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)

In previous reports we have demonstrated the presence of a soluble factor that responds to cAMP signals to induce steroid synthesis in adrenocortical tissue. Here, we describe the purification of this factor from adrenal zona fasciculata cells by using a five-step procedure that includes DEAE-cellulose, gel filtration, Mono Q HPLC and Superose HPLC, and elution of the protein from SDS/PAGE. This procedure results in the purification to homogeneity of a protein of 43-kDa that retains the capacity to stimulate steroid synthesis in an in vitro recombination assay. This activity is inhibited by the use of phospholipase A2 inhibitors. Antipeptide antibodies against the N-terminal region recognize p43 as a double band on SDS/PAGE that resolves in different spots on two-dimensional gel electrophoresis. Adrenocorticotropin treatment of adrenal glands results in the appearance of multiple spots that migrated towards a lower pH compared to controls, suggesting the presence of phosphorylated and dephosphorylated forms of p43. Sequencing of the N-terminal region and internal peptides reveals no significant similarities with other proteins, suggesting that p43 is a novel protein. We conclude from our data that the isolated protein (p43) is a novel, soluble protein that acts as intermediary in adrenocorticotropin-induced stimulation of arachidonic acid release and steroid synthesis.
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PMID:Purification of a novel 43-kDa protein (p43) intermediary in the activation of steroidogenesis from rat adrenal gland. 792 88

The mechanism of the adrenal corticotropin hormone (ACTH)-stimulated increase in cytosolic free Ca2+ concentration ([Ca2+]i) was investigated in rat white adipocytes. ACTH at concentrations > 10 mU/ml caused a rapid and transient increase in [Ca2+]i followed by a small but sustained elevation of [Ca2+]i. A similar phenomenon was also induced by alpha-adrenergic or synthetic ACTH stimulation. The effect of norepinephrine (NE) plus ACTH on [Ca2+]i was nearly additive. Pertussis toxin completely blocked the ability of ACTH or NE to increase [Ca2+]i. NE but not ACTH caused a significant increase in inositol 1,4,5-trisphosphate levels. ACTH caused a rapid and transient accumulation of [3H]arachidonic acid (AA) and a marked loss of [3H]AA from phosphatidylinositol (PI) and phosphatidylcholine (PC) 10 s after stimulation. Neither a lipoxygenase inhibitor nor a dual inhibitor of cyclooxygenase and lipoxygenase blocked the increases in [Ca2+]i and the accumulation of [3H]AA in response to ACTH. On the other hand, either pertussis toxin or phospholipase A2 inhibitor drastically blocked both parameters in response to ACTH. These results indicate that ACTH stimulates AA release from PC and PI via the activation of phospholipase A2 coupled with pertussis toxin-sensitive GTP-binding protein(s), which leads to an increase in [Ca2+]i in rat white adipocytes.
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PMID:Increase in cytosolic free Ca2+ in corticotropin-stimulated white adipocytes. 816 62

Our previous studies have shown that the microinjection of interleukin (IL)-2 into the third ventricle of conscious rats evokes the release of adrenocorticotropin hormone (ACTH) and that its incubation with hemipituitaries in vitro was also effective in releasing ACTH. In the present experiments, we evaluated the effect of IL-2 on the release of corticotropin-releasing factor (CRF) from medial basal hypothalami (MBHs) incubated in vitro and studied the effect of other agents, whose release is altered in stress, on CRF release. IL-2 significantly stimulated CRF release at concentrations of 10(-13) and 10(-14) M, whereas increasing the concentration to 10(-12) to 10(-10) M did not produce significant release of CRF. A high concentration of potassium (55 mM) in the medium also significantly stimulated CRF release and this stimulation was not modified by IL-2. Since high-potassium-induced release of CRF is probably due to opening of voltage-dependent calcium channels, it is likely that IL-2 is releasing CRF by this mechanism. Since the release of luteinizing-hormone-releasing hormone (LHRH) is modified by stress, we evaluated the action of LHRH on CRF release and the release induced by IL-2. Although LHRH failed to alter basal CRF release, except for a slight decrease at 10(-7) M, it completely blocked IL-2-induced CRF release at this concentration. To examine a possible role for opioid peptides in CRF release, the opiate receptor blocker, naloxone (NAL), was tested. At concentrations of 5 x 10(-6) and 10(-5) M, it produced a marked increase in CRF release; however, the simultaneous exposure of MBHs to each of these concentrations of NAL plus IL-2 caused a dose-dependent decrease in IL-2-induced CRF release, suggesting that beta-endorphin or other opioid peptides may play a role in IL-2-induced CRF release. As has been previously shown for IL-1 and IL-6, IL-2-induced CRF release was blocked by alpha-melanocyte-stimulating hormone (alpha-MSH), which at high concentrations also reduced basal CRF release. As in the case of IL-1 and IL-2, dexamethasone (DEX), the highly active synthetic glucocorticoid, although not altering basal CRF release, completely blocked the response to IL-2. The inhibitor of cyclooxygenase, indomethacin (IND), also blocked IL-2-induced CRF release just as it has previously been shown to block IL-1- and IL-6-induced CRF release. The results are consistent with the hypothesis that IL-2 acts on its recently discovered receptors to induce an increase in intracellular calcium. In other experiments, we have shown that this activates nitric oxide (NO) synthase leading to production of NO by a NOergic neuron. NO diffuses to the CRF neuron and activates cyclo-oxygenase leading to generation of prostaglandin E2, which activates adenylate cyclase and increases cyclic AMP release, which then causes extrusion of CRF secretory granules. DEX presumably acts on its receptors on the CRF neuron to inhibit the increase in intracellular calcium and thereby blocks activation of phospholipase A2 necessary for activation of the arachidonic acid cascade. alpha-MSH and LHRH may similarly act on their receptors on these cells to, in some manner, block the pathway. On the other hand, beta-endorphin and/or other opioid peptides inhibit the pathway. Further experiments will be necessary to elucidate the exact points in the pathway at which these compounds are effective.
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PMID:Effects of luteinizing-hormone-releasing hormone, alpha-melanocyte-stimulating hormone, naloxone, dexamethasone and indomethacin on interleukin-2-induced corticotropin-releasing factor release. 864 67

We have previously isolated and partially-sequenced a soluble phosphoprotein (p43) that acts as intermediary in the stimulation of steroid synthesis. In this report we have used synthetic peptides whose sequences match those obtained from p43 to generate antipeptide antibodies and show that these antibodies bind to purified p43 protein as determined by immunoblot analysis. The presence of p43 was detected by Western blot in both steroidogenic and non-steroidogenic tissues. One of the antibodies was also used to purify p43 on immunoaffinity chromatography columns. Proteins eluting from affinity columns produce a twelve-fold stimulation of progesterone synthesis. This effect was blocked by the use of an inhibitor of phospholipase A2. These results suggest the involvement of p43 in transducing the adrenocorticotropin signal to mitochondria in zona fasciculata cells. We also describe a partial cDNA clone with a predicted amino acid sequence that matches the sequences of the internal peptides of p43.
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PMID:Characterization of the cDNA corresponding to a phosphoprotein (p43) intermediary in the action of ACTH. 896 6

The biochemical basis of the short-term inhibitory effects of glucocorticoids on corticotropin release from pituitary corticotrophs is still obscure. A well-characterized effect of glucocorticoids in several cell types is the inhibition of arachidonic acid (AA) generation by phospholipase A2 (PLA2). Arachidonic acid and its metabolites have been implicated in the secretory process from a number of pituitary cells, such as the corticotrophs. We have thus examined the role of AA in the anti-secretagogue effects of glucocorticoids in a corticotropin-secreting clonal corticotroph line (AtT-20 D16/16). Glucocorticoids decreased AA release induced by melittin, a bee venom protein related to extracellular PLA2. When a possible role of AA in corticotropin release was studied, the following results were obtained: (a) all corticotropin secretagogues tested, including corticotropin-releasing factor (CRF), did not alter AA generation; (b) calcium and guanine nucleotides, which stimulate corticotropin release in permeabilized cells, inhibited the release of AA under the same conditions; (c) administration of melittin or of exogenous AA had no effect on basal and CRF-stimulated corticotropin release; (d) administration of large amounts of exogenous AA was unable to restore the ability to secrete corticotropin under suppression by glucocorticoids. Altogether, the data suggest that whereas glucocorticoids can inhibit both AA generation and corticotropin release, these two effects appear to be causally unrelated.
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PMID:Functional dissociation between glucocorticoid-induced decrease in arachidonic acid release and inhibition of adrenocorticotropic hormone secretion in AtT-20 corticotrophs. 918 58

Immune neuroendocrine interactions are vital for the individual's survival in certain physiopathological conditions, such as sepsis and tissular injury. It is known that several animal venoms, such as those from different snakes, are potent neurotoxic compounds and that their main component is a specific phospholipase A type 2 (PLA2). It has been described recently that the venom from Crotalus durissus terrificus [snake venom (SV), in the present study] possesses some cytotoxic effect in different in vitro and in vivo animal models. In the present study, we investigated whether SV and its main component, PLA2 (obtained from the same source), are able to stimulate both immune and neuroendocrine functions in mice, thus characterizing this type of neurotoxic shock. For this purpose, several in vivo and in vitro designs were used to further determine the sites of action of SV-PLA2 on the hypothalamo-pituitary-adrenal (HPA) axis function and on the release of the pathognomonic cytokine, tumor necrosis factor alpha (TNF alpha), of different types of inflammatory stress. Our results indicate that SV (25 microg/animal) and PLA2 (5 microg/animal), from the same origin, stimulate the HPA and immune axes when administered (i.p.) to adult mice; both preparations were able to enhance plasma glucose, ACTH, corticosterone (B), and TNF alpha plasma levels in a time-related fashion. SV was found to activate CRH- and arginine vasopressin-ergic functions in vivo and, in vitro, SV and PLA2 induced a concentration-related (0.05-10 microg/ml) effect on the release of both neuropeptides. SV also was effective in changing anterior pituitary ACTH and adrenal B contents, also in a time-dependent fashion. Direct effects of SV and PLA2 on anterior pituitary ACTH secretion also were found to function in a concentration-related fashion (0.001-1 microg/ml), and the direct corticotropin-releasing activity of PLA2 was additive to those of CRH and arginine vasopressin; the corticotropin-releasing activity of both SV and PLA2 were partially reversed by the specific PLA2 inhibitor, manoalide. On the other hand, neither preparation was able to directly modify spontaneous and ACTH-stimulated adrenal B output. The stimulatory effect of SV and PLA2 on in vivo TNF alpha release was confirmed by in vitro experiments on peripheral mononuclear cells; in fact, both PLA2 (0.001-1 microg/ml) and SV (0.1-10 microg/ml), as well as concavalin A (1-100 microg/ml), were able to stimulate TNF alpha output in the incubation medium. Our results clearly indicate that PLA2-dependent mechanisms are responsible for several symptoms of inflammatory stress induced during neurotoxemia. In fact, we found that this particular PLA2-related SV is able to stimulate both HPA axis and immune functions during the acute phase response of the inflammatory processes.
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PMID:A phospholipase A2-related snake venom (from Crotalus durissus terrificus) stimulates neuroendocrine and immune functions: determination of different sites of action. 944 33

We have previously shown that the stimulatory effect of TRH on alpha-MSH secretion from the frog pars intermedia is associated with Ca2+ influx through voltage-dependent Ca2+ channels, activation of a phospholipase C and mobilization of intracellular Ca2+ stores. The aim of the present study was to investigate the contribution of protein kinase C (PKC), adenylyl cyclase (AC), Ca2+/calmodulin-dependent protein kinase II (CAM KII), phospholipase A2, and protein tyrosine kinase (PTK) in TRH-induced alpha-MSH release. Incubation of frog neurointermediate lobes (NILs) with phorbol 12-myristate-13-acetate (24 h), which causes desensitization of PKC, or with the PKC inhibitor NPC-15437, reduced by approximately 50% of the effect of TRH on alpha-MSH release. In most melanotrope cells, TRH induces a sustained and biphasic increase in cytosolic Ca2+ concentration ([Ca2+]i). Preincubation with phorbol 12-myristate-13-acetate or NPC-15437 suppressed the plateau phase of the Ca2+ response. Incubation of NILs with TRH (10(-6) M; 20 min) had no effect on cAMP production. In addition, the AC inhibitor SQ 22,536 did not affect the secretory response of NILs to TRH. These data indicate that the phospholipase C/PKC pathway, but not the AC/protein kinase A pathway, is involved in TRH-induced alpha-MSH release. The calmodulin inhibitor W-7 and the CAM KII inhibitor KN-93 did not significantly reduce the response to TRH. Similarly, the phospholipase A2 inhibitors quinacrine and 7-7'-DEA did not impair the effect of TRH on alpha-MSH secretion. The PTK inhibitors ST638 and Tyr-A23 had no effect on TRH-induced [Ca2+]i increase but inhibited in a dose-dependent manner TRH-evoked alpha-MSH release (ED50 = 1.22x10(-5) M and ED50 = 1.47x10(-5) M, respectively). Taken together, these data indicate that, in frog melanotrope cells, PKC and PTK are involved in TRH-induced alpha-MSH secretion. Activation of PKC is responsible for the sustained phase of the increase in [Ca2+]i, whereas activation of PTK does not affect Ca2+ mobilization.
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PMID:Involvement of protein kinase C and protein tyrosine kinase in thyrotropin-releasing hormone-induced stimulation of alpha-melanocyte-stimulating hormone secretion in frog melanotrope cells. 1038 23

The binding of [(125)I] orexin-A (Ox-A) to particulates from Chinese hamster ovary (CHO) cells expressing the cloned orexin-A receptor, or from rat forebrain areas, was sensitive to blockers of phosphatidylinositol-specific phospholipase C (PtdIns-PLC) U-73122 and ET-18-OCH(3), little affected by phospholipase A(2) inhibitor quinacrine, and not sensitive to D609, a xanthate inhibitor of phosphatidylcholine-selective PLC. Interaction of the receptor with a PtdIns-PLC was further indicated by a large sensitivity of the binding to Ca(2+). Up to 50% of the binding was sensitive to the G-protein nucleotide site agonist GTP-gamma-S. Ligand attachment to the orexin-A receptor thus depends on an association with both PtdIns-PLC and G-protein alpha-subunits. In all paradigms examined, the binding of [(125)I]orexin-A was competed by human/rat neuropeptide Y (hNPY) and porcine secretin with a potency similar to orexin-A (IC(50) range 30-100 nM). The rank order of potency for NPY-related peptides was hNPY > porcine peptide YY (pPYY) > (Leu(31), Pro(34)) human PYY > human PYY(3-36) > hNPY free acid > human pancreatic polypeptide. Among secretin-related peptides, the rank order of potency was porcine secretin > or = orexin-A > human pituitary adenylate cyclase-activating peptide > orexin-B > porcine vasoactive intestinal peptide. Among opioid peptides, rat beta-endorphin and camel delta-endorphin were much less active than NPY and secretin, and two enkephalins were inactive at 1 microM. In view of high abundance of NPY in forebrain, the above cross-reactivity could indicate a significant contribution of NPY to signaling via orexin-A receptors.
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PMID:Sensitivity of orexin-A binding to phospholipase C inhibitors, neuropeptide Y, and secretin. 1086 Aug 58

Previously, we reported that the elevation of plasma noradrenaline and adrenaline induced by intracerebroventricularly (i.c.v.) administered corticotropin-releasing hormone (CRH) was abolished by i.c.v. administered indomethacin, an inhibitor of cyclooxygenase, in rats [Yokotani et al., Eur. J. Pharmacol. 419, 183-189, 2001]. The result suggests the involvement of active metabolites of brain arachidonic acid in the CRH-induced activation of the central sympatho-adrenomedullary outflow. Arachidonic acid is released mainly by two different pathways: phospholipase A2-dependent pathway; phospholipase C- and diacylglycerol lipase-dependent pathway. In the present study, therefore, we tried to identify which pathway is involved in the CRH-induced elevation of plasma catecholamines in urethane-anesthetized rats. CRH (1.5 nmol/animal, i.c.v.)-induced elevation of plasma noradrenaline and adrenaline was abolished by neomycin [0.55 micromol (500 microg)/animal, i.c.v.] and 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U-73122) [5 nmol (2.3 microg)/animal, i.c.v.] (inhibitors of phospholipase C), and also by 1,6-bis-(cyclohexyloximinocarbonylamino)-hexane (RHC-80267) [1.3 micromol (500 microg)/animal, i.c.v.] (an inhibitor of diacylglycerol lipase). On the other hand, mepacrine [1.1 micromol (500 microg)/animal, i.c.v.] (an inhibitor of phospholipase A2) and 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-2,5-pyrrolidinedione (U-73343) [5 nmol (2.3 microg)/animal, i.c.v.] (an inactive analog of U-73122) had no effect. These results suggest that CRH activates the central sympatho-adrenomedullary outflow by the brain phospholipase C- and diacylglycerol lipase-dependent mechanisms in rats.
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PMID:Brain phospholipase C and diacylglycerol lipase are involved in corticotropin-releasing hormone-induced sympatho-adrenomedullary outflow in rats. 1295 58

We developed C57BL/6 mice with targeted deletion of group X secretory phospholipase A(2) (GX KO). These mice have approximately 80% higher plasma corticosterone concentrations compared with wild-type (WT) mice under both basal and adrenocorticotropic hormone (ACTH)-induced stress conditions. This increased corticosterone level was not associated with increased circulating ACTH or a defect in the hypothalamic-pituitary axis as evidenced by a normal response to dexamethasone challenge. Primary cultures of adrenal cells from GX KO mice exhibited significantly increased corticosteroid secretion compared with WT cells. Conversely, overexpression of GX secretory phospholipase A(2) (sPLA(2)), but not a catalytically inactive mutant form of GX sPLA(2), significantly reduced steroid production 30-40% in Y1 mouse adrenal cell line. This effect was reversed by the sPLA(2) inhibitor, indoxam. Silencing of endogenous M-type receptor expression did not restore steroid production in GX sPLA(2)-overexpressing Y1 cells, ruling out a role for this sPLA(2) receptor in this regulatory process. Expression of steroidogenic acute regulatory protein (StAR), the rate-limiting protein in corticosteroid production, was approximately 2-fold higher in adrenal glands of GX KO mice compared with WT mice, whereas StAR expression was suppressed in Y1 cells overexpressing GX sPLA(2). Results from StAR-promoter luciferase reporter gene assays indicated that GX sPLA(2) antagonizes StAR promoter activity and liver X receptor-mediated StAR promoter activation. In summary, GX sPLA(2) is expressed in mouse adrenal glands and functions to negatively regulate corticosteroid synthesis, most likely by negatively regulating StAR expression.
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PMID:Group X secretory phospholipase A2 regulates the expression of steroidogenic acute regulatory protein (StAR) in mouse adrenal glands. 2042 6


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