UNIPROT:P01189 - FACTA Search

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Query: UNIPROT:P01189 (beta-endorphin)
21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracts of rat anterior and intermediate-posterior pituitary were fractionated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and assayed for immunoactive ACTH and endorphin. In both lobes the major forms of immunoactive ACTH have apparent molecular weights of 31,000 (31K), 20--21K, 14K, and 4.5K, and the major forms of immunoactive endorphin have apparent molecular weights of 31K (coincident with the peak of immunoactive ACTH), 13K (a betaLPH-like peptide), and 3.5K (a beta-endorphin-like peptide). However, the quantitative distribution of immunoactivity among the various forms differs greatly between the lobes. Assays using an extreme COOH-terminal ACTH antiserum indicate that the 31K ACTH/endorphin molecule in rat anterior and intermediate pituitary is similar to the pro-ACTH/endorphin molecule from mouse pituitary tumor cells. A radioimmunoassay that is specific for the NH2-terminal non-ACTH, nonendorphin segment (referred to as 16K fragment) of the mouse pro-ACTH/endorphin molecule was used to assay extracts of rat pituitary. In addition to detecting material at 31K and 20--21K, the 16K fragment radioimmunoassay detects significant amounts of cross-reactive material with an apparent molecular weight of 16K in extracts of both lobes. This result also suggests that the structure and processing of the rat 31K ACTH/endorphin molecule is similar to that of mouse tumor cell pro-ACTH/endorphin. Cell suspensions were prepared from the anterior and intermediate lobes of the rat pituitary and maintained in culture for a 24-h period. The isolated cells from both lobes incorporate [3H] phenylalanine into immunoprecipitable ACTH- and endorphin-containing molecules. By sequential immunoprecipitation with ACTH and endorphin antisera, it is possible to demonstrate directly that a single molecule (31K ACTH/endorphin) has antigenic determinants for both ACTH and endorphin. Significant amounts of 31K ACTH/endorphin are released into the culture medium by isolated anterior lobe and intermediate lobe cells. The isolated intermediate lobe cells synthesize and secrete relatively large amounts of a beta-endorphin-like molecule; the isolated anterior lobe cells secrete significant amounts of both a betaLPH-like molecule and a beta-endorphin-like molecule. These same quantitative differences between anterior and intermediate lobe tissue were observed in immunoassays of extracts of the separated lobes and probably reflect differences in the processing of the common precursor. The isolated anterior lobe cells can be stimulated to release increased amounts of immunoprecipitable ACTH and endorphin by incubation with a cyclic AMP analog and a phosphodiesterase inhibitor.
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PMID:Existence of a common precursor to ACTH and endorphin in the anterior and intermediate lobes of the rat pituitary. 8 77

Lipolysis in isolated swine adipocytes was stimulated by epinephrine, dibutyryl cyclic AMP, and weakly by adrenocorticotropin but not by glucagon or cyclic AMP. Theophylline, a phosphodiesterase inhibitor, stimulated lipolysis and greatly enhanced the activity of adrenocorticotropin. The epinephrine-stimulated lipolytic activity, expressed on a tissue or cell volume basis, was greatest at 25 days postpartum, whereas, expressed on a cell basis, the activity was maximal at day 80. Regardless of the mode of expression, the activity at day 150 was low. Cells from younger animals were more sensitive to epinephrine than cells from older animals.
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PMID:Lipolytic activity of swine adipocytes. 17 32

Cyclic AMP and cyclic GMP phosphodiesterase activities (3',5'-cyclic AMP 5'-nucleotidohydrolase, EC 3.1.4.17) were investigated in the human thyroid gland from patients with hyperthyroidism. Low substrate concentration (0.4 muM) was used. About 60% of the cyclic-AMP and 80% of the cyclic-GMP hydrolytic activities in the homogenate were obtained in the soluble fraction (105 000 X g supernatant). The thyroid gland contains two forms of cyclic-AMP phosphodiesterase, one with a Km of 1.3-10(-5) M and the second with a Km of 2-10(-6) M. Cyclic-AMP and cyclic-GMP phosphodiesterase were purified by gel filtration on a Sepharose-6B column. Cyclic-AMP phosphodiesterase activities were found in a broad area corresponding to molecular weights ranging from approx. 200 000 to 250 000 and cyclic-GMP phosphodiesterase activity was found in a single area corresponding to a molecular weight of 260 000. Cyclis-AMP phosphodiesterase activities were stimulated by the protein activator which was found in human thyroid and this stimulation was dependent on Ca2+. Stimulation of cyclic-AMP phosphodiesterase by the activator was not significant even in the presence of enough Ca2+. The effect of D,L-triiodothyronine, D,L-thyroxine, L-diiodotyrosine, L-monoiodotyrosine, L-thyronine, L-diiodothyronine, thyrotropin, hydrocortisone, adrenocorticotropin, cyclic-AMP and cyclic-GMP on the phosphodiesterase activities was studied. Cyclic-AMP, cyclic-GMP, D,L-triiosothyronine, D,L-thyroxine, adrenocorticotropin and hydrocortisone where found to inhibit the phophodiesterase. Triiodothyronine and thyroxine inhibited cyclic-AMP phosphodiesterase more effectively than cyclic-GMP phosphodiesterase. Thyroxine was a more potent inhibitor than triiodothyronine. The concentration of cyclic AMP producing a 50% inhibition of cyclic-GMP phosphodiesterase activity was 5-10(-5) M, while the concentration of cyclic GMP producing a 50% inhibition of cyclic-AMP phosphodiesterase was 3-10(-3) M. Both cyclic-AMP and cyclic-GMP phosphodiesterase activities in the homogenate of hyperthyroidism, thyroid carcinoma and adenoma were higher than in normal thyroid tissue, when assayed with a low concentration of the substrate (0.4 muM). When a higher concentration (1 mM) of cyclic nucleotides was used as the substrate, cyclic-AMP hydrolytic activity in adenoma tissue was similar to that of normal tissue, while the other activities were higher than normal.
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PMID:Human thyroid cyclic nucleotide phosphodiesterase. Its characterization and the effect of several hormones on the activity. 18 33

1. Lipolysis by isolated white adipocytes from hamsters, as measured by glycerol production, was stimulated by corticotropin, isopropylnorepinephrine (INE), norepinephrine, or epinephrine (EPI), in a dose-dependent fashion. 2. Lipolysis was stimulated by five inhibitors of cyclic 3',5'-adenosine monophosphate phosphodiesterase: caffeine, theophylline, 1-methyl-3-isobutyl xanthine, 1-ethyl-4-(isopropylidenehydrazine)-1H-pyrazolo-(3,4,-b)-pyridine-5-carboxylic acid ethyl ester (SQ 20009), and 4-(3,4-dimethoxybenzyl)-2-imidazolidinone (Ro 7-2956). Caffeine-stimulated lipolysis consistently attained higher rates than did hormone-stimulated lipolysis. However, when cells were stimulated by both caffeine and a hormone, lipolytic rates were consistently lower than those attained under the influence of caffeine alone. 3. Isolated white adipocytes from hamsters were sensitive to both alpha- and beta-adrenergic antagonists. The beta-adrenergic antagonist propranolol could completely inhibit norepinephrine-stimulated glycerol production. The alpha-adrenergic antagonist phentolamine, on the other hand, had a biphasic effect on the cells. At 5-10(-7) M or 5-10(-6) M, phentolamine enhanced norepinephrine-stimulated lipolysis, while concentrations higher than 5-10(-5) M caused inhibition. 4. The effects of two different concentrations of six antilipolytic agents, prostaglandin E1, nicotinic acid, phenylisopropyladenosine, 5-methylpyrazole-3-carboxylic acid, adenosine and insulin, were measured. With the exception of insulin, all of these agents showed much more potent inhibition of caffeine-stimulated lipolysis than of hormone-stimulated lipolysis. Insulin, in contrast, showed only modest inhibition of hormone-stimulated lipolysis and virtually no inhibition of caffeine-stimulated lipolysis.
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PMID:Characterization of lipolytic responses of isolated white adipocytes from hamsters. 18 45

The effects of prostaglandins E on the concentration of cyclic AMP (cAMP) and a possible antagonism of opiates vs. prostaglandins E were studied in homogenates and in slices of rat striata in vitro. In homogenates, PGE1 or PGE2 did not affect the synthesis of cAMP. Morphine slightly lowered the cAMP synthesis, in presence or absence of PGE1 or PGE2. In slices, PGE2 significantly elevated the cAMP concentrations, either in presence or in absence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Morphine, met-enkephalin and levorphanol, but not dextrorphan, antagonized this rise of cAMP. The effect of morphine was antagonized by naloxone. Adenosine or an elevation of K+-ions raised the cAMP concentrations, and PGE2 induced a further increase. In presence of elevated K+-ions or adenosine, however, morphine did not antagonize the PGE2-induced rise of cAMP concentration. It is suggested that under some experimental conditions described in the literature, endogenous activators of cAMP formation, e.g. adenosine, might mask the inhibitory effect of opiates on stimulation of opiates on stimulation of cAMP synthesis induced by prostaglandins E.
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PMID:Interactions of opiates and prostaglandins E with regard to cyclic AMP in striatal tissue of rats in vitro. 20 43

The role of cyclic AMP in the regulation of aldosterone production by adrenocorticotropic hormone (ACTH), angiotensin II (A II), potassium, and serotonin was examined in collagenase-dispersed adrenal glomerulosa cells. The ability of 8-bromo cyclic AMP and choleragen to stimulate maximum aldosterone production indicated that cyclic AMP could act as second messenger for certain of the aldosterone-stimulating factors. The actions of ACTH and choleragen on aldosterone and cyclic AMP production were correlated in dog and rat cells, and a similar relation was seen during stimulation of rat cells by serotonin. In contrast, A II and potassium did not cause changes in cyclic AMP formation while stimulating aldosterone production. Intracellular and receptor-bound cyclic AMP were increased 3-fold by 10(-7) M ACTH but not by A II. Addition of a phosphodiesterase inhibitor increased the magnitude of the cyclic AMP response to ACTH but did not change the lack of stimulation by A II or potassium. In dog cells, the effects of A II and potassium on aldosterone production were partially additive to those of ACTH, choleragen, and 8-bromo cyclic AMP. In contrast, no additivity was observed between A II and potassium, or between combinations of the cyclic AMP-dependent stimuli. These results indicate that the actions of ACTH on aldosterone secretion are mediated by cyclic AMP formation, whereas A II and potassium stimulate aldosterone production through an independent mechanism. The lack of additivity between steroid responses to A II and potassium suggests that these factors could share a common mode of action on steroidogenesis in zona glomerulosa cells.
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PMID:The role of cyclic AMP in aldosterone production by isolated zona glomerulosa cells. 22 59

Because several groups have recently questioned a mediating role for cyclic AMP in adrenocortical steroidogenesis, we analysed the problem in more detail by measuring three different cyclic AMP pools in cells isolated from decapsulated rat adrenals. Extra-cellular, total intracellular and bound intracellular cyclic AMP were determined by radioimmunoassay in comparison with corticosterone production induced by low corticotropin concentrations. The increase in extracellular and total intracellular cyclic AMP with low corticotropin concentrations was dependent on the presence of a phosphodiesterase inhibitor and short incubation times. Bound intracellular cyclic AMP was less dependent on these two parameters. In unstimulated cells cyclic AMP bound to its receptor represents only a small fraction of the total intracellular cyclic AMP. After stimulation by a concentration of corticotropin around the threshold for corticosterone production, an increase in bound cyclic AMP was observed which correlated very well with steroidogenesis both temporally and with respect to corticotropin concentration. This finding was complemented by measuring a concomitant decrease in free receptor sites. Full occupancy of the receptors was not necessary for maximal steroidogenesis. Binding kinetics of cyclic [(3)H]AMP in concentrations equivalent to the intracellular cyclic AMP concentration suggest the presence of at least three different intracellular cyclic AMP pools. These observations are in agreement with a possible role for cyclic AMP as a mediator of acute steroidogenesis induced by low corticotropin concentrations.
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PMID:Steroidogenesis in isolated adrenocortical cells. Correlation with receptor-bound adenosine e 3':5'-cyclic monophosphate. 22 72

An important factor in regulating secretion from endocrine cells is the cytoplasmic concentration of cyclic-AMP. Many regulatory substances are known to either stimulate or inhibit the production of this second messenger through activation of their receptors. In the present study, we have monitored changes in cyclic-AMP efflux from melanotrope cells of Xenopus laevis in response to established neurochemical regulators of alpha-MSH secretion. In vitro superfusion of neurointermediate lobes allows for a dynamic recording of cyclic-AMP production in relation to hormone secretion. Unlike alpha-MSH secretion, the efflux of cyclic-AMP was not dependent on the concentration of extracellular calcium, indicating that hormone release and cyclic-AMP efflux are mediated by different mechanisms. The phosphodiesterase inhibitor IBMX and the adenylate cyclase activator forskolin stimulated cyclic-AMP efflux, but had no stimulatory effect on alpha-MSH release. This indicates that an increase in cyclic-AMP production in melanotrope cells is not necessarily accompanied by an increase in the rate of alpha-MSH release. Corticotropin-releasing factor stimulated cyclic-AMP efflux with dynamics similar to that induced by the amphibian peptide sauvagine. Dopamine and the GABAB receptor agonist baclofen both inhibited cyclic-AMP efflux and alpha-MSH release, with similar dynamics of inhibition and similar dose-response relationships. It is proposed that an inhibition of cyclic-AMP efflux is coupled to an inhibition of alpha-MSH secretion.
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PMID:Dynamics of cyclic-AMP efflux in relation to alpha-MSH secretion from melanotrope cells of Xenopus laevis. 127 39

The regulation of the expression of the human corticotropin-releasing-hormone gene (hCRH) was studied in a mouse anterior pituitary cell line (AtT20) after transiently transfection with a chimeric gene containing the hCRH gene promoter fused to the bacterial chloramphenicol acetyltransferase (CAT) gene. Expression of the chimeric hCRH-CAT gene in AtT20 cells was enhanced by the cAMP analog (8-bromo-cAMP) about 5-fold but not by phorbol 12-myristate-13-acetate. The cAMP phosphodiesterase inhibitor isobutylmethylxanthine also strongly stimulated 15-fold the expression of the chimeric hCRH-CAT gene. Coincubation of cAMP analog and isobutylmethylxanthine resulted in a moderate 2-fold synergistic enhancement of CAT activity. Sequence comparison of the hCRH gene revealed a core sequence for a cAMP responsive element 5'-TGACGTCA-3' at -221 relative to the cap site. This regulatory element also confers cAMP inducibility on a heterologous promoter when placed upstream of the thymidine kinase promoter from herpes simplex virus. Finally, treatment with 0.5 microM dexamethasone reduced CAT activity about 2.0-fold in cAMP-stimulated cells. This result suggests that cAMP and glucocorticoids coordinately control hCRH gene expression.
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PMID:Glucocorticoid repression of 3',5'-cyclic-adenosine monophosphate-dependent human corticotropin-releasing-hormone gene promoter activity in a transfected mouse anterior pituitary cell line. 169 84

The role of melanocyte stimulating hormone (MSH) as a mediator of the melanogenic response to ultraviolet radiation (UVR) was examined in C57 BL/6 mice. While exposure to UVR (250-300 nm) for 7, 14 and 27 days increased tyrosinase activity in epidermal melanocytes of the ear MSH had no effect and failed to alter the response to UVR. Plasma alpha-MSH concentrations were unchanged following UVR. Theophylline, a phosphodiesterase inhibitor, also had no effect on epidermal tyrosinase activity in non-irradiated and UV irradiated mice. Prostaglandin E2 and arachidonic acid were also ineffective in non-irradiated and UV irradiated mice and indomethacin, an inhibitor of prostaglandin synthesis, failed to increase epidermal tyrosinase activity after UVR. On the other hand, 12-0-tetradecanoyl phorbol 13 acetate, an activator of protein kinase C, increased epidermal tyrosinase activity in non-irradiated mice and also enhanced the effect of UVR.
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PMID:The effect of ultraviolet radiation and melanocyte-stimulating hormone on tyrosinase activity in epidermal melanocytes of the mouse. 212 69

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