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)

Transplantable mouse melanomas possess a melanotropin-sensitive adenylate cyclase system which is responsive to alpha-melanotropin, beta-melanotropin, adrenocorticotropin (ACTH) and prostaglandin E1. It was found that sensitivity to ACTH was not directed towards the ACTH activity but to the intrinsic melanotropin activity of the ACTH molecule. Therefore, the melanotropin-sensitive adenylate cyclase system is hormonally specific to the intrinsic melanotropin activity of peptide hormones and is unique in the melanoma tissue. The significance of the sensitivity to prostaglandin E1 is obscure at present. The melanotropin-sensitive adenylate cyclase requires the presence of Mg2+ or Mn2+, for its enzymic activity. Ca2+ inhibit the enzyme in the presence of a wide range of concentrations of Mg2+. The enzymic activity is ATP concentration-dependent and the saturation concentration appears to be 1 mM. The enzyme is very labile in the unfractionated tumor homogenates. A washed 11000 X g particulate fraction, representing about 30-60% of the total enzymic activity, was found to be more stable and could be stored at 5 degrees C for 2 h without appreciable loss of the activity. This fraction retained sensitivity to melanotropin, prostaglandin E1 and NaF. About 20% of the activity of the tumor homogenate could not be sedimented by centrifugation at 105000 X g for 60 min. This "soluble" fraction was not responsive to melanotropin, prostaglandin E1 and NaF and might be a degradative product produced by the fractionation. Cyclic AMP and alpha-melanotropin were able to increase the tyrosinase activity of isolated mouse melanoma-cells in vitro under the same conditions.
 ...
PMID:PHrmonal specificity of the melanotropin-sensitive adenylate cyclase of mouse melanoma and effect of cyclic AMP on the tyrosinase activity of mouse melanoma cells, in vitro. 0 31

The tumor production of human calcitonin (CT) was examined by radioimmunoassay, and it was found that 50 of 85 (59%) tumor tissues collected at random contained immunoreactive CT. These tumors were grouped as to whether they were derived from the amine precursor uptake and decarboxylation (APUD) series. The group that was derived from APUD cells showed appreciable amounts of CT in 30 of 31 (97%) of these tumors or in 20 of 21 (95%) when the medullary carcinomas of the thyroid were excluded. However, of the non-APUD group of tumors only 20 of 54 (37%) were found to contain CT, so that the difference between these two groups was highly significant (p less than 0.001). Of the tumors with ectopic adrenocorticotropic hormone-melanocyte-stimulating hormone production, 12 of 14 were shown to contain CT. These data indicate that CT is a common product of the APUD tumors and that tumor production of CT is often associated with that of adrenocorticotropic hormone and beta-melanocyte-stimulating hormone.
 ...
PMID:Production of calcitonin, adrenocorticotropic hormone, and beta-melanocyte-stimulating hormone in tumors derived from amine precursor uptake and decarboxylation cells. 2 Feb 27

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.
 ...
PMID:Existence of a common precursor to ACTH and endorphin in the anterior and intermediate lobes of the rat pituitary. 8 77

This report considers the potential usefulness of adrenocorticotropic hormone (ACTH) determinations in diagnosis and in prognosis for therapy of patients with carcinoma of the lung but without clinical Cushing's syndrome. The report is based on radioimmunoassay data from 129 patients, including 62 with lung cancers and 67 with nonmalignant pulmonary conditions. Elevated plasma ACTH was found in 21 of 24 patients with untreated cancer and the hormone was detected in tumor extracts and/or bronchial washings from the remaining 3. Elevation of plasma ACTH was found in only 10 of 38 treated patients. Absence of clinical Cushing's syndrome in spite of high plasma ACTH concentrations is explained by the observation that the predominant form of ectopic ACTH in plasma is immunoreactive but nonbioactive 'big' ACTH. Prolonged survival, for longer than 19 months, was observed in only 5 patients: all patients with low plasma ACTH after resection of the lung tumor and 2 of 3 patients with low plasma ACTH without therapy. ACTH was found in all available malignant tissue, primary and metastatic, from the lung carcinoma group,but not in normal lung or in 5 tumors metastatic to the lung. Of the 39 patients diagnosed initially to have chronic obstructive pulmonary disease, 14 showed plasma ACTH elevation. However, 3 of these patients with the highest concentrations subsequently manifested carcinoma or carcinoma in situ.
 ...
PMID:Ectopic production of big ACTH in carcinoma of the lung. Its clinical usefulness as a biologic marker. 16 43

Glucagon activated adenylate cyclase in a homogenate of a pheochromocytoma over the concentration range 1 times 10 minus 8M to 1 times 10 minus 6M. Several other hormones including adrenocorticotropin, thyrotropin, parathyroid hormone and histamine were without effect. The tumor glucagon receptor was characterized and found to be similar in several ways to the glucagon receptor previously reported in normal tissue such as liver and heart. One, the receptor specifically bound 125-I-glucagon. Two, solubilization of the pheochromocytoma abolished glucagon-activation of the adenylate cyclase. Three, glucagon-responsiveness of the adenylate cyclase was partially restored by the addition of phosphatidylserine to the incubations. One major difference was observed between the glucagon receptor in tumor tissue and that in liver and heart, namely, a marked lability in 125-I-glucagon binding and adenylate cyclase activity. Within four days, despite storage in liquid nitrogen, 75% of the binding activity and all of the adenylate cyclase activity in the solubilized preparation were lost. The factor(s) responsible for this lability remains unidentified.
 ...
PMID:Characterization of the glucagon receptor in a pheochromocytoma. 16 16

Tumor tissues obtained from 4 patients with the ectopic ACTH syndrome were studied for release and synthesis of tumor ACTH, using an in vitro incubation system. The effect of various agents on release of tumor ACTH was evaluated in three cases; beta-MSH released and adenosine 3',5'-monophosphate (cyclic AMP) formed in the tissue were determined in one. Biosynthetic experiments using labeled amino acid incorporation were performed in two cases. Secretion of tumor ACTH was significantly stimulated in all cases by crude rat median eminence extract which was also effective in stimulating beta-MSH secretion associated with elevated tissue cyclic AMP levels in one. Addition of cyclic AMP and dibutyryl cyclic AMP caused a significant increase in release of both tumor ACTH and beta-MSH in one. Biogenic amines (norepinephrine and serotonin) markedly elevated tussie cyclic AMP levels without a corresponding increase of hormone release in one. Incorporation experiments revealed that 3H- or 14C-phenylalanine was incorporated into immunoreactive ACTH of a larger molecular size (big ACTH) in both cases by chromatographic procedures. However, biological activity of big ACTH was found to be undetectable by an in vivo steroidogenic assay. A mild tryptic digestion of the big forms resulted in the appearance of little ACTH to which the major radioactive peak shifted. These data suggest that the mechanism of release of tumor ACTH and beta-MSH is very similar to that of the pituitary, and that intracellular cyclic AMP may in part play some role in release of both hormones. It is also suggested that some ectopic ACTH producing tumors predominantly synthesize big ACTH, a possible precursor of ACTH, with less bioactivity.
 ...
PMID:In vitro release and biosynthesis of tumor ACTH in ectopic ACTH producing tumors. 16 26

The failure of certain adrenal tumors to respond to ACTH was investigated in vivo be administration of corticotropin-(1-24)-tetracosapeptide (ACTH1-24) and dexamethasone and in vitro by studying the binding properties of ACTH1-24 and prostaglandin E1 (PGE1) and their effect on adenylate cyclase activity of the tumors' crude membranes; in addition, in five cases the stimulation of cortisol production in isolated adrenal cells by both hormones and dibuttyryl cyclic adenosine 3',5'-monophosphate (cAMP) was also studied. The results obtained in 13 hormone-producing tumors of the human adrenal cortex, i.e. 10 carcinomas and 3 adenomas, were compared with those found in normal human adrenal glands. According to the adenylate cyclase responses to ACTH1-24 and PGE1, the tumors fall into different categories. In the first group are six rumors in which the adenylate cyclase was stimulated by both ACTH1-24 and PGE; in addition specific binding could be demonstrated for the two hormones in all six. The binding affinity for 125I-ACTH1-24 was found to be about 10 times higher than that for 125I-ACTH11-24. In the one tumor in which the experiment was performed, bound 125I-ACTH1-24 was displaced by ACTH1-10. These results are similar to the ones found in normal human adrenal preparations. For two rumors of the group in which ACTH did not increase steroidogenesis in vivo, the biochemical abnormality might be located beyond cAMP formation. A second group encompasses six tumors in which the steroidogenesis in vivo and the adenylate cyclase activity were insensitive to ACTH1-24 but in which the enzyme was stimulated by PGE1 and NaF. However, these preparations bound 125I-ACTH1-24 and 125I-ACTH11-24, the binding affinity being similar for both peptides but 10 times lower than the one found in normal adrenal cortex for 125I-ACTH1-24. In the only case of this group where it was tested, ACTH1-10 did not displace bound 125I-ACTH1-24. This result strongly suggests the possibility of a modification or a loss of the receptor site that binds the N-terminal sequency (1-10) of ACTH, the biologically active part of the molecule. In the last tumor, both PGE1 and ACTH were unable to stimulate adenylate cyclase activity and steroid production in a preparation of isolated adrenal cells, although steroidogenesis was stimulated by dibutyryl though steroidogenesis was stimulated by dibutyryl cAMP. No specific binding for PGE1 could be demonstrated. However, 125I-ACTH1-24 and 125I-ACTH11-24 were found to be bound to the tumor with the same affinity.
 ...
PMID:ACTH and prostaglandin receptors in human adrenocortical tumors. Apparent modification of a specific component of the ACTH-binding site. 16 92

Denaturing solvents have been used to determine the molecular weight of the adrenocorticotropic hormone (ACTH) activity in mouse pituitary, in an ACTH secreting mouse pituitary tumor cell line (AtT-20/D-16v), and in the tissue culture medium from the pituitary tumor cells. ACTH activity was quantitated by radioimmunoassay and by bioassay. It is possible to utilize guanidine hydrochloride or sodium dodecyl sulfate in characterizing the multiple forms of ACTH because treatment of porcine ACTH (the 39 amino acid polypeptide form of ACTH, alpha(1-39)), pituitary extracts, tumor cell extracts, and tumor cell tissue culture medium with these denaturants does not diminish the immunological ACTH activity. Based on gel filtration in the presence of guanidine hydrocholoride, extracts of the pituitary tumor cells and the mouse pituitary contain three distinct molecular weight classes of ACTH activity. The major form of ACTH has a molecular weight similar to alpha(1-39) (molecular weight 4000-5500), but there are significant amounts of two higher molecular weight forms of ACTH: molecular weight 6500-9000 and molecular weight 20,000-30,000. The 6500-9000 molecular weight form of ACTH is the major form of ACTH in the tissue culture medium; there is no peak of alpha(1-39) size ACTH in the medium. In the radioimmunoasay all three forms of ACTH generate competitive binding curves parallel to that of porcine alpha(1-39); in the bioassay (stimulation of steroidogenesis in a mouse adrenal tumor cell line) the dose response curve for each of the molecular forms of ACTH is parallel to that for porcine alpha(1-39).
 ...
PMID:High molecular weight forms of adrenocorticotropic hormone in the mouse pituitary and in a mouse pituitary tumor cell line. 16 85

Choleragen stimulates steroid secretion and adenylate cyclase in three cell lines, adrenal tumor line (Y-1), a corticotropin-resistant mutant derived from Y-1 called OS-3, and a receptor-deficient Leydig tumor line (I-10). Sensitivity for half-maximal stimulation varies from 3 to 36 pM choleragen, the I-10 line being the most sensitive. Latency before the onset of steroidogenesis is longer in OS-3 and I-10 cells than in the Y-1 line. In both OS-3 and I-10 cells choleragen stimulates adenylate cyclase whether ITP or 5'-guanylylimidodiphosphate is the regulatory cofactor used. In addition to the responses of the receptor-deficient lines, choleragen does not, during its latency, block the response to corticotropin in Y-1 cells; corticotropin does not block binding of 125I-labeled choleragen to Y-1 cells; gangliosides do not interfere with the corticotropin-induced stimulation of Y-1 cells. We conclude that the corticotropin and choleragen receptors are different.
 ...
PMID:Choleragen stimulates steroidogenesis and adenylate cyclase in cells lacking functional hormone receptors. 17 54

Lipopolysaccharides (endotoxins) from Escherichia coli, Serratia marcesens and Salmonella typhosa stimulated steroid production in Y-1 adrenal tumor cells in culture with a latent period of 3-4 h. Lipid A, derived from Escherichia coli lipopolysaccharide, also stimulated steroidogenesis. Lipopolysaccharides and lipid A also stimulate adenylate cyclase activity and cause rounding of the cells. In contrast, lipopolysaccharides do not stimulate steroidogenesis in receptor-deficient adrenal tumor cells (OS-3) or Leydig tumor cells (I-10). This tends to rule out contamination by enterotoxin to which these lines respond. Although both hormone and lipopolysaccharide responses are lost in these lines, there was no interaction between these sites as judged by the failure of lipopolysaccharides to block, during their latency, the response to corticotropin in Y-1 cells. The possibility that the lipopolysaccharide effect is one on membrane conformation is discussed.
 ...
PMID:Endotoxic lipopolysaccharides stimulate steroidogenesis and adenylate cyclase in adrenal tumor cells. 17 55


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