Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We explored the potential role of cyclic nucleotide-dependent protein phosphorylation in regulating ion transport across flounder intestinal mucosa by studying the effects of N-[2(methylamino)-ethyl]-s-isoquinolinesulfonamide (H-8), a selective inhibitor of cyclic nucleotide-dependent protein kinase in vitro. Addition of H-8 reversed the inhibitory effects of 8-bromoguanosine 3',5'-cyclic-monophosphate (8-BrcGMP), 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), atriopeptin III (AP III), and vasoactive intestinal peptide (VIP) on the short-circuit current (Isc) and transepithelial potential difference (PD). Flux measurements established that these changes in Isc and PD directly reflected changes in Na and Cl absorption by the intestine. H-8 was unable, however, to reverse the inhibitory effects on Isc and PD of the Ca ionophore ionomycin and of substance P at dosages exceeding those needed to reverse the effects of AP III, VIP, and the cyclic nucleotides. We conclude that 1) H-8 (100 microM or less) does not exert toxic effects, 2) exogenously added cyclic nucleotide analogues inhibit ion transport through activation of cyclic nucleotide-dependent kinases resulting in protein phosphorylation, 3) activation of these kinases is an essential intermediate step in the inhibitory action of AP III and VIP on ion transport, and 4) the Ca ionophore ionomycin and substance P appear to inhibit ion transport by a mechanism that is independent of cyclic nucleotide-dependent protein phosphorylation.
 ...
PMID:Cyclic nucleotide-dependent protein kinase inhibition by H-8: effects on ion transport. 282 9

HT 29, a cell line derived from a human colonic adenocarcinoma, is highly responsive to the vasoactive intestinal peptide (VIP) as shown by a more than 100-fold intracellular cAMP increase (Ka = 0.3 nM), the stimulations of protein kinase A (Ka = 0.1 nM) and the low-Km cAMP phosphodiesterase (Ka = 40 nM). Remarkably, adenylate cyclase, cAMP-dependent kinase and cAMP-specific phosphodiesterase are activated in a sequential manner. Binding studies with [125I]-labeled VIP indicate a high affinity site with a Kd value (0.5 nM) close to the activation constant value (Ka) of the three enzymes. The molecular structure of the VIP receptor was studied by immunological and chemical approaches. A monoclonal antibody (mAb 109-10-16) which partially decreased the binding of VIP to its receptor allowed the characterization of Mr = 53,000 and Mr = 48-49,000 polypeptides. More precise identification of protein components of the VIP receptor resulted from covalent cross-linking on intact HT 29 cells by four bifunctional reagents: dithiobis-(succinimidyl propionate) and its non-cleavable analog disuccinimidyl suberate, the photoactivable azido phenyl glyoxal and dimethylpimelimidate. Analysis by SDS-polyacrylamide gel electrophoresis demonstrated a major band of Mr = 67,000 regardless of which cross-linker was used. The same band and an Mr = 49,000 species were found in experiments using a crude membrane fraction of HT 29 cells. Assuming one molecule of VIP (Mr = 3326) linked per polypeptide, these observations suggest that an Mr = 64,000 species belongs to the VIP specific plasma membrane receptor. This protein contains an Mr = 20,000 N-linked sialic acid rich oligosaccharidic moiety.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:HT 29, a model cell line: stimulation by the vasoactive intestinal peptide (VIP); VIP receptor structure and metabolism. 284 4

The action of vasoactive intestinal peptide (VIP) on Ca2(+)-dependent K+ currents, in dissociated mouse lacrimal cells, was investigated using patch clamp techniques. In whole cell recordings, VIP (10-100 pM) increased the magnitude of the Ca2(+)-dependent K+ current. In single channel recordings, VIP increased the fraction of time the large charybdotoxin-sensitive Ca2(+)-activated K+ channel spent in the open state. The activity of this channel was also increased by adding forskolin or 8-bromo cAMP to the bath. Additionally, application of either cAMP or catalytic subunit of cAMP-dependent protein kinase directly to the cytoplasmic surface of excised inside out patches reversibly lengthened the time Ca2(+)-activated K+ channels spent in the open state. These data suggest that VIP stimulates Ca2(+)-activated K+ channels by a cAMP-dependent pathway in mouse lacrimal acinar cells.
 ...
PMID:Vasoactive intestinal peptide activates Ca2(+)-dependent K+ channels through a cAMP pathway in mouse lacrimal cells. 285 94

Evidence is rapidly accumulating to support the existence of a neuroimmune axis. However, the precise role of individual neurotransmitters in regulating immune function remains to be elucidated. In this review we focus on the role of vasoactive intestinal peptide (VIP) in modulation of lymphocyte function. We examine its status as a neurotransmitter, including evidence for neuronal and possible extraneuronal sites of synthesis. Further, we present data to demonstrate the presence of VIP receptors in human lymphocytes and, using the Molt 4b lymphoblastic cell line as a model, show VIP-mediated activation of adenylate cyclase leading to cAMP-dependent protein kinase-mediated phosphorylation of a specific Molt protein. Finally, we discuss the functional significance of VIP receptors on lymphocytes and present a model of neuropeptide-induced inflammation with possible therapeutic applications of this exciting new field of neuroimmunology.
 ...
PMID:Vasoactive intestinal peptide and neuropeptide modulation of the immune response. 286 Dec 33

alpha 1-Adrenergic agonists have recently been found to potentiate vasoactive intestinal peptide (VIP) stimulation of rat pinealocyte cAMP and cGMP. alpha 1-Adrenergic agonists also elevate pineal intracellular Ca2+ [( Ca2+]i) and activate protein kinase-C. In the present study, the possible involvement of Ca2+ and protein kinase-C in the alpha 1-adrenergic potentiation of VIP-stimulated cAMP and cGMP accumulation was examined with agents that alter [Ca2+]i or activate protein kinase-C. It was found that treatment with a Ca2+ chelator or with inorganic Ca2+ channel blockers inhibited alpha 1-adrenergic potentiation of VIP-stimulated cAMP and cGMP responses. Increasing [Ca2+]i by treatment with A23187, ouabain, or K+ potentiated VIP stimulation of cAMP and cGMP response. These observations indicate that Ca2+ mediates the alpha 1-adrenergic potentiation of VIP-stimulated cAMP and cGMP accumulation, as is true for the alpha 1-adrenergic potentiation of beta-adrenergic stimulated cAMP and cGMP accumulation. Activators of protein kinase-C mimicked the large effect alpha 1-adrenergic agonists have on cAMP accumulation in VIP-treated pinealocytes and had a small effect on cGMP accumulation in VIP-treated cells. These effects were not blocked by the Ca2+ chelator EGTA. However, the effects of a protein kinase-C activator on the cGMP response in VIP-stimulated cells were amplified by K+ (15 mM) or ouabain (1 microM), presumably through an action causing an increase in [Ca2+]i. These results suggest protein kinase-C is involved in the alpha 1-adrenergic potentiation of VIP-stimulated cAMP accumulation, as is the case for the alpha 1-adrenergic potentiation of beta-adrenergic stimulated cAMP. Protein kinase-C is also involved in cGMP accumulation, provided that there is a modest increase in [Ca2+]i.
 ...
PMID:Alpha 1-adrenergic potentiation of vasoactive intestinal peptide stimulation of rat pinealocyte adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate: evidence for a role of calcium and protein kinase-C. 289 67

Protein kinase C was identified as a major protein kinase enzyme activity in rabbit ciliary processes. Phorbol myristate acetate (4 beta-PMA) in the presence of Ca2+ activated protein kinase C but did not directly affect the cyclic AMP-dependent protein kinase enzyme isolated from ciliary processes. To elucidate possible roles of protein kinase C, PMA was injected intravitreally into rabbit eyes. Fifty pmoles of PMA produced approximately a 40% decrease of the intraocular pressure relative to the control eye lasting for more than 72 hr. A reduction of intraocular pressure was still elicited by this dose of PMA in animals pretreated with systemic indomethacin given to suppress a possible inflammatory response. The biologically inactive analogue, 4 alpha-phorbol didecanoate (100 pmoles/eye) had no significant effect on intraocular pressure. In vivo and in vitro treatment with PMA had no significant effect on adenylate cyclase in ciliary process membranes assayed in vitro. However, protein kinase C isolated from rat brain, when added together with cofactors to membranes in vitro, augmented adenylate cyclase activation by isoproterenol, vasoactive intestinal peptide and aluminum fluoride. A slight increase in the basal activity and in the forskolin response was not statistically significant. The effect of protein kinase C to increase responsiveness of ciliary process adenylate cyclase was totally dependent on the presence of Ca2+ and was augmented by addition of PMA. These findings indicate modulation of adenylate cyclase activity by protein kinase C acting at the level of the G-proteins and suggest a possible role for this enzyme in water and electrolyte transport in the ciliary processes.
 ...
PMID:Phorbol ester: effect on intraocular pressure, adenylate cyclase, and protein kinase in the rabbit eye. 367 53

Cyclic nucleotide metabolism was examined in rat distal colonic epithelial cells with different proliferative activities. Lower crypt cells had DNA synthetic rates 7-10-fold higher than surface cells. Without a phosphodiesterase inhibitor proliferative cells had reduced basal cyclic AMP-, cyclic GMP-, and cyclic AMP-dependent protein kinase activity ratios, as well as blunted cyclic AMP responses to prostaglandin E2 and vasoactive intestinal peptide compared to superficial cells. In the presence of 3-isobutyl-1-methylxanthine, basal cyclic AMP and responses to prostaglandin E2 and vasoactive intestinal peptide of proliferative cells exceeded values in superficial cells. This correlated with higher membrane adenylate cyclase activity in the proliferative cells. By contrast, particulate and soluble guanylate cyclase activities of superficial cells were higher than in proliferative cells. The apparent high Km soluble and particulate cyclic AMP and cyclic GMP phosphodiesterase activities of proliferative cells were 4-7-fold higher than those in superficial cells. Moreover, the apparent low Km soluble activity was absent in superficial cells. Thus, an altered rate of nucleotide degradation may mediate reduced cyclic AMP and cyclic GMP in proliferative versus superficial cells. Dibutyryl cyclic AMP, prostaglandin E2 or vasoactive intestinal peptide inhibited [3H]thymidine incorporation into DNA of colonic segments. Thus, reduced cyclic AMP in lower crypt cells may be a determinant of their greater proliferative activity.
 ...
PMID:Cyclic nucleotide metabolism in rat colonic epithelial cells with different proliferative activities. 616 89

The regulation of intestinal mucin secretion by cytokines, soluble factors released by mucosal activated immune cells, is so far unknown. The aim of the present study was (1) to investigate the regulatory effects of interferon-gamma on baseline and stimulated mucin secretion elicited by an increase in intracellular cAMP, either a short-term increase (induced by vasoactive intestinal peptide or by forskolin) or a long-term increase (cholera toxin-induced), and (2) to attempt to delineate the site of action of interferon-gamma. The in vitro model used was the human colonic goblet cell line Cl.16E, which has already been shown to respond to physiological secretagogues in terms of mucin secretion. We examined the effects of interferon-gamma 1) on mucin exocytosis, measured as release of [3H]glucosamine-labeled macromolecules trapped at the stacking/running gel interface of polyacrylamide gels, and 2) on mucin biosynthesis, examined at the RNA level using a cDNA probe directed to the MUC2 mucin gene. We demonstrated that, while interferon-gamma did not alter baseline Cl.16E mucin secretion and MUC2 gene expression, it strongly inhibited the protein kinase A-dependent secretory response to VIP, forskolin, or cholera toxin. However, interferon-gamma had no effect on the protein kinase A-dependent MUC2 over-expression induced by cholera toxin. We thus concluded that the target for interferon-gamma inhibition of cAMP-stimulated Cl.16E mucin secretion is distal to protein kinase A and might be a component of the exocytotic machinery. Together, our results establish interferon-gamma as a pharmacologically powerful tool to specifically inhibit stimulated secretory processes without affecting baseline secretion.
 ...
PMID:Interferon-gamma modulates cAMP-induced mucin exocytosis without affecting mucin gene expression in a human colonic goblet cell line. 751 24

Osmotic stress elicits hypertonic NaCl secretion and promotes structural and biochemical differentiation in avian salt glands. In addition to cholinergic control, Cl- secretion is stimulated by vasoactive intestinal peptide (VIP), suggesting that the cystic fibrosis transmembrane conductance regulator (CFTR) may be present and that its expression may be regulated by chronic salt stress. Anion efflux, assayed by 6-methoxy-N-(3-sulfopropyl)quinolinium fluorescence changes in single cells, was stimulated by VIP or 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate. Immunoblots with a COOH-terminal peptide antibody to human CFTR revealed approximately 170- and approximately 180-kDa bands in lysates from control and salt-stressed glands, respectively. Both variants reduced to approximately 140 kDa after N-glycanase digestion and gave identical tryptic phosphopeptide maps after immunoprecipitation and phosphorylation by protein kinase A. CFTR was localized to apical membranes by immunofluorescence and, additionally, to subapical vesicles by immunoelectron microscopy. Salt stress induced an approximately twofold increase in CFTR abundance/cell protein (approximately 5-fold/cell) and intensified apical membrane immunofluorescence. For comparison, Na+ pump expression increased approximately fourfold per cell protein with little change in actin. Thus differentiation induced by salt stress is accompanied by alteration in CFTR abundance and glycosylation. Upregulation of CFTR likely contributes to increased efficiency of Cl- secretion.
 ...
PMID:Salt stress increases abundance and glycosylation of CFTR localized at apical surfaces of salt gland secretory cells. 752 45

PTH-related peptide (PTHrP), which shares 8 of 13 NH2-terminal residues with PTH, causes similar biological effects and interacts with the same receptor as PTH. In the gastrointestinal tract, human PTH and PTHrP-(1-34) relax rat fundic strips. However, the level of their action and the receptor involved in this effect are unknown. The aims of this study were 1) to determine the effects of human PTH-(1-34), human PTHrP-(1-34), -(1-16), and -(7-34) and vasoactive intestinal peptide (VIP) on circular isolated smooth muscle cells from guinea pig ileum; 2) to study the intracellular pathways involved in these effects; and 3) and to characterize the receptors involved by using specific antagonists. Smooth muscle cells were dispersed by enzymatic digestion. Contraction was assessed by measuring the length of 50 cells and expressed as the percent decrease in cell length from the control value. The relaxing effects of PTH, PTHrP and analogs, VIP, or antagonists were expressed as a percentage of the maximal effect observed in their absence. VIP, PTH-(1-34), and PTHrP-(1-34), -(1-16), and -(7-34) had no effect by themselves on these cells. However, when cells were contracted by the sulfated C-terminal octapeptide of cholecystokinin (10 nM), VIP, PTH-(1-34), and PTHrP(1-34) inhibited the sulfated C-terminal octapeptide of cholecystokinin-induced contraction in a concentration-dependent manner, whereas PTHrP-(1-16) and -(7-34) had no effect. The EC50 values of VIP, PTH-(1-34), and PTH-(1-34), and PTHrP-(1-34) were 7 nM, 20 pM, and 20 pM, respectively. The VIP antagonist ([D-P-Cl-Phe6,Leu17]VIP) inhibited VIP-, PTH-(1-34)-, and PTHrP(1-34)-induced relaxation, with IC50 values of 20, 500, and 400 pM, respectively. Likewise, the PTH/PTHrP antagonist [Tyr34-bovine PTH-(7-34)NH2] inhibited PTH-(1-34)-, PTHrP(1-34)-, and VIP-induced relaxation, with IC50 values of 1, 1, and 90 pM, respectively. Preincubation of cells with somatostatin, N-ethylmaleimide, and (R)-p-cyclic adenosine-3',5'-monophosphothioate inhibited the PTH-(1-34), PTHrP(1-34)-, and VIP-induced relaxation. In conclusion, human PTH and PTHrP induce a relaxation of intestinal smooth muscle by a direct myogenic effect. This effect requires the 1-34 amino acid sequence and is mediated by the activation of adenylate cyclase and protein kinase-A. Interactions among PTH, PTHrP, and VIP indicate that they may cross-react with their respective receptors.
 ...
PMID:Parathyroid hormone (PTH) and PTH-related peptide induce relaxation of smooth muscle cells from guinea pig ileum: interaction with vasoactive intestinal peptide receptors. 752 62


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