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Adenylate Cyclase Activity (adenylate + cyclase_activity)
Selected AbstractsRegulation of endogenous human NPFF2 receptor by neuropeptide FF in SK-N-MC neuroblastoma cell lineJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Minna-Liisa Änkö Abstract Neuropeptide FF has many functions both in the CNS and periphery. Two G protein-coupled receptors (NPFF1 and NPFF2 receptors) have been identified for neuropeptide FF. The expression analysis of the peptide and receptors, together with pharmacological and physiological data, imply that NPFF2 receptor would be the primary receptor for neuropeptide FF. Here, we report for the first time a cell line endogenously expressing hNPFF2 receptor. These SK-N-MC neuroblastoma cells also express neuropeptide FF. We used the cells to investigate the hNPFF2 receptor function. The pertussis toxin-sensitive inhibition of adenylate cyclase activity upon receptor activation indicated coupling to Gi/o proteins. Upon agonist exposure, the receptors were internalized and the mitogen-activated protein kinase cascade was activated. Upon neuropeptide FF treatment, the actin cytoskeleton was reorganized in the cells. The expression of hNPFF2 receptor mRNA was up-regulated by neuropeptide FF. Concomitant with the receptor mRNA, the receptor protein expression was increased. The homologous regulation of hNPFF2 receptor correlates with our previous results in vivo showing that during inflammation, the up-regulation of neuropeptide FF mRNA precedes that of NPFF2 receptor. The regulation of hNPFF2 receptor by NPFF could also be important in the periphery where neuropeptide FF has been suggested to function as a hormone. [source] Adenosine A2a receptor-mediated inhibition of rod opsin mRNA expression in tiger salamanderJOURNAL OF NEUROCHEMISTRY, Issue 3 2002Peter D. Alfinito Abstract The neuromodulator adenosine mediates dark-adaptive changes in retinal photoreceptors through A2a receptors. In cold-blooded vertebrates, opsin mRNA expression is lower at night than during the day. In the present study, we tested whether adenosine could inhibit opsin mRNA expression in cultured rod cells and if endogenous adenosine acts to suppress opsin mRNA in the intact retina at night. Semi-quantitative in situ hybridization showed that treatment with 100 nm of the A2a/A2b agonist N,6 -[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA) reduced opsin mRNA 41% in cultured rod cells. The effect of DPMA was blocked by 10 µm of the A2a antagonist 8-(3-chlorostyryl)caffeine (CSC) but not by 10 µm of the A2b antagonist alloxazine. One micromolar adenosine alone had no effect on opsin mRNA. However, in the presence of the adenosine deaminase inhibitor erythro -9-(2-hydroxy-3-nonyl)adenine hydrochloride (EHNA), 1 µm adenosine reduced opsin mRNA 61%. EHNA alone reduced opsin mRNA by 26%. Consistent with an A2a receptor mechanism, 100 nm forskolin (adenylate cyclase agonist) decreased opsin mRNA 34%. Finally, northern blots showed that intravitreal injection of 10 µm CSC at night increased opsin I mRNA 38%. Thus, endogenous adenosine suppresses rod opsin I mRNA expression at night; in vitro results indicate this reduction occurs through A2a -like receptor binding and stimulation of adenylate cyclase activity. [source] Interaction of ACTH synthetic fragments with rat adrenal cortex membranesJOURNAL OF PEPTIDE SCIENCE, Issue 8 2007Yulia A. Kovalitskaya Abstract Synthetic peptide, corresponding to the amino acid sequence 11,24 of human adrenocorticotropic hormone (ACTH), was labeled with tritium (specific activity of 22 Ci/mmol). [3H]ACTH (11,24) was found to bind to rat adrenal cortex membranes with high affinity and specificity (Kd = 1.8 ± 0.1 nM). Twenty nine fragments of ACTH (11,24) have been synthesized and their ability to inhibit the specific binding of [3H]ACTH (11,24) to adrenocortical membranes has been investigated. Unlabeled fragment ACTH 15,18 (KKRR) was found to replace in a concentration-dependent manner [3H]ACTH (11,24) in the receptor,ligand complex (Ki = 2.3 ± 0.2 nM). ACTH (15,18) was labeled with tritium (specific activity of 20 Ci/mmol). [3H]ACTH (15,18) was found to bind to rat adrenal cortex membranes with high affinity (Kd = 2.1 ± 0.1 nM). The specific binding of [3H]ACTH (15,18) was inhibited by unlabeled ACTH (11,24) (Ki = 2.2 ± 0.1 nM). ACTH (15,18) at the concentration range of 1,1000 nM did not affect the adenylate cyclase activity in adrenocortical membranes. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Biological Markers of Alcohol Consumption in Nondrinkers, Drinkers, and Alcohol-Dependent Brazilian PatientsALCOHOLISM, Issue 7 2002N. B. Figlie Background The purpose of this study was to compare the sensitivity and specificity of some new and traditional biological markers and indicators of health among Brazilian nondrinkers, drinkers, and alcohol-dependent patients. Material and Methods We evaluated 130 nondrinkers, 167 drinkers, and 183 alcohol-dependent drinkers from Brazil who participated in the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence. A standardized WHO/ISBRA Interview Schedule provided background information on the subjects' characteristics including reported health problems and alcohol consumption. Blood samples were analyzed for aspartate aminotransferase (AST), carbohydrate deficient transferrin (CDT), ,-glutamyltransferase (GGT), blood alcohol levels (BAL), and platelet adenylate cyclase activity (basal levels [AC] and levels after stimulation with Gpp(NH)p, cesium fluoride, and forskolin). Results The alcohol-dependent drinkers presented higher levels of AST, GGT, AC, CDT, and BAL than the nondrinkers and drinkers, whose levels were similar. Sex differences in the sensitivity of CDT and AC were found. The alcohol-dependent women presented a lower prevalence of abnormal values of CDT and Gpp(NH)p-stimulated AC than the alcohol-dependent men, despite the fact that they presented similar alcohol consumption levels. The alcohol-dependent drinkers presented a higher prevalence of clinical disorders than the nondrinkers and drinkers. The drinkers and alcohol-dependent patients presented significantly higher rates of gastritis than the nondrinkers. Conclusions Sex differences in the sensitivity of CDT and AC suggest that these markers are not as sensitive at detecting excessive alcohol use in women as they are in men. If data from this Brazilian sample are compared with those reported for international samples, relevant differences are detected, which suggests that genetic and cultural differences should be considered in the selection of biological markers of heavy alcohol consumption. [source] Laminin acts via focal adhesion kinase/phosphatidylinositol-3, kinase/protein kinase B to down-regulate ,1 -adrenergic receptor signalling in cat atrial myocytesTHE JOURNAL OF PHYSIOLOGY, Issue 3 2009Y. G. Wang We previously reported that short-term (2 h) plating of cat atrial myocytes on the extracellular matrix protein, laminin (LMN) decreases adenylate cyclase activity and ,1 -adrenergic receptor (,1 -AR) stimulation of L-type Ca2+ current (ICa,L). The present study sought to determine whether LMN-mediated down-regulation of ,1 signalling is due to down-regulation of adenylate cyclase and to gain insight into the signalling mechanisms responsible. ,1 -AR stimulation was achieved by 0.01 ,m isoproterenol (isoprenaline) plus 0.1 ,m ICI 118551, a selective ,2 -AR antagonist. Atrial myocytes were plated for at least 2 h on uncoated cover-slips (,LMN) or cover-slips coated with LMN (+LMN). As previously reported, ,1 -AR stimulation of ICa,L was significantly smaller in +LMN compared to ,LMN atrial myocytes. In ,LMN myocytes, 10 ,m LY294002 (LY), a specific inhibitor of PI-(3)K, had no effect on ,1 -AR stimulation of ICa,L. In +LMN myocytes, however, LY significantly increased ,1 -AR stimulation of ICa,L. Western blots revealed that compared with ,LMN myocytes, +LMN myocytes showed a significant increase in Akt phosphorylation at Ser-473, which was prevented by LY. In another approach, +LMN myocytes were infected (multiplicity of infection (MOI), 100; 24 h) with replication-defective adenoviruses (Adv) expressing dominant-negative inhibitors of focal adhesion kinase (FAK) (Adv-FRNK or Adv-Y397F-FAK) or Akt (Adv-dnAkt). Compared with control cells infected with Adv-,-galactosidase, cells infected with Adv-FRNK, Adv-Y397F-FAK or Adv-dnAkt each exhibited a significantly greater ,1 -AR stimulation of ICa,L. In ,LMN myocytes LY had no effect on forskolin (FSK)-stimulated ICa,L. However, in +LMN myocytes LY significantly increased FSK-stimulated ICa,L. Similar results were obtained in +LMN atrial myocytes infected with Adv-FRNK. We conclude that LMN binding to ,1 -integrin receptors acts via FAK/PI-(3)K/Akt to inhibit adenylate cyclase activity and thereby down-regulates ,1 -AR-mediated stimulation of ICa,L. These findings provide new insight into the cellular mechanisms by which the extracellular matrix can modulate atrial ,-AR signalling. 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