UNIPROT:P01189 - FACTA Search

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)

Because of the microheterogeneities of gonadotropins, measurement of immunoreactivity of these glycoproteins does not necessarily reflect changes in their bioactivity. In addition, LH bioactivities in human samples analyzed by a rodent LH bioassay have been discordant with findings based on human granulosa-luteal cells. We have isolated a human LH/choriogonadotropin (CG) receptor cDNA and expressed the recombinant protein. Using 293 cells permanently transfected with the human LH receptor cDNA and a luciferase reporter gene driven by a cAMP-dependent promoter, we have developed a luminescence LH/CG bioassay. After cells were treated with human LH or CG for 20 h, luciferase activity was measured through use of a luminometer. Luciferase activity in the cells was increased in a dose-dependent manner. In contrast, treatment with FSH, thyroid-stimulating hormone, prolactin, growth hormone, adrenocorticotropin, insulin, prostaglandins, and several neurotransmitters had no effect. Because treatment with basic fibroblast growth factor (bFGF) caused significant increases in basal luciferase activity, a fixed amount of bFGF was included in all reactions. Incubation with 0.1 to 30 microliters serum from women during different physiological states stimulated the luciferase activity in parallel with the hCG standard curve. In 4 conception cycles, bioactive LH/hCG levels began to increase 2 wk after the midcycle LH surge, followed by a logarithmic increase from 22 days on. Due to the lack of a homologous RIA for measuring CG levels in monkeys, we analyzed serum bioactive monkey CG (mCG) in macaque during early pregnancy. Bioactive mCG was detected about 12 days after the midcycle LH surge and fertile mating and persisted until Days 21-23, followed by a decline.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Luminescence luteinizing hormone/choriogonadotropin (LH/CG) bioassay: measurement of serum bioactive LH/CG during early pregnancy in human and macaque. 828 13

We recently described the expression of leukemia inhibitory factor (LIF) in human fetal and murine corticotrophs. LIF and the related cytokine oncostatin M induced basal, and corticotropin-releasing hormone (CRH) induced proopiomelanocortin (POMC) mRNA and ACTH secretion in AtT20 cells. LIF signaling and regulation of POMC gene transcription were therefore tested. Dexamethasone inhibited both basal- and LIF-induced ACTH secretion (P<0.05) and LIF induction of ACTH was also attenuated by immuneutralization of either the LIF receptor (35%, P<0.05) or the gp130 affinity converter (41%, P<0.05). These antisera also attenuated basal ACTH secretion in the absence of added ligand (P<0.05). To examine intrapituitary LIF signaling, phosphorylation of post-receptor substrates was measured. 1 nM LIF rapidly induced tyrosyl phosphorylation of STAT 1 and STAT 3 proteins, as well as tyrosyl phosphorylation of a 115-kD protein, coimmunoprecipitated with STAT 1. The transfected rat POMC promoter -706/+64, fused to the luciferase reporter gene, was induced by LIF, which exerted strong (18-fold) synergy with CRH. Deletion of the major CRH responsive region in POMC (-323/-166) abolished CRH induction of transcription and severely limited LIF synergy. Although 8 bromo cAMP or forskolin modestly enhanced POMC transcription (2.8-fold), LIF markedly potentiated (7.4-fold) these cAMP activators. These results demonstrate that corticotroph LIF action is receptor mediated and involves activation of STAT signaling pathways. LIF potently synergizes with both CRH and cAMP induction of POMC transcription. This novel intrapituitary signaling mechanism may mediate a neuroimmune pituitary interface.
...
PMID:Leukemia inhibitory factor (LIF) stimulates proopiomelanocortin (POMC) expression in a corticotroph cell line. Role of STAT pathway. 862 68

DMS-79 is a human cell line derived from a small cell lung carcinoma (SCLC), which expresses the pro-opiomelanocortin (POMC) gene. We took it as a model in which to study the mechanism of POMC gene expression in these tumors: precursor processing is altered and gene expression is essentially unresponsive to glucocorticoids. POMC gene structure appeared normal by Southern blot analysis, indicating that gene rearrangement was not responsible for its expression in DMS-79. Indeed, using transient expression of human POMC-luciferase fusion genes in DMS-79, we showed that (1) the normal human POMC promoter was functional in DMS-79, and (2) the same proximal promoter region (-417; + 21) produced the full transcriptional activity in DMS-79 and in the mouse pituitary cell line AtT-20. Progressive 5' deletion analysis revealed differences between AtT-20 and DMS-79: region (-611; -376) was active in AtT-20 and not in DMS-79, whereas region (-95; -161) was active in both cell lines and (-376; -417) was only active in DMS-79. The latter partially overlaps a motif homologous to the DE-2 rat element which confers the tissue-specific expression of POMC in AtT-20 cells; however, this motif had no effect in DMS-79. These data suggest that POMC gene transcription is achieved through a different set of transacting factors in DMS-79 and AtT-20. Altogether, our results provide evidence that DMS-79 is a valid model of tumors responsible for the ectopic ACTH syndrome and that the mechanism of POMC gene expression in these SCLC cells is different from that in pituitary cells.
...
PMID:Functional analysis of the human pro-opiomelanocortin promoter in the small cell lung carcinoma cell line DMS-79. 880 Jun 43

Using murine AtT20 pituitary cells transfected with a rat pro-opiomelanocortin (POMC) promoter (-706/+64) linked to the luciferase reporter, we showed leukemia inhibitory factor (LIF) to strongly potentiate corticotropin-releasing hormone (CRH) induction of POMC gene expression. We therefore tested mechanisms for molecular interactions between LIF and CRH. Although LIF and CRH synergized to induce an 8-fold induction of POMC transcription, CRH alone (but not LIF) induced cAMP response element-binding protein phosphorylation (5-fold) or an increase of c-fos mRNA levels (>100-fold), suggesting that these pathways are not implicated in LIF transcriptional synergistic effects. Using a DNase I footprint assay, POMC promoter regions protected by AtT20 cell nuclear extracts were identified (-121/-109, and -143/-134, and -173/-160). The protected -173/-160 element fused to a heterologous promoter conferred LIF-CRH synergy (6.5-fold induction of POMC) and formed a specific complex with AtT20 cell nuclear extracts. This complex was supershifted by an anti-phosphoserine antibody, and a serine/threonine kinase inhibitor also altered both this complex and LIF-CRH transcriptional synergy on the POMC promoter-luciferase reporter construct, indicating that these events depend on post-translational serine phosphorylations. LIF-CRH synergy on POMC transcription is therefore mediated at least in part by -173/-160 sequences conferring confluent transcriptional activity of both peptides.
...
PMID:A common pro-opiomelanocortin-binding element mediates leukemia inhibitory factor and corticotropin-releasing hormone transcriptional synergy. 909

Although the effects of the various secretagogues on corticotropin (ACTH) secretion have been well studied, their effects on the POMC gene expression have not been thoroughly characterized. In this study, we established a new model system using the AtT20 mouse corticotroph tumor cell line transfected stably with a plasmid containing 0.7 kb of the rat POMC 5' promoter-luciferase fusion gene. The responsiveness to exogenous CRH improved markedly when the cells were cultured with low serum medium (1% FBS) compared with serum rich medium (10%). Using this culture condition, we examined the effects of not only CRH but also other secretagogues such as catecholamines, vasopressin, and angiotensin II, upon the transcriptional activity of the POMC gene. CRH stimulated POMC promoter activity (3.5-fold increase) as well as cAMP generation and ACTH secretion in a dose- and time-dependent manner, with the maximal effect being observed 3-5 h after the start of incubation. Catecholamines, especially epinephrine (10 nM and above), also stimulated all parameters, although less potently than CRH, and the effect was mimicked by the beta-, but not alpha-adrenergic, agonist, suggesting the involvement of the beta-adrenergic receptor. The combined effects of epinephrine and CRH were greater in all parameters than those of CRH alone, and the effects of both hormones were completely blocked by H89, an inhibitor of protein kinase A. Vasopressin and angiotensin II showed minimal effects on POMC expression. Our results suggest that 1) catecholamines, as well as CRH, positively regulate the POMC gene at physiological concentrations; 2) the cAMP-PKA system is the common intracellular signaling pathway for CRH and catecholamines; and 3) vasopressin and angiotensin II also have weak but significant stimulatory effects on POMC promoter activity.
...
PMID:Regulation of the rat proopiomelanocortin gene expression in AtT-20 cells. I: Effects of the common secretagogues. 911 88

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP), members of the glucagon-secretin family, have recently been suggested to be involved in the regulation of corticotropin (ACTH) secretion. In this study, we examined the effects of both peptides on POMC gene expression. Using AtT20PL, a clone of the AtT20 mouse corticotroph tumor cells stably transfected with 0.7 kb of the rat POMC 5' promoter-luciferase fusion gene, the effects of both peptides on the POMC promoter activity were estimated by a luciferase assay. PACAP stimulated POMC 5' promoter activity as well as cAMP generation and ACTH secretion in a dose- and time-dependent manner, with the maximal effect being observed 3 h after the start of incubation. A similar effect was observed with VIP. Although the combined effects of PACAP/CRH or VIP/CRH were greater than that of either hormone alone, no such effect was observed between PACAP and VIP. Furthermore, RT-PCR analysis showed the presence of only the PVR3 receptor subtype in this cell line, which is known to have a similar affinity to PACAP and VIP, indicating that both peptides exert their effects through the same receptor. In contrast to the effect of CRH, which was completely abolished by a protein kinase A inhibitor H89, the effects of PACAP/VIP on POMC expression persisted during H89 treatment, suggesting the involvement of alternative intracellular signaling pathway(s) distinct from the protein kinase A system. Our results suggest that PACAP and VIP have positive effects on POMC gene expression and that multiple signaling pathways are involved in the transcriptional event.
...
PMID:Regulation of the rat proopiomelanocortin gene expression in AtT-20 cells. II: Effects of the pituitary adenylate cyclase-activating polypeptide and vasoactive intestinal polypeptide. 911 89

We have shown recently that leukemia inhibitory factor (LIF) and oncostatin M (OSM), two members of the gp130-dependent cytokine family, stimulate murine proopiomelanocortin (POMC) transcription and adrenocorticotropin hormone (ACTH) secretion. LIF and corticotropin-releasing hormone (CRH) also synergistically induced in vivo ACTH secretion in fetal nonhuman primates. To elucidate the role of the gp130-related cytokines in human pituitary hormone regulation, we tested expression of gp130-related cytokine receptors in human fetal pituitaries. Using RT-PCR, mRNA expression of receptors for LIF, IL-6, and CRH, and the gp130 subunit, were all detected in fetal pituitaries of 18- and 31-wk gestation. Recombinant human IL-6, LIF, and OSM treatments of primary human fetal pituitary cultures (16-31 wk) increased ACTH secretion by up to 48% (P < 0.05) using doses of 1 nM, and when fetal cultures were cotreated with CRH, ACTH was induced five- to sixfold as compared to CRH alone (three- to fourfold; P = 0.01). Incubation with gp130-specific antibody suppressed basal and cytokine-stimulated ACTH secretion (alone or with CRH) from human fetal cells. Human POMC promoter -879/+6 fused to the luciferase reporter gene and transfected into AtT-20 cells, was stimulated by LIF (7-fold), which also exerted strong (22-fold) synergy with CRH on POMC transcription. Growth hormone (GH) release from fetal cultures was modestly stimulated (15-31%, P < 0.05), while other anterior pituitary hormones were not altered by these cytokines. Thus, physiologic concentrations of the gp130-related cytokines have direct effects on ACTH and GH regulation in the human pituitary, indicating that gp130-dependent signals serve as a paracrine system controlling early human pituitary function.
...
PMID:Cytokine-dependent gp130 receptor subunit regulates human fetal pituitary adrenocorticotropin hormone and growth hormone secretion. 921 12

The adrenocorticotropin receptor or ACTH-R which is the type 2 among the melanocortin receptor family is almost exclusively expressed in the adrenal cortex, reflecting a high degree of tissue specificity. In human cultured adrenocortical cells, we have previously reported that ACTH in contrast to most of the peptide hormones, is able to up-regulate the number of its own receptors through an increase of the transcriptional activity of the encoding gene. Three putative SF-1 binding sites are present in the sequence of the human ACTH-R gene promoter at -35 (SF-35), -98 (SF-98) and -209 (SF-209). By EMSA studies, we demonstrated that these sites effectively bind SF-1 protein. After transient transfection of H295R cells using a construct containing the first 263 bp upstream of the transcriptional start site, in front of the luciferase gene in the pGL3 vector, we demonstrated the involvement of all three SF-1 sites to confer maximal constitutive activity to a proximal region of the hACTH-R gene promoter. Only SF-35 and SF-98 play a role in cAMP-induced regulation of this gene.
...
PMID:SF-1 and the transcriptional regulation of the human ACTH receptor gene. 988 12

Corticotropin releasing factor (CRF) receptors belong to the super-family of G protein-coupled receptors. These receptors are classified into two subtypes (CRF1 and CRF2). Both receptors are positively coupled to adenylyl cyclase but they have a distinct pharmacology and distribution in brain. Two isoforms belonging to the CRF2 subtype receptors, CRF2alpha and CRF2beta, have been identified in rat and man. The neuropeptides CRF and urocortin mediate their actions through this CRF G protein-coupled receptor family. In this report, we describe the pharmacological characterization of the recently identified hCRF2, receptor. We have used radioligand binding with [125I]-tyr0-sauvagine and a gene expression assay in which the firefly luciferase gene expression is under the control of cAMP responsive elements. Association kinetics of [125I]-tyr0-sauvagine binding to the hCRF2beta receptor were monophasic while dissociation kinetics were biphasic, in agreement with the kinetics results obtained with the hCRF2alpha receptor. Saturation binding analysis revealed two affinity states in HEK 293 cells with binding parameters in accord with those determined kinetically and with parameters obtained with the hCRF2alpha receptor. A non-hydrolysable GTP analog, Gpp(NH)p, reduced the high affinity binding of [125I]-tyr0-sauvagine to both hCRF2 receptor isoforms in a similar manner. The rank order of potency of CRF agonist peptides in competition experiments was identical for both hCRF2 isoforms (urocortin > sauvagine > urotensin 1 > r/hCRF > alpha-helical CRF(9-41) > oCRF). Similarly, agonist potency was similar for the two isoforms when studied using the luciferase gene reporter system. The peptide antagonist alpha-helical CRF(9-41) exhibited a non-competitive antagonism of urocortin-stimulated luciferase expression with both hCRF2 receptor isoforms. Taken together, these results indicate that the pharmacological profiles of the CRF2 splice variants are identical. This indicates that the region of the N-terminus that varies between the receptors is probably not important in the binding of peptide CRF receptor ligands or functional activation of the receptor.
...
PMID:Human CRF2 alpha and beta splice variants: pharmacological characterization using radioligand binding and a luciferase gene expression assay. 1021 82

Pituitary corticotroph SOCS-3 is a novel intracellular regulator of leukemia inhibitory factor (LIF)-mediated proopiomelanocortin gene expression and adrenocorticotropic hormone (ACTH) secretion, inhibiting LIF-activated Janus kinase-signal transducers and activators of transcription (STAT) signaling in a negative autoregulatory loop. We now demonstrate in corticotroph AtT-20 cells that LIF-stimulated endogenous SOCS-3 mRNA expression is blocked in stable transfectants of SOCS-3 wild type or in dominant negative STAT-3 mutants, respectively. We characterized approximately 3.8-kb genomic 5' sequence of murine SOCS-3, including approximately 2.9-kb sequence upstream of the transcription start site (+1), which was determined by 5' rapid amplification of cDNA ends and RNase protection assay. Different 5' constructs were cloned into the pGL3Basic vector, and luciferase activity was assayed in transiently transfected ACTH-secreting corticotroph AtT-20 cells. A STAT-1/STAT-3 binding element, located at nucleotides -72 to -64, was essential for LIF stimulation of SOCS-3 promoter activity. LIF induced 10-fold increased luciferase activity in a wild-type construct spanning -2757 to +929 bases. However, deletion or point mutation of the STAT-1/STAT-3 binding element abrogated LIF action (2- to 3-fold). Electrophoretic mobility-shift assay analysis confirmed specific binding of STAT-1 and STAT-3 to this region. These results characterize the genomic 5' region of murine SOCS-3 and identify an important STAT-1/STAT-3 binding element therein. Thus, LIF-stimulated SOCS-3 gene expression is at least in part mediated by STAT-3 and STAT-1. The cytokine inhibitor SOCS-3 acts in a negative loop to autoregulate its own gene expression, thus limiting its accumulation in the corticotroph cell. These results demonstrate a mechanism for corticotroph plasticity with rapid "on" and "off" ACTH induction in response to neuro-immuno-endocrine stimuli, such as LIF.
...
PMID:Autoregulation of pituitary corticotroph SOCS-3 expression: characterization of the murine SOCS-3 promoter. 1035 22

1 2 3 4 5 Next >>