Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Melanocortins (alphaMSH and ACTH-related peptides) influence the physiological functions of certain peripheral organs, including exocrine and endocrine glands. This study was designed to determine the identity and anatomical localization of the melanocortin receptors (MC-R) expressed in these organs in the rat. MC5-R messenger RNA was found in exocrine glands, including lacrimal, Harderian, preputial, and prostate glands and pancreas, as well as in adrenal gland, esophagus, and thymus, as demonstrated by ribonuclease protection assays. In exocrine glands, MC5-R messenger RNA expression was restricted to secretory epithelia. MC-R protein was likewise present in secretory epithelia of exocrine glands, as determined by 125I-labeled [Nle4,D-Phe7]alphaMSH ([125I]NDP-MSH) binding and autoradiography in tissue sections. Specific [125I]NDP-MSH binding was also observed in adrenal cortex, thymus, spleen, and esophageal and trachealis muscle. MC receptors in these sites are accessible to circulating MC-R agonists in vivo, as specific binding of [125I]NDP-MSH was observed in exocrine and adrenal glands after systemic injection in vivo. Taken together, these findings show that the MC5 receptor is commonly and selectively expressed in exocrine glands and other peripheral organs. Based on these findings and compelling evidence from other studies, a functional coherence is suggested between central and peripheral actions of melanocortins and melanocortin receptors in physiological functions, including thermoregulation, immunomodulation, and sexual behavior.
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PMID:Expression of melanocortin-5 receptor in secretory epithelia supports a functional role in exocrine and endocrine glands. 956 44

Expression of melanocortin-4 receptor (MC4R) mRNA in developing rat limb buds, teeth, and skull bone first indicated a possible role for MC4R in bone metabolism. We therefore investigated whether MC4R mRNA was expressed in the rat osteosarcoma UMR106.06 cell line and in primary rat osteoblast cells. Reverse transcriptase-polymerase chain reaction (RT-PCR), Northern blot analysis, and ribonuclease protection assay (RPA) were used to demonstrate MC4R mRNA expression in UMR106.06 and primary osteoblast cells. MC4R mRNA was found to be localized to the periosteum of mouse bone using in situ hybridization. We also used RT-PCR and rat specific MC2R and MC5R oligonucleotides to amplify the correct size DNA fragments for these melanocortin receptors from rat primary osteoblasts. In conclusion, melanocortin receptor expression in mouse periosteum and rat osteoblasts suggests a direct role for POMC derived peptides in bone development and bone metabolism.
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PMID:Evidence for direct actions of melanocortin peptides on bone metabolism. 1597 63