Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have combined gene cloning with an assay for prohormone biosynthesis and processing in Xenopus oocytes to identify the genes that encode mammalian prohormone processing enzymes. The coinjection of RNA encoding murine prohormone convertase 1 (mPC1), a mammalian endoprotease, along with proopiomelanocortin RNA into an oocyte results in the appropriate cleavage after paired basic residues in the proopiomelanocortin polyprotein necessary to generate corticotropin. The ability of mPC1 to generate corticotropin, along with the observation that mPC1 is specifically expressed in endocrine and neuronal cells, suggests that the mPC1 gene encodes the endopeptidase responsible for the pathway of proopiomelanocortin cleavage observed in the anterior pituitary.
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PMID:Isolation and functional expression of a mammalian prohormone processing enzyme, murine prohormone convertase 1. 186 7

Vesicular transport within the secretory pathway can be arrested by incubating cells at 15 degrees C or 20 degrees C to block exit from the endoplasmic reticulum or trans-Golgi network, respectively. Using this powerful tool we have compared the intracellular sites of endoproteolytic processing of proopiomelanocortin and two prohormone processing enzymes in AtT-20 mouse pituitary corticotrope tumor cells. For comparison, proopiomelanocortin processing was also evaluated in primary neurointermediate pituitary cultures. AtT-20 cells synthesize and store endogenous proopiomelanocortin and prohormone convertase 1; AtT-20 cells expressing high levels of integral membrane or soluble peptidylglycine alpha-amidating monooxygenase were generated by stable transfection. Cells were incubated with [35S]methionine and chased at 4 degrees C, 15 degrees C, 20 degrees C or 37 degrees C. The endoproteolytic processing of peptidylglycine alpha-amidating mono-oxygenase, prohormone convertase 1, and proopiomelanocortin was compared following immunoprecipitation. Endoproteolytic processing of integral membrane and soluble peptidylglycine alpha-amidating monooxygenase proteins was completely blocked by incubation of cells at 20 degrees C. In contrast, prohormone convertase 1 processing from the 87 kDa precursor to the 81 kDa intermediate proceeded to completion at both 15 degrees C and 20 degrees C, while cleavage to generate the 63 kDa prohormone convertase 1 protein was completely blocked at 20 degrees C. In AtT-20 cells and neurointermediate pituitary cultures, generation of beta-lipotropin from proopiomelanocortin continued at a slow but significant rate at 20 degrees C, while processing of beta-lipotropin to beta-endorphin was blocked. Thus prohormone convertase 1 processing begins in the endoplasmic reticulum and is not completed until after the trans-Golgi network, while peptidylglycine alpha-amidating monooxygenase processing begins after the trans-Golgi network. Selected proopiomelanocortin cleavages begin before entry into immature granules.
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PMID:Differential effects of temperature blockade on the proteolytic processing of three secretory granule-associated proteins. 800 87

GVHD in animal models induces severe thymic atrophy as a result of prolonged secretion of high concentrations of adrenal glucocorticoids. In this study we investigated the mechanism responsible for the persistent stimulation of the adrenal glands to secrete glucocorticoids in mice undergoing GVHD. GVHD was induced across the major and multiple minor histocompatibility antigen difference in unirradiated C57Bl/6 x AF1 hybrid mice by the intravenous injection of A strain parental lymphoid cells. Our results showed plasma corticosterone (CS) levels were elevated in association with high concentrations of corticotropin (ACTH) in both the GVHD and control syngeneic (SYN) groups on day 9. By days 16 and 24, plasma CS and ACTH in the SYN mice returned to basal levels. In contrast, plasma CS levels remained elevated in the GVHD animals on days 16 and 24 despite decreasing concentrations of plasma ACTH. Reverse transcription-polymerase chain reaction (RT-PCR) showed several-fold increase in POMC mRNA in the adrenal glands of GVHD mice compared with SYN animals. In addition, high mRNA levels for murine prohormone convertase 1, the enzyme that cleaves POMC into ACTH, were also detected in GVHD adrenals. Histological analysis of GVHD adrenals failed to show any sign of adrenalitis, and RT-PCR of GVHD adrenals also failed to detect mRNA for interferon-gamma (IFN-gamma), a cytokine expressed by activated T and natural killer (NK) cells. However, mRNA for IL-12, a cytokine produced by activated macrophages, was increased in GVHD adrenals, suggesting that resident adrenal macrophages were activated during GVHD. Our findings suggest that persistent elevated levels of plasma glucocorticoids during GVHD could be mediated by intra-adrenal ACTH produced by resident adrenal macrophages activated as a consequence of GVHD.
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PMID:Increased expression of proopiomelanocortin (POMC) mRNA in adrenal glands of mice undergoing graft-versus-host disease (GVHD): association with persistent elevated plasma corticosterone levels. 853 78

Prohormone substrates are required for investigation of the proteolytic processing of prohormones and proproteins into active peptide hormones and neurotransmitters. However, the lack of prohormone proteins has been a limiting factor in elucidating proteolytic mechanisms for conversion of prohormones into active peptides. Therefore, in this study, cloned cDNAs encoding the prohormones proenkephalin (PE), pro-neuropeptide Y (pro-NPY), pro-opiomelanocortin (POMC), and beta-protachykinin (beta-PT) were utilized to express recombinant prohormones in Escherichia coli. High-level expression of milligrams of prohormones was achieved with the pET3c expression vector utilizing the T7 promoter for production of PE, pro-NPY, and POMC, as demonstrated by SDS-PAGE gel electrophoresis, Western blots, and 35S-methionine labeling. In addition, beta-PT was expressed at high levels as fusion proteins with the maltose-binding protein and glutathione S-transferase by the pMAL-c and pGEX-2T expression vectors, respectively. Relative rates of processing by the established processing proteases "prohormone thiol protease" (PTP), 70-kDa aspartyl protease, and PC1/ 3 and PC2 (PC, prohormone convertase) were examined with purified PE, pro-NPY, and POMC. Distinct preferences of processing enzymes for different prohormones was demonstrated. PTP preferred PE and pro-NPY substrates, whereas little processing of POMC was detected. In contrast, the 70-kDa aspartyl protease cleaved POMC more readily than pro-NPY or PE. However, PC1/3 and PC2 prefer POMC as substrate. Demonstration of selectivity of processing enzymes for prohormone substrates illustrates the importance of expressing recombinant prohormones for in vitro processing studies.
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PMID:High-level expression of the prohormones proenkephalin, pro-neuropeptide Y, proopiomelanocortin, and beta-protachykinin for in vitro prohormone processing. 917 94

Human obesity has an inherited component, but in contrast to rodent obesity, precise genetic defects have yet to be defined. A mutation of carboxypeptidase E (CPE), an enzyme active in the processing and sorting of prohormones, causes obesity in the fat/fat mouse. We have previously described a women with extreme childhood obesity (Fig. 1), abnormal glucose homeostasis, hypogonadotrophic hypogonadism, hypocortisolism and elevated plasma proinsulin and pro-opiomelanocortin (POMC) concentrations but a very low insulin level, suggestive of a defective prohormone processing by the endopeptidase, prohormone convertase 1 (PC1; ref. 4). We now report this proband to be a compound heterozygote for mutations in PC1. Gly-->Arg483 prevents processing of proPC1 and leads to its retention in the endoplasmic reticulum (ER). A-->C+4 of the intro-5 donor splice site causes skipping of exon 5 leading to loss of 26 residues, a frameshift and creation of a premature stop codon within the catalytic domain. PC1 acts proximally to CPE in the pathway of post-translational processing of prohormones and neuropeptides. In view of the similarity between the proband and the fat/fat mouse phenotype, we infer that molecular defects in prohormone conversion may represent a generic mechanism for obesity, common to humans and rodents.
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PMID:Obesity and impaired prohormone processing associated with mutations in the human prohormone convertase 1 gene. 920 82

Prohormone convertase (PC) 1/3 and PC2 are involved in post-translational processing of endocrine tissues, including the pancreatic islets and pituitary glands. Our immunohistochemical studies disclosed the presence of PC1/3 and PC2 in non-neoplastic pituitary glands, especially in corticotrophs, gonadotrophs, and thyrotrophs. Among 58 pituitary adenomas obtained by trans-sphenoidal surgery, adrenocorticotropin (ACTH)-secreting adenomas showed a high incidence of the presence of PC1/3 and PC2, i.e., nine of nine cases were positive for ACTH. Five of nine cases showed consistency between PC2 localization and alpha-melanocyte stimulating hormone immunoreactivity, which suggests the functional correlation between PC2 and the processing of ACTH. In four cases, we observed inconsistency in immunolocalization, which suggested the possibility of inactive PC2 and abnormal processing of alpha-melanocyte stimulating hormone. The high incidence of PC1/3 and PC2 in nonfunctioning adenomas might be related to the processing of chromogranin A.
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PMID:Localization of prohormone convertases 1/3 and 2 in the human pituitary gland and pituitary adenomas: analysis by immunohistochemistry, immunoelectron microscopy, and laser scanning microscopy. 952 68

Recently, great progress has been made towards understanding the molecular basis of body fat regulation. Identification of mutations in several genes in spontaneous monogenic animal models of obesity and development of transgenic models have indicated the physiological roles of many genes in the regulation of body fat distribution. In humans, mutations in leptin, leptin receptor, prohormone convertase 1 (PC1), pro-opiomelanocortin (POMC), melanocortin 4-receptor (MC4-R), and peroxisome proliferator-activated receptor (PPAR) gamma2 genes have been described in patients with severe obesity. Most of these obesity disorders exhibit a distinct phenotype with varying degrees of hypothalamic and pituitary dysfunction and a recessive inheritance, whereas MC4-R mutation has a nonsyndromic phenotype with dominant inheritance. These mutations suggest the critical role of central signaling systems composed of leptin/leptin receptor and alpha-melanocyte stimulating hormone/MC4-R in human energy homeostasis. Although the genetic basis of monogenic disorders of body fat distribution, such as congenital generalized lipodystrophy and familial partial lipodystrophy, Dunnigan variety, is still unknown, the genes for these have recently been localized to chromosomes 9q34 and 1q21-22, respectively. The advances in our knowledge of the phenotypic manifestations and underlying molecular mechanisms of genetic body fat disorders may lead to better treatment and prevention of obesity and other disorders of adipose tissue in the future.
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PMID:Monogenic disorders of obesity and body fat distribution. 1050 93

The processing of pro-opiomelanocortin (POMC) to generate bioactive ACTH in the anterior pituitary is mediated by prohormone convertase 1 (PC1). Leukemia inhibitory factor (LIF) and interleukin 6 (IL-6), two cytokines sharing the common gp130 receptor subunit and functioning through activation of the intracellular JAK/STAT pathway, induce POMC synthesis and ACTH release. We investigated the effects of LIF and IL-6 on PC1 expression and its subsequent processing of POMC. A significant time-dependent up-regulation of both PC1 protein and mRNA by LIF and IL-6 was seen in mouse corticotroph AtT-20 cells. IL-6 or LIF increased the synthesis of ACTH-related products with a concomitant increase in bioactive 5 and 13 kDa ACTH indicating coordinated regulation of substrate and processing enzyme. AtT-20 cells transiently transfected with a human PC1-promoter-luciferase reporter construct and treated with LIF or IL-6 showed significantly increased luciferase activity. Additionally, lipopolysaccharide (LPS) administration to rats resulted in an increase in both pituitary PC1 and POMC mRNA. These findings suggest that the ACTH increase induced by LIF and IL-6 is due to both increased POMC synthesis as well as increased POMC processing by up-regulation of PC1. These two coordinately regulated processing events probably exert central roles in the pathophysiological response to some stresses, such as inflammatory stress.
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PMID:Regulation of prohormone convertase 1 (PC1) by gp130-related cytokines. 1063 Apr 14

Human dermal microvascular endothelial cells (HDMEC) are capable of mediating leukocyte-endothelial interactions by the expression of cellular adhesion molecules and the release of proinflammatory cytokines and chemokines during cutaneous inflammation. Recent studies support the important role for proopiomelanocortin (POMC) peptides, such as alpha-melanocyte stimulating hormone (alpha-MSH), as immunomodulators in the cutaneous immune system. The purpose of the studies described here was to determine whether HDMEC serves as both target and source for POMC peptides. RT-PCR and Northern blot studies demonstrated the constitutive expression of mRNA for the adrenocorticotropin (ACTH) and alpha-MSH-specific melanocortin receptor 1 (MC-1R) in HDMEC, and the microvascular endothelial cell line HMEC-1 that could be upregulated by stimulation with IL-1 beta and alpha-MSH. HDMEC responded to stimulation by alpha-MSH with a dose- and time-dependent synthesis and release of the CXC chemokines, IL-8 and GRO alpha. Likewise, alpha-MSH augmented HDMEC chemokine release induced by TNF or IL-1. HD-MEC were found to constitutively express POMC and prohormone convertase 1 (PC-1); the latter being required to generate ACTH from the POMC prohormone. POMC and PC-1 mRNA expression are increased as a result of stimulation with UVB and UVA1 radiation, IL-1, and alpha-MSH. In addition, UV-radiation is capable of inducing the release of HDMEC, ACTH, and alpha-MSH in a time- and dose-dependent fashion. Thus, these data provide evidence that HDMEC are capable of expressing functional MC-1R, POMC, and PC-1 mRNA; and of releasing POMC peptides with UV light, IL-1, and alpha-MSH as regulatory factors. The expression and regulation of these peptides may be of importance, not only for the autocrine or paracrine regulation of physiologic functions of dermal endothelial cells, but also for the regulation of certain microvascular-mediated cutaneous or systemic inflammatory responses.
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PMID:Expression of functional melanocortin receptors and proopiomelanocortin peptides by human dermal microvascular endothelial cells. 1081 57

Proopiomelanocortin peptides such as alpha-melanocyte-stimulating hormone and adrenocorticotropin are expressed in the epidermal and dermal compartment of the skin after noxious stimuli and are recognized as modulators of immune and inflammatory reactions. Human dermal microvascular endothelial cells mediate leukocyte-endothelial interactions during cutaneous inflammation by the expression of cellular adhesion molecules and cytokines such as interleukin-1. This study addresses the hypothesis that human dermal microvascular endothelial cells express both proopiomelanocortin and prohormone convertases, which are required to generate proopiomelanocortin peptides. Semiquantitative reverse transcriptase polymerase chain reaction and northern blot studies revealed a constitutive expression of proopiomelanocortin mRNA by human dermal microvascular endothelial cells in vitro that was time- and concentration-dependently upregulated by interleukin-1 beta. Furthermore, irradiation of human dermal microvascular endothelial cells with ultraviolet A1 (30J per cm(2)) or ultraviolet B (12.5 mJ per cm(2)) enhanced proopiomelanocortin expression as well as the production and release of the proopiomelanocortin peptides adrenocorticotropin and alpha-melanocyte-stimulating hormone. In addition to proopiomelanocortin, prohormone convertase 1 mRNA expression was detected by reverse transcriptase polymerase chain reaction in unstimulated human dermal microvascular endothelial cells and was augmented after exposure to alpha-melanocyte- stimulating hormone, interleukin-1 beta, or irradiation with ultraviolet. These findings demonstrate that human dermal microvascular endothelial cells express proopiomelanocortin and prohormone convertase 1 required for the generation of adrenocorticotropin. Additionally, human dermal microvascular endothelial cells express mRNA for the prohormone convertase 2 binding protein 7B2. Taken together these findings indicate that human dermal microvascular endothelial cells upon stimulation express both proopiomelanocortin and prohormone convertases required for the generation of alpha-melanocyte-stimulating hormone. As proopiomelanocortin peptides were found to regulate the production of human dermal microvascular endothelial cell cytokines and adhesion molecules and to have a variety of anti-inflammatory properties these peptides may significantly contribute to the modulation of skin inflammation. J Invest Dermatol 115:1021-1028 2000
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PMID:Expression of proopiomelanocortin peptides in human dermal microvascular endothelial cells: evidence for a regulation by ultraviolet light and interleukin-1. 1112 Nov 36


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