Contribution of Melanocortin Receptor Exoloops to Agouti-related Protein Binding

Yang, Ying; Dickinson, Chris J.; Zeng, Qun; Li, Ji Yao; Thompson, Darren A.; Gantz, Ira

doi:10.1074/jbc.274.20.14100

Cited by 52 publications

(64 citation statements)

References 22 publications

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“…Cassette mutagenesis studies have shown that the second and third extracellular loops (exoloops) connecting transmembrane helices are particularly important (44,45). As discussed previously, AGRP exhibits high affinity for MC4R but little affinity for MC1R.…”

Section: Discussionmentioning

confidence: 78%

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,

et al. 2001

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The agouti-related protein (AGRP) is an endogenous antagonist of the melanocortin receptors MC3R and MC4R found in the hypothalamus and exhibits potent orexigenic (appetite-stimulating) activity. The cysteine-rich C-terminal domain of this protein, corresponding to AGRP(87-132), contains five disulfide bonds and exhibits receptor binding affinity and antagonism equivalent to that of the full-length protein. The three-dimensional structure of this domain has been determined by 1 H NMR at 800 MHz. The first 34 residues of AGRP(87-132) are well-ordered and contain a three-stranded antiparallel sheet, where the last two strands form a hairpin. The relative spatial positioning of the disulfide cross-links demonstrates that the ordered region of AGRP(87-132) adopts the inhibitor cystine knot (ICK) fold previously identified for numerous invertebrate toxins. Interestingly, this may be the first example of a mammalian protein assigned to the ICK superfamily. The hairpin's turn region presents a triplet of residues (Arg-Phe-Phe) known to be essential for melanocortin receptor binding. The structure also suggests that AGRP possesses an additional melanocortin-receptor contact region within a loop formed by the first 16 residues of its C-terminal domain. This specific region shows little sequence homology to the corresponding region of the agouti protein, which is an MC1R antagonist involved in pigmentation. Consideration of these sequence differences, along with recent experiments on mutant and chimeric melanocortin receptors, allows us to postulate that this loop in the first 16 residues of its C-terminal domain confers AGRP's distinct selectivity for MC3R and MC4R.Obesity and associated disorders such as diabetes are now at epidemic levels in the United States and other developed countries (1, 2). An understanding at the molecular level of the normal processes governing energy homeostasis and weight regulation is therefore essential for developing a comprehensive understanding of these disorders and producing effective pharmaceutical treatments. Recent studies have demonstrated the key role played by brain melanocortin receptors (MCRs) in the regulation of energy homeostasis (3-6). Although MCRs are found in various tissues, these studies indicate that the specific receptors MC3R and MC4R are directly implicated in energy balance. All MCRs are G-protein-coupled receptors (GPCRs) that up-regulate the production of cAMP in the presence of small endogenous peptide agonists (7). These agonists are derived in vivo from the single pro-opiomelanocortin peptide (POMC) that is cleaved post-translationally to form the melanocortinstimulating hormones (MSHs) and the adrenocorticotropin hormone (ACTH). MCR function is also modulated by potent endogenous antagonists known as the agouti protein and the agouti-related protein (AGRP) that indeed may exert even greater control over MCR signaling than the peptide agonists (8-11). Relative to the small peptide agonists, these antagonists are larger in size and possess a five-dis...

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Section: Discussionmentioning

confidence: 78%

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,

et al. 2001

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“…2. The chimeric receptors were constructed by PCR using Pfu polymerase (Stratagene, La Jolla, CA) (23). hMC4R served as a template.…”

Section: Methodsmentioning

confidence: 99%

Third Transmembrane Domain of the Adrenocorticotropic Receptor Is Critical for Ligand Selectivity and Potency

Yang

Mishra²,

Crasto³

et al. 2015

Journal of Biological Chemistry

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Background:The ACTH receptor regulates adrenocortical function. Results: Substitution of Phe 7 in ACTH with D-Phe or D-Nal(2Ј) and mutation of MC2R TM3 resulted in decreased ACTH binding and signaling. Conclusion: Phe 7 in the ligand ACTH and TM3 of the ACTH receptor are crucial for ligand binding and signaling. Significance: Elucidating the ACTH receptor is crucial for development of MC2R drugs.

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“…In addition, the analog, SHU9119, a synthetic peptide with a ␤-(2-naphthyl)-D-alanine (D-Nal) substituted in position 7 of MTII, has been found to be a potent but non-selective antagonist for the MC3 and MC4 receptors (13,14). Intracerebroventricular administration of MTII has been found to induce weight loss, whereas SHU9119 has been found to increase animal food intake and body weight (15, 16).Because of potentially important therapeutic implications in the treatment of obesity and perhaps anorexia syndromes, determination of the molecular basis for ligand-receptor interaction between hMC4R and melanocortin peptides is valuable (17,18). Structure-function studies of NDP-MSH have demonstrated that D-Phe-Arg-Trp of NDP-MSH is the minimal peptide required for hMC4R binding and activation.…”

mentioning

confidence: 99%

“…Because of potentially important therapeutic implications in the treatment of obesity and perhaps anorexia syndromes, determination of the molecular basis for ligand-receptor interaction between hMC4R and melanocortin peptides is valuable (17,18). Structure-function studies of NDP-MSH have demonstrated that D-Phe-Arg-Trp of NDP-MSH is the minimal peptide required for hMC4R binding and activation.…”

mentioning

confidence: 99%

Molecular Determinants of Human Melanocortin-4 Receptor Responsible for Antagonist SHU9119 Selective Activity

Yang¹,

Chen²,

Lai³

et al. 2002

Journal of Biological Chemistry

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The hypothalamic melanocortin-4 receptor (MC4R), a seven transmembrane G-protein-coupled receptor, plays an important role in the regulation of body weight. The synthetic melanocortin analog SHU9119 has been widely used to characterize the physiological role of MC4R in feeding behavior and energy homeostasis. Previous studies indicated that SHU9119 is an agonist at the melanocortin-1 receptor (MC1R) but an antagonist at the MC4R. However, the molecular basis of the interaction between hMC4R and SHU9119 has not been clearly defined. To gain insight into the molecular determinants of hMC4R in the selectivity of SHU9119 chimeras and mutants hMC1R and hMC4R were expressed in cell lines and pharmacologically analyzed. A region of receptor containing the third transmembrane of hMC4R was found to be required for selective SHU9119 antagonism. Further mutagenesis studies of this region of hMC4R demonstrated that the amino acid residue leucine 133 in the third transmembrane was critical for the selective antagonist activity of SHU9119. The single substitution of leucine 133 to methionine did not affect SHU9119 binding to hMC4R. However, this substitution did convert SHU9119 from an antagonist to an agonist. Conversely, exchange of Met 128 in hMC1R to Leu, the homologous residue 133 of hMC4R, displayed a reduction in SHU9119 binding affinity and potency. This report provides the details of the molecular recognition of SHU9119 antagonism at hMC4R and shows that amino acid Leu 133 of hMC4R plays a key role in melanocortin receptor subtype specificity. The melanocortin-4 receptor (MC4R)1 is a seven transmembrane G-protein-coupled receptor, principally expressed in the hypothalamic nucleus. This receptor plays an important role in the regulation of body weight in rodents and humans (1-3). When stimulated by its putative physiological agonist, ␣-melanocyte-stimulating hormone (␣-MSH) inhibits feeding in mice through MC4R. Furthermore, mice with MC4R deletion develop hyperphagia, hyperinsulinism, and obesity (4). Recently, mutations in the MC4R have been reported as the most common causes of monogenic human obesity (5-7). MC4R mutations may play a particularly important role in the early onset of childhood obesity, resulting in more severe obesity-related complications, such as hypertension and diabetes, when compared with late onset obesity found in adults (8,9). In light of these findings, the molecular basis of the role that MC4R plays in obesity has been the subject of intense investigation.Many new, potent, and enzyme-resistant analogs of melanocortin peptides have been developed based on the extensive studies of the melanocortin peptide, ␣-MSH (10 -12 ]amide), which have been identified as potent, non-selective agonists at human melanocortin-1, -3, -4, and -5 receptors. In addition, the analog, SHU9119, a synthetic peptide with a ␤-(2-naphthyl)-D-alanine (D-Nal) substituted in position 7 of MTII, has been found to be a potent but non-selective antagonist for the MC3 and MC4 receptors (13,14). Intracerebroventricular admini...

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Contribution of Melanocortin Receptor Exoloops to Agouti-related Protein Binding

Cited by 52 publications

References 22 publications

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,

Third Transmembrane Domain of the Adrenocorticotropic Receptor Is Critical for Ligand Selectivity and Potency

Molecular Determinants of Human Melanocortin-4 Receptor Responsible for Antagonist SHU9119 Selective Activity

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Contribution of Melanocortin Receptor Exoloops to Agouti-related Protein Binding

Cited by 52 publications

References 22 publications

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein,

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein,

Third Transmembrane Domain of the Adrenocorticotropic Receptor Is Critical for Ligand Selectivity and Potency

Molecular Determinants of Human Melanocortin-4 Receptor Responsible for Antagonist SHU9119 Selective Activity

Contact Info

Product

Resources

About

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,

High-Resolution NMR Structure of the Chemically-Synthesized Melanocortin Receptor Binding Domain AGRP(87−132) of the Agouti-Related Protein^,