Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A lanthanide-based assay for ligand-receptor interactions provides an attractive alternative to the traditional radiolabeled determinations in terms of sensitivity, throughput, and biohazards. We designed and tested peptide ligands modified with an Eu-DTPA chelate. These labeled ligands were used in competitive binding assays with results comparable to those obtained using the traditional radiolabeled binding assays. The sensitivity of time-resolved fluorescence is sufficient to detect attomoles of europium, allowing assays in 96-well plates, compared with 30-mm dishes for (125)I binding assays to whole cells. We verified binding of Eu-DTPA-NDP-alpha-MSH to cells overexpressing the human melanocortin-4 receptor. The Eu-labeled ligand bound to these cells with an affinity similar to that of unlabeled NDP-alpha-MSH and was used to optimize a competitive binding assay. The lanthanide-based assays provided superior results with higher throughput and eliminated the need for radioactive waste disposal. This assay is appropriate for high-throughput screening of ligand libraries.
 ...
PMID:Lanthanide-based time-resolved fluorescence of in cyto ligand-receptor interactions. 1520 29

Melanocortins are known to be involved in the inhibition of food intake and energy metabolism. Acute and chronic intracerebroventricular administration of several different analogues of alpha-MSH, such as alpha-MSH, NDP-MSH, alpha-MSH-ND, [Gln(6)]alpha-MSH-ND, and [Lys(6)]alpha-MSH-ND, which were substituted in the position of His(6) with Gln and Lys, and cyclic16k-MSH to C57J/BL6 mice resulted in a significant inhibition of both time course food intake and body weight gain, compared to the saline-administered control. However, [Gln(6)]alpha-MSH-ND(6-10), the truncated form of [Gln(6)]alpha-MSH-ND, had no inhibitory effects on food intake. In situ hybridization analysis revealed that the expression levels of AGRP and NPY in the hypothalamus were significantly and rapidly diminished while POMC expression was strongly induced by [Gln(6)]alpha-MSH-ND. Administration of JKC-363, a selective MC4R-specific antagonist, coupled with [Gln(6)]alpha-MSH-ND, specifically reversed the [Gln(6)]alpha-MSH-ND-induced inhibition of food intake, but also reversed the hypothalamic expression levels of neuropeptides such as AGRP, NPY, MCH, and POMC, which suggests [Gln(6)]alpha-MSH-ND can function as a selective MC4R agonist.
 ...
PMID:Dynamic regulation of hypothalamic neuropeptide gene expression and food intake by melanocortin analogues and reversal with melanocortin-4 receptor antagonist. 1576 51

alpha-MSH and gamma-MSH are the natural endogenous hormones for the human melanocortin-1, 3, 4 and 5 receptors (hMC1R, hMC3R, hMC4R and hMC5R). These and more potent, stable and prolonged acting analogues such as NDP-alpha-MSH, MT-II and SHU-9119 are not very receptor selective. To develop potent and selective agonist and antagonist ligands for the melanocortin receptors we have used state-of-the-art biophysical studies, computational chemistry, and design of conformational and topographical constraints with novel templates.
 ...
PMID:Design of novel melanotropin agonists and antagonists with high potency and selectivity for human melanocortin receptors. 1587 75

The present work comparatively analyzes the interaction of alpha-MSH and its more potent and long-acting analog [Nle4, D-Phe7]alpha-MSH (NDP-MSH) with lipid bilayers. The peptides were spin labeled with Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at the N-terminal, as those derivatives had been previously shown to keep their full biological activity. Due to the special rigidity of the Toac covalent binding to the peptide molecule, this spin label is highly sensitive to the peptide backbone conformation and dynamics. The peptides were investigated both by the electron spin resonance (ESR) of Toac0 and the time resolved fluorescence of Trp9 present in the peptides. The Toac0 ESR of the membrane-bound peptides indicates that the two peptides are inserted into the bilayer, close to the bilayer surface, in rather similar environments. A residue titration around pKa 7.5, possibly that of His6, can be clearly monitored by peptide-lipid partition. Trp9 time resolved fluorescence indicates that the peptides, and their Toac-labeled derivatives, present rather similar conformations when membrane bound, though Trp9 in NDP-MSH, and in its Toac-labeled derivative, goes somewhat further down into the bilayer. Yet, Toac0 ESR signal shows that the Toac-labeled N-terminal of NDP-MSH is in a shallower position in the bilayer, as compared to the hormone.
 ...
PMID:Peptide-lipid interaction monitored by spin labeled biologically active melanocortin peptides. 1600 9

alpha-MSH has potent antiinflammatory properties, but little is known about the specific melanocortin receptors (MC-Rs) that mediate these effects or about the role of the melanocortin system in modulating cytokine responses to an inflammatory challenge in the primate in vivo. We, therefore, studied the effects of infusion of the alpha-MSH agonist, [Nle(4),d-Phe(7)]-alpha-MSH (NDP-MSH); the alpha-MSH antagonist, SHU9119; and the selective MC3-R agonist, D-Trp8-gamma-MSH, compared with saline, on proinflammatory cytokine (TNF-alpha, IL-1beta, and IL-6), antiinflammatory cytokine [IL-10 and IL-1 receptor antagonist (IL-1ra)], and pituitary-adrenal responses to endotoxin in ovariectomized monkeys. In the first study NDP-MSH or SHU9119 was infused iv for 7 h starting at 0800 h, endotoxin was injected at 1000 h, and serial blood samples were collected (n = 6). NDP-MSH significantly attenuated proinflammatory cytokine responses to endotoxin. The area under the response curve (AUC) decreased by 61% for TNF-alpha (P = 0.02), 47% for IL-1beta (P = 0.02), and 41% for IL-6 (P = 0.04); there was no effect on IL-1ra or IL-10. SHU9119 did not affect proinflammatory cytokine responses, but decreased the IL-10 response by 31% (P = 0.03). NDP-MSH also attenuated ACTH (P < 0.001) and cortisol (P = 0.02) responses. In a second study, the effects of d-Trp8-gamma-MSH were similarly examined in seven monkeys. The AUC for IL-6 was decreased by 37% (P = 0.04) by d-Trp8-gamma-MSH; the AUC for IL-10 was increased by 22%, but this was not significant. However, the ratio of IL-6 to IL-10 was significantly decreased by d-Trp8-gamma-MSH (P = 0.04), consistent with a relatively more antiinflammatory cytokine environment. These results indicate that NDP-MSH can attenuate proinflammatory cytokine responses in the primate, consistent with previous studies in the rodent, and provide new evidence for a role for MC3-R in this process. Moreover, they show for the first time that SHU9119, a mixed MC3/4-R antagonist, can decrease the IL-10 response, establishing a physiological role for endogenous MSH in modulating the release of an antiinflammatory cytokine.
 ...
PMID:Melanocortin modulation of inflammatory cytokine and neuroendocrine responses to endotoxin in the monkey. 1641 Feb 97

Melanocortin peptides have been shown to produce neuroprotection in experimental ischemic stroke. The aim of the present investigation was to identify the therapeutic treatment window of melanocortins, and to determine whether these neuropeptides chronically protect against damage consequent to brain ischemia. A 10-min period of global cerebral ischemia in gerbils, induced by occluding both common carotid arteries, caused impairment in spatial learning and memory (Morris test: four sessions from 4 to 67 days after the ischemic episode), associated with neuronal death in the hippocampus. Treatment with a nanomolar dose (340 microg/kg i.p., every 12 h for 11 days) of the melanocortin analog [Nle(4), D-Phe(7)]alpha-melanocyte-stimulating hormone (NDP-alpha-MSH), starting 3-18 h after the ischemic episode, reduced hippocampal damage with improvement in subsequent functional recovery. The protective effect was long-lasting (67 days, at least) with all schedules of NDP-alpha-MSH treatment; however, in the latest treated (18 h) gerbils, some spatial memory deficits were detected. Pharmacological blockade of melanocortin MC(4) receptors prevented the protective effects of NDP-alpha-MSH. Our findings indicate that, in conditions of brain ischemia, melanocortins can provide strong and long-lasting protection with a broad therapeutic treatment window, and with involvement of melanocortin MC(4) receptors, 18 h being the approximately time-limit for stroke late treatment to be effective.
 ...
PMID:Broad therapeutic treatment window of [Nle(4), D-Phe(7)]alpha-melanocyte-stimulating hormone for long-lasting protection against ischemic stroke, in Mongolian gerbils. 1664

The melanocortin-4 receptor (MC4R) is a G-protein coupled receptor (GPCR) that is expressed in the central nervous system and has a role in regulating energy homeostasis and obesity. Up to a remarkable 6% of morbidly obese adults and children studied possess single nucleotide polymorphisms (SNPs) of the MC4R. Upon stimulation by agonist, the MC4R signals through the intracellular adenylate cyclase signal transduction pathway. Posttranslational modification of the pro-opiomelanocortin (POMC) gene transcript results in the generation of several endogenous melanocortin receptor agonists including alpha-, beta-, gamma-melanocyte stimulating hormones (MSH) and adrenocorticotropin (ACTH) ligands. The endogenous MC4R antagonist, agouti-related protein (AGRP), is expressed in the brain and is only one of two naturally occurring antagonists of GPCRs identified to date. Herein, we have generated 40 hMC4 polymorphic receptors and evaluated their cell surface expression by flow cytometry as well as pharmacologically characterized their functionality using the endogenous agonists alpha-MSH, beta-MSH, gamma2-MSH, ACTH(1-24), the antagonist hAGRP(87-132), and the synthetic agonists NDP-MSH and MTII. This is the first study in which polymorphic hMC4Rs have been pharmacologically characterized simultaneously with multiple endogenous ligands. Interestingly, at the N97D, L106P, and C271Y hMC4Rs beta-MSH was more potent than the other endogenous agonists alpha-MSH, gamma2-MSH, ACTH(1-24). The S58C and R165Q/W hMC4Rs possessed significantly reduced endogenous agonist potency (15- to 90-fold), but the synthetic ligands NDP-MSH and MTII possessed only 2-9-fold reduced potency as compared to the wild-type receptor, suggesting their potential as therapeutic ligands to treat individuals with these polymorphisms.
 ...
PMID:Pharmacological characterization of 40 human melanocortin-4 receptor polymorphisms with the endogenous proopiomelanocortin-derived agonists and the agouti-related protein (AGRP) antagonist. 1675 16

We have previously reported that the peptide a-melanocyte stimulating hormone (alpha-MSH) has antiproliferative effects in human malignant mesothelioma cells. To determine the molecular mechanisms underlying such effects, we investigated the changes in gene expression profile induced by the alpha-MSH analog [Nle4 -DPhe7 ]-alpha-MSH (NDP-alpha-MSH) in a human malignant mesothelioma cell line. The cDNA macroarray technique revealed changes in expression of genes involved in cell growth, adhesion, signal transduction, and transcription. In particular, NDP-alpha-MSH down-regulated expression of B-Myb and Myc, two oncogenes considered of paramount importance for cell proliferation and cancer. Further, NDP-alpha-MSH exerted a favorable transcriptional regulation of certain integrins and their signaling pathways. Finally, peptide treatment was associated with a prominent inhibition of IL-13, a cytokine with tumor-promoting effects. The data indicate that the influences of alpha-MSH extend beyond the established anti-inflammatory effects in normal cells to include cell cycle regulatory properties in malignant cells.
 ...
PMID:Change in gene expression profile induced by alpha-melanocyte stimulating hormone in a malignant mesothelioma cell line. 1691 89

Rigid linkers of variable length were used to connect two high-affinity Nle4-D-Phe7-alpha-melanocyte stimulating hormone (NDP-alpha-MSH) or two low-affinity MSH(4) ligands. The linked peptides were synthesized by solid-phase methods. Control experiments indicate there is little or no effect of these linkers on NDP-alpha-MSH or MSH(4) binding to the human melanocortin 4 receptor (hMC4R). Tethering two high-affinity ligands gave no binding enhancement, while tethering two low-affinity ligands resulted in binding enhancement that decreased with increased linker length. Furthermore, for the low-affinity ligands, the enhancement of affinity is inversely proportional to the estimated molecular moments of inertia. These results are consistent with a model wherein binding is enhanced when the rate of ligand reattachment to the receptor is fast relative to the rate of ligand diffusion.
 ...
PMID:Rigid linkers for bioactive peptides. 1710 35

Mutations in the melanocortin-4 receptor (MC4R) are associated with early-onset obesity in humans. Furthermore, a null Mc4r allele in mice leads to severe obesity due to hyperphagia and decreased energy expenditure. As part of independent N-ethyl- N-nitrosourea (ENU) mutagenesis screens, two obesity mutants, Fatboy and Southbeach, were isolated. Mapping revealed linkage to the melanocortin-4 receptor (Mc4r) and sequencing found single amino acid changes in Mc4r for each line. Expression of the mutant receptors in HEK 293 cells revealed defects in receptor signaling. The mutated Fatboy receptor (I194T) shows an increase in the effective concentration necessary for 50% of maximal signaling (EC(50)) when stimulated with alpha-MSH. Based on competitive binding, I194T is expressed on the cell surface at lower levels than the nonmutated receptor. In contrast, Southbeach (L300P) displays minimal receptor signaling when stimulated with the natural ligand alpha-MSH or the synthetic agonist NDP-alpha-MSH. Cell surface binding is absent, which usually indicates a lack of cell surface expression. However, antibody binding to Flag-tagged receptors by flow cytometry analysis and immunofluorescence demonstrates that L300P is translocated to the plasma membrane at a level comparable to the wild-type receptor. These results indicate a correlation with remaining receptor activity and the severity of the obesity in the mice homozygous for the mutations. Southbeach has less receptor activity and becomes more obese. These mutants will serve as good models for the variability in phenotype in humans carrying mutations in the MC4R gene.
 ...
PMID:Point mutations in the melanocortin-4 receptor cause variable obesity in mice. 1714 85


<< Previous 1 2 3 4 5 6 7 Next >>