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 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 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 Analysis of BvgA Activation of the Pertactin Gene Promoter in Bordetella pertussis

1999 ◽  
Vol 181 (17) ◽  
pp. 5234-5241 ◽  
Author(s):  
Susan M. Kinnear ◽  
Philip E. Boucher ◽  
Scott Stibitz ◽  
Nicholas H. Carbonetti
Keyword(s):  
Virulence Factors ◽  
Bordetella Pertussis ◽  
Whooping Cough ◽  
Gene Promoter ◽  
In Vitro Transcription ◽  
Start Site ◽  
Reading Frame ◽  
Dnase I Footprinting ◽  
Rapid Amplification

ABSTRACT Bordetella pertussis, the causative agent of whooping cough, regulates expression of its virulence factors via a two-component signal transduction system encoded by the bvgregulatory locus. It has been shown by activation kinetics that several of the virulence factors are differentially regulated. fhais transcribed at 10 min following an inducing signal, whileptx is not transcribed until 2 to 4 h after the inducing signal. We present data indicating that prn is transcribed at 1 h, an intermediate time compared to those offha and ptx. We have identifiedcis-acting sequences necessary for expression ofprn in B. pertussis by usingprn-lac fusions containing alterations in the sequence upstream of the prn open reading frame. In vitro transcription and DNase I footprinting analyses provided evidence to support our hypothesis that BvgA binds to this sequence upstream ofprn to activate transcription from the promoter. Our genetic data indicate that the region critical for prnactivation extends upstream to position −84. However, these data do not support the location of the prn transcription start site as previously published. We used a number of methods, includingprn-lac fusions, reverse transcriptase PCR, and 5′ rapid amplification of cDNA ends, to localize and identify thebvg-dependent 5′ end of the prn transcript to the cytosine at −125 with respect to the published start site.

scholarly journals The membrane associated accessory protein is an adeno-associated viral egress factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zachary C. Elmore ◽  
L. Patrick Havlik ◽  
Daniel K. Oh ◽  
Leif Anderson ◽  
George Daaboul ◽  
...  
Keyword(s):  
Extracellular Vesicle ◽  
Lytic Infection ◽  
Open Reading Frame ◽  
Accessory Protein ◽  
Start Site ◽  
Wild Type ◽  
Reading Frame ◽  
Viral Egress ◽  
Plausible Mechanism ◽  
Multiple Processing

AbstractAdeno-associated viruses (AAV) rely on helper viruses to transition from latency to lytic infection. Some AAV serotypes are secreted in a pre-lytic manner as free or extracellular vesicle (EV)-associated particles, although mechanisms underlying such are unknown. Here, we discover that the membrane-associated accessory protein (MAAP), expressed from a frameshifted open reading frame in the AAV cap gene, is a novel viral egress factor. MAAP contains a highly conserved, cationic amphipathic domain critical for AAV secretion. Wild type or recombinant AAV with a mutated MAAP start site (MAAPΔ) show markedly attenuated secretion and correspondingly, increased intracellular retention. Trans-complementation with MAAP restored secretion of multiple AAV/MAAPΔ serotypes. Further, multiple processing and analytical methods corroborate that one plausible mechanism by which MAAP promotes viral egress is through AAV/EV association. In addition to characterizing a novel viral egress factor, we highlight a prospective engineering platform to modulate secretion of AAV vectors or other EV-associated cargo.

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.

scholarly journals Melanocortin receptor accessory proteins in adrenal gland physiology and beyond

2013 ◽  
Vol 217 (1) ◽  
pp. R1-R11 ◽  
Author(s):  
T V Novoselova ◽  
D Jackson ◽  
D C Campbell ◽  
A J L Clark ◽  
L F Chan
Keyword(s):  
Adrenal Gland ◽  
Energy Homeostasis ◽  
Functional Expression ◽  
Surface Expression ◽  
Vital Role ◽  
Melanocortin Receptor ◽  
Exocrine Function ◽  
Zona Fasciculata ◽  
Accessory Factor

The melanocortin receptor (MCR) family consists of five G-protein-coupled receptors (MC1R–MC5R) with diverse physiological roles. MC1R controls pigmentation, MC2R is a critical component of the hypothalamic–pituitary–adrenal axis, MC3R and MC4R have a vital role in energy homeostasis and MC5R is involved in exocrine function. The melanocortin receptor accessory protein (MRAP) and its paralogue MRAP2 are small single-pass transmembrane proteins that have been shown to regulate MCR expression and function. In the adrenal gland, MRAP is an essential accessory factor for the functional expression of the MC2R/ACTH receptor. The importance of MRAP in adrenal gland physiology is demonstrated by the clinical condition familial glucocorticoid deficiency, where inactivating MRAP mutations account for ∼20% of cases. MRAP is highly expressed in both the zona fasciculata and the undifferentiated zone. Expression in the undifferentiated zone suggests that MRAP could also be important in adrenal cell differentiation and/or maintenance. In contrast, the role of adrenal MRAP2, which is highly expressed in the foetal gland, is unclear. The expression of MRAPs outside the adrenal gland is suggestive of a wider physiological purpose, beyond MC2R-mediated adrenal steroidogenesis.In vitro, MRAPs have been shown to reduce surface expression and signalling of all the other MCRs (MC1,3,4,5R). MRAP2 is predominantly expressed in the hypothalamus, a site that also expresses a high level of MC3R and MC4R. This raises the intriguing possibility of a CNS role for the MRAPs.

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.

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