Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of the antidiarrheal drug loperamide, a mu-opiate agonist, on ACTH secretion and biosynthesis, cAMP generation and phosphoinositide turnover was studied in rat anterior pituitary cell cultures. The cAMP-dependent protein kinase A pathway was stimulated with both corticotropin-releasing hormone (CRH; 2-5 nM) and the membrane-permeable Bu(2)cAMP (0.5-2.5 mM). The protein kinase C pathway was stimulated with 1 microM arginine vasopressin (AVP) and 1-10 nM phorbol 12-myristate 13-acetate (PMA). After 3.5 h, loperamide (10 microM) had no effect on basal ACTH levels but significantly suppressed CRH-induced ACTH release, in a dose-dependent manner, to 60 +/- 4% of control (100%) (p < 0.0001). After 24 h, basal proopiomelanocortin mRNA was significantly decreased to 50% of control by loperamide (p < 0.05). The suppressive effect of loperamide on CRH-induced ACTH secretion was not reversible by naloxone (0.1-1,000 microM). Morphine (0.01-10 microM) had no effect on basal and CRH-induced ACTH secretion. Loperamide did not influence basal and CRH-induced adenylate cyclase activity in anterior pituitary cell membrane preparations, but it significantly blunted Bu(2)cAMP-induced ACTH secretion in cell culture from 100 +/- 4 to 77 +/- 4% (p < 0.05). In Ca(2+)-depleted medium (Ca2+ < 0.1 mM), loperamide had no suppressive effect on CRH-induced ACTH secretion. AVP-induced ACTH secretion was significantly suppressed by loperamide from 100 +/- 5 to 74 +/- 3% (p < 0.0001), while basal and AVP-induced inositol 1-phosphate generation and PMA-induced ACTH secretion were not affected by loperamide.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Loperamide inhibits corticotrophic cell function by a naloxone-insensitive mechanism in the rat in vitro. 823 60

Smooth muscle cells isolated separately from the caecal circular smooth muscle layer of the guinea pig were used to investigate whether corticotropin releasing hormone (CRH) can inhibit directly the contraction produced by cholecystokinin octapeptide (CCK-8). In addition, the role of adenylate cyclase and guanylate cyclase in the direct inhibitory effect of CRH was examined. CRH inhibited the contractile response produced by 10(-9)M CCK-8 in a concentration-dependent manner, with an IC50 value of 0.16nM. An inhibitor of particulate guanylate cyclase and an inhibitor of soluble guanylate cyclase had no significant effect of the relaxation produced by CRH. In contrast, an inhibitor of adenylate cyclase and an inhibitor of cAMP-dependent protein kinase significantly inhibited the relaxation produced by CRH. This is the first report demonstrating the direct inhibitory action of CRH on the isolated caecal smooth muscle cells via adenylate cyclase system.
...
PMID:Direct inhibitory effect of corticotropin releasing hormone on isolated caecal circular smooth muscle cells of guinea pig via adenylate cyclase system. 864 11

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

The ACTH-secreting mouse AtT-20/D16-16 anterior pituitary tumour cell line was used to study adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) and protein kinase C (PKC) involvement in stimulus-secretion coupling pathways. In permeabilised AtT-20 cells under calcium ion-free conditions, forskolin (1O mu M), CRH-41 (1OOnM), guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S; 100 mu M) but not mastoparan (10 mu M) stimulated cAMP accumulation. Measurement of ACTH secretion under identical incubation conditions revealed that GTP-gamma-S and mastoparan significantly stimulated ACTH secretion but forskolin and CRH-41 did not. This dissociates cAMP accumulation from ACTH secretion under calcium ion-free conditions and indicated that the effects of mastoparan and GTP-gamma-S on ACTH secretion are not mediated by cAMP production. Calcium ions (1 nM to I mM) stimulated ACTH secretion from electrically permeabilised cells in a concentration-dependent manner. cAMP (100 mu M) and phorbol 12-myristate 13-acetate (PMA; 100 nM) synergistically enhanced the response to calcium ions. cAMP did not stimulate ACTH secretion in the absence of calcium ions nor did it alter the concentrations at which calcium stimulated ACTH secretion. This suggests that stimulation of ACTH secretion via the calcium-dependent pathway is necessary before any cAMP-mediated enhancement of secretion is manifest. PMA, however, did stimulate ACTH secretion in the absence of calcium ions, indicating distinct mechanisms for PKC-evoked secretion. Co-incubation with cAMP and PMA did not exceed the secretory response obtained with the combination of PMA and calcium ions. CRH-41 (1 pM to 100 nM) and forskolin (1 nM to 100 mu M) stimulated ACTH secretion from intact cells in a concentration-dependent manner. Co-incubation with PMA (100 nM) further enhanced the ACTH response to CRH-41 and forskolin; the effects were simply additive. The present study indicates that there are distinct roles for PKA and PKC in stimulus-secretion coupling in AtT-20 cells. The PKA-dependent pathway, acting in concert with the calcium messenger system, serves as part of the stimulus-secretion coupling pathway by which activation of CRH-41 receptors control ACTH secretion. The PKC-dependent pathway, in contrast, seems to be independent of the calcium messenger system and may represent a separate control mechanism of ACTH secretion.
...
PMID:The roles of adenosine 3',5'-cyclic monophosphate-dependent protein kinase A and protein kinase C in stimulus-secretion coupling in AtT-20 cells. 915 16

The hypothalamic hormone CRH is also expressed in the placentas of humans and higher primates and may play an important role in the regulation of labor. In choriocarcinoma cell lines, activation of cAMP-dependent pathways increases human (h)CRH reporter gene expression. A cAMP-responsive region distinct from the cAMP response element at -220 bp, has been identified between -200 and -99 bp, and a candidate transcription factor was identified in nuclear extracts of human, but not rodent, choriocarcinoma cell lines. This region, which does not contain a canonical cAMP response element (CRE), transfers protein kinase A responsiveness to a heterologous promoter. Electromobility shift assays and methylation and uracil interference studies localized factor binding to a 20-bp region from -128 to -109 bp of the hCRH promoter. This 20-bp fragment exhibited a similar shift in nuclear extracts from both human term placenta and from human JEG-3 cells. Base contacts, identified in interference studies, were confirmed as critical for binding, as a mutation of these bases abolished factor binding. Furthermore, a CRH promoter containing this mutation exhibited a diminished response to forskolin. UV cross-linking demonstrated the protein in nuclear extracts from human, but not rodent, choriocarcinoma cell lines and estimated its size as 58 kDa. Although this factor participates in cAMP-regulated gene expression, competition electrophoretic mobility assays demonstrated that the factor does not bind to a CRE. Furthermore, neither anti-CREB nor anti-ATF2 antibodies alter factor binding. These data identify this 58-kDa protein as the human-specific CRH activator previously identified as a candidate factor contributing to the species-specific expression of CRH in human placenta.
...
PMID:Characterization of a human-specific regulator of placental corticotropin-releasing hormone. 971 48

In general, DNA-binding factors that activate gene transcription are thought to do so via reversible interaction with DNA. However, most studies, largely performed in vitro, suggest that the transcriptional activator, cAMP response element-binding protein (CREB), is exceptional in that it is constitutively bound to the promoter, where its phosphorylation leads to the recruitment of CREB-binding protein (CBP) to form a CREB/CBP/promoter complex. We have studied how CREB interacts with DNA in vivo to regulate the cAMP-responsive gene encoding human CRH (hCRH). Protein-DNA complexes were cross-linked in cells expressing the endogenous hCRH gene by exposure to a 10 nsec pulse of high-energy UV-laser light, followed by immunoaffinity purification of CREB-DNA complexes. Binding of CREB to a fragment of the hCRH promoter containing a canonical, functional cAMP response element was absent in untreated cells, but was specifically induced after activation of the protein kinase A pathway with forskolin. These data indicate that, in vivo, CREB, like the majority of other DNA-binding transcriptional activators, undergoes signal-mediated promoter interaction.
...
PMID:Inducible binding of cyclic adenosine 3',5'-monophosphate (cAMP)-responsive element binding protein (CREB) to a cAMP-responsive promoter in vivo. 1031 17

The molecular mechanisms involved in regulation of CRH-binding protein (CRH-BP) gene expression were examined using primary rat astrocyte cultures. The cells were treated with various regulators, and CRH-BP messenger RNA (mRNA) levels were determined using ribonuclease protection assays. Forskolin (Fsk, 10 microM) or 12-O-tetradecanoyl-phorbol 13-acetate (TPA, 100 nM) increases CRH-BP mRNA levels up to 30 times control level, and together they act synergistically to increase CRH-BP gene expression up to 100 times control levels. CRH can also positively regulate CRH-BP gene expression to 6.1 times control levels. All of these increases in steady-state CRH-BP mRNA levels can be repressed by dexamethasone, a synthetic glucocorticoid. To determine whether these changes in steady-state CRH-BP mRNA levels are caused by altered transcription or RNA stability, heteronuclear (hn) CRH-BP species were examined using ribonuclease protection assays. CRH-BP hnRNA transcripts can be detected transiently after the addition of Fsk or TPA, and dexamethasone can repress Fsk- or TPA-induced CRH-BP hnRNA levels in this assay. These results demonstrate that CRH, glucocorticoids, and the protein kinase A and protein kinase C signaling pathways are involved in regulation of CRH-BP gene expression in astrocyte cultures, and that this regulation is caused, at least in part, by altered transcription of the gene.
...
PMID:Transcriptional regulation of corticotropin-releasing hormone-binding protein gene expression in astrocyte cultures. 1046 81

CRH directly stimulates dehydroepiandrosterone sulfate (DHEAS) production in human fetal adrenal cells. In the human fetal and adult pituitary, CRH acts via protein kinase A (PKA). We determined the CRH signal transduction pathway in fetal adrenal cells, i.e. whether CRH modulates human fetal adrenal steroidogenesis via PKA and/or protein kinase C (PKC). In primary cultures, CRH increased inositol trisphosphate. After CRH treatment, inositol tris-, bis-, and monophosphates increased within 1 min, reaching maximal levels at 5 min. In contrast, PGF2alpha, known to act via PKC, induced a sustained response for up to 20 min. The response to CRH was dose dependent, maximal at 1 micromol/L at both 1 and 5 min. CRH increased DHEAS production, with a much lesser effect on cortisol. CRH did not stimulate inositol phospholipid in adult adrenal glands, suggesting that this pathway is unique to the fetal adrenal. CRH increased messenger ribonucleic acid encoding 17alpha-hydroxylase/17,20 lyase (P450c17), but not 3beta-hydroxysteroid dehydrogenase/delta(4-5) isomerase. However, 3betaHSD expression was stimulated by ACTH. PKC, but not PKA, inhibitors blocked CRH-stimulated P450c17 induction, whereas PKA inhibitors blocked ACTH-stimulated cortisol. Thus, CRH is coupled to the phospholipase C-inositol phosphate second messenger system and preferentially induces the expression of P450c17 and DHEAS, suggesting a unique role of CRH regulating human fetal adrenal function via PKC.
...
PMID:Corticotropin-releasing hormone stimulates P450 17alpha-hydroxylase/17,20-lyase in human fetal adrenal cells via protein kinase C. 1052 22

The neuropeptide CRH is the central regulator of the hypothalamic-pituitary-adrenal (HPA) stress response system and is implicated in various stress-related conditions. In the neurodegenerative disorder Alzheimer's disease (AD), levels of CRH are decreased. AD pathology is characterized by the deposition of the nonsoluble amyloid beta protein (A beta), oxidative stress, and neuronal cell death. Employing primary neurons and clonal cells, we demonstrate that CRH has a neuroprotective activity in CRH-receptor type 1 (CRH-R1)-expressing neurons against oxidative cell death. The protective effect of CRH was blocked by selective and nonselective CRH-R1 antagonists and by protein kinase A inhibitors. Overexpression of CRH-R1 in clonal hippocampal cells lacking endogenous CRH-receptors established neuroprotection by CRH. The activation of CRH-R1 and neuroprotection are accompanied by an increased release of non-amyloidogenic soluble A beta precursor protein. At the molecular level CRH caused the suppression of the DNA-binding activity and transcriptional activity of the transcription factor NF-kappaB. Suppression of NF-kappaB by overexpression of a super-repressor mutant form of IkappaB-alpha, a specific inhibitor of NF-kappaB, led to protection of the cells against oxidative stress. These data demonstrate a novel cytoprotective effect of CRH that is mediated by CRH-R1 and downstream by suppression of NF-kappaB and indicate CRH as an endogenous protective neuropeptide against oxidative cell death in addition to its function in the HPA-system. Moreover, the protective function of CRH proposes a molecular link between oxidative stress-related degenerative events and the CRH-R1 system.
...
PMID:Corticotropin-releasing hormone-mediated neuroprotection against oxidative stress is associated with the increased release of non-amyloidogenic amyloid beta precursor protein and with the suppression of nuclear factor-kappaB. 1062 54


<< Previous 1 2 3 4 5 6 Next >>

---