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Rowlands J, Heng J, Newsholme P, Carlessi R. Pleiotropic Effects of GLP-1 and Analogs on Cell Signaling, Metabolism, and Function. Front Endocrinol (Lausanne) 2018; 9:672. [PMID: 30532733 PMCID: PMC6266510 DOI: 10.3389/fendo.2018.00672] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022] Open
Abstract
The incretin hormone Glucagon-Like Peptide-1 (GLP-1) is best known for its "incretin effect" in restoring glucose homeostasis in diabetics, however, it is now apparent that it has a broader range of physiological effects in the body. Both in vitro and in vivo studies have demonstrated that GLP-1 mimetics alleviate endoplasmic reticulum stress, regulate autophagy, promote metabolic reprogramming, stimulate anti-inflammatory signaling, alter gene expression, and influence neuroprotective pathways. A substantial body of evidence has accumulated with respect to how GLP-1 and its analogs act to restore and maintain normal cellular functions. These findings have prompted several clinical trials which have reported GLP-1 analogs improve cardiac function, restore lung function and reduce mortality in patients with obstructive lung disease, influence blood pressure and lipid storage, and even prevent synaptic loss and neurodegeneration. Mechanistically, GLP-1 elicits its effects via acute elevation in cAMP levels, and subsequent protein kinase(s) activation, pathways well-defined in pancreatic β-cells which stimulate insulin secretion in conjunction with elevated Ca2+ and ATP. More recently, new studies have shed light on additional downstream pathways stimulated by chronic GLP-1 exposure, findings which have direct relevance to our understanding of the potential therapeutic effects of longer lasting analogs recently developed for clinical use. In this review, we provide a comprehensive description of the diverse roles for GLP-1 across multiple tissues, describe downstream pathways stimulated by acute and chronic exposure, and discuss novel pleiotropic applications of GLP-1 mimetics in the treatment of human disease.
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Affiliation(s)
| | | | - Philip Newsholme
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia
| | - Rodrigo Carlessi
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Perth, WA, Australia
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2
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Nasibyan LS, Philyppov IB. EFFECT OF PEPTIDOGLYCANE OF STAPHYLOCOCCUS AUREUS CELL WALL ON THE MECHANISM OF REGULATION OF CONTRACTILE ACTIVITY OF RAT MYOMETRIUM BY ADENYLATE CYCLASE SYSTEM. ACTA ACUST UNITED AC 2018. [PMID: 29537197 DOI: 10.15407/fz62.01.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The revue deals with the role of each component of adenylate cyclase regulatory system in the rat myometrial contractile activity modulation by the peptidoglycane of Staphylococcus aureus. Noradrenalin and salbutamol were used to investigate peptidoglycane impact on the myometrial β-adrenergic receptors. It was shown that inhibited by these substances myometrial contractility increased to the initial level after peptidoglycane application. The same effect we observed under the cAMP level elevation by forscolin. Peptidoglycan’ s ability to strengthen contractions was inhibited by the 8-brom-cAMP and papaverine application. Stimulation of Gs-protein by the cholera toxin didn’t influence on the peptidoglycane effect while the blocking of Gi/o-protein by the pertussis toxin caused stopping it’s manifestation. We concluded that the modulating effect of peptidoglycane implemented via Gi/o-protein activation, which causes adenilatcyclase desensitization.
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MESH Headings
- 8-Bromo Cyclic Adenosine Monophosphate/pharmacology
- Adenylyl Cyclases/genetics
- Adenylyl Cyclases/metabolism
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic beta-2 Receptor Agonists
- Albuterol/pharmacology
- Animals
- Cell Wall/chemistry
- Cholera Toxin/pharmacology
- Colforsin/pharmacology
- Female
- GTP-Binding Protein alpha Subunits, Gi-Go/antagonists & inhibitors
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/antagonists & inhibitors
- GTP-Binding Protein alpha Subunits, Gs/genetics
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Myometrium/drug effects
- Myometrium/physiology
- Norepinephrine/pharmacology
- Papaverine/pharmacology
- Peptidoglycan/pharmacology
- Pertussis Toxin/pharmacology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Staphylococcus aureus/chemistry
- Tissue Culture Techniques
- Uterine Contraction/drug effects
- Uterine Contraction/physiology
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3
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Mou T, Masada N, Cooper DMF, Sprang SR. Structural basis for inhibition of mammalian adenylyl cyclase by calcium. Biochemistry 2009; 48:3387-97. [PMID: 19243146 PMCID: PMC2680196 DOI: 10.1021/bi802122k] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Type V and VI mammalian adenylyl cyclases (AC5, AC6) are inhibited by Ca(2+) at both sub- and supramicromolar concentration. This inhibition may provide feedback in situations where cAMP promotes opening of Ca(2+) channels, allowing fine control of cardiac contraction and rhythmicity in cardiac tissue where AC5 and AC6 predominate. Ca(2+) inhibits the soluble AC core composed of the C1 domain of AC5 (VC1) and the C2 domain of AC2 (IIC2). As observed for holo-AC5, inhibition is biphasic, showing "high-affinity" (K(i) = approximately 0.4 microM) and "low-affinity" (K(i) = approximately 100 microM) modes of inhibition. At micromolar concentration, Ca(2+) inhibition is nonexclusive with respect to pyrophosphate (PP(i)), a noncompetitive inhibitor with respect to ATP, but at >100 microM Ca(2+), inhibition appears to be exclusive with respect to PP(i). The 3.0 A resolution structure of Galphas.GTPgammaS/forskolin-activated VC1:IIC2 crystals soaked in the presence of ATPalphaS and 8 microM free Ca(2+) contains a single, loosely coordinated metal ion. ATP soaked into VC1:IIC2 crystals in the presence of 1.5 mM Ca(2+) is not cyclized, and two calcium ions are observed in the 2.9 A resolution structure of the complex. In both of the latter complexes VC1:IIC2 adopts the "open", catalytically inactive conformation characteristic of the apoenzyme, in contrast to the "closed", active conformation seen in the presence of ATP analogues and Mg(2+) or Mn(2+). Structures of the pyrophosphate (PP(i)) complex with 10 mM Mg(2+) (2.8 A) or 2 mM Ca(2+) (2.7 A) also adopt the open conformation, indicating that the closed to open transition occurs after cAMP release. In the latter complexes, Ca(2+) and Mg(2+) bind only to the high-affinity "B" metal site associated with substrate/product stabilization. Ca(2+) thus stabilizes the inactive conformation in both ATP- and PP(i)-bound states.
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Affiliation(s)
- Tung—Chung Mou
- Center for Biomolecular Structure and Dynamics and the Division of Biological Sciences, The University of Montana, Missoula, MT 59812
| | - Nanako Masada
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, United Kingdom
| | - Dermot M. F. Cooper
- Center for Biomolecular Structure and Dynamics and the Division of Biological Sciences, The University of Montana, Missoula, MT 59812
| | - Stephen R. Sprang
- Center for Biomolecular Structure and Dynamics and the Division of Biological Sciences, The University of Montana, Missoula, MT 59812
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4
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Willoughby D, Cooper DMF. Organization and Ca2+Regulation of Adenylyl Cyclases in cAMP Microdomains. Physiol Rev 2007; 87:965-1010. [PMID: 17615394 DOI: 10.1152/physrev.00049.2006] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The adenylyl cyclases are variously regulated by G protein subunits, a number of serine/threonine and tyrosine protein kinases, and Ca2+. In some physiological situations, this regulation can be readily incorporated into a hormonal cascade, controlling processes such as cardiac contractility or neurotransmitter release. However, the significance of some modes of regulation is obscure and is likely only to be apparent in explicit cellular contexts (or stages of the cell cycle). The regulation of many of the ACs by the ubiquitous second messenger Ca2+provides an overarching mechanism for integrating the activities of these two major signaling systems. Elaborate devices have been evolved to ensure that this interaction occurs, to guarantee the fidelity of the interaction, and to insulate the microenvironment in which it occurs. Subcellular targeting, as well as a variety of scaffolding devices, is used to promote interaction of the ACs with specific signaling proteins and regulatory factors to generate privileged domains for cAMP signaling. A direct consequence of this organization is that cAMP will exhibit distinct kinetics in discrete cellular domains. A variety of means are now available to study cAMP in these domains and to dissect their components in real time in live cells. These topics are explored within the present review.
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Affiliation(s)
- Debbie Willoughby
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
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5
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Trubey KR, Culpepper S, Maruyama Y, Kinnamon SC, Chaudhari N. Tastants evoke cAMP signal in taste buds that is independent of calcium signaling. Am J Physiol Cell Physiol 2006; 291:C237-44. [PMID: 16510847 DOI: 10.1152/ajpcell.00303.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We previously showed that rat taste buds express several adenylyl cyclases (ACs) of which only AC8 is known to be stimulated by Ca2+. Here we demonstrate by direct measurements of cAMP levels that AC activity in taste buds is stimulated by treatments that elevate intracellular Ca2+. Specifically, 5 microM thapsigargin or 3 microM A-23187 (calcium ionophore), both of which increase intracellular Ca2+ concentration ([Ca2+]i), lead to a significant elevation of cAMP levels. This calcium stimulation of AC activity requires extracellular Ca2+, suggesting that it is dependent on Ca2+ entry rather than release from stores. With immunofluorescence microscopy, we show that the calcium-stimulated AC8 is principally expressed in taste cells that also express phospholipase Cbeta2 (i.e., cells that elevate [Ca2+]i in response to sweet, bitter, or umami stimuli). Taste transduction for sucrose is known to result in an elevation of both cAMP and calcium in taste buds. Thus we tested whether the cAMP increase in response to sucrose is a downstream consequence of calcium elevation. Even under conditions of depletion of stored and extracellular calcium, the cAMP response to sucrose stimulation persists in taste cells. The cAMP signal in response to monosodium glutamate stimulation is similarly unperturbed by calcium depletion. Our results suggest that tastant-evoked cAMP signals are not simply a secondary consequence of calcium modulation. Instead, cAMP and released Ca2+ may represent independent second messenger signals downstream of taste receptors.
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Affiliation(s)
- Kristina R Trubey
- Dept. of Physiology and Biophysics (R430 Univ. of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL 33136, USA
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6
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Cooper DMF. Regulation and organization of adenylyl cyclases and cAMP. Biochem J 2003; 375:517-29. [PMID: 12940771 PMCID: PMC1223734 DOI: 10.1042/bj20031061] [Citation(s) in RCA: 276] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Revised: 08/07/2003] [Accepted: 08/26/2003] [Indexed: 11/17/2022]
Abstract
Adenylyl cyclases are a critically important family of multiply regulated signalling molecules. Their susceptibility to many modes of regulation allows them to integrate the activities of a variety of signalling pathways. However, this property brings with it the problem of imparting specificity and discrimination. Recent studies are revealing the range of strategies utilized by the cyclases to solve this problem. Microdomains are a consequence of these solutions, in which cAMP dynamics may differ from the broad cytosol. Currently evolving methodologies are beginning to reveal cAMP fluctuations in these various compartments.
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Affiliation(s)
- Dermot M F Cooper
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
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7
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Cioffi DL, Moore TM, Schaack J, Creighton JR, Cooper DMF, Stevens T. Dominant regulation of interendothelial cell gap formation by calcium-inhibited type 6 adenylyl cyclase. J Cell Biol 2002; 157:1267-78. [PMID: 12082084 PMCID: PMC2173565 DOI: 10.1083/jcb.200204022] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute transitions in cytosolic calcium ([Ca2+]i) through store-operated calcium entry channels catalyze interendothelial cell gap formation that increases permeability. However, the rise in [Ca2+]i only disrupts barrier function in the absence of a rise in cAMP. Discovery that type 6 adenylyl cyclase (AC6; EC 4.6.6.1) is inhibited by calcium entry through store-operated calcium entry pathways provided a plausible explanation for how inflammatory [Ca2+]i mediators may decrease cAMP necessary for endothelial cell gap formation. [Ca2+]i mediators only modestly decrease global cAMP concentrations and thus, to date, the physiological role of AC6 is unresolved. Present studies used an adenoviral construct that expresses the calcium-stimulated AC8 to convert normal calcium inhibition into stimulation of cAMP, within physiologically relevant concentration ranges. Thrombin stimulated a dose-dependent [Ca2+]i rise in both pulmonary artery (PAECs) and microvascular (PMVEC) endothelial cells, and promoted intercellular gap formation in both cell types. In PAECs, gap formation was progressive over 2 h, whereas in PMVECs, gap formation was rapid (within 10 min) and gaps resealed within 2 h. Expression of AC8 resulted in a modest calcium stimulation of cAMP, which virtually abolished thrombin-induced gap formation in PMVECs. Findings provide the first direct evidence that calcium inhibition of AC6 is essential for endothelial gap formation.
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Affiliation(s)
- Donna L Cioffi
- Department of Pharmacology, University of South Alabama College of Medicine, Mobile, AL 36688, USA
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8
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Dunne MJ, Ämmälä C, Straub SG, Sharp GWG. Electrophysiology of the β Cell and Mechanisms of Inhibition of Insulin Release. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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9
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Abstract
Rat islets express several isoforms of adenylyl cyclase (AC), and the regulation of AC activity in isolated islets by Ca(2+) and protein kinase C (PKC) was investigated. At basal 2.8 mmol/l glucose, the muscarinic receptor agonist carbamylcholine chloride (CCh) evoked a concentration-dependent increase in cAMP generation with a maximum increase at least 4.5-fold above control. In contrast, forskolin and glucagon-like peptide 1 fragment 7-36 amide increased cAMP accumulation 23-fold and almost 10-fold, respectively. Cholecystokinin 26-33 sulfated amide (CCK) also stimulated cAMP production by up to eightfold, as did the phorbol ester, phorbol 12,13-dibutyrate (PDBu). PDBu and CCh or CCK responses were not additive. The effects of phorbol ester, CCh, and CCK were inhibited by as much as 75% by the PKC inhibitors GF 109203X and Ro-32-0432 and after PKC downregulation. In the absence of extracellular Ca(2+), PDBu-, CCh-, and CCK-induced cAMP production was inhibited by approximately 50% in each case. Chelation of intracellular Ca(2+) with 1,2-bis(o-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA/AM) inhibited CCh- and CCK-stimulated cAMP generation by approximately 50% but did not inhibit the stimulatory effect of PDBu. Stringent Ca(2+) depletion by removal of extracellular Ca(2+) and inclusion of BAPTA/AM allowed for increased cAMP production in response to CCh and CCK; PKC inhibitors and PKC downregulation prevented this stimulation. Glucose stimulation also increased islet cAMP production, but PDBu did not potentiate the glucose response. The results suggest that Ca(2+) influx, Ca(2+) mobilization, and PKC activation play important roles in the modulation of AC activity in pancreatic islets.
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Affiliation(s)
- Y Tian
- Department of Pharmacology and Toxicology, the State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, New York 14214, USA
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10
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Watson EL, Jacobson KL, Singh JC, Idzerda R, Ott SM, DiJulio DH, Wong ST, Storm DR. The type 8 adenylyl cyclase is critical for Ca2+ stimulation of cAMP accumulation in mouse parotid acini. J Biol Chem 2000; 275:14691-9. [PMID: 10799557 DOI: 10.1074/jbc.275.19.14691] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Capacitative Ca(2+) entry stimulates cAMP synthesis in mouse parotid acini, suggesting that one of the Ca(2+)-sensitive adenylyl cyclases (AC1 or AC8) may play an important role in the regulation of parotid function (Watson, E. L., Wu, Z., Jacobson, K. L., Storm, D. R., Singh, J. C., and Ott, S. M. (1998) Am. J. Physiol. 274, C557-C565). To evaluate the role of AC1 and AC8 in Ca(2+) stimulation of cAMP synthesis in parotid cells, acini were isolated from AC1 mutant (AC1-KO) and AC8 mutant (AC8-KO) mice and analyzed for Ca(2+) stimulation of intracellular cAMP levels. Although Ca(2+) stimulation of intracellular cAMP levels in acini from AC1-KO mice was indistinguishable from wild type mice, acini from AC8-KO mice showed no Ca(2+)-stimulated cAMP accumulation. This indicates that AC8, but not AC1, plays a major role in coupling Ca(2+) signals to cAMP synthesis in parotid acini. Interestingly, treatment of acini from AC8-KO mice with agents, i.e. carbachol and thapsigargin that increase intracellular Ca(2+), lowered cAMP levels. This decrease was dependent upon Ca(2+) influx and independent of phosphodiesterase activation. Immunoblot analysis revealed that AC5/6 and AC3 are expressed in parotid glands. Inhibition of calmodulin (CaM) kinase II with KN-62, or inclusion of the CaM inhibitor, calmidazolium, did not prevent agonist-induced inhibition of stimulated cAMP accumulation. In vitro studies revealed that Ca(2+), independently of CaM, inhibited isoproterenol-stimulated AC. Data suggest that agonist augmentation of stimulated cAMP levels is due to activation of AC8 in mouse parotid acini, and strongly support a role for AC5/6 in the inhibition of stimulated cAMP levels.
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Affiliation(s)
- E L Watson
- Department of Oral Biology, University of Washington, Seattle, Washington 98195, USA.
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11
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Aztiria EM, Sogayar MC, Barrantes FJ. Expression of a neuronal nicotinic acetylcholine receptor in insect and mammalian host cell systems. Neurochem Res 2000; 25:171-80. [PMID: 10685617 DOI: 10.1023/a:1007512121082] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Different mammalian and insect somatic host cell systems were tested in their ability to express, fold, and assemble alpha7-type neuronal acetylcholine receptor (AChR) both at the transcriptional and translational level. For this purpose we employed clonal cell lines derived from the neural crest, such as PC12 cells from a rat adrenal pheochromocytoma, and GH3 cells isolated from a rat pituitary tumor, as well as non-neuronal cells such as NIH-3T3 fibroblasts from embryonic NIH Swiss mouse and Sf9 cells from ovary tissue of the Spodoptera frugiperda butterfly. Total RNA, isolated from either transfected or non-transfected PC12, GH3 or 3T3 cells, or recombinant AcNPV-infected and mock-infected Sf9 cells was analyzed by Northern blot. PC12 cells, which endogenously express alpha7 AChR, and all its heterologous alpha7-transfectant clones, exhibited variable but generally high amounts of a single transcript. GH3 and NIH-3T3 transfectant clones and recombinant AcNPV-infected Sf9 cells expressed variable levels of alpha7-mRNA, with a single transcript that co-migrated with the 28S rat rRNA. Only the neural crest-derived cell lines appeared to functionally express the alpha7 AChR, as measured by their [125I]alpha-bungarotoxin binding ability. The results suggest that heterologous expression of alpha7 is regulated not at the transcriptional, but at the postranslational level and that not all host cell systems appear to express the cellular factors needed for the correct postranslational modifications leading to mature and functional alpha7 AChR. Furthermore, the results suggest that tightly controlled expression mechanisms have evolved in parallel with this ancient cholinergic sequence.
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Affiliation(s)
- E M Aztiria
- Instituto de Investigaciones Bioquímicas, Universidad Nacional del Sur-CONICET, Bahía Blanca, Argentina
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12
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Takekoshi K, Isobe K, Nomura F, Motooka M, Nanmoku T, Nakai T. Effects of PAMP on mRNAs coding for catecholamine-synthesizing enzymes in PC12 cells. Life Sci 1999; 65:771-81. [PMID: 10466743 DOI: 10.1016/s0024-3205(99)00304-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide found in the N-terminal portion of the precursor of adrenomedullin (AM). Although PAMP and AM originate from the same precursor and exert both a potent hypotensive action, they seem to control blood pressure through different mechanisms. To gain new insight into the anticholinergic actions of PAMP, we determined the effects of PAMP on the tyrosine hydroxylase (TH)- and dopamine beta-hydroxylase (DBH) mRNA expression in the rat pheochromocytoma cell line PC12 stimulated by nicotine. PAMP (> or =1 microM) significantly inhibited the nicotine-induced increases of TH- and DBH mRNA expression in a concentration-dependent manner. Also, PAMP at the concentrations (> or =1 microM) significantly inhibited nicotine-induced cyclic adenosine monophosphate (cAMP) production. These results indicate that the anticholinergic hypotensive actions of PAMP can be explained, at least in part, by its inhibition of the expression of mRNAs coding for catecholamine-synthesizing enzymes, and that the inhibitory effect is mediated by the cAMP/protein kinase A pathway.
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Affiliation(s)
- K Takekoshi
- Department of Clinical Pathology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
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13
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Abstract
Ca2+ stimulation of adenylyl cyclase type VIII (ACVIII) occurs through loosely bound calmodulin. However, where calmodulin binds in ACVIII and how the binding activates this cyclase have not yet been investigated. We have located two putative calmodulin-binding sites in ACVIII. One site is located at the N terminus as revealed by overlay assays; the other is located at the C terminus, as indicated by mutagenesis studies. Both of these calmodulin-binding sites were confirmed by synthetic peptide studies. The N-terminal site has the typical motif of a Ca2+-dependent calmodulin-binding domain, which is defined by a characteristic pattern of hydrophobic amino acids, basic and aromatic amino acids, and a tendency to form amphipathic alpha-helix structures. Functional, mutagenesis studies suggest that this binding makes a minor contribution to the Ca2+ stimulation of ACVIII activity, although it might be involved in calmodulin trapping by ACVIII. The primary structure of the C-terminal site resembles another calmodulin-binding motif, the so-called IQ motif, which is commonly Ca2+-independent. Mutagenesis and functional assays indicate that this latter site is a calcium-dependent calmodulin-binding site, which is largely responsible for the Ca2+ stimulation of ACVIII. Removal of this latter calmodulin-binding region from ACVIII results in a hyperactivated enzyme state and a loss of Ca2+ sensitivity. Thus, Ca2+/calmodulin regulation of ACVIII may be through a disinhibitory mechanism, as is the case for a number of other targets of Ca2+/calmodulin.
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Affiliation(s)
- C Gu
- Neuroscience Program and Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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14
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Cooper DM, Schell MJ, Thorn P, Irvine RF. Regulation of adenylyl cyclase by membrane potential. J Biol Chem 1998; 273:27703-7. [PMID: 9765307 DOI: 10.1074/jbc.273.42.27703] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian adenylyl cyclases possess 12 transmembrane-spanning domains and bear a superficial resemblance to certain classes of ion channels. Some evidence suggests that bacterial and sea urchin sperm adenylyl cyclases can be regulated by membrane depolarization. In the present study, we explored the effect of altering membrane potential on the adenylyl cyclase activity of cerebellar granule cells with acute potassium depolarization. A biphasic stimulatory and then inhibitory response is evoked by progressive increases in the extracellular [K]:[Na] ratio in the absence of extracellular Ca2+. This effect does not mimic the linear increase in membrane potential elicited under the same conditions. Instead it appears as though membrane depolarization opens L-type (nimodipine-sensitive) Ca2+ channels, allowing the entry of Na+, which directly stimulates adenylyl cyclase activity. Gramicidin, which generates pores that are permeable to monovalent cations, and concurrently eliminates the membrane potential, permits a similar stimulation by extracellularly applied Na+. Although the results indicate no direct sensitivity of cerebellar granule cell adenylyl cyclase to membrane potential, they do demonstrate that, as a result of membrane depolarization, the influx of Na+, as well as Ca2+, will elevate cAMP levels.
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Affiliation(s)
- D M Cooper
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1QJ, United Kingdom.
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15
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Mons N, Decorte L, Jaffard R, Cooper DM. Ca2+-sensitive adenylyl cyclases, key integrators of cellular signalling. Life Sci 1998; 62:1647-52. [PMID: 9585151 DOI: 10.1016/s0024-3205(98)00122-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The concept of second messenger signalling originated from the discovery of the role of cyclic AMP, although it is now known that cytosolic calcium [Ca2+]i mediates numerous signalling pathways and plays an equally vital role in many cellular events. In the last few years there has been a great deal of interest in the substantial molecular and functional diversity of mammalian adenylyl cyclases (ACs). Although AC was viewed as a generic activity, which was either stimulated or inhibited by stimulatory or inhibitory receptors, respectively, acting via alpha-subunits of trimeric GTP-regulatory proteins, the recent cloning of nine full-length isoforms, which significantly differ in their regulatory properties and tissue distributions, has revealed an unexpected level of complex regulation. In fact, each AC may integrate convergent inputs from many distinct signal-generating pathways. The nine isoforms can be divided into four distinct families, which reflect their distinct patterns of regulation by betagamma subunits of G-proteins, protein kinase C (PKC) and Ca2+. The mechanisms of regulation are often highly synergistic or conditional, suggesting a function of ACs as coincident detectors. Since all nine isoforms can be regulated either directly or indirectly by Ca2+ or PKC, a complex range of responses is possible. The Ca2+ concentration that stimulates the major ACs in brain has been found to inhibit AC activity in a number of peripheral tissues and cell lines. The purpose of this article is to review many of the important aspects about the distinct regulatory properties and cellular distribution of Ca2+-regulated ACs. Indeed, the notion that Ca2+ and cAMP are "synarchic" messengers acting in concert to regulate cellular activity was formally proposed some time ago. Here, we will focus on acute interactions between Ca2+ and cAMP and attempt to understand how AC activities can be regulated by discrete, physiological [Ca2+]i rises in intact cells. All Ca2+-regulated isoforms have characteristic distribution patterns in the brain. Also discussed are emerging insights on the temporal and spatial regulation of Ca2+- and cAMP-regulated pathways which may enable cell stimuli to elicit specific responses.
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Affiliation(s)
- N Mons
- Laboratory of Functional Neurobiology, URA-CNRS 339, University of Bordeaux I, Talence, France
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16
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DeBernardi MA, Brooker G. Simultaneous fluorescence ratio imaging of cyclic AMP and calcium kinetics in single living cells. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1998; 32:195-213. [PMID: 9421592 DOI: 10.1016/s1040-7952(98)80012-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M A DeBernardi
- Department of Cell Biology, Georgetown University School of Medicine, Washington, DC 20007, USA
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Wang D, Chen P, Liu W, Li CS, Halpern M. Chemosignal transduction in the vomeronasal organ of garter snakes: Ca(2+)-dependent regulation of adenylate cyclase. Arch Biochem Biophys 1997; 348:96-106. [PMID: 9390179 DOI: 10.1006/abbi.1997.0366] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Earthworm shock secretion contains a 20-kDa vomeronasally mediated chemoattractive protein for garter snakes. Both the ligand-receptor binding and the chemoattractivity of ES20 are Ca(2+)-dependent. When ES20 binds to its G-protein-coupled receptors in the vomeronasal epithelium, the inositol 1,4,5-trisphosphate (IP3) level is increased, but the level of cAMP is reduced. Furthermore, forskolin-stimulated levels of cAMP are completely blocked by ES20-receptor binding or by Ca2+ alone and the effect of calcium ions can be nullified by EGTA. Previously, we hypothesized that the decrease in cAMP was due to activation of a Ca(2+)-dependent phosphodiesterase. In the present study, we provide evidence that the decrease in cAMP is due mainly to the regulation of adenylate cyclase (AC) activity by Ca2+ or is indirectly mediated by ES20. Results obtained with intact vomeronasal sensory epithelium suggest that the binding of ES20 to its receptors facilitates generation of IP3 which mobilizes intracellularly sequestered Ca2+, resulting in an increase of cystosolic Ca2+. A further increase in cytosolic Ca2+ occurs through Ca2+ influx from extracellular sources. Garter snake vomeronasal AC does not require calmodulin for its activity and shows a biphasic response to increasing concentrations of Ca2+; its activity is modulated both positively and negatively by this bivalent cation.
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Affiliation(s)
- D Wang
- Department of Biochemistry, State University of New York Health Science Center at Brooklyn, New York 11203, USA
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Alvaro D, Alpini G, Jezequel AM, Bassotti C, Francia C, Fraioli F, Romeo R, Marucci L, Le Sage G, Glaser SS, Benedetti A. Role and mechanisms of action of acetylcholine in the regulation of rat cholangiocyte secretory functions. J Clin Invest 1997; 100:1349-62. [PMID: 9294100 PMCID: PMC508313 DOI: 10.1172/jci119655] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
UNLABELLED We investigated, in isolated bile duct units (IBDU) and cholangiocytes isolated from normal rat liver, the occurrence of acetylcholine (ACh) receptors, and the role and mechanisms of ACh in the regulation of the Cl-/HCO3- exchanger activity. The Cl-/HCO3- exchanger activity was evaluated measuring changes in intracellular pH induced by acute Cl- removal/readmission. M3 subtype ACh receptors were detected in IBDU and isolated cholangiocytes by immunofluorescence, immunoelectron microscopy, and reverse transcriptase PCR. M1 subtype ACh receptor mRNA was not detected by reverse transcriptase PCR and M2 subtype was negative by immunofluorescence. ACh (10 microM) showed no effect on the basal activity of the Cl-/HCO3- exchanger. When IBDU were exposed to ACh plus secretin, ACh significantly (P < 0.03) increased the maximal rate of alkalinization after Cl- removal and the maximal rate of recovery after Cl- readmission compared with secretin alone (50 nM), indicating that ACh potentiates the stimulatory effect of secretin on the Cl-/HCO3- exchanger activity. This effect of ACh was blocked by the M3 ACh receptor antagonist, 4-diphenyl-acetoxy-N-(2-chloroethyl)-piperidine (40 nM), by the intracellular Ca2+ chelator, 1,2-bis (2-Aminophenoxy)- ethane-N,N,N', N'-tetraacetic acid acetoxymethylester (50 microM), but not by the protein kinase C antagonist, staurosporine (0.1 microM). Intracellular cAMP levels, in isolated rat cholangiocytes, were unaffected by ACh alone, but were markedly higher after exposure to secretin plus ACh compared with secretin alone (P < 0.01). The ACh-induced potentiation of the secretin effect on both intracellular cAMP levels and the Cl-/HCO3- exchanger activity was individually abolished by two calcineurin inhibitors, FK-506 and cyclosporin A (100 nM). CONCLUSIONS M3 ACh receptors are markedly and diffusively represented in rat cholangiocytes. ACh did not influence the basal activity of the Cl-/HCO3- exchanger, but enhanced the stimulation by secretin of this anion exchanger by a Ca2+-dependent, protein kinase C-insensitive pathway that potentiates the secretin stimulation of adenylyl cyclase. Calcineurin most likely mediates the cross-talk between the calcium and adenylyl cyclase pathways. Since secretin targets cholangiocytes during parasympathetic predominance, coordinated regulation of Cl-/HCO3- exchanger by secretin (cAMP) and ACh (Ca2+) could play a major role in the regulation of ductal bicarbonate excretion in bile just when the bicarbonate requirement in the intestine is maximal.
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Affiliation(s)
- D Alvaro
- Division of Gastroenterology, Department of Clinical Medicine, University of Rome, "La Sapienza," Viale dell'Universita' 37, 00185 Rome, Italy.
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Menninger JA, Tabakoff B. Forskolin-stimulated platelet adenylyl cyclase activity is lower in persons with major depression. Biol Psychiatry 1997; 42:30-8. [PMID: 9193739 DOI: 10.1016/s0006-3223(96)00245-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We investigated platelet adenylyl cyclase activity in 17 subjects with a history of major depression ("depressed subjects") and 20 controls. Forskolin was used to directly activate adenylyl cyclase, while guanine nucleotides (Gpp(NH)p) and fluoride ions were used to measure adenylyl cyclase activity modulated through the G proteins. Forskolin-stimulated adenylyl cyclase was significantly lower in the depressed subjects (p < 0.0005). There was a statistically significant difference in basal adenylyl cyclase activity between male depressed subjects and male controls. The basal adenylyl cyclase activity was also lower in female depressed subjects, but this difference did not reach statistical significance (p < 0.2). The adenylyl cyclase activity measured after stimulation with a guanine nucleotide or cesium fluoride did not differ between control and depressed male or female subjects. Severity of current depression and the current use of antidepressant medication were not related to the lower forskolin-stimulated enzyme activity in the depressed subjects. The difference in forskolin-stimulated adenylyl cyclase activity appears to reflect a qualitative difference in the adenylyl cyclase enzyme activity in persons with a history of major depression.
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Affiliation(s)
- J A Menninger
- Department of Pharmacology and Psychiatry, University of Colorado Health Sciences Center, Denver, USA
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Ishiguro H, Ichino N, Yamada K, Nagatsu T. Nicotine regulates mRNA level of tyrosine hydroxylase gene but not that of nicotinic acetylcholine receptor genes in PC12 cells. Neurosci Lett 1997; 228:37-40. [PMID: 9197282 DOI: 10.1016/s0304-3940(97)00360-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To understand the molecular mechanism of nicotine addiction, we examined the mRNA level of the tyrosine hydroxylase (TH) gene and that of the nicotinic acetylcholine receptor (nAChR) genes by long-term nicotine treatment. The transcript levels of the four subunit genes of the nAChR (alpha3, alpha5, alpha7, and beta4) were down-regulated by the treatment with forskolin, whereas the mRNA levels of the TH gene was increased in PC12 cells. By long-term nicotine treatment, the mRNA level of the nAChR genes did not change, but transcript levels of alpha3, alpha5, alpha7, and beta4 nAChR genes were still negatively regulated by forskolin. However, the mRNA level of TH gene did not change by forskolin under long-term nicotine treatment. The TH gene may be regulated by a nicotine-related signaling pathway, whereas alpha3, alpha5, alpha7, and beta4 nAChR genes may be further regulated by a protein kinase A (PKA) pathway under long-term nicotine treatment.
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Affiliation(s)
- H Ishiguro
- Institute for Comprehensive Medical Science, School of Medicine, Fujita Health University, Aichi, Japan
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Cooper DM, Karpen JW, Fagan KA, Mons NE. 2 Ca2+-sensitive adenylyl cyclases. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1997. [DOI: 10.1016/s1040-7952(98)80004-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Wei J, Wayman G, Storm DR. Phosphorylation and inhibition of type III adenylyl cyclase by calmodulin-dependent protein kinase II in vivo. J Biol Chem 1996; 271:24231-5. [PMID: 8798667 DOI: 10.1074/jbc.271.39.24231] [Citation(s) in RCA: 129] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Inhibition of type III adenylyl cyclase (III-AC) by intracellular Ca2+ in vivo provides a mechanism for attenuation of hormone-stimulated cAMP signals in olfactory epithelium, heart, and other tissues (Wayman, G. A., Impey, S., and Storm, D. R. (1995) J. Biol. Chem. 270, 21480-21486). Although the mechanism for Ca2+ inhibition of III-AC in vivo has not been defined, inhibition is not mediated by Gi, cAMP-dependent protein kinase, or protein kinase C. However, Ca2+ inhibition of III-AC is antagonized by KN-62, a CaM-dependent kinase inhibitor. In addition, constitutively activated CaM kinase II inhibits the enzyme. These data suggest that CaM kinase II regulates the activity of III-AC by direct phosphorylation or by an indirect mechanism involving phosphorylation of a protein that inhibits III-AC. Here we report that III-AC is phosphorylated in vivo when intracellular Ca2+ is increased and that phosphorylation is prevented by CaM-dependent kinase inhibitors. Site-directed mutagenesis of a CaM kinase II consensus site (Ser-1076 to Ala-1076) in III-AC greatly reduced Ca2+-stimulated phosphorylation and inhibition of III-AC in vivo. These data support the hypothesis that Ca2+ inhibition of III-AC is due to direct phosphorylation of the enzyme by CaM kinase II in vivo.
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Affiliation(s)
- J Wei
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7820, USA
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Fagan KA, Mahey R, Cooper DM. Functional co-localization of transfected Ca(2+)-stimulable adenylyl cyclases with capacitative Ca2+ entry sites. J Biol Chem 1996; 271:12438-44. [PMID: 8647849 DOI: 10.1074/jbc.271.21.12438] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Three adenylyl cyclases (ACI, ACIII, and ACVIII) have been described, which are putatively Ca(2+)-stimulable, based on in vitro assays. However, it is not clear that these enzymes can be regulated by physiological rises in [Ca2+]i when expressed in intact cells. Furthermore, it is not known whether transfected adenylyl cyclases might display the strict requirement for capacitative Ca2+ entry that is shown by the Ca(2+)-inhibitable ACVI, which is indigenous to C6-2B glioma cells (Chiono, M., Mahey, R., Tate, G., and Cooper, D. M. F. (1995) J. Biol. Chem. 270, 1149-1155). In the present study, ACI, ACIII, and ACVIII were heterologously expressed in HEK 293 cells, and conditions were devised that distinguished capacitative Ca2+ entry from both internal release and nonspecific elevation in [Ca2+]i around the plasma membrane. Remarkably, not only were ACI and ACVIII largely insensitive to Ca2+ release from stores, but they were robustly stimulated only by capacitative Ca2+ entry and not al all by a substantial increase in [Ca2+]i at the plasma membrane elicited by ionophore. (ACIII, reflecting its feeble in vitro sensitivity to Ca2+, was unaffected by any [Ca2+]i rise.) These results suggest a quite unsuspected, essential association of Ca(2+)-sensitive adenylyl cyclases with capacitative Ca2+ entry sites, even when expressed heterologously.
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Affiliation(s)
- K A Fagan
- Department of Pharmacology and Neuroscience Program, University of Colorado Health Sciences Center, Denver 80262, USA
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Thekkumkara TJ, Du J, Zwaagstra C, Conrad KM, Krupinski J, Baker KM. A role for cAMP in angiotensin II mediated inhibition of cell growth in AT1A receptor-transfected CHO-K1 cells. Mol Cell Biochem 1995; 152:77-86. [PMID: 8609915 DOI: 10.1007/bf01076466] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
G-protein coupled Angiotensin II receptors (AT1A), mediate cellular responses through multiple signal transduction pathways. In AT1A receptor-transfected CHO-K1 cells (T3CHO/AT1A), angiotensin II (AII) stimulated a dose-dependent EC50 = 3.3 nM) increase in cAMP accumulation, which was inhibited by the selective AT1, nonpeptide receptor antagonist EXP3174. Activation of protein kinase C, or increasing intracellular Ca2+ with ATP, the calcium ionophore A23187 or ionomycin failed to stimulate cAMP accumulation. Thus, AII-induced cAMP accumulation was not secondary to activation of a protein kinase C- or ca2+/calmodulin-dependent pathway. Since cAMP has an established role in cellular growth responses, we investigated the effect of the AII-mediated increase in cAMP on cell number and [3H]thymidine incorporation in T3CHOA/AT1A cells. AII (1 microM) significantly inhibited cell number (51% at 96 h) and [3H]thymidine incorporation of 68% at 24 h) compared to vehicle controls. These effects were blocked by EXP3174, confirming that these responses were mediated through the AT1 receptor. Forskolin (10 microM) and the cAMP analog dibutyryl-cAMP (1 mM) also inhibited [3H]thymidine incorporation by 55 and 25% respectively. We extended our investigation on the effect of AII-stimulated increases in cAMP, to determine the role for established growth related signaling events, i.e., mitogen-activated protein kinase activity an tyrosine phosphorylation of cellular proteins. AII-stimulated mitogen-activated protein kinase activity and phosphorylation of the 42 and 44 kD forms. These events were unaffected by forskolin stimulated increases in cAMP, thus the AII-stimulated mitogen-activated protein kinase activity was independent of cAMP in these cells. AII also stimulated tyrosine phosphorylation of a number of cellular proteins in T3CHO/AT1A cells, in particular at 127 kD protein. The phosphorylation of the 127 kD protein was transient, reaching a maximum at 1 min, and returning to basal levels within 10 min. The dephosphorylation of this protein was blocked by a selective inhibitor of cAMP dependent protein kinase A, H89-dihydrochloride and preexposure to forskolin prevented the AII-induced transient tyrosine phosphorylation of the 127 kD protein. These data suggest that cAMP, and therefore protein kinase A can contribute to AII-mediated growth inhibition by stimulating the dephosphorylation of substrates that are tyrosine phosphorylated in response to AII.
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Affiliation(s)
- T J Thekkumkara
- Weis Center for Research, Geisinger Clinic, Danville, PA 17822, USA
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Abstract
Isolated islets were either studied immediately after isolation (fresh; F), or were cultured for 6 days at 11 mM glucose (desensitized; D), or were incubated for 2 h at 5.5 mM glucose following D (recovered; R). Glucose-stimulated insulin secretion in D islets was reduced compared with F and R islets. In the presence of 3-isobutyl-1-methylxanthine, glucose also increased cyclic adenosine monophosphate (cAMP) levels in F islets, but failed to affect cAMP generation in R or D islets. Glucagon alone or in the presence of glucose stimulated insulin release in F and R islets, but the response was blunted in D islets. Glucagon-like peptide 1 (GLP) potentiated insulin secretion in R islets, but not in D islets. Glucagon (0.01-0.1 microM) did not increase cAMP levels in D islets, whereas GLP (0.1 microM) increased cAMP as much as 4.5-fold. R islets recovered adenylyl cyclase responsivity to glucagon, and GLP increased cAMP levels as much as 9-fold. In F islets pretreated with forskolin for 2 h, the cAMP responses to glucose and GLP were inhibited. The cAMP response to forskolin stimulation was similarly inhibited in D islets and in islets pretreated for 2 h with forskolin. Forskolin pretreatment significantly attenuated the islet insulin release response to glucose, although the combined stimulus of glucose and GLP restored insulin release to control values. Insulin secretion in response to glucose and cAMP analogue (Sp)5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3'-5'-cyclic monophosphorothioate was lower than that observed in F islets. In conclusion, beta-cell cAMP accumulation in response to several stimuli acting through different mechanisms is impaired following continuous glucose stimulation. However, cAMP levels are not the definitive second messenger in the recovery of glucose-sensitive insulin secretion in glucose desensitized islets.
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Affiliation(s)
- S G Laychock
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, School of Medicine and Biomedical Sciences 14214, USA
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Sipma H, den Hertog A, Nelemans A. Ca(2+)-dependent and -independent mechanism of cyclic-AMP reduction: mediation by bradykinin B2 receptors. Br J Pharmacol 1995; 115:937-44. [PMID: 7582524 PMCID: PMC1909031 DOI: 10.1111/j.1476-5381.1995.tb15901.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
1. Bradykinin caused a transient reduction of about 25% in the cyclic AMP level in forskolin prestimulated DDT1 MF-2 smooth muscle cells (IC50: 36.4 +/- 4.9 nM) and a pronounced, sustained inhibition (40%) of the isoprenaline-stimulated cyclic AMP level (IC50: 37.5 +/- 1.1 nM). 2. The Ca2+ ionophore, ionomycin, mimicked both the bradykinin-induced transient reduction in the forskolin-stimulated cyclic AMP level and the sustained reduction in the isoprenaline-stimulated cyclic AMP level. 3. The Ca(2+)-dependent effect on cyclic AMP induced by bradykinin was mediated solely by Ca2+ release from internal stores, since inhibition of Ca2+ entry with LaCl3 did not reduce the response to bradykinin. 4. The involvement of calmodulin-dependent enzyme activities, protein kinase C or an inhibitory GTP binding protein in the bradykinin-induced responses was excluded since a calmodulin inhibitor, calmidazolium, a PKC inhibitor, staurosporine and pertussis toxin, respectively did not affect the decline in the cyclic AMP level. 5. Bradykinin enhanced the rate of cyclic AMP breakdown in intact cells, which effect was not mimicked by ionomycin. This suggested a Ca(2+)-independent activation of phosphodiesterase activity by bradykinin in DDT1 MF-2 cells. 6. The bradykinin B1 receptor agonist, desArg9-bradykinin, did not affect cyclic AMP formation in isoprenaline prestimulated cells, while the bradykinin B2 receptor antagonists, Hoe 140 (D-Arg[Hyp3, Thi5, D-Tic7, Oic8]-BK) and D-Arg[Hyp3, Thi5,8, D-Phe7]-BK completely abolished the bradykinin response in both forskolin and isoprenaline prestimulated cells. 7. Bradykinin caused an increase in intracellular Ca2+, which was antagonized by the bradykinin B2 receptor antagonists, Hoe 140 and D-Arg[Hyp3, Thi5,8, D-Phe7]-BK. The bradykinin B2 receptor agonist,desArg9-bradykinin, did not evoke a rise in cytoplasmic Ca2 .8. It is concluded, that stimulation of bradykinin B2 receptors causes a reduction in cellular cyclic AMP in DDT1, MF-2 cells. This decline in cyclic AMP is partly mediated by a Ca2+/calmodulin independent activation of phosphodiesterase activity. The increase in [Ca2+], mediated by bradykinin B2 receptors inhibited forskolin- and isoprenaline-activated adenylyl cyclase differently, most likely by interfering with different components of the adenylyl cyclase signalling pathway.
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Affiliation(s)
- H Sipma
- Groningen Institute for Drugs Studies GIDS, Department of Clinical Pharmacology, University of Groningen, The Netherlands
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Stevens T, Nakahashi Y, Cornfield DN, McMurtry IF, Cooper DM, Rodman DM. Ca(2+)-inhibitable adenylyl cyclase modulates pulmonary artery endothelial cell cAMP content and barrier function. Proc Natl Acad Sci U S A 1995; 92:2696-700. [PMID: 7708708 PMCID: PMC42285 DOI: 10.1073/pnas.92.7.2696] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Maintenance by the endothelium of a semi-permeable barrier is critically important in the exchange of oxygen and carbon dioxide in the lung. Intracellular free Ca2+ ([Ca2+]i) and cAMP are principal determinants of endothelial cell barrier function through their mutually opposing actions on endothelial retraction. However, details of the mechanisms of this antagonism are lacking. The recent discovery that certain adenylyl cyclases (EC 4.6.1.1) could be acutely inhibited by Ca2+ in the intracellular concentration range provided one possible mechanism whereby elevated [Ca2+]i could decrease cAMP content. This possibility was explored in pulmonary artery endothelial cells. The results indicate that a type VI Ca(2+)-inhibitable adenylyl cyclase exists in pulmonary artery endothelial cells and is modulated by physiological changes in [Ca2+]i. Furthermore, the results suggest the inverse relationship between [Ca2+]i and cAMP that is established by Ca(2+)-inhibitable adenylyl cyclase plays a critical role in modulating pulmonary artery endothelial cell permeability. These data provide evidence that susceptibility to inhibition of adenylyl cyclase by Ca2+ can be exploited in modulating a central physiological process.
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Affiliation(s)
- T Stevens
- Department of Anesthesiology, University of Colorado Health Sciences Center, Denver 80262, USA
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McDermott AM, Sharp GW. Noradrenaline induces supersensitivity of adenylyl cyclase in NG108-15 and HT29-18 cells but not in the beta-cell RINm5F. Cell Signal 1995; 7:277-85. [PMID: 7662513 DOI: 10.1016/0898-6568(94)00086-q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In some cells a supersensitive adenylyl cyclase response follows hormonal inhibition of the enzyme. We have compared the effect of pre-treatment with noradrenaline in RINm5F cells to that in cells known to demonstrate supersensitivity. In NG108-15 cells, 12 or 24 hours pre-treatment with 1-10 microM noradrenaline markedly enhanced forskolin (1 microM) stimulated cAMP accumulation compared to that in untreated cells (12 h, 429 +/- 123 vs 72 +/- 8 pmol/mg protein; 24 h 190 +/- 32 vs 82 +/- 10 for treated and untreated cells, respectively). In a second cell, HT29-18, 30 min pre-treatment with 10 microM noradrenaline enhanced forskolin (10 microM) stimulated cAMP accumulation from 47 +/- 13 pmol/mg protein to 405 +/- 109 pmol/mg protein. In contrast, pre-treatment of RINm5F cells with noradrenaline under the same conditions did not enhance the forskolin response. These data indicate that noradrenaline which induces a supersensitive adenylyl cyclase response in NG108-15 and HT29-18 cells does not induce the response in the insulin secreting cell RINm5F.
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Affiliation(s)
- A M McDermott
- Department of Pharmacology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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Mons N, Cooper DM. Adenylyl cyclase mRNA expression does not reflect the predominant Ca2+/calmodulin-stimulated activity in the hypothalamus. J Neuroendocrinol 1994; 6:665-71. [PMID: 7894469 DOI: 10.1111/j.1365-2826.1994.tb00633.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Only three (Types I, II, V) of the six currently-described subtypes of adenylyl cyclase are prominently expressed in the rat brain. These species are differently sensitive to Ca2+, beta gamma subunits of G-proteins and protein kinase C. A knowledge of the susceptibility of the cAMP-signalling system in particular brain regions to these diverse modes of regulation can shed light on the mechanism of action of the neurotransmitters that modify neuronal activity in such regions. Cyclic AMP is extensively involved in the physiological functions of the hypothalamus. We have used in situ hybridization histochemistry with synthetic oligonucleotides to examine the expression in the rat hypothalamus of the three major brain subtypes of adenylyl cyclase-Ca2+/calmodulin-stimulable (Type I), Ca(2+)-insensitive (Type II) and Ca(2+)-inhibitable (Type V). The hypothalamus expresses high levels only of Type II mRNA, particularly in the supraoptic and paraventricular nuclei. Curiously, the strong expression of the Ca(2+)-insensitive Type II mRNA and the lack of expression of the major brain specific Type I mRNA does not correlate with the adenylyl cyclase activity, which is largely Ca2+/calmodulin stimulable in plasma membranes prepared from the hypothalamus.
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Affiliation(s)
- N Mons
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262
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Affiliation(s)
- D M Cooper
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, U.S.A
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Warhurst G, Fogg KE, Higgs NB, Tonge A, Grundy J. Ca(2+)-mobilising agonists potentiate forskolin- and VIP-stimulated cAMP production in human colonic cell line, HT29-cl.19A: role of [Ca2+]i and protein kinase C. Cell Calcium 1994; 15:162-74. [PMID: 8149416 DOI: 10.1016/0143-4160(94)90055-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This study has examined the involvement of the Ca(2+)-signalling pathway in the regulation of agonist-stimulated cAMP responses in the human colonic adenocarcinoma cell line, HT29-cl.19A. The muscarinic agonist, carbachol (CCh) stimualted rapid increases in cellular IP3 and cytosolic Ca2+, [Ca2+]i in HT29-cl.19A cells. These were accompanied by a small but significant increase in basal cAMP levels and a marked (3-4-fold) potentiation of both forskolin- (FSK) and VIP-stimulated cAMP generation. Similar effects were observed with two other Ca(2+)-mobilising agonists, neurotensin and ATP. The failure of CCh to elicit potentiation of adenylate cyclase in broken cell preparations indicated an indirect action. Potentiation could be mimicked by the calcium ionophore, ionomycin, and thapsigargin and inhibited 70-90% by depleting intracellular Ca2+ stores suggesting that a rise in [Ca2+]i is the primary mediator of this response. In contrast, increasing [Ca2+]i levels to > 500 nM caused a significant inhibition of FSK-stimulated cAMP generation. The involvement of protein kinase C (PKC) was also assessed. PKC activators phorbol 12,13 dibutyrate (PDB) and 1-oleoyl-2-acetyl glycerol (OAG) potentiated FSK-stimulated cAMP production by 50-70% though PDB markedly inhibited the cAMP response to the receptor-mediated cAMP agonist, VIP. Neither effect could be elicited by the inactive phorbol ester, 4 alpha-phorbol, 12,13 didecanoate (PDD). PKC inhibitors staurosporine and H7 reduced by approximately 25% the CCh-induced potentiation of FSK-stimulated cAMP generation. In conclusion, these results suggest that stimulation of the phosphoinositidase C pathway in HT29-cl.19A colonocytes induces a 'sensitisation' of the adenylate cyclase system resulting in a dramatic amplification of agonist-stimulated cAMP generation. Increases in [Ca2+]i appear to be an important mediator of potentiation though activation of PKC may also play a significant role.
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Affiliation(s)
- G Warhurst
- Department of Medicine, University of Manchester, Hope Hospital, Salford, UK
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Chapter 29. Adenylate Cyclase Subtypes as Molecular Drug Targets. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1994. [DOI: 10.1016/s0065-7743(08)60742-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Cooper DM. Regulation of Ca(2+)-sensitive adenylyl cyclases by calcium ion in vitro and in vivo. Methods Enzymol 1994; 238:71-81. [PMID: 7799804 DOI: 10.1016/0076-6879(94)38007-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- D M Cooper
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262
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Hiremagalur B, Nankova B, Nitahara J, Zeman R, Sabban E. Nicotine increases expression of tyrosine hydroxylase gene. Involvement of protein kinase A-mediated pathway. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)49518-5] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Paul S, Ebadi M. Vasoactive intestinal peptide: its interactions with calmodulin and catalytic antibodies. Neurochem Int 1993; 23:197-214. [PMID: 8220166 DOI: 10.1016/0197-0186(93)90111-h] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S Paul
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha 68198-6830
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Smith JA, Griffin M, Mireylees SE, Long RG. The inhibition of human duodenal adenylate cyclase activity by Ca2+ and the effects of EGTA. FEBS Lett 1993; 327:137-40. [PMID: 8335102 DOI: 10.1016/0014-5793(93)80157-p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study demonstrates that the inhibition of adenylate cyclase activity by Ca2+ is enhanced in the presence of increasing [EGTA] (0, 0.3, 1, 2.5 mM) by 2 orders of magnitude. It has been established that this effect is not because of poor Ca2+ buffering by low [EGTA] or high Ca2+ binding by the membrane preparation. It is present irrespective of stimulus. We suggest the enhanced sensitivity of adenylate cyclase to Ca2+ induced by EGTA is caused by the Ca-EGTA complex being a more inhibitory species than Ca2+. Thus consideration of the effects of the Ca-EGTA complex should be made when interpreting the results from experiments involving Ca2+ and EGTA.
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Affiliation(s)
- J A Smith
- Medical Research Centre, City Hospital, Nottingham, UK
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Debernardi MA, Munshi R, Yoshimura M, Cooper DM, Brooker G. Predominant expression of type-VI adenylate cyclase in C6-2B rat glioma cells may account for inhibition of cyclic AMP accumulation by calcium. Biochem J 1993; 293 ( Pt 2):325-8. [PMID: 8393657 PMCID: PMC1134362 DOI: 10.1042/bj2930325] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In C6-2B cells, agonist-stimulated cyclic AMP accumulation is inhibited when the cytosolic Ca2+ concentration is increased. We now demonstrate that in C6-2B cells: (i) the early kinetics of the cyclic AMP inhibition by substance K (t1/2 = 35 s) and thapsigargin (t1/2 = 1.6 min) closely mimic the kinetics of the cytosolic Ca2+ increase evoked by either agent (t1/2 = 25 s and 1.5 min respectively); (ii) the Ca2+ rise and cyclic AMP inhibition by substance K or thapsigargin are similarly affected in EGTA-containing medium; (iii) PCR detects type-III and type-VI adenylate cyclase cDNAs, and RNAase protection assays show that the mRNA for type-VI adenylate cyclase, an isoform inhibitable by submicromolar Ca2+ concentrations, is the predominant species, strongly suggesting that type-VI adenylate cyclase is probably the target molecule for Ca(2+)-mediated inhibition of cyclic AMP accumulation.
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Affiliation(s)
- M A Debernardi
- Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC 20007
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Yoshimura M, Cooper DM. Cloning and expression of a Ca(2+)-inhibitable adenylyl cyclase from NCB-20 cells. Proc Natl Acad Sci U S A 1992; 89:6716-20. [PMID: 1379717 PMCID: PMC49574 DOI: 10.1073/pnas.89.15.6716] [Citation(s) in RCA: 226] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A cDNA that encodes an adenylyl cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] has been cloned from NCB-20 cells, in which adenylyl cyclase activity is inhibited by Ca2+ at physiological concentrations. The cDNA clone (5.8 kilobases) was isolated by polymerase chain reaction (PCR) using degenerate primers designed by comparison of three adenylyl cyclase sequences (types I, II, and III) and subsequent library screening. Northern analysis revealed expression of mRNA (6.1 kilobases) corresponding to this cDNA in cardiac tissue, which is a prominent source of Ca(2+)-inhibitable adenylyl cyclase. The clone encodes a protein of 1165 amino acids, whose hydrophilicity profile was very similar to those of other mammalian adenylyl cyclases that have recently been cloned. A noticeable difference between this protein and other adenylyl cyclases was a lengthy aminoterminal region before the first transmembrane span. Transient expression of this cDNA in the human embryonic kidney cell line 293 revealed a 3-fold increase in cAMP production in response to forskolin compared with control transfected cells. In purified plasma membranes from transfected cells, increased adenylyl cyclase activity was also detected, which was susceptible to inhibition by submicromolar Ca2+. Thus, this adenylyl cyclase seems to represent the Ca(2+)-inhibitable form that is encountered in NCB-20 cells, cardiac tissue, and elsewhere. Its identification should permit a determination of the structural features that determine the mode of regulation of adenylyl cyclase by Ca2+.
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Affiliation(s)
- M Yoshimura
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262
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Knoll G, Kerboeuf D, Plattner H. A rapid calcium influx during exocytosis in Paramecium cells is followed by a rise in cyclic GMP within 1 s. FEBS Lett 1992; 304:265-8. [PMID: 1319928 DOI: 10.1016/0014-5793(92)80634-s] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The synchrony of trichocyst exocytosis in Paramecium allows temporal correlation of associated events. Using quenched flow we observed a Ca2+ influx concurrent with exocytosis within 80 ms after stimulation with the secretagogue aminoethyldextran. Cyclic AMP did not change in depency of stimulation. Cyclic GMP transiently increased after 500 ms, culminating at 2 s, and thus considerably lags behind exocytosis induction and influx of Ca2+. Both Ca2+ influx and rise in cGMP are known to be induceable also by Ba2+ or veratridine, allegedly via the opening of ciliary Ca2+ channels. However, only veratridine stimulated exocytosis. We conclude that both aminoethyldextran and veratridine induce an exocytosis-associated Ca2+ influx, which is responsible for the rise in cGMP, through an as yet unknown pathway.
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Affiliation(s)
- G Knoll
- University of Konstanz, Faculty of Biology, Germany
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