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Liu L, Bulla LA. Cell death signaling in Anopheles gambiae initiated by Bacillus thuringiensis Cry4B toxin involves Na +/K + ATPase. Exp Biol Med (Maywood) 2023; 248:1191-1205. [PMID: 37642306 PMCID: PMC10621475 DOI: 10.1177/15353702231188072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/10/2023] [Indexed: 08/31/2023] Open
Abstract
Identifying the mechanisms by which bacterial pathogens kill host cells is fundamental to understanding how to control and prevent human and animal disease. In the case of Bacillus thuringiensis (Bt), such knowledge is critical to using the bacterium to kill insect vectors that transmit human and animal disease. For the Cry4B toxin produced by Bt, its capacity to kill Anopheles gambiae, the primary mosquito vector of malaria, is the consequence of a variety of signaling activities. We show here that Cry4B, acting as first messenger, binds specifically to the bitopic cadherin BT-R3 G-protein-coupled receptor (GPCR) localized in the midgut of A. gambiae, activating the downstream second messenger cyclic adenosine monophosphate (cAMP). The direct result of the Cry4B-BT-R3 binding is the release of αs from the heterotrimeric αβγ-G-protein complex and its activation of adenylyl cyclase (AC). The upshot is an increased level of cAMP, which activates protein kinase A (PKA). The functional impact of cAMP-PKA signaling is the stimulation of Na+/K+-ATPase (NKA) which serves as an Na+/K+ pump to maintain proper gradients of extracellular Na+ and intracellular K+. Increased level of cAMP amplifies NKA and upsets normal ion concentration gradients. NKA, as a scaffolding protein, accelerates the first messenger signal to the nucleus, generating additional BT-R3 molecules and promoting their exocytotic trafficking to the cell membrane. Accumulation of BT-R3 on the cell surface facilitates recruitment of additional toxin molecules which, in turn, amplify the original signal in a cascade-like manner. This report provides the first evidence of a bacterial toxin using NKA via AC/PKA signaling to execute cell death.
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Affiliation(s)
- Li Liu
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080-3021 USA
| | - Lee A Bulla
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080-3021 USA
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Dessauer CW, Watts VJ, Ostrom RS, Conti M, Dove S, Seifert R. International Union of Basic and Clinical Pharmacology. CI. Structures and Small Molecule Modulators of Mammalian Adenylyl Cyclases. Pharmacol Rev 2017; 69:93-139. [PMID: 28255005 PMCID: PMC5394921 DOI: 10.1124/pr.116.013078] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenylyl cyclases (ACs) generate the second messenger cAMP from ATP. Mammalian cells express nine transmembrane AC (mAC) isoforms (AC1-9) and a soluble AC (sAC, also referred to as AC10). This review will largely focus on mACs. mACs are activated by the G-protein Gαs and regulated by multiple mechanisms. mACs are differentially expressed in tissues and regulate numerous and diverse cell functions. mACs localize in distinct membrane compartments and form signaling complexes. sAC is activated by bicarbonate with physiologic roles first described in testis. Crystal structures of the catalytic core of a hybrid mAC and sAC are available. These structures provide detailed insights into the catalytic mechanism and constitute the basis for the development of isoform-selective activators and inhibitors. Although potent competitive and noncompetitive mAC inhibitors are available, it is challenging to obtain compounds with high isoform selectivity due to the conservation of the catalytic core. Accordingly, caution must be exerted with the interpretation of intact-cell studies. The development of isoform-selective activators, the plant diterpene forskolin being the starting compound, has been equally challenging. There is no known endogenous ligand for the forskolin binding site. Recently, development of selective sAC inhibitors was reported. An emerging field is the association of AC gene polymorphisms with human diseases. For example, mutations in the AC5 gene (ADCY5) cause hyperkinetic extrapyramidal motor disorders. Overall, in contrast to the guanylyl cyclase field, our understanding of the (patho)physiology of AC isoforms and the development of clinically useful drugs targeting ACs is still in its infancy.
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Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Val J Watts
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Rennolds S Ostrom
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Marco Conti
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Stefan Dove
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Roland Seifert
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
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Kore AR, Yang B, Srinivasan B, Senthilvelan A. Concise and efficient synthesis of 3'-O-tetraphosphates of 2'-deoxyadenosine and 2'-deoxycytidine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2015; 34:33-9. [PMID: 25513862 DOI: 10.1080/15257770.2014.955193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We describe concise and efficient synthesis of biologically very important 3'-O-tetraphosphates namely 2'-deoxyadenosine-3'-O-tetraphosphate (2'-d-3'-A4P) and 2'-deoxycytidine-3'-O-tetra-phosphate (2'-d-3'-C4P). N(6)-benzoyl-5'-O-levulinoyl-2'-deoxyadenosine was converted into N(6)-benzoyl-5'-O-levulinoyl-2'-deoxyadenosine-3'-O-tetraphosphate in 87% yield using a one-pot synthetic methodology. One-step concurrent deprotection of N(6)-benzoyl and 5'-O-levulinoyl groups using concentrated aqueous ammonia resulted 2'-d-3'-A4P in 74% yield. The same synthetic strategy was successfully employed to convert N(4)-benzoyl-5'-O-levulinoyl-2'-deoxycytidine into 2'-d-3'-C4P in 68% yield.
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Affiliation(s)
- Anilkumar R Kore
- a Life Sciences Solutions Group, Thermo Fisher Scientific , Austin , Texas , USA
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Chimote AA, Hajdu P, Kucher V, Boiko N, Kuras Z, Szilagyi O, Yun YH, Conforti L. Selective inhibition of KCa3.1 channels mediates adenosine regulation of the motility of human T cells. THE JOURNAL OF IMMUNOLOGY 2013; 191:6273-80. [PMID: 24227782 DOI: 10.4049/jimmunol.1300702] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Adenosine, a purine nucleoside, is present at high concentrations in tumors, where it contributes to the failure of immune cells to eliminate cancer cells. The mechanisms responsible for the immunosuppressive properties of adenosine are not fully understood. We tested the hypothesis that adenosine's immunosuppressive functions in human T lymphocytes are in part mediated via modulation of ion channels. The activity of T lymphocytes relies on ion channels. KCa3.1 and Kv1.3 channels control cytokine release and, together with TRPM7, regulate T cell motility. Adenosine selectively inhibited KCa3.1, but not Kv1.3 and TRPM7, in activated human T cells. This effect of adenosine was mainly mediated by A2A receptors, as KCa3.1 inhibition was reversed by SCH58261 (selective A2A receptor antagonist), but not by MRS1754 (A2B receptor antagonist), and it was mimicked by the A2A receptor agonist CGS21680. Furthermore, it was mediated by the cAMP/protein kinase A isoform (PKAI) signaling pathway, as adenylyl-cyclase and PKAI inhibition prevented adenosine effect on KCa3.1. The functional implication of the effect of adenosine on KCa3.1 was determined by measuring T cell motility on ICAM-1 surfaces. Adenosine and CGS21680 inhibited T cell migration. Comparable effects were obtained by KCa3.1 blockade with TRAM-34. Furthermore, the effect of adenosine on cell migration was abolished by pre-exposure to TRAM-34. Additionally, adenosine suppresses IL-2 secretion via KCa3.1 inhibition. Our data indicate that adenosine inhibits KCa3.1 in human T cells via A2A receptor and PKAI, thereby resulting in decreased T cell motility and cytokine release. This mechanism is likely to contribute to decreased immune surveillance in solid tumors.
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Affiliation(s)
- Ameet A Chimote
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267
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5
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Bitterman JL, Ramos-Espiritu L, Diaz A, Levin LR, Buck J. Pharmacological distinction between soluble and transmembrane adenylyl cyclases. J Pharmacol Exp Ther 2013; 347:589-98. [PMID: 24091307 DOI: 10.1124/jpet.113.208496] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The second messenger cAMP is involved in a number of cellular signaling pathways. In mammals, cAMP is produced by either the hormonally responsive, G protein-regulated transmembrane adenylyl cyclases (tmACs) or by the bicarbonate- and calcium-regulated soluble adenylyl cyclase (sAC). To develop tools to differentiate tmAC and sAC signaling, we determined the specificity and potency of commercially available adenylyl cyclase inhibitors. In cellular systems, two inhibitors, KH7 and catechol estrogens, proved specific for sAC, and 2',5'-dideoxyadenosine proved specific for tmACs. These tools provide a means to define the specific contributions of the different families of adenylyl cyclases in cells and tissues, which will further our understanding of cell signaling.
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Affiliation(s)
- Jacob L Bitterman
- Department of Pharmacology, Weill Cornell Medical College, New York, New York
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Enyeart JJ, Liu H, Enyeart JA. Evidence for cAMP-independent bTREK-1 inhibition by ACTH and NPS-ACTH in adrenocortical cells. Mol Cell Endocrinol 2012; 348:305-12. [PMID: 21952081 DOI: 10.1016/j.mce.2011.09.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 08/30/2011] [Accepted: 09/09/2011] [Indexed: 11/26/2022]
Abstract
Bovine adrenal zona fasciculata (AZF) cells express bTREK-1 K(+) channels that are inhibited by ACTH through cAMP-dependent pathways. In whole cell patch clamp recordings from AZF cells, we found that ACTH may also inhibit bTREK-1 by a cAMP-independent mechanism. When the potent adenylyl cyclase (AC) antagonist 2,5-dideoxyadenosine-3'-triphosphate (2,5-dd-3'-ATP) was applied intracellularly through the patch pipette, bTREK-1 inhibition by the AC activator forskolin was blocked. In contrast, bTREK-1 inhibition by ACTH was unaltered. The selective G(Sα) antagonist NF449 also failed to blunt bTREK-1 inhibition by ACTH. At concentrations that produce little measurable increase in cAMP in bovine AZF cells, the O-nitrophenyl, sulfenyl-derivative of ACTH (NPS-ACTH) also inhibited bTREK-1 almost completely. Accordingly, 2,5-dd-3'-ATP at concentrations more than 1000× its reported IC(50) did not block bTREK-1 inhibition by NPS-ACTH. These results indicate that ACTH and NPS-ACTH can inhibit native bTREK-1 K(+) channels in AZF cells by a mechanism that does not involve activation of AC.
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Affiliation(s)
- John J Enyeart
- Department of Neuroscience, The Ohio State University, College of Medicine and Public Health, Columbus, OH 43210-1239, USA.
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8
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Pavan B, Biondi C, Dalpiaz A. Adenylyl cyclases as innovative therapeutic goals. Drug Discov Today 2009; 14:982-91. [PMID: 19638320 DOI: 10.1016/j.drudis.2009.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 06/30/2009] [Accepted: 07/17/2009] [Indexed: 11/16/2022]
Abstract
Pharmacological modulation of intracellular cyclic AMP (cAMP) signalling could provide new therapeutic and experimental tools. Although drugs interfering with this pathway have traditionally targeted membrane receptors, the effector enzyme adenylyl cyclase (AC), which functions as a signalling catalyst, also presents an interesting target. Thus, development of isoform-selective stimulator and/or inhibitor compounds for AC could lead to organ-specific pharmacotherapeutics for treating heart failure, cancer and neurodegenerative diseases. In this review, the potential of AC as the object of drug therapy is discussed.
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Affiliation(s)
- Barbara Pavan
- Department of Biology and Evolution, General Physiology Section, University of Ferrara, Ferrara, Italy.
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9
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Kumar S, Kostin S, Flacke JP, Reusch HP, Ladilov Y. Soluble adenylyl cyclase controls mitochondria-dependent apoptosis in coronary endothelial cells. J Biol Chem 2009; 284:14760-8. [PMID: 19336406 DOI: 10.1074/jbc.m900925200] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The cAMP signaling pathway plays an essential role in modulating the apoptotic response to various stress stimuli. Until now, it was attributed exclusively to the activity of the G-protein-responsive transmembrane adenylyl cyclase. In addition to transmembrane AC, mammalian cells possess a second source of cAMP, the ubiquitously expressed soluble adenylyl cyclase (sAC). However, the role of this cyclase in apoptosis was unknown. A mitochondrial localization of this cyclase has recently been demonstrated, which led us to the hypothesis that sAC may play a role in apoptosis through modulation of mitochondria-dependent apoptosis. To prove this hypothesis, apoptosis was induced by simulated in vitro ischemia or by acidosis, which is an important component of ischemia. Suppression of sAC activity with the selective inhibitor KH7 or sAC knockdown by small interfering RNA transfection abolished endothelial apoptosis. Furthermore, pharmacological inhibition or knockdown of protein kinase A, an important cAMP target, demonstrated a significant anti-apoptotic effect. Analysis of the underlying mechanisms revealed (i) the translocation of sAC to mitochondria under acidic stress and (ii) activation of the mitochondrial pathway of apoptosis, i.e. cytochrome c release and caspase-9 cleavage. sAC inhibition or knockdown abolished the activation of the mitochondrial pathway of apoptosis. Analysis of mitochondrial co-localization of Bcl-2 family proteins demonstrated sAC- and protein kinase A-dependent translocation of Bax to mitochondria. Taken together, these results suggest the important role of sAC in modulating the mitochondria-dependent pathway of apoptosis in endothelial cells.
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Affiliation(s)
- Sanjeev Kumar
- Abteilung für Klinische Pharmakologie, Ruhr-Universität Bochum, D-44801 Bochum, Germany
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10
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Joubert S, McNicoll N, De Léan A. Biochemical and pharmacological characterization of P-site inhibitors on homodimeric guanylyl cyclase domain from natriuretic peptide receptor-A. Biochem Pharmacol 2006; 73:954-63. [PMID: 17196175 DOI: 10.1016/j.bcp.2006.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 10/19/2006] [Accepted: 12/07/2006] [Indexed: 10/23/2022]
Abstract
Guanylyl cyclases catalyze the formation of cGMP from GTP. This family of enzymes includes soluble (sGC) and particulate guanylyl cyclases (pGC). The sGC are heterodimers containing one active catalytic site and one inactive pseudo-site. They are activated by nitric oxide. The pGC are homodimers whose activity is notably regulated by peptide binding to the extracellular domain and by ATP binding to the intracellular kinase homology domain (KHD). The catalytic mechanism of the pGC is still not well understood. Homology modeling of the structure of the homodimeric guanylyl cyclase domain, based on the crystal structure of adenylyl cyclase, suggests the existence of two functional sites for the substrate GTP. We used a purified and fully active recombinant catalytic domain from mammalian pGC, to document its enzyme kinetics properties in the absence of the KHD. The enzyme presents positive cooperativity with the substrate Mg-GTP. However, a heterodimeric catalytic domain mutant (GC-HET) containing only one active catalytic site is non-cooperative and is more similar to sGC. Structure-activity studies of purine nucleoside analogs indicate that 2'd3'GMP is the most potent inhibitor of pGC tested. It displays mixed non-competitive inhibition properties that are potentiated by the second catalytic product inorganic pyrophosphate (PPi). It appears to be equivalent to purinergic site (P-site) inhibitors characterized on particulate adenylyl cyclase. Inhibition of pGC by 2'd3'GMP in the presence of PPi is accompanied by a loss of cooperative enzyme kinetics. These results are best explained by an allosteric dimer model with positive cooperativity for both the substrate and inhibitors.
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Affiliation(s)
- Simon Joubert
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H3T 1J4
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Shenoy AR, Srinivas A, Mahalingam M, Visweswariah SS. An adenylyl cyclase pseudogene in Mycobacterium tuberculosis has a functional ortholog in Mycobacterium avium. Biochimie 2005; 87:557-63. [PMID: 15908099 DOI: 10.1016/j.biochi.2005.01.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2004] [Revised: 01/24/2005] [Accepted: 01/28/2005] [Indexed: 10/25/2022]
Abstract
A number of genes similar to mammalian Class III nucleotide cyclases are found in mycobacteria, and biochemical characterization of some of these proteins has indicated that they code for adenylyl cyclases, with properties similar to the mammalian enzymes. Our earlier bioinformatic analysis had predicted that the Rv1120c gene in Mycobacterium tuberculosis is a pseudogene, while analysis of the genome of Mycobacterium avium indicated the presence of a functional ortholog. We therefore cloned and expressed Rv1120c and its ortholog from M. avium, Ma1120, in Escherichia coli, and find that while the protein from M. tuberculosis is misfolded and found in inclusion bodies, Ma1120 is expressed to high levels as a functional adenylyl cyclase. Sequence analysis of Ma1120 indicates interesting variations in critical amino acids that are known to be important for catalytic activity. Ma1120 is maximally active in the presence of MnATP as substrate ((app)Km approximately 400 microM), and is inhibited by P-site inhibitors (IC50 of 2',5'-dideoxy-3'-adenosine triphosphate approximately 730 nM) and tyrphostins (IC50 approximately 36 microM) in a manner similar to the mammalian enzymes. This therefore represents the first Class III cyclase biochemically characterized from M. avium, and the absence of a functional ortholog in M. tuberculosis suggests a unique role for this enzyme in M. avium.
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Affiliation(s)
- A R Shenoy
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
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12
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Mou TC, Gille A, Fancy DA, Seifert R, Sprang SR. Structural basis for the inhibition of mammalian membrane adenylyl cyclase by 2 '(3')-O-(N-Methylanthraniloyl)-guanosine 5 '-triphosphate. J Biol Chem 2004; 280:7253-61. [PMID: 15591060 DOI: 10.1074/jbc.m409076200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane-bound mammalian adenylyl cyclase (mAC) catalyzes the synthesis of intracellular cyclic AMP from ATP and is activated by stimulatory G protein alpha subunits (Galpha(s)) and by forskolin (FSK). mACs are inhibited with high potency by 2 '(3')-O-(N-methylanthraniloyl) (MANT)-substituted nucleotides. In this study, the crystal structures of the complex between Galpha(s).GTPgammaS and the catalytic C1 and C2 domains from type V and type II mAC (VC1.IIC2), bound to FSK and either MANT-GTP.Mg(2+) or MANT-GTP.Mn(2+) have been determined. MANT-GTP coordinates two metal ions and occupies the same position in the catalytic site as P-site inhibitors and substrate analogs. However, the orientation of the guanine ring is reversed relative to that of the adenine ring. The MANT fluorophore resides in a hydrophobic pocket at the interface between the VC1 and IIC2 domains and prevents mAC from undergoing the "open" to "closed" domain rearrangement. The K(i) of MANT-GTP for inhibition of VC1.IIC2 is lower in the presence of mAC activators and lower in the presence of Mn(2+) compared with Mg(2+), indicating that the inhibitor binds more tightly to the catalytically most active form of the enzyme. Fluorescence resonance energy transfer-stimulated emission from the MANT fluorophore upon excitation of Trp-1020 in the MANT-binding pocket of IIC2 is also stronger in the presence of FSK. Mutational analysis of two non-conserved amino acids in the MANT-binding pocket suggests that residues outside of the binding site influence isoform selectivity toward MANT-GTP.
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Affiliation(s)
- Tung-Chung Mou
- Department of Biochemistry, Howard Hughes Medical Institute, The University of Texas Southwestern Medical, Dallas, Texas 75390-9050, USA
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Phillips PG, Long L, Wilkins MR, Morrell NW. cAMP phosphodiesterase inhibitors potentiate effects of prostacyclin analogs in hypoxic pulmonary vascular remodeling. Am J Physiol Lung Cell Mol Physiol 2004; 288:L103-15. [PMID: 15377497 DOI: 10.1152/ajplung.00095.2004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the effects of prostacyclin analogs and isoform-selective phosphodiesterase (PDE) inhibitors, alone and in combination, on pulmonary vascular remodeling in vitro and in vivo. Vascular smooth muscle cells (VSMC) isolated from pulmonary (proximal and distal) and systemic circulations demonstrated subtle variations in expression of PDE isoform mRNA. However, using biochemical assays, we found PDE3 and PDE4 isoforms to be responsible for the majority of cAMP hydrolysis in all VSMC. In growth assays, the prostacyclin analogs cicaprost and iloprost inhibited mitogen-induced proliferation of VSMC in a cAMP-dependent manner. In addition, isoform-selective antagonists of PDEs 1, 3, or 4 inhibited VSMC proliferation, an effect that synergized with the effect of prostacyclin analogs. The inhibitory effects were greater in cells isolated from pulmonary circulation. In an in situ perfused rat lung preparation, administration of prostacyclin analogs or the PDE inhibitors vinpocetine (PDE1), cilostamide (PDE3), or rolipram (PDE4), but not EHNA (PDE2), attenuated acute hypoxic vasoconstriction (HPV). Combinations of agents led to a greater reduction in HPV. Furthermore, during exposure to hypoxia for 13 days, Wistar rats were treated with iloprost, rolipram, cilostamide, or combinations of these agents. Compared with normoxic controls, hypoxic animals developed pulmonary hypertension and distal pulmonary artery muscularization. These parameters were attenuated by iloprost+cilostamide, iloprost+rolipram, and cilostamide+rolipram but were not significantly affected by single agents. Together, these findings provide a greater understanding of the role of cAMP PDEs in VSMC proliferation and provide rationale for combined use of prostacylcin analogs plus PDE3/4 inhibitors in treatment of pulmonary vascular remodeling.
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Affiliation(s)
- Peter G Phillips
- Section of Clinical Pharmacology, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK
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Seyedi N, Mackins CJ, Machida T, Reid AC, Silver RB, Levi R. Histamine H3-receptor-induced attenuation of norepinephrine exocytosis: a decreased protein kinase a activity mediates a reduction in intracellular calcium. J Pharmacol Exp Ther 2004; 312:272-80. [PMID: 15306634 DOI: 10.1124/jpet.104.072504] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We had reported that activation of presynaptic histamine H(3)-receptors inhibits norepinephrine exocytosis from depolarized cardiac sympathetic nerve endings, an action associated with a marked decrease in intraneuronal Ca(2+) that we ascribed to a decreased Ca(2+) influx. An H(3)-receptor-mediated inhibition of cAMP-dependent phosphorylation of Ca(2+) channels could cause a sequential attenuation of Ca(2+) influx, intraneuronal Ca(2+) and norepinephrine exocytosis. We tested this hypothesis in sympathetic nerve endings (cardiac synaptosomes) expressing native H(3)-receptors and in human neuroblastoma SH-SY5Y cells transfected with H(3)-receptors. Norepinephrine exocytosis was elicited by K(+) or by stimulation of adenylyl cyclase with forskolin. H(3)-receptor activation markedly attenuated the K(+)- and forskolin-induced norepinephrine exocytosis; pretreatment with pertussis toxin prevented this effect. Similar to forskolin, 8-bromo-cAMP elicited norepinephrine exocytosis but, unlike forskolin, it was unaffected by H(3)-receptor activation, demonstrating that inhibition of adenylyl cyclase is a pivotal step in the H(3)-receptor transductional cascade. Indeed, we found that H(3)-receptor activation attenuated norepinephrine exocytosis concomitantly with a decrease in intracellular cAMP and PKA activity in SH-SY5Y-H(3) cells. Moreover, pharmacological PKA inhibition acted synergistically with H(3)-receptor activation to reduce K(+)-induced peak intracellular Ca(2+) in SH-SY5Y-H(3) cells and norepinephrine exocytosis in cardiac synaptosomes. Furthermore, H(3)-receptor activation synergized with N- and L-type Ca(2+) channel blockers to reduce norepinephrine exocytosis in cardiac synaptosomes. Our findings suggest that the H(3)-receptor-mediated inhibition of norepinephrine exocytosis from cardiac sympathetic nerves results sequentially from H(3)-receptor-G(i)/G(o) coupling, inhibition of adenylyl cyclase activity, and decreased cAMP formation, leading to diminished PKA activity, and thus, decreased Ca(2+) influx through voltage-operated Ca(2+) channels.
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Affiliation(s)
- Nahid Seyedi
- Department of Pharmacology, 1300 York Ave., Weill Medical College of Cornell University, New York, NY 10021, USA
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15
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Gille A, Lushington GH, Mou TC, Doughty MB, Johnson RA, Seifert R. Differential inhibition of adenylyl cyclase isoforms and soluble guanylyl cyclase by purine and pyrimidine nucleotides. J Biol Chem 2004; 279:19955-69. [PMID: 14981084 DOI: 10.1074/jbc.m312560200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammals express nine membranous adenylyl cyclase isoforms (ACs 1-9), a structurally related soluble guanylyl cyclase (sGC) and a soluble AC (sAC). Moreover, Bacillus anthracis and Bacillus pertussis produce the AC toxins, edema factor (EF), and adenylyl cyclase toxin (ACT), respectively. 2'(3')-O-(N-methylanthraniloyl)-guanosine 5'-[gamma-thio]triphosphate is a potent competitive inhibitor of AC in S49 lymphoma cell membranes. These data prompted us to study systematically the effects of 24 nucleotides on AC in S49 and Sf9 insect cell membranes, ACs 1, 2, 5, and 6, expressed in Sf9 membranes and purified catalytic subunits of membranous ACs (C1 of AC5 and C2 of AC2), sAC, sGC, EF, and ACT in the presence of MnCl(2). N-Methylanthraniloyl (MANT)-GTP inhibited C1.C2 with a K(i) of 4.2 nm. Phe-889 and Ile-940 of C2 mediate hydrophobic interactions with the MANT group. MANT-inosine 5'-[gamma-thio]triphosphate potently inhibited C1.C2 and ACs 1, 5, and 6 but exhibited only low affinity for sGC, EF, ACT, and G-proteins. Inosine 5'-[gamma-thio]triphosphate and uridine 5'-[gamma-thio]triphosphate were mixed G-protein activators and AC inhibitors. AC5 was up to 15-fold more sensitive to inhibitors than AC2. EF and ACT exhibited unique inhibitor profiles. At sAC, 2',5'-dideoxyadenosine 3'-triphosphate was the most potent compound (IC(50), 690 nm). Several MANT-adenine and MANT-guanine nucleotides inhibited sGC with K(i) values in the 200-400 nm range. UTP and ATP exhibited similar affinities for sGC as GTP and were mixed sGC substrates and inhibitors. The exchange of MnCl(2) against MgCl(2) reduced inhibitor potencies at ACs and sGC 1.5-250-fold, depending on the nucleotide and cyclase studied. The omission of the NTP-regenerating system from cyclase reactions strongly reduced the potencies of MANT-ADP, indicative for phosphorylation to MANT-ATP by pyruvate kinase. Collectively, AC isoforms and sGC are differentially inhibited by purine and pyrimidine nucleotides.
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Affiliation(s)
- Andreas Gille
- Department of Pharmacology and Toxicology, Molecular Graphics and Modeling Laboratory, the University of Kansas, Lawrence, KS 66045-7582, USA
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16
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Laux WHG, Pande P, Shoshani I, Gao J, Boudou-Vivet V, Gosselin G, Johnson RA. Pro-nucleotide inhibitors of adenylyl cyclases in intact cells. J Biol Chem 2003; 279:13317-32. [PMID: 14699161 DOI: 10.1074/jbc.m309535200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
9-substituted adenine derivatives with protected phosphoryl groups were synthesized and tested as inhibitors of adenylyl cyclase in isolated enzyme and intact cell systems. Protected 3'-phosphoryl derivatives of 2',5'-dideoxyadenosine (2',5'-dd-Ado) and beta-l-2',5'-dd-Ado, protected 5'-phosphoryl derivatives of beta-l-2',3'-dd-Ado, and protected phosphoryl derivatives of two 9-(2-phosphonomethoxy-acyl)-adenines were synthesized. Protection was afforded by two cyclosaligenyl- or three S-acyl-2-thioethyl-substituents. These pro-nucleotides were tested for their capacity to block forskolin-induced increases in [(3)H]cAMP in OB1771 and F442A preadipocytes and human macrophages prelabeled with [(3)H]adenine. A striking selectivity for 2',5'-dd-Ado-3'-phosphoryl derivatives was observed. Cyclosaligenyl-derivatives (IC(50) approximately 2 microm) were much less potent than S-acyl-2-thioethyl-derivatives. Best studied of these was 2',5'-dd-Ado-3'-O-bis(S-pivaloyl-2-thioethyl)-phosphate, which blocked [(3)H]cAMP formation in preadipocytes (IC(50) approximately 30 nm) and suppressed opening of cAMP-dependent Cl(-) channels in cardiac myocytes (IC(50) approximately 800 nm). None of the pro-nucleotides inhibited adenylyl cyclase per se, whether isolated from rat brain or OB1771 cells. These compounds exhibit the hallmarks of prodrugs. Data suggest they are taken up, are deprotected, and are converted to a potent inhibitory form to inhibit adenylyl cyclase, but only by intact cells. The availability and characteristics of these prodrugs should make them useful for blocking cAMP-mediated pathways in intact cell systems, in biochemical, pharmacological, and potentially therapeutic contexts.
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Affiliation(s)
- Wolfgang H G Laux
- Department of Physiology and Biophysics, Health Sciences Center, State University of New York, Stony Brook, New York 11794-8661, USA.
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17
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Iwatsubo K, Tsunematsu T, Ishikawa Y. Isoform-specific regulation of adenylyl cyclase: a potential target in future pharmacotherapy. Expert Opin Ther Targets 2003; 7:441-51. [PMID: 12783579 DOI: 10.1517/14728222.7.3.441] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Adenylyl cyclase (AC) is a target enzyme of multiple G-protein-coupled receptors (GPCRs). In the past decade, the cloning, structure and biochemical properties of nine AC isoforms were reported, and each isoform of AC shows distinct patterns of tissue distribution and biochemical/pharmacological properties. In addition to the conventional regulators of this enzyme, such as calmodulin (CaM) or PKC, novel regulators, for example, caveolin, have been identified. Most importantly, these regulators work on AC in an isoform dependent manner. Recent studies have demonstrated that certain classic AC inhibitors, i.e., P-site inhibitors, show an isoform-dependent inhibition of AC. The side chain modifications of forskolin, a diterpene extract from Coleus forskolii, markedly enhance its isoform selectivity. When taken together, these findings suggest that it is feasible to develop new pharmacotherapeutic agents that target AC isoforms to regulate various neurohormonal signals in a highly tissue-/organ-specific manner.
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Affiliation(s)
- Kousaku Iwatsubo
- Department of Physiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
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18
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Krawiec K, Kierdaszuk B, Kalinichenko EN, Rubinova EB, Mikhailopulo IA, Eriksson S, Munch-Petersen B, Shugar D. Striking ability of adenosine-2'(3')-deoxy-3'(2')-triphosphates and related analogues to replace ATP as phosphate donor for all four human, and the Drosophila melanogaster, deoxyribonucleoside kinases. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2003; 22:153-73. [PMID: 12744603 DOI: 10.1081/ncn-120019510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In extension of an earlier report, six non-conventional analogues of ATP, three adenosine-2'-triphosphates (3'-deoxy, 3'-deoxy-3'-fluoro- and 3'-deoxy-3'-fluoroxylo-), and three adenosine-3'-triphosphates (2'-deoxy-, 2'-deoxy-2'-fluoro- and 2'-deoxy-2'-fluoroara-), were compared with ATP as potential phosphate donors for human deoxycytidine kinase (dCK), cytosolic thymidine kinase (TK1), mitochondrial TK2, deoxyguanosine kinase (dGK), and the deoxyribonucleoside kinase (dNK) from Drosophila melanogaster. With one group of enzymes, comprising TK1, TK2, dNK and dCK (with dAdo as acceptor), only 3'-deoxyadenosine-2'-triphosphate was an effective donor (5-60% that for ATP), and the other five analogues much less so, or inactive. With a second set, including dCK (dCyd, but not dAdo, as acceptor) and dGK (dGuo as acceptor), known to share high sequence similarity (approximately 45% sequence identity), all six analogues were good to excellent donors (13-119% that for ATP). With dCK and ATP1, products were shown to be 5'-phosphates. With dCK, donor properties of the analogues were dependent on the nature of the acceptor, as with natural 5'-triphosphate donors. With dCK (dCyd as acceptor), Km and Vmax for the two 2'(3')-deoxyadenosine-3'(2')-triphosphates are similar to those for ATP. With dGK, Km values are higher than for ATP, while Vmax values are comparable. Kinetic studies further demonstrated Michaelis-Menten (non-cooperative) or cooperative kinetics, dependent on the enzyme employed and the nature of the donor. The physiological significance, if any, of the foregoing remains to be elucidated. The overall results are, on the other hand, highly relevant to studies on the modes of interaction of nucleoside kinases with donors and acceptors; and, in particular, to interpretations of the recently reported crystal structures of dGK with bound ATP, of dNK with bound dCyd, and associated modeling studies.
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Affiliation(s)
- Krzysztof Krawiec
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
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19
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D'Angelo MA, Montagna AE, Sanguineti S, Torres HN, Flawiá MM. A novel calcium-stimulated adenylyl cyclase from Trypanosoma cruzi, which interacts with the structural flagellar protein paraflagellar rod. J Biol Chem 2002; 277:35025-34. [PMID: 12121994 DOI: 10.1074/jbc.m204696200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trypanosoma cruzi adenylyl cyclases are encoded by a large polymorphic gene family. Although several genes have been identified in this parasite, little is known about the properties and regulation of these enzymes. Here we report the cloning and characterization of TczAC, a novel member of T. cruzi adenylyl cyclase family. The TczAC gene is expressed in all of the parasite life forms and encodes a 1,313-amino acid protein that can complement a Saccharomyces cerevisiae mutant deficient in adenylyl cyclase activity. The recombinant enzyme expressed in yeasts is constitutively active, has a low affinity for ATP (K(m) = 406 microm), and requires a divalent cation for catalysis. TczAC is inhibited by Zn(2+) and the P-site inhibitor 2'-deoxyadenosine 3'-monophosphate, suggesting some level of conservation in the catalytic mechanism with mammalian adenylyl cyclases. It shows a dose-dependent stimulation by Ca(2+) which can be reversed by high concentrations of phenothiazinic calmodulin inhibitors. However, bovine calmodulin fails to stimulate the enzyme. Using a yeast two-hybrid screen it was found that TczAC interacts through its catalytic domain with the paraflagellar rod protein, a component of the flagellar structure. Furthermore, we demonstrate that TczAC can dimerize through the same domain. These results provide novel evidence of the possible localization and regulation of this protein.
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Affiliation(s)
- Maximiliano A D'Angelo
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires 1428, Argentina
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20
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Dessauer CW, Chen-Goodspeed M, Chen J. Mechanism of Galpha i-mediated inhibition of type V adenylyl cyclase. J Biol Chem 2002; 277:28823-9. [PMID: 12058044 DOI: 10.1074/jbc.m203962200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The topology of mammalian adenylyl cyclase reveals an integral membrane protein composed of an alternating series of membrane and cytoplasmic domains (C1 and C2). The stimulatory G protein, Galpha(s), binds within a cleft in the C2 domain of adenylyl cyclase while Galpha(i) binds within the opposite cleft in the C1 domain. The mechanism of these two regulators also appears to be in opposition. Activation of adenylyl cyclase by Galpha(s) or forskolin results in a 100-fold increase in the apparent affinity of the two domains for one another. We show herein that Galpha(i) reduces C1/C2 domain interaction and thus formation of the adenylyl cyclase catalytic site. Mutants that increase the affinity of C1 for C2 decrease the ability of Galpha(i) to inhibit the enzyme. In addition, Galpha(i) can influence binding of molecules to the catalytic site, which resides at the C1/C2 interface. Adenylyl cyclase can bind substrate analogs in the presence of Galpha(i) but cannot simultaneously bind Galpha(i) and transition state analogs such as 2'd3'-AMP. Galpha(i) also cannot inhibit the membrane-bound enzyme in the presence of manganese, which increases the affinity of adenylyl cyclase for ATP and substrate analogs. Thus homologous G protein alpha-subunits promote bidirectional regulation at the domain interface of the pseudosymmetrical adenylyl cyclase enzyme.
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Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030, USA.
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21
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Yamada H, Adachi T, Fukatsu A, Misao S, Yamada Y, Aoki T, Miura N, Sakuma M, Nishikawa K, Futenma A, Kakumu S. Extracellular superoxide dismutase and glomerular mesangial cells: its production and regulation. FEBS Lett 2002; 519:77-81. [PMID: 12023021 DOI: 10.1016/s0014-5793(02)02714-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Extracellular superoxide dismutase (EC-SOD) is synthesized in mesenchymally derived cells and prevents the oxygen radical-induced injury. We studied whether kidney mesangial cells (MCs) produce EC-SOD and how its production is associated with chemokine secretion. Under unstimulated condition, MCs produced EC-SOD, and its production was correlated positively with cyclic adenosine monophosphate (cAMP), but negatively with interleukin (IL)-6 or IL-8 production. By prednisolone or phorbol myristate acetate treatment, EC-SOD levels were correlated negatively with levels of IL-6 and IL-8. The presence of adenylate cyclase inhibitor 2',3'-dideoxyadenosine lost the prednisolone effect. The stimulation of EC-SOD production might be one of the important effects of prednisolone via cAMP pathway in MCs.
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Affiliation(s)
- Harutaka Yamada
- First Department of Internal Medicine, Aichi Medical University, Yazako-Karimata, Nagakute, Aichi, Japan.
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22
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Tesmer JJG, Sunahara RK, Fancy DA, Gilman AG, Sprang SR. Crystallization of complex between soluble domains of adenylyl cyclase and activated Gs alpha. Methods Enzymol 2002; 345:198-206. [PMID: 11665605 DOI: 10.1016/s0076-6879(02)45017-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- John J G Tesmer
- Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA
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23
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Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, Houston, Texas 77030, USA
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24
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Abstract
At least nine closely related isoforms of adenylyl cyclases (ACs), the enzymes responsible for the synthesis of cyclic AMP (cAMP) from ATP, have been cloned and characterized in mammals. Depending on the properties and the relative levels of the isoforms expressed in a tissue or a cell type at a specific time, extracellular signals received through the G-protein-coupled receptors can be differentially integrated. The present review deals with various aspects of such regulations, emphasizing the role of calcium/calmodulin in activating AC1 and AC8 in the central nervous system, the potential inhibitory effect of calcium on AC5 and AC6, and the changes in the expression pattern of the isoforms during development. A particular emphasis is given to the role of cAMP during drug and ethanol dependency and to some experimental limitations (pitfalls in the interpretation of cellular transfection, scarcity of the invalidation models, existence of complex macromolecular structures, etc).
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Affiliation(s)
- J Hanoune
- Institut National de la Santé et de la Recherche Scientifique, U-99 Hôpital Henri Mondor, F-94010 Créteil, France.
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25
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Patel TB, Du Z, Pierre S, Cartin L, Scholich K. Molecular biological approaches to unravel adenylyl cyclase signaling and function. Gene 2001; 269:13-25. [PMID: 11376933 DOI: 10.1016/s0378-1119(01)00448-6] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Signal transduction through the cell membrane requires the participation of one or more plasma membrane proteins. For many transmembrane signaling events adenylyl cyclases (ACs) are the final effector enzymes which integrate and interpret divergent signals from different pathways. The enzymatic activity of adenylyl cyclases is stimulated or inhibited in response to the activation of a large number of receptors in virtually all cells of the human body. To date, ten different mammalian isoforms of adenylyl cyclase (AC) have been cloned and characterized. Each isoform has its own distinct tissue distribution and regulatory properties, providing possibilities for different cells to respond diversely to similar stimuli. The product of the enzymatic reaction catalyzed by ACs, cyclic AMP (cAMP) has been shown to play a crucial role for a variety of fundamental physiological cell functions ranging from cell growth and differentiation, to transcriptional regulation and apoptosis. In the past, investigations into the regulatory mechanisms of ACs were limited by difficulties associated with their purification and the availability of the proteins in any significant amount. Moreover, nearly every cell expresses several AC isoforms. Therefore, it was difficult to perform biochemical characterization of the different AC isoforms and nearly impossible to assess the physiological roles of the individual isoforms in intact cells, tissue or organisms. Recently, however, different molecular biological approaches have permitted several breakthroughs in the study of ACs. Recombinant technologies have allowed biochemical analysis of adenylyl cyclases in-vitro and the development of transgenic animals as well as knock-out mice have yielded new insights in the physiological role of some AC isoforms. In this review, we will focus mainly on the most novel approaches and concepts, which have delineated the mechanisms regulating AC and unravelled novel functions for this enzyme.
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Affiliation(s)
- T B Patel
- Department of Pharmacology and the Vascular Biology Center of Excellence, University of Tennessee, Memphis, 874 Union Avenue, Memphis, TN 38163, USA.
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26
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Kudlacek O, Mitterauer T, Nanoff C, Hohenegger M, Tang WJ, Freissmuth M, Kleuss C. Inhibition of adenylyl and guanylyl cyclase isoforms by the antiviral drug foscarnet. J Biol Chem 2001; 276:3010-6. [PMID: 11050094 DOI: 10.1074/jbc.m007910200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pyrophosphate (PP(i)) analog foscarnet inhibits viral DNA-polymerases and is used to treat cytomegalovirus and human immunodeficiency vius infections. Nucleotide cyclases and DNA-polymerases catalyze analogous reactions, i.e. a phosphodiester bond formation, and have similar topologies in their active sites. Inhibition by foscarnet of adenylyl cyclase isoforms was therefore tested with (i) purified catalytic domains C1 and C2 of types I and VII (IC1 and VIIC1) and of type II (IIC2) and (ii) membrane-bound holoenzymes (from mammalian tissues and types I, II, and V heterologously expressed in Sf9 cell membranes). Foscarnet was more potent than PP(i) in suppressing forskolin-stimulated catalysis by both, IC1/IIC2 and VIIC1/IIC2. Stimulation of VIIC1/IIC2 by Galpha(s) relieved the inhibition by foscarnet but not that by PP(i). The IC(50) of foscarnet on membrane-bound adenylyl cyclases also depended on their mode of regulation. These findings predict that receptor-dependent cAMP formation is sensitive to inhibition by foscarnet in some, but not all, cells. This was verified with two cell lines; foscarnet blocked cAMP accumulation after A(2A)-adenosine receptor stimulation in PC12 but not in HEK-A(2A) cells. Foscarnet also inhibited soluble and, to a lesser extent, particulate guanylyl cylase. Thus, foscarnet interferes with the generation of cyclic nucleotides, an effect which may give rise to clinical side effects. The extent of inhibition varies with the enzyme isoform and with the regulatory input.
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Affiliation(s)
- O Kudlacek
- Institute of Pharmacology, University of Vienna, Währinger Str. 13a, A-1090 Vienna, Austria
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27
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Bieger B, Essen LO. Structural analysis of adenylate cyclases from Trypanosoma brucei in their monomeric state. EMBO J 2001; 20:433-45. [PMID: 11157750 PMCID: PMC133460 DOI: 10.1093/emboj/20.3.433] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cyclic AMP is a major trigger of the differentiation process of Trypanosoma brucei, a bloodstream parasite causing sleeping sickness. Its generation in trypanosomes is accomplished by a unique battery of membrane-bound adenylate cyclases (ACs). We have determined the high-resolution X-ray structures of the catalytic domains of two trypanosomal ACs (tACs), GRESAG4.1 and GRESAG4.3. The tAC domains are structurally highly related to the AC domains of higher eukaryotes, but also comprise a highly conserved structural element near the active site, the Delta-subdomain. A cavity below the Delta-subdomain might correspond to an allosteric regulator site as indicated by the stereospecific binding of a single (2S,3S)-1,4- dimercapto-2,3-butanediol molecule. In three different crystal forms, the tAC domains are exclusively observed in a monomeric, catalytically inactive state. Biochemical analysis and the mutagenesis profile of GRESAG4.1 confirmed a common catalytic mechanism of tACs that involves transient dimerization of the AC domain. A low dimerization tendency might play a regulatory role in T. brucei if the activation of tACs is similarly driven by ligand-induced dimerization as in membrane-bound guanylate cyclases.
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Affiliation(s)
| | - Lars-Oliver Essen
- Max-Planck-Institute for Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried bei München, Germany
Corresponding author e-mail:
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28
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Shoshani I, Taussig R, Iyengar R, Johnson RA. Synthesis and use of 3'-(azidoiodosalicyl) derivatives of 2', 5'-dideoxyadenosine as photoaffinity ligands for adenylyl cyclase. Arch Biochem Biophys 2000; 376:221-8. [PMID: 10729209 DOI: 10.1006/abbi.1999.1690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
3'-[(4-Azidosalicyl)glycyl]-2',5'-dideoxyadenosine (1), 3'- [(4-azidosalicyl)-gamma-aminobutyryl]-2',5'-dideoxyadenosine (2), and the (125)I-labeled mono- and diiodinated analogs of 1 were synthesized and tested as photoaffinity probes for adenylyl cyclases. Kinetics for inhibition of purified type I enzyme by 1 was noncompetitive with respect to Mn(*)5'-ATP in the absence of light, implying a P-site mechanism of inhibition. In a UV-dependent manner both 1 and 2 and the iodinated derivative of 1 irreversibly inactivated membrane-bound and purified forms of recombinant type I bovine adenylyl cyclase expressed in ovarian cells of either the fall armyworm (Sf9) or Trichoplasia ni (High Five). Irreversible inactivation was independent of 5'-ATP and was prevented by 2', 5'-dideoxyadenosine. Adenylyl cyclase, whether purified from bovine brain or in membranes from High Five cells expressing type I enzyme, when subjected to UV irradiation in the presence of (125)I-labeled 1 resulted in radioactive incorporation into protein migrating at approximately 116 kDa. The cross-linking of 1 and its iodinated derivative with adenylyl cyclase suggests potential for such compounds to be useful in structural studies of adenylyl cyclases or of other proteins for which adenine nucleosides are substrates or allosteric regulators.
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Affiliation(s)
- I Shoshani
- Department of Physiology and Biophysics, State University of New York, Stony Brook, New York, 11794, USA
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29
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Shoshani I, Bianchi G, Désaubry L, Dessauer CW, Johnson RA. Lys-Ala mutations of type I adenylyl cyclase result in altered susceptibility to inhibition by adenine nucleoside 3'-polyphosphates. Arch Biochem Biophys 2000; 374:389-94. [PMID: 10666322 DOI: 10.1006/abbi.1999.1612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Native and recombinant wild type and mutant forms of type I adenylyl cyclase, expressed in fall army worm ovarian cells (Sf9) cells, with mutations Lys-923-Ala, Lys-921-Ala, and Lys-350-Ala, retained the characteristic noncompetitive inhibition by adenine nucleoside 3'-polyphosphates, but exhibited substantially different sensitivities to inhibition by them. The type I K923A enzyme resulted in increased IC(50) values, e.g., >100-fold for 2'-deoxyadenosine-3'-monophosphate, but the shift diminished as the number of 3'-phosphates increased. The K921A mutation increased IC(50) values approximately 5-fold for all adenine nucleosides tested, whereas the K350A mutation increased IC(50) values approximately 6- to 8-fold for all adenine nucleosides tested except 2'-deoxyadenosine-3'-diphosphate, which was increased >/=2-fold. The data suggest that 3'-phosphates sufficiently increase binding affinity of these ligands to compensate for the reduced coordination of the adenine moiety induced by the K923A mutation. Moreover, the altered structures induced by both K350A and K921A mutations impair ligand binding in general, but paradoxically those resulting from the K350A change minimally affected nucleoside 3'-diphosphate binding, implying that selective changes in ligand binding can be induced by this site-specific mutation.
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Affiliation(s)
- I Shoshani
- Department of Physiology and Biophysics, State University of New York, Stony Brook, New York 11794-8661, USA
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30
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Shoshani I, Laux WH, Périgaud C, Gosselin G, Johnson RA. Inhibition of adenylyl cyclase by acyclic nucleoside phosphonate antiviral agents. J Biol Chem 1999; 274:34742-4. [PMID: 10574942 DOI: 10.1074/jbc.274.49.34742] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acyclic derivatives of adenine, known as highly effective nucleotide analogs with broad spectrum antiviral activity, were evaluated for potential cross-reactivity with adenylyl cyclases, a family of membrane-bound enzymes that share putative topologies at their catalytic sites with oligonucleotide polymerases and reverse transcriptases. A series of derivatives of 9-(2-phosphonylmethoxyethyl)adenine (PMEA) inhibited a preparation of adenylyl cyclase derived from rat brain with IC(50) values that ranged from 66 microM (PMEA) to 175 nM for its diphosphate derivative (PMEApp) and mimics of it. PMEApp mimics included PMEAp(NH)p, PMEAp(CH(2))p, PMEAp(CX(2))p (X = fluorine, chlorine, or bromine), PMEAp(CHX)pp, and PMEAp(C(OH)CH(3)pp. The data suggest that inhibition of adenylyl cyclases may contribute to the therapeutic action of some of these or similar compounds or constitute part of their side effects in therapeutic settings.
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Affiliation(s)
- I Shoshani
- Department of Physiology, State University of New York, Health Sciences Center, Stony Brook, New York 11794-8661, USA
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Shoshani I, Boudou V, Pierra C, Gosselin G, Johnson RA. Enzymatic synthesis of unlabeled and beta-(32)P-labeled beta-L-2', 3'-dideoxyadenosine-5'-triphosphate as a potent inhibitor of adenylyl cyclases and its use as reversible binding ligand. J Biol Chem 1999; 274:34735-41. [PMID: 10574941 DOI: 10.1074/jbc.274.49.34735] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-L-2',3'-Dideoxyadenosine-5'-triphosphate (beta-L-2', 3'-dd-5'-ATP) was prepared enzymatically from the corresponding monophosphate by the use of adenylate kinase, creatine phosphate, and creatine kinase in a single step. The beta-(32)P-labeled analog was prepared similarly, but in a two step reaction. beta-L-2', 3'-dd-5'-ATP inhibited adenylyl cyclase from rat brain competitively with respect to substrate (5'-ATP.Mn(2+)) and exhibited an IC(50) approximately 24 nM. The labeled ligand was used in the development of a reversible binding assay for adenylyl cyclases. Binding of beta-L-2',3'-dd-[beta-(32)P]5'-ATP was saturable with increasing concentrations of ligand and increased in proportion to membrane protein, and was enhanced by Mn(2+) to a greater extent than by Mg(2+). Binding was displaced with adenine nucleotides known to be either competitive or noncompetitive inhibitors but not by agents known not to act on the cyclase, or by 3-isobutyl-1-methylxanthine, creatine phosphate, or creatine kinase. Binding was rapid, with a half-time for the on-rate <1.8 min and for the off-rate <0.8 min. The potency and mechanism of the inhibition of this ligand and the pattern of agents that displace binding suggest an interaction with adenylyl cyclase per se and to a configuration of the enzyme consistent with an interaction at the catalytic active site. The data suggest that this is a pretransition state inhibitor and contrasts with the equipotent 2',5'-dd-3'ATP, a post-transition state noncompetitive inhibitor.
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Affiliation(s)
- I Shoshani
- Department of Physiology, Health Sciences Center, State University of New York, Stony Brook, New York 11794-8661, USA
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32
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Doronin S, Murray L, Dessauer CW, Johnson RA. Covalent labeling of adenylyl cyclase cytosolic domains with gamma-methylimidazole-2',5'-dideoxy-[gamma-(32)P]3'-ATP and the mechanism for P-site-mediated inhibition. J Biol Chem 1999; 274:34745-50. [PMID: 10574943 DOI: 10.1074/jbc.274.49.34745] [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: 11/06/2022] Open
Abstract
A truncated first cytosolic domain of type V adenylyl cyclase (VC(1)) and a truncated second cytosolic domain of type II adenylyl cyclase (IIC(2)) were used alone and in the readily reversible complex (VC(1).IIC(2)) to evaluate interactions with each other and with reversible and irreversible P-site ligands. Enzyme activity was used to assess formation and dissolution of VC(1).IIC(2). The data suggest that binding of 2',5'-dideoxy-3'-ATP to VC(1) and IIC(2) prevented formation of VC(1).IIC(2) and that 2',5'-dideoxy-3'-ATP dissociation occurred slowly. To enable configuration specific cross-linking to the catalytic site, 2',5'-dideoxyadenosine 3'-[gamma-(1-methylimidazole)-triphosphate] (gamma-MetIm-2', 5'-dd-3'-ATP) and 2',5'-dd-adenosine 3'-(gamma-azidoanilido)-triphosphate (gamma-azidoanilido-2', 5'-dd-3'-ATP) were synthesized, the former also as its gamma-(32)P-labeled analog. gamma-Azidoanilido-2',5'-dd-3'-ATP exhibited an inhibitory potency comparable with that of 2', 5'-dd-3'-ATP. gamma-MetIm-2',5'-dd-[gamma-(32)P]3'-ATP labeled the individual VC(1) and IIC(2) domains comparably and covalently to approximately 20% within 1 h. Formation of VC(1).IIC(2) resulted in reduced labeling of VC(1) but enhanced labeling of IIC(2). The data imply that formation of the catalytically active VC(1).IIC(2) complex affects the interaction of each domain with the 2', 5'-dd-3'-ATP, the binding of which also affects the interaction between the two cytosolic domains, leading to a pseudo-irreversible inhibition.
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Affiliation(s)
- S Doronin
- Department of Physiology, Health Sciences Center, State University of New York, Stony Brook, New York 11794-8661, USA
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Dessauer CW, Tesmer JJ, Sprang SR, Gilman AG. The interactions of adenylate cyclases with P-site inhibitors. Trends Pharmacol Sci 1999; 20:205-10. [PMID: 10354616 DOI: 10.1016/s0165-6147(99)01310-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Recent kinetic, binding and crystallographic studies using P-site inhibitors of mammalian adenylate bases provide new insights into the catalytic mechanism of these highly regulated enzymes. Here, Carmen Dessauer and colleagues discuss the conformational states of adenylate cyclase, the structural determinants of inhibitor binding and the potential uses of these inhibitors as pharmacological agents.
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Affiliation(s)
- C W Dessauer
- Department of Integrative Biology, Pharmacology and Physiology, University of Texas Health Science Center at Houston, Houston, TX, USA
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Affiliation(s)
- J H Hurley
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0580, USA.
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Doronin S, Dessauer C, Johnson RA. Direct photoaffinity labeling of individual cytosolic domains of adenylyl cyclase by [32P]2'-deoxy-3'-AMP and [alpha-32P]5'-ATP. J Biol Chem 1998; 273:32416-20. [PMID: 9829971 DOI: 10.1074/jbc.273.49.32416] [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: 11/06/2022] Open
Abstract
The susceptibility of purines to form a covalent attachment with proteins upon exposure to UV irradiation was applied to adenylyl cyclase by use of [32P]2'-d-3'-AMP, a dead-end inhibitor that binds to the post-transition configuration of the enzyme. [32P]2'-d-3'-AMP was synthesized enzymatically. It and [alpha-32P]5'-ATP were used for direct photocross-linking to individually expressed cytosolic domains of adenylyl cyclase. Both the C1 domain of the type V isozyme (VC1) and the C2 domain of the type II isozyme (IIC2) were labeled, whether alone or combined, upon photolysis of [32P]2'-d-3'-AMP in the presence of acetone. Labeling of VC1 and IIC2 was greatly enhanced in the presence of PPi, was almost completely suppressed by 50 microM 2',5'-dideoxy-3'-ATP, the most potent reported P-site inhibitor of adenylyl cyclases, but was partially suppressed by 1 mM 3'-IMP, a ligand that does not inhibit the enzyme via the P-site. Neither 3':5'-cAMP nor 5'-ATP had a major effect on labeling by [32P]2'-d-3'-AMP. Direct cross-linking of VC1 with [alpha-32P]5'-ATP was substantially suppressed by 2', 5'-dideoxy-3'-ATP and partially suppressed by 2'-d-3'-AMP, whereas cross-linking of IIC2 was less affected by the 3'-triphosphate. The data imply that either cytosolic domain can interact directly with either substrate or P-site ligand and that subunit interaction modifies the susceptibility of each domain to UV-induced covalent modification by either [alpha-32P]5'-ATP or [32P]2'-d-3'-AMP.
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Affiliation(s)
- S Doronin
- Department of Physiology and Biophysics, Health Sciences Center, State University of New York, Stony Brook, New York 11794-8661, USA
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36
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Abstract
New structures solved in 1997 revealed that the adenylyl cyclase core consists of a pair of catalytic domains arranged in a wreath. Homologous catalytic domains are arranged in diverse adenylyl and guanylyl cyclases as symmetric homodimers or pseudosymmetric heterodimers. The kinship of the adenylyl and guanylyl cyclases has been confirmed by the structure-based interconversion of their nucleotide specificities. Catalysis is activated when two metal-binding aspartate residues on one domain are juxtaposed with a key aspargine-arginine pair on the other. Allosteric activators of mammalian adenylyl cyclase, forskolin and the stimulatory G protein alpha subunit, promote the catalytically optimal juxtaposition of the two domains.
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Affiliation(s)
- J H Hurley
- Laboratory of Molecular Biology National Institute of Diabetes, Digestive and Kidney Diseases National Institutes of Health Bethesda MD 20892-0580 USA.
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37
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Abstract
The recent structure determinations of the mammalian effector enzyme adenylyl cyclase reveal the structure of its catalytic core, provide new insights into its catalytic mechanism and suggest how diverse signaling molecules regulate its activity.
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Affiliation(s)
- J J Tesmer
- Howard Hughes Medical Institute Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas TX 75235-9050 USA.
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38
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Weng G, Chen Y, Iyengar R. Mammalian G
s
‐Stimulated Adenylyl Cyclases. Compr Physiol 1998. [DOI: 10.1002/cphy.cp070108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Désaubry L, Johnson RA. Adenine nucleoside 3'-tetraphosphates are novel and potent inhibitors of adenylyl cyclases. J Biol Chem 1998; 273:24972-7. [PMID: 9733805 DOI: 10.1074/jbc.273.38.24972] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
2'-Deoxyadenosine 3'-tetraphosphate (2'-deoxy-3'-A4P) and 2', 5'-dideoxyadenosine 3'-tetraphosphate (2',5'-dideoxy-3'-A4P) were synthesized, and their effects were tested on crude and purified forms of native adenylyl cyclases isolated from brain. Syntheses combined the method of alkoxide activation with the use of tribromoethyl phosphoromorpholino-chloridate as an initial phosphorylating agent. Inhibition of adenylyl cyclase was rapid in onset. With 2'-d-3'-A4P or 2',5'-dd-3'-A4P inhibition of a purified native enzyme conformed to a linear noncompetitive behavior with respect to substrate, metal-5'ATP. Order of potency was 2', 5'-dideoxy- > 2'-deoxyadenosine and 3'-tetraphosphate > 3'-triphosphate. Both mechanism of inhibition and rank order of potency were consistent with inhibition via the 3'-nucleotide-(P)-site on adenylyl cyclase. Neither 2',5'-dd-3'-ATP nor 2',5'-dd-3'-A4P had any effect on the activities of other adenosine nucleotide binding proteins such as Ca2+/calmodulin-sensitive cyclic nucleotide phosphodiesterase, Na+/K+-ATPase, or cAMP-dependent protein kinase. With purified adenylyl cyclase from bovine brain 2',5'-dd-3'-A4P and 2'-d-3'-A4P gave, respectively, IC50 values of 9.3 and 15 nM and Ki values of 23 and 53 nM. These 3'-nucleotides are the most potent regulators described for adenylyl cyclases.
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Affiliation(s)
- L Désaubry
- Department of Physiology and Biophysics, State University of New York, Health Sciences Center, Stony Brook, New York 11794-8661, USA
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40
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Skiba NP, Hamm HE. How Gsalpha activates adenylyl cyclase. NATURE STRUCTURAL BIOLOGY 1998; 5:88-92. [PMID: 9461067 DOI: 10.1038/nsb0298-88] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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41
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Smit MJ, Iyengar R. Mammalian adenylyl cyclases. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1998; 32:1-21. [PMID: 9421583 DOI: 10.1016/s1040-7952(98)80003-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- M J Smit
- Department of Pharmacology, Mount Sinai Medical Center, New York, New York 10029, USA
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42
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Tang WJ, Yan S, Drum CL. Class III adenylyl cyclases: regulation and underlying mechanisms. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1998; 32:137-51. [PMID: 9421589 DOI: 10.1016/s1040-7952(98)80009-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- W J Tang
- Department of Pharmacological and Physiological Sciences, University of Chicago, Illinois 60637, USA
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43
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Dessauer CW, Gilman AG. The catalytic mechanism of mammalian adenylyl cyclase. Equilibrium binding and kinetic analysis of P-site inhibition. J Biol Chem 1997; 272:27787-95. [PMID: 9346923 DOI: 10.1074/jbc.272.44.27787] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The mechanism of P-site inhibition of adenylyl cyclase has been probed by equilibrium binding measurements using 2'-[3H]deoxyadenosine, a P-site inhibitor, and by kinetic analysis of both the forward and reverse reactions (i.e. cyclic AMP and ATP synthesis, respectively). There is one binding site for 2'-deoxyadenosine per C1/C2 heterodimer; the Kd is 40 +/- 3 microM. Binding is observed only in the presence of one of the products of the adenylyl cyclase reaction, pyrophosphate (PPi). A substrate analog, Ap(CH2)pp (alpha,beta-methylene adenosine 5'-triphosphate), and cyclic AMP compete for the P-site in the presence of PPi, but P-site analogs do not compete for substrate binding (in the absence of PPi). Kinetic analysis indicates that release of products from the enzyme is random. These facts permit formulation of a model for the adenylyl cyclase reaction, for which we provide substantial kinetic support. We propose that P-site analogs act as dead-end inhibitors of product release, stabilizing an enzyme-product (E-PPi) complex by binding at the active site. Although product release is random, cyclic AMP dissociates from the enzyme preferentially. Release of PPi is slow and partially rate-limiting.
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Affiliation(s)
- C W Dessauer
- Department of Pharmacology, University of Texas, Southwestern Medical Center, Dallas, Texas 75235-9041, USA
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44
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Johnson RA, Désaubry L, Bianchi G, Shoshani I, Lyons E, Taussig R, Watson PA, Cali JJ, Krupinski J, Pieroni JP, Iyengar R. Isozyme-dependent sensitivity of adenylyl cyclases to P-site-mediated inhibition by adenine nucleosides and nucleoside 3'-polyphosphates. J Biol Chem 1997; 272:8962-6. [PMID: 9083018 DOI: 10.1074/jbc.272.14.8962] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Recombinant adenylyl cyclase isozyme Types I, II, VI, VII, and three splice variants of Type VIII were compared for their sensitivity to P-site-mediated inhibition by several adenine nucleoside derivatives and by the family of recently synthesized adenine nucleoside 3'-polyphosphates (Désaubry, L., Shoshani, I., and Johnson, R. A. (1996) J. Biol. Chem. 271, 14028-14034). Inhibitory potencies were dependent on isozyme type, the mode of activation of the respective isozymes, and on P-site ligand. For the nucleoside derivatives potency typically followed the order 2',5'-dideoxyadenosine (2',5'-ddAdo) > beta-adenosine > 9-(cyclopentyl)-adenine (9-CP-Ade) >/= 9-(tetrahydrofuryl)-adenine (9-THF-Ade; SQ 22,536), with the exception of Type II adenylyl cyclase, which was essentially insensitive to inhibition by 9-CP-Ade. For the adenine nucleoside 3'-polyphosphates inhibitory potency followed the order Ado < 2'-dAdo < 2',5'-ddAdo and 3'-mono- < 3'-di- < 3'-triphosphate. Differences in potency of these ligands were noted between isozymes. The most potent ligand was 2',5'-dd-3'-ATP with IC50 values of 40-300 nM. The data demonstrate isozyme selectivity for some ligands, suggesting the possibility of isozyme-selective inhibitors to take advantage of differences in P-site domains among adenylyl cyclase isozymes. Differential expression of adenylyl cyclase isozymes may dictate the physiological sensitivity and hence importance of this regulatory mechanism in different cells or tissues.
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Affiliation(s)
- R A Johnson
- Department of Physiology and Biophysics, State University of New York, Health Sciences Center, Stony Brook, New York 11794-8661, USA.
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46
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MacEwan DJ, Milligan G. Up-regulation of a constitutively active form of the beta2-adrenoceptor by sustained treatment with inverse agonists but not antagonists. FEBS Lett 1996; 399:108-12. [PMID: 8980131 DOI: 10.1016/s0014-5793(96)01300-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In neuroblastoma X glioma hybrid, NG1O8-15, cells transfected to stably express a constitutively active mutant (CAM) form of the human beta2-adrenoceptor, the beta-adrenoceptor ligands sotalol and betaxolol functioned as inverse agonists as they reduced basal adenylyl cyclase activity whereas the antagonists dihydroalprenolol and propranolol did not. Maintained presence of the CAMbeta2-adrenoceptor inverse agonists but not the antagonists in the culture medium of the cells resulted in a substantial, concentration-dependent, up-regulation of the CAMbeta2-adrenoceptor. Up-regulation of the CAMbeta2-adrenoceptor by the inverse agonists was prevented by co-incubation of the cells with either propranolol or dihydroalprenolol. Neither maintained elevation of cAMP levels nor the inhibition of adenylyl cyclase activity altered the ability of the inverse agonist ligands to cause receptor up-regulation.
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Affiliation(s)
- D J MacEwan
- Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, UK
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47
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Désaubry L, Shoshani I, Johnson RA. Inhibition of adenylyl cyclase by a family of newly synthesized adenine nucleoside 3'-polyphosphates. J Biol Chem 1996; 271:14028-34. [PMID: 8662735 DOI: 10.1074/jbc.271.24.14028] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The synthesis of a number of adenine nucleoside 3'-polyphosphates has been devised via a phosphotriester approach that combines the method of alkoxide activation with the use of 2,2,2-tribromoethyl phosphoromorpholinochloridate as a phosphorylating agent. The family of compounds included 3'ADP, 3'ATP, 2'-deoxy-3'ADP, 2'-deoxy-3'ATP, 2',5'-dideoxy-3'ADP, and 2',5'-dideoxy-3'ATP. Potency as inhibitors of adenylyl cyclases followed the order: 3'-mono- < 3'-di- < 3'-triphosphate and adenosine (Ado) < 2'-d-Ado < 2',5'-dd-Ado derivatives, with 2',5'-dideoxy-3'ATP exhibiting an IC50 of approximately 40 nM. This order was maintained with purified and recombinant forms of the type I enzyme. The nucleoside 3'-phosphates caused noncompetitive inhibition of the type I adenylyl cyclase from bovine brain, consistent with inhibition via the P-site. Inhibition was not due to hydrolytic products because this was minimal and inhibition kinetics by inorganic polyphosphates were inconsistent with those caused by the nucleoside 3'-polyphosphates. Only 3'ATP underwent cation-catalyzed, nonenzymatic hydrolysis, with the primary product being 2':3'-cAMP. Because 3'-ADP and 3'-ATP are naturally occurring, this class of compounds may physiologically regulate adenylyl cyclases and possibly other enzymes, mediating responses that include a reduction in 3':5'-cAMP levels and consequent reductions in protein kinase A-activated pathways.
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Affiliation(s)
- L Désaubry
- Department of Physiology and Biophysics, State University of New York, Health Sciences Center, Stony Brook, New York 11794-8661, USA
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