scholarly journals The Melanocortin Receptor Accessory Protein 2 promotes food intake through inhibition of the Prokineticin Receptor-1

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Anna L Chaly ◽  
Dollada Srisai ◽  
Ellen E Gardner ◽  
Julien A Sebag
Keyword(s):  
Food Intake ◽  
Energy Homeostasis ◽  
Severe Obesity ◽  
Melanocortin Receptor ◽  
Accessory Protein ◽  
Important Regulator ◽  
Receptor Accessory Protein

The Melanocortin Receptor Accessory Protein 2 (MRAP2) is an important regulator of energy homeostasis and its loss causes severe obesity in rodents. MRAP2 mediates its action in part through the potentiation of the MC4R, however, it is clear that MRAP2 is expressed in tissues that do not express MC4R, and that the deletion of MRAP2 does not recapitulate the phenotype of Mc4r KO mice. Consequently, we hypothesized that other GPCRs involved in the control of energy homeostasis are likely to be regulated by MRAP2. In this study we identified PKR1 as the first non-melanocortin GPCR to be regulated by MRAP2. We show that MRAP2 significantly and specifically inhibits PKR1 signaling. We also demonstrate that PKR1 and MRAP2 co-localize in neurons and that Mrap2 KO mice are hypersensitive to PKR1 stimulation. This study not only identifies new partners of MRAP2 but also a new pathway through which MRAP2 regulates energy homeostasis.

scholarly journals Melanocortin 3 Receptor Has a 5′ Exon That Directs Translation of Apically Localized Protein From the Second In-Frame ATG

2014 ◽  
Vol 28 (9) ◽  
pp. 1547-1557 ◽  
Author(s):  
Jeenah Park ◽  
Neeraj Sharma ◽  
Garry R. Cutting
Keyword(s):  
Energy Homeostasis ◽  
Melanocortin Receptor ◽  
Accessory Protein ◽  
Start Site ◽  
Reading Frame ◽  
Accessory Factor ◽  
Rapid Amplification ◽  
Translational Start ◽  
Apical Membranes ◽  
Receptor Accessory Protein

Melanocortin-3 receptor (MC3R) is a canonical MSH receptor that plays an essential role in energy homeostasis. Variants in MC3R have been implicated in obesity in humans and mice. However, interpretation of the functional consequences of these variants is challenging because the translational start site of MC3R is unclear. Using 5′ rapid amplification of cDNA ends, we discovered a novel upstream exon that extends the length of the 5′ untranslated region (UTR) in MC3R without changing the open-reading frame. The full-length 5′ UTR directs utilization of an evolutionarily conserved second in-frame ATG as the primary translation start site. MC3R synthesized from the second ATG is localized to apical membranes of polarized Madin-Darby canine kidney cells, consistent with its function as a cell surface mediator of melanocortin signaling. Expression of MC3R causes relocalization of melanocortin receptor accessory protein 2, an accessory factor for melanocortin-2 receptor, to the apical membrane, coincident with the location of MC3R. In contrast, protein synthesized from MC3R cDNAs lacking the 5′ UTR displayed diffuse cytosolic distribution and has no effect on the distribution of melanocortin receptor accessory protein 2. Our findings demonstrate that a previously unannotated 5′ exon directs translation of MC3R protein that localizes to apical membranes of polarized cells. Together, our work provides insight on the structure of human MC3R and reveals a new pathway for regulation of energy metabolism.

scholarly journals Melanocortin Receptor Accessory Protein 2-Induced Adrenocorticotropic Hormone Response of Human Melanocortin 4 Receptor

2018 ◽  
Vol 3 (2) ◽  
pp. 314-323 ◽  
Author(s):  
Lucia Soletto ◽  
Sergio Hernández-Balfagó ◽  
Ana Rocha ◽  
Patrick Scheerer ◽  
Gunnar Kleinau ◽  
...  
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Melanocortin Receptor ◽  
Accessory Protein ◽  
Hormone Response ◽  
Melanocortin 4 Receptor ◽  
Receptor Accessory Protein

Decreased melanocortin-4 receptor function conferred by an infrequent variant at the human melanocortin receptor accessory protein 2 gene

Obesity ◽  
2016 ◽  
Vol 24 (9) ◽  
pp. 1976-1982 ◽  
Author(s):  
Laura Schonnop ◽  
Gunnar Kleinau ◽  
Nikolas Herrfurth ◽  
Anna-Lena Volckmar ◽  
Cigdem Cetindag ◽  
...  
Keyword(s):  
Melanocortin Receptor ◽  
Accessory Protein ◽  
Receptor Function ◽  
Melanocortin 4 Receptor ◽  
Receptor Accessory Protein

scholarly journals Loss of Mrap2 is associated with Sim1 deficiency and increased circulating cholesterol

2016 ◽  
Vol 230 (1) ◽  
pp. 13-26 ◽  
Author(s):  
T V Novoselova ◽  
R Larder ◽  
D Rimmington ◽  
C Lelliott ◽  
E H Wynn ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Metabolic Regulation ◽  
Energy Homeostasis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Melanocortin Receptor ◽  
Accessory Protein ◽  
Loss Of Function ◽  
Deficient Mice

Melanocortin receptor accessory protein 2 (MRAP2) is a transmembrane accessory protein predominantly expressed in the brain. Both global and brain-specific deletion of Mrap2 in mice results in severe obesity. Loss-of-function MRAP2 mutations have also been associated with obesity in humans. Although MRAP2 has been shown to interact with MC4R, a G protein-coupled receptor with an established role in energy homeostasis, appetite regulation and lipid metabolism, the mechanisms through which loss of MRAP2 causes obesity remains uncertain. In this study, we used two independently derived lines of Mrap2 deficient mice (Mrap2tm1a/tm1a) to further study the role of Mrap2 in the regulation of energy balance and peripheral lipid metabolism. Mrap2tm1a/tm1a mice have a significant increase in body weight, with increased fat and lean mass, but without detectable changes in food intake or energy expenditure. Transcriptomic analysis showed significantly decreased expression of Sim1, Trh, Oxt and Crh within the hypothalamic paraventricular nucleus of Mrap2tm1a/tm1a mice. Circulating levels of both high-density lipoprotein and low-density lipoprotein were significantly increased in Mrap2 deficient mice. Taken together, these data corroborate the role of MRAP2 in metabolic regulation and indicate that, at least in part, this may be due to defective central melanocortin signalling.

Effect of intracerebroventricular α-MSH on food intake, adiposity, c-Fos induction, and neuropeptide expression

2000 ◽  
Vol 279 (2) ◽  
pp. R695-R703 ◽  
Author(s):  
Julie E. McMinn ◽  
Charles W. Wilkinson ◽  
Peter J. Havel ◽  
Stephen C. Woods ◽  
Michael W. Schwartz
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Energy Homeostasis ◽  
Melanocortin Receptor ◽  
Mrna Levels ◽  
Melanocyte Stimulating Hormone ◽  
The Third ◽  
Chronic Infusion ◽  
Plasma Insulin Levels ◽  
Cumulative Food Intake

α-Melanocyte-stimulating hormone (α-MSH) is a hypothalamic neuropeptide proposed to play a key role in energy homeostasis. To investigate the behavioral, metabolic, and hypothalamic responses to chronic central α-MSH administration, α-MSH was infused continuously into the third cerebral ventricle of rats for 6 days. Chronic α-MSH infusion reduced cumulative food intake by 10.7% ( P < 0.05 vs. saline) and body weight by 4.3% ( P < 0.01 vs. saline), which in turn lowered plasma insulin levels by 29.3% ( P < 0.05 vs. saline). However, α-MSH did not cause adipose-specific wasting nor did it alter hypothalamic neuropeptide mRNA levels. Central α-MSH infusion acutely activated neurons in forebrain areas such as the hypothalamic paraventricular nucleus, as measured by a 254% increase in c-Fos-like immunoreactivity ( P < 0.01 vs. saline), as well as satiety pathways in the hindbrain. Our findings suggest that, although an increase of central melanocortin receptor signaling acutely reduces food intake and body weight, its anorectic potency wanes during chronic infusion and causes only a modest decrease of body weight.

scholarly journals Topmouth culter melanocortin-3 receptor: regulation by two isoforms of melanocortin-2 receptor accessory protein 2

2021 ◽  
Author(s):  
Ren-Lei Ji ◽  
Lu Huang ◽  
Yin Wang ◽  
Ting Liu ◽  
Si-Yu Fan ◽  
...  
Keyword(s):  
Expression Analysis ◽  
Energy Homeostasis ◽  
Radioligand Binding ◽  
Critical Role ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Accessory Protein ◽  
Intracellular Camp ◽  
Camp Generation ◽  
Receptor Accessory Protein

Melanocortin-3 receptor (MC3R) is a regulator of energy homeostasis, and interaction of MC3R and melanocortin-2 receptor accessory protein 2 (MRAP2) plays a critical role in MC3R signaling of mammals. However, the physiological roles of MC3R in teleosts are not well understood. In this study, qRT-PCR was used to measure gene expression. Radioligand binding assay was used to study the binding properties of topmouth culter MC3R (caMC3R). Intracellular cAMP generation was determined by radioimmunoassay and caMC3R expression was quantified with flow cytometry. We showed that culter mc3r had higher expression in the central nervous system. All agonists could bind and stimulate caMC3R to increase dose-dependently intracellular cAMP accumulation. Compared to hMC3R, culter MC3R showed higher constitutive activity, higher efficacies and Rmax to α-MSH, des-α-MSH, and ACTH. Both caMRAP2a and caMRAP2b markedly decreased caMC3R basal cAMP production. However, only caMRAP2a significantly decreased cell surface expression, Bmax and Rmax of caMC3R. Expression analysis suggested that MRAP2a and MRAP2b might be more important in regulating MC3R/MC4R signaling during larval period, and reduced mc3r, mc4r, and pomc expression might be primarily involved in modulation of MC3R/MC4R in adults. These data indicated that the cloned caMC3R was a functional receptor. MRAP2a and MRAP2a had different effects on expression and signaling of caMC3R. In addition, expression analysis suggested that MRAP2s, receptors, and hormone might play different roles in regulating culter development and growth.

scholarly journals Arcuate nucleus and lateral hypothalamic CART neurons in the mouse brain exert opposing effects on energy expenditure

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Aitak Farzi ◽  
Jackie Lau ◽  
Chi Kin Ip ◽  
Yue Qi ◽  
Yan-Chuan Shi ◽  
...  
Keyword(s):  
Physical Activity ◽  
Food Intake ◽  
Energy Expenditure ◽  
Lateral Hypothalamus ◽  
Energy Homeostasis ◽  
Arcuate Nucleus ◽  
Neuronal Populations ◽  
Neuron Activation ◽  
Important Regulator ◽  
Opposing Effects

Cocaine- and amphetamine-regulated transcript (CART) is widely expressed in the hypothalamus and an important regulator of energy homeostasis; however, the specific contributions of different CART neuronal populations to this process are not known. Here, we show that depolarization of mouse arcuate nucleus (Arc) CART neurons via DREADD technology decreases energy expenditure and physical activity, while it exerts the opposite effects in CART neurons in the lateral hypothalamus (LHA). Importantly, when stimulating these neuronal populations in the absence of CART, the effects were attenuated. In contrast, while activation of CART neurons in the LHA stimulated feeding in the presence of CART, endogenous CART inhibited food intake in response to Arc CART neuron activation. Taken together, these results demonstrate anorexigenic but anabolic effects of CART upon Arc neuron activation, and orexigenic but catabolic effects upon LHA-neuron activation, highlighting the complex and nuclei-specific functions of CART in controlling feeding and energy homeostasis.

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