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)

Rats bearing kidney grafts of the pituitary pars intermedia were divided into three groups: unstressed, acutely stressed, and chronically stressed. Corresponding sham-operated rats were used for comparisons. Twenty days after grafting, the rats were sacrificed and alpha-melanocyte-stimulating hormone (alpha-MSH), adrenocorticotropin (ACTH), and corticosterone were estimated in plasma. The adrenal/body weight ratio and DNA content of the glands were also investigated. The following results were obtained: MSH was found not to be increased in unstressed rats, but it was in grafted animals subjected to acute and chronic swimming stress. ACTH and corticosterone rose in all three groups. Adrenal/body weight ratio and DNA content increased only in grafted chronically stressed rats. Moreover, plasma corticosterone was found higher in grafted hypophysectomized rats than in non-grafted hypophysectomized animals. Administration of ergocryptine to nonstressed grafted rats induced a decrease in the blood content of ACTH and MSH, indicating that the grafts were the source of a part of the circulating ACTH. On the other hand, the fall in MSH levels could show the effect of the drug upon the pars intermedia. Comparison of the ratios of both hormones released in incubations showed that grafts secreted more ACTH than MSH; on the other hand, when intact neurointermediate lobes were incubated, MSH predominated over ACTH. For the first time it is demonstrated that the pars intermedia can secrete ACTH in vivo. Nevertheless, the ability to secrete this hormone is not a property of normal intact pars intermedia, but it manifests in the transplantations probably due to the overactivity of light cells induced by chronic stoppage of dopaminergic inhibition.
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PMID:Secretion of melanocyte-stimulating hormone and adrenocorticotropin from transplanted pituitary pars intermedia in stressed and nonstressed rats. 254 38

Specific DNA sequence elements which contain binding sites for the glucocorticoid receptor mediate the action of glucocorticoid hormones on gene transcription. In glucocorticoid-inducible genes, these glucocorticoid-responsive elements behave as hormone-inducible enhancers of transcription. We have taken advantage of the bovine papillomavirus (BPV) system to test the stringency of glucocorticoid regulation of transcription. BPV episomes were constructed to contain two hormone-regulated transcription units in close proximity; one transcription unit is under control of a glucocorticoid-inducible promoter (mouse mammary tumor virus) while the other is under control of a glucocorticoid-inhibited promoter (pro-opiomelanocortin). Glucocorticoids independently regulated transcription of the two physically linked transcription units, irrespective of their relative orientation and of their proximity on the BPV episomes. This result contrasts with the so-called position-independent activity of enhancers and suggests that the multicomponent organization of eucaryotic promoters restricts the action of hormone-responsive regulatory elements to a specific transcription unit, thus accounting for the stringency of hormonal regulation observed in vivo.
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PMID:Independent glucocorticoid induction and repression of two contiguous responsive genes. 255 Jul 96

Glucocorticoids rapidly and specifically inhibit transcription of the pro-opiomelanocortin (POMC) gene in the anterior pituitary, thus offering a model for studying negative control of transcription in mammals. We have defined an element within the rat POMC gene 5'-flanking region that is required for glucocorticoid inhibition of POMC gene transcription in POMC-expressing pituitary tumor cells (AtT-20). This element contains an in vitro binding site for purified glucocorticoid receptor. Site-directed mutagenesis revealed that binding of the receptor to this site located at position base pair -63 is essential for glucocorticoid repression of transcription. Although related to the well-defined glucocorticoid response element (GRE) found in glucocorticoid-inducible genes, the DNA sequence of the POMC negative glucocorticoid response element (nGRE) differs significantly from the GRE consensus; this sequence divergence may result in different receptor-DNA interactions and may account at least in part for the opposite transcriptional properties of these elements. Hormone-dependent repression of POMC gene transcription may be due to binding of the receptor over a positive regulatory element of the promoter. Thus, repression may result from mutually exclusive binding of two DNA-binding proteins to overlapping DNA sequences.
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PMID:Glucocorticoid receptor binding to a specific DNA sequence is required for hormone-dependent repression of pro-opiomelanocortin gene transcription. 258 21

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.
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PMID:Expression and partial purification of human pro-opiomelanocortin in Escherichia coli. 267 85

The gene encoding pro-opiomelanocortin (POMC) is specifically expressed in two different cell types of the pituitary gland. We have defined the regulatory DNA sequences of the POMC gene that are responsible for this cell-specific expression. In addition, we have defined a regulatory element, located in the proximal region of the POMC promoter, that confers glucocorticoid repression in the anterior pituitary. Using DNA-mediated gene transfer into transgenic mice and tissue culture cells, the POMC regulatory sequences required for cell-specific expression and glucocorticoid repression were localized within a 543-bp fragment in the 5'-flanking region of the gene. Multiple regulatory elements that bind nuclear proteins are present within this region. In particular, a sequence that binds the glucocorticoid receptor and behaves as a "negative glucocorticoid response element" (nGRE) also binds nuclear proteins of the COUP (chicken ovalbumin upstream promoter) family of transcription factors. Thus, glucocorticoid repression of POMC transcription may result from the mutually exclusive binding of the glucocorticoid receptor and the COUP transcription factor to the POMC nGRE.
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PMID:Tissue-specific activity of the pro-opiomelanocortin (POMC) gene and repression by glucocorticoids. 269 28

The compound U74006F (21-[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl]-16 alpha-methyl- pregna-1,4,9(11)-triene-3,20-dione) is one of a novel series of 21-aminosteroids that are potent inhibitors of iron-dependent lipid peroxidation. Chronic (4-6 days) dosing of mice or rats with high doses of U74006F (30-200 mg/kg/day) has indicated that the compound is devoid of both glucocorticoid and mineralocorticoid activity. Although the compound is not a glucocorticoid antagonist, it markedly stimulated secretion of adrenocorticotropin by the murine pituitary tumor (AtT-20) cell. The enhanced secretion of adrenocorticotropin was not associated with an increased incorporation of [3H]thymidine or [14C]leucine into DNA or protein, respectively. Although not a glucocorticoid, U74006F also blocked the release of [14C]arachidonic acid from AtT-20 cells damaged by either Fe++ or the metabolic poison, iodoacetate. U74006F represents a novel class of antioxidant which displays cytoprotective activity and may uniquely affect cell growth or function in culture systems.
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PMID:A new 21-aminosteroid antioxidant lacking glucocorticoid activity stimulates adrenocorticotropin secretion and blocks arachidonic acid release from mouse pituitary tumor (AtT-20) cells. 283 38

Stimulation of adrenal DNA synthesis by ACTH and its fragments ACTH (Synacthen) and ACTH was investigated. Synthesis of DNA was measured as the increase in the percentage of cells in S-phase (Feulgen densitometry) in guinea-pig adrenal explants kept in organ culture and exposed to the peptides for 5 h at 37 degrees C. ACTH and its C-terminal fragment ACTH (corticotrophin-like intermediate lobe peptide) were found to be potent stimulators of in-vitro adrenal DNA synthesis. The dose-response kinetics were biphasic and optimal responsiveness was reached in both instances at 1 fmol/1-10 pmol/1 (this biological effect of ACTH has hitherto not been described). The N-terminal fragment ACTH gave only minimal responses. Thyrotrophin and LH, tested as controls, did not induce adrenal DNA synthesis. Epidermal growth factor was a potent stimulator of adrenal DNA synthesis in vitro. Our data suggest a trophic action of the C-terminal part of the corticotrophic molecule. Clear trophic effects were also found for the N-terminal part of the pro-opiomelanocortin molecule N-POC (optimum 0.1 nmol/l) and N-POC(51-62) (optimum 0.1 pmol/l). The latter observations support earlier concepts that this part of the pro-opiomelanocortin molecule has a stimulatory effect on adrenal DNA synthesis.
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PMID:Effects of ACTH and ACTH fragments on DNA synthesis in guinea-pig adrenal segments kept in organ culture. 283

In order to demonstrate the mitogenic effects of N-terminal pro-opiomelanocortin (N-POMC) peptides on the adrenal glands further, female rats with bilateral adrenal enucleation (hereafter referred to as enucleation) were hypophysectomized 11 days after enucleation and injected twice daily with 5 micrograms purified human N-POMC(1-28), ACTH(1-24) or 0.9% (w/v) NaCl. On day 14 after enucleation, rats were injected with colchicine and, after killing, their adrenal glands weighed, fixed and mitotic counts in histological sections assessed. Plasma corticosterone was measured fluorometrically. In other experiments, rats 7 days after enucleation were hypophysectomized and implanted with osmotic minipumps delivering 5 micrograms purified N-POMC(1-28) per day. On day 14 after enucleation, animals were treated as above. Collagenase-dispersed adrenal cells were incubated with purified or synthetic N-POMC(1-28) or synthetic N-POMC (1-36) (1-300 nmol/l) and [3H]thymidine incorporation into DNA was determined. Intact female rats were implanted with osmotic minipumps delivering 8 micrograms purified or synthetic N-POMC(1-28)/day, 8 micrograms synthetic N-POMC(1-36)/day or saline alone. Mitotic counts were performed on histological sections. Both s.c. injection or continuous delivery from minipumps of purified N-POMC(1-28) partially prevented the atrophy of regenerating adrenal glands after hypophysectomy (s.c. injection of N-POMC: 2.29 +/- 0.92 mitoses/section compared with 0.52 +/- 0.39 for controls; minipump delivery: 5.02 +/- 0.97 compared with 0.13 +/- 0.05; P less than 0.01 for both experiments). ACTH did not augment mitotic activity in enucleated-hypophysectomized rats but significantly increased plasma concentrations of corticosterone in s.c. injection experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Further evidence that N-terminal pro-opiomelanocortin peptides are involved in adrenal mitogenesis. 283 1

The sensitivity of the retinal pigment epithelium (RPE) to the melanotropic effects of alpha-MSH and dbcAMP was assayed in an organ culture of the eye scleral part in the Hunter rats with inherited retinal dystrophy. The melanin synthesis was estimated by liquid scintillation on the RPE isolated enzymatically after 48-h cultivation. One eye from every animal was cultivated in a medium without natural components and with the hormone or dbcAMP (experiment), while the other in a hormone-free medium (control). The melanin synthesis was estimated by 14C-thiouracil incorporation. The result was expressed as a cpm/microgram DNA (experiment) to cpm/microgram DNA (control) ratio. In addition, the index of labelled nuclei was determined using 3H-thymidine autoradiography in the central RPE zone of the eyes from young rats of the same litter. The experiments with alpha-MSH confirmed the earlier data according to which the RPE of the 3 day old Hunter rats were insensitive to melanotropic hormones. This was not due to defects in the cytoplasmic melanin-synthesizing system, since under the influence of dbcAMP the melanin synthesis in the RPE increases more than four-fold as compared with the control; dbcAMP stimulates also the total protein synthesis, as estimated by 3H-leucine incorporation. The RPE of the 4 day old rats proved to be sensitive to alpha-MSH: the melanin synthesis increases more than twice suggesting the healthy state of the RPE membrane melanotropic receptors. alpha-MSH also stimulates the total protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A hormone-sensitive stage in the development of the retinal pigment epithelium in Hunter rats with hereditary retinal dystrophy]. 283 21

Cultured human adrenal cortical adenocarcinoma cells (SW-13) form a confluent monolayer of epithelial-like cells when seeded into culture flasks. Following a 24-48 hr non-mitotic period, cells begin to divide and become confluent within a week after seeding at 5 X 10(4) cells/cm2. The SW-13 cells were exposed to dibutyryl cyclic AMP (DbcAMP), cyclic AMP (cAMP), sodium butyrate, and adrenocorticotropin (ACTH). The rate of SW-13 cell proliferation was measured with a DNA microfluorometric assay, as well as by procedures measuring the incorporation of 3H-thymidine. In addition, following administration of ACTH and DbcAMP, the fractional area of membrane covered by gap junctions was quantitated with freeze-fracture electron microscopic techniques. Dibutyryl cyclic AMP at a concentration of 1 X 10(-3) M decreased the growth rate of the cell population. There was a corresponding increase in the fractional area of gap junctions found on the cell membrane in 96-hr DbcAMP-treated cultures. ACTH (40 mU/ml) exposure failed to produce an increase in the fractional area of gap junctions or to alter the rate of cell proliferation. From these data it can be suggested that elevations in cAMP levels within the cell can be related to both the proliferation of gap junctions and the decrease in cell proliferation in the SW-13 tumor cell.
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PMID:Dibutyryl cyclic AMP modulation of gap junctions in SW-13 human adrenal cortical tumor cells. 283 94


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