Endocrine Abstracts

The melanocortin 4 receptor (MC4R) plays a prominent role in hypothalamic weight regulation. Activation of this receptor results by so far not understood mechanisms in a decrease of food-intake and an increase of energy expenditure. Recently a functional role downstream of MC4R signalling for brain derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B receptor (TrkB) was reported. TrkB signalling influences several neuronal processes like synapse for...

The melanocortin 4 receptor (MC4R), a G protein coupled receptor, has a prominent role in hypothalamic weight regulation. The MC4R was recently shown to form receptor dimers. The cannabinoid 1 receptor (CB1R) is the nearest phylogenetic relative of MC4R but fails to interact with the MC4R in vitro. In this study we aim to investigate receptor domains that are necessary for MC4R interaction. Four different chimeric receptors of MC4R and CB1R were constructed. The generated cons...

By a systematic approach we investigated the interaction of a selective number of GPCRs that are expressed in the arcuate nucleus and known to play an essential role in hypothalamic weight regulation. Based on the results of a sandwich ELISA and fluorescence resonance energy transfer (FRET) approach we report the interaction of the melanocortin three receptor (MC3R) and the growth hormone secretagogue receptor (GHSR) which are coexpressed on arcuate NPY/AgRP neurons. Fu...

Food intake is centrally regulated in hypothalamic nuclei. Peripheral hormonal signals activate their corresponding receptors in the arcuate nucleus (arc) and modulate the expression of pro-opiomelanocortin (POMC) and neuropetide Y (NPY)/agouti-related-protein (AgRP). Cleavage products of POMC stimulate melanocortin-4-receptors (MC4R) in the paraventricular nucleus (PVN) to inhibit food intake or stimulate MC3Rs in the arc to activate a feedback loop. Further mor...

Objectives: Food intake is centrally regulated in hypothalamic nuclei where many G-protein-coupled receptors (GPCRs) are expressed which are known to be involved in weight regulation. Peripheral hormonal signals activate their corresponding receptors in the arcuate nucleus. Orexigenic signals activate POMC expression in one subset of neurons and inhibit AgRP and NPY expression in a second subset. Cleavage products of POMC, α- and β-MSH then stimulate melanocortin-4-r...

Mutations in the hypothalamic expressed MC4R gene are the most frequent cause of monogenetic obesity. This Gαs-Protein coupled receptor (GPCR) is activated by endogenous ligands α- and β-MSH and is inhibited by the only known endogenous inverse agonist and antagonist Agouti related peptide (AgRP). Naturally occurring mutations help to understand activation mechanisms of the human MC4R.We previously described a constitutively act...