Novel Targets in Glucose Homeostasis and Obesity-Lesson from Rare Mutations

PURPOSE OF REVIEW

Obesity and diabetes have already become the second largest risk factor for cardiovascular disease. During the last decade, remarkable advances have been made in understanding the human genome's contribution to glucose homeostasis disorders and obesity. A few studies on rare mutations of candidate genes provide potential genetic targets for the treatment of diabetes and obesity. In this review, we discussed the detailed findings of these studies and the possible causalities between specific genetic variations and dysfunctions in energy or glucose homeostasis. We are optimistic that novel therapeutic strategies targeting these specific mutants for treating and preventing diabetes and obesity will be developed in the near future.

RECENT FINDINGS

Studies on rare genetic mutation-caused obesity or diabetes have identified potential genetic targets to decrease body weight or reduce the risk of diabetes. Rare mutations observed in lipodystrophy, obese, or diabetic human patients are promising targets in the treatment of diabetes and obesity.