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

While the transcriptional effects of glucocorticoid hormone manipulation on the pituitary pro-opiomelanocortin (POMC) gene have been documented, it is not yet clear whether glucocorticoids activate additional post-transcriptional mechanisms to regulate POMC gene expression. We have used RNA probes that span exon/intron junctions in sensitive nuclease protection assays in order to examine changes in POMC precursor RNA as well as mature mRNA in nucleus and cytoplasm following both adrenalectomy (ADX) and administration of exogenous glucocorticoids. ADX led to a rapid and sustained 8- to 10-fold increase in the level of POMC primary transcript in the anterior lobe (AL), from 1 to 14 days after ADX. Stimulation of mature POMC mRNA in the nucleus was also rapid, with 7- to 8-fold increases evident by 1 day after ADX. In sharp contrast, the time-dependent accumulation of POMC mRNA in the cytoplasm was slow in comparison, reaching levels approximately 2-fold higher than sham-operated animals by 1 day post-ADX and 12-fold higher by 14 days after ADX. Despite the constant elevated level of nuclear POMC precursor RNA, the rate of accumulation of POMC mRNA in the corticotroph cytoplasm after ADX was not linear, with the greatest increase occurring within the first 1-4 days post-ADX. This led to alterations in the molar ratio of POMC primary transcript: nuclear mRNA: cytoplasmic mRNA in the AL at 1 and 4 days after ADX and showed a relative increase in the proportion of POMC RNA transcripts within the nucleus. Acute administration of dexamethasone to ADX rats resulted in rapid 80-90% inhibition of POMC primary transcript levels in the AL that was maximal by 30 min but with no associated change in mature mRNA. No significant changes in POMC RNA were seen in neurointermediate lobe in any of these studies. These studies suggest that following ADX, time-dependent alterations in nuclear transport of mature POMC mRNA and/or changes in POMC mRNA stability, in addition to changes in gene transcription may account for the overall level of POMC mRNA expressed in the AL. Furthermore, we have illustrated the use of exon/intron probes for accurately quantitating rapid alterations in steady-state levels of nuclear precursor RNA that may reflect transcriptional responses and/or changes in post-transcriptional processing of the primary transcript.
Mol Cell Endocrinol 1989 Oct
PMID:Changes in rat pituitary nuclear and cytoplasmic pro-opiomelanocortin RNAs associated with adrenalectomy and glucocorticoid replacement. 261 30

We describe here the in situ hybridization procedure which we have used to detect the pro-opiomelanocortin (POMC) gene primary transcript in nuclei of individual neurons in the periarcuate region of the hypothalamus. An exon-intron RNA probe was used to detect POMC primary transcript and mature mRNA in nuclear extracts of nucleic acids using a sensitive S1 nuclease protection assay. The levels per cell of nuclear primary transcript were similar to those seen in the anterior pituitary, suggesting that intervening sequence in situ hybridization should be feasible. A nonrepetitive complementary RNA probe specific for the first intervening sequence of the rat POMC gene (POMC IVS-A) was used to detect the POMC primary transcript in hypothalamic tissue sections by in situ hybridization. The distribution of nuclear localized autoradiographic grains was similar to that previously reported for immunocytochemically defined POMC neurons, suggesting that the procedure is also effective in brain cells.
Brain Res Mol Brain Res 1989 Nov
PMID:Intervening sequence-specific in situ hybridization: detection of the pro-opiomelanocortin gene primary transcript in individual neurons. 261 95

A large portion of the human pro-opiomelanocortin (POMC) peptide corresponding to amino acid residues 59-241 has been cloned and expressed in Escherichia coli. A 1.0 kb DNA fragment encoding this peptide was cloned into the expression vectors pUC8 and pUR291. Plasmid pJMBG51 (a pUC8 recombinant) was found to direct the expression of a 24 kDa peptide. The recombinant pUR291 (pJMBG52) was shown to produce a beta-galactosidase fusion protein of 140 kDa. Western blot analysis showed that both the 24 kDa and 140 kDa peptides are recognized by antibodies raised against POMC-derived peptides. The beta-galactosidase fusion protein has been partially purified from crude E. coli cell lysates using affinity chromatography on p-amino-benzyl-1-thio-beta-D-galactopyranoside agarose.
J Mol Endocrinol 1989 Sep
PMID:Expression and partial purification of human pro-opiomelanocortin in Escherichia coli. 267 85

Using a semi-empirical method, and a priori conformational analysis of the tridecapeptide alpha-melanocyte-stimulating (alpha-MSH) was carried out. The spatial structure of alpha-MSH can be described by ten low-energy conformations. Calculations produced the values of all dihedral angles of the backbones and side chains of these forms as well as intra- and inter-residue interaction energies.
Mol Biol (Mosk)
PMID:[Structural organization of alpha-melanotropin molecules]. 273 44

As an approach to understanding the abnormalities of pro-opiomelanocortin (POMC) gene regulation in human ACTH-secreting tumours, we have analysed the POMC mRNA content of nine such tumours using the Northern blot technique. Most of the tumours and normal human pituitary contained easily detectable quantities of POMC mRNA. The length of this message in most tumours was similar to, or slightly larger than, that in the normal pituitary (1150-1200 bases). Ribonuclease H studies suggested that the origin of any size heterogeneity was a longer poly(A) tail in the tumour RNA. Some tumours, however, expressed a short POMC mRNA (800 bases) which may lack the first two exons of the POMC gene as has been described. A third POMC mRNA size variant (1500 bases) was also seen in low levels in two cases, and as the principal mRNA species in one case. Primer extension and S1 nuclease protection studies suggested that most transcripts in the tumours analysed originated from the conventional promoter, and thus the use of an alternative promoter is not an adequate explanation for the expression of this gene in ectopic ACTH-secreting tumours.
J Mol Endocrinol 1989 Jan
PMID:Pro-opiomelanocortin mRNA size heterogeneity in ACTH-dependent Cushing's syndrome. 276 13

The effects of the protein kinase C activator, phorbol myristate acetate (PMA), on cytosolic calcium levels and adrenocorticotropin (ACTH) release from the mouse anterior pituitary tumor cell line, AtT-20, were compared to those induced by the hormone, corticotropin-releasing factor (CRF), a stimulant of cAMP-dependent protein kinase activity. Cytosolic calcium levels were measured using the fluorescence probe Quin 2. PMA induced a time- and concentration-dependent rise in cytosolic calcium levels and ACTH release from AtT-20 cells that was blocked by verapamil and nifedipine, antagonists of voltage-regulated calcium channels, and tetraethylammonium (TEA), a K+ channel antagonist. The inactive phorbol ester, 4-phorbol 12,13-didecanoate, did not alter cytosolic calcium levels or ACTH release. Several minutes after the initial stimulation of calcium influx by PMA, cytosolic calcium levels returned to basal levels despite the continued presence of the phorbol ester. A short pretreatment (2-4 min) of AtT-20 cells with PMA abolished the ability of K+, CRF, and forskolin to raise intracellular calcium levels. These findings indicate that phorbol esters induce a secondary inhibition of calcium influx after an initial stimulation. In contrast to the effects of PMA, CRF induced a sustained rise in cytosolic calcium levels and did not reduce the subsequent stimulation of calcium influx by K+ or PMA. CRF-stimulated calcium influx was blocked by verapamil but not TEA. The ability of CRF to elevate cytosolic calcium levels was mediated by cAMP-dependent protein kinase because the insertion of a synthetic peptide inhibitor of cAMP-dependent protein kinase activity into AtT-20 cells attenuated the ability of CRF and forskolin but not PMA to raise cytosolic calcium levels. The results suggest that activators of protein kinase C and cAMP-dependent protein kinase regulate intracellular calcium levels in AtT-20 cells through different mechanisms.
Mol Pharmacol 1987 Oct
PMID:Activators of protein kinase C and cyclic AMP-dependent protein kinase regulate intracellular calcium levels through distinct mechanisms in mouse anterior pituitary tumor cells. 282 94

The properties of [125I]beta h-endorphin-binding sites from rat brain membranes and membranes from the NG108-15 cell line were compared using a monoclonal antibody directed against the opioid receptor and opioid peptides as probes. The binding of [125I]beta h-endorphin to both rat brain and NG108-15 membranes yielded linear Scatchard plots with Kd values of 1.2 nM and 1.5 nM, respectively, and Bmax values of 865 fmol/mg rat brain membrane protein and 1077 fmol/mg NG108-15 membrane protein. A monoclonal antibody, OR-689.2.4, capable of inhibiting mu and delta binding but not kappa binding to rat brain membranes, noncompetitively inhibited the binding of 1 nM [125I]beta h-endorphin to rat brain and NG108-15 membranes with an IC50 value of 405 nM for rat brain membranes and 543 nM for NG108-15 membranes. The monoclonal antibody also inhibited the binding of 3 nM [3H] [D-penicillamine2, D-penicillamine5] enkephalin to NG108-15 membranes with an IC50 value of 370 nM. In addition to blocking the binding of [125I]beta h-endorphin to brain membranes, the antibody also displaced [125I]beta h-endorphin from membranes. Site-specific opioid peptides had large variations in their IC50 values depending on whether they were inhibiting [125I]beta h-endorphin binding to rat brain or the NG108-15 membranes. When the peptides were tested with the monoclonal antibody for their combined ability to inhibit [125I]beta h-endorphin binding to both membrane preparations, the peptides and antibody blocked binding as though they were acting at allosterically coupled sites, not two totally independent sites. These studies suggest that mu-, delta-, and beta-endorphin-binding sites share some sequence homology with the 35,000-dalton protein that the antibody is directed against.
Mol Pharmacol 1988 Feb
PMID:Comparison of [125I]beta-endorphin binding to rat brain and NG108-15 cells using a monoclonal antibody directed against the opioid receptor. 282 12

The xenograft line, UCRU-PR-2, has been characterized further. Established from a primary human undifferentiated small cell carcinoma of the prostate, it has been maintained as a stable xenograft line in nude mice and is currently in passage 9. The tumor has maintained the features of small cell undifferentiated carcinoma but shows epithelial as well as neuroendocrine characteristics. In this paper, we describe synthesis and secretion of peptide hormones, ACTH, beta-endorphin and somatostatin in vivo and ACTH and beta-endorphin in vitro by the tumor, UCRU-PR-2. This suggests that the gene for proopiomelanocortin is expressed and that processing of the molecule occurs. This line may yield insights into the histogenesis of the subtypes of prostate cancer, and also aid studies of regulation of ectopic hormone production.
Mol Cell Endocrinol 1988 Feb
PMID:Ectopic hormone production by a prostatic small cell carcinoma xenograft line. 283 15

Immunoreactive (IR) POMC peptides have been detected in several human nonpituitary tissues and most pheochromocytomas and lung cancers, including those not associated with ectopic ACTH syndrome. We found IR-ACTH, IR-gamma MSH, IR-beta-endorphin (beta END), and IR-lipotropin in extracts from the following 10 normal human tissues, listed in order of decreasing POMC peptide concentrations: adrenal, testis, spleen, kidney, ovary, lung, thyroid, liver, colon, and duodenum. IR-ACTH, IR-gamma MSH, and IR-beta END were detected in all six pheochromocytomas and all 12 lung tumors (six squamous cell carcinomas, five adenocarcinomas, and one small cell carcinoma) we examined, as well as in a squamous cell carcinoma of the larynx. None of the patients had clinical evidence of ectopic ACTH syndrome. To determine whether these nonpituitary tissues and tumors actually synthesize POMC, rather than simply absorb POMC peptides from plasma, we examined poly(A) RNA prepared from these tissues and total RNA from pituitary by Northern blot hybridization for the presence of POMC-like mRNA with an exon 3 riboprobe. Pituitary contained a single POMC mRNA species of about 1150 bases. A short POMC-like mRNA of about 900 bases was found in all normal nonpituitary tissues, three of five pheochromocytomas, eight of nine lung cancers, and the laryngeal squamous cell tumor. In addition, larger POMC-like mRNA species between 1200 to 1500 bases were detected in adrenal, testis, ovary, placenta, two pheochromocytomas, and three squamous cell lung tumors.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1988 Sep
PMID:Proopiomelanocortin gene is expressed in many normal human tissues and in tumors not associated with ectopic adrenocorticotropin syndrome. 284 57

A monoclonal antibody generated against the tertiary structure of a partially purified opioid binding protein was used to probe the structure of the dynorphin and beta-endorphin receptors. The Fab fragment 3B4F11 inhibited completely the binding of 125I-beta-endorphin and [3H]dynorphin to rat brain P2 membranes with IC50 values of 26 ng/ml and 40 ng/ml, respectively. To explore further the interaction of 3B4F11 with the beta-endorphin receptor, the effect of the Fab fragment on 125I-beta-endorphin cross-linking to rat brain membranes was examined. 125I-beta-endorphin was covalently bound to three major species of approximate molecular weights 108,000, 73,000, and 49,000. The delta-selective ligand D-Pen2, D-pen5enkephalin was least effective at inhibiting the cross-linking of beta-endorphin, whereas the micro-selective ligand Tyr-D-Ala-Gly-NMe-Phe-Gly-ol and kappa-selective ligand U50488 inhibited beta-endorphin cross-linking to the 108,000 and 73,000 Da species. Both 3B4F11 and beta-endorphin prevented the covalent binding of 125I-beta-endorphin to all three labeled species. These findings suggest that micro and kappa receptor types might have some structural similarities, whereas the delta receptor type might differ in molecular size. In addition, the micro, kappa, and delta ligands might have different primary sequences, whereas their tertiary structures might share regions of molecular homology with all three receptor constituents labeled by 125I-beta-endorphin. 3B4F11 will be a valuable tool for the purification and isolation of the several components of the beta-endorphin receptor complex.
Mol Pharmacol 1988 Nov
PMID:Identification of endogenous opioid receptor components in rat brain using a monoclonal antibody. 284 85


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>