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Bhatia V, Maghsoudi S, Hinton M, Bhagirath AY, Singh N, Jaggupilli A, Chelikani P, Dakshinamurti S. Characterization of Adenylyl Cyclase Isoform 6 Residues Interacting with Forskolin. BIOLOGY 2023; 12:biology12040572. [PMID: 37106773 PMCID: PMC10135528 DOI: 10.3390/biology12040572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/26/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023]
Abstract
BACKGROUND The adenylyl cyclase (AC) pathway, crucial for pulmonary vasodilation, is inhibited by hypoxia. Forskolin (FSK) binds allosterically to AC, stimulating ATP catalysis. As AC6 is the primary AC isoform in the pulmonary artery, selective reactivation of AC6 could provide targeted reinstatement of hypoxic AC activity. This requires elucidation of the FSK binding site in AC6. METHODS HEK293T cells stably overexpressing AC 5, 6, or 7 were incubated in normoxia (21% O2) or hypoxia (10% O2) or exposed to s-nitrosocysteine (CSNO). AC activity was measured using terbium norfloxacin assay; AC6 structure built by homology modeling; ligand docking to examine FSK-interacting amino acids; roles of selected residues determined by site-directed mutagenesis; FSK-dependent cAMP generation measured in wild-type and FSK-site mutants by biosensor-based live cell assay. RESULTS Only AC6 is inhibited by hypoxia and nitrosylation. Homology modeling and docking revealed residues T500, N503, and S1035 interacting with FSK. Mutation of T500, N503, or S1035 decreased FSK-stimulated AC activity. FSK site mutants were not further inhibited by hypoxia or CSNO; however, mutation of any of these residues prevented AC6 activation by FSK following hypoxia or CSNO treatment. CONCLUSIONS FSK-interacting amino acids are not involved in the hypoxic inhibition mechanism. This study provides direction to design FSK derivatives for selective activation of hypoxic AC6.
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Affiliation(s)
- Vikram Bhatia
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB R3A 1S1, Canada
| | - Saeid Maghsoudi
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Martha Hinton
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Anjali Y Bhagirath
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Nisha Singh
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | | | - Prashen Chelikani
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Shyamala Dakshinamurti
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB R3A 1S1, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
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Doyle TB, Hayes MP, Chen DH, Raskind WH, Watts VJ. Functional characterization of AC5 gain-of-function variants: Impact on the molecular basis of ADCY5-related dyskinesia. Biochem Pharmacol 2019; 163:169-177. [PMID: 30772269 DOI: 10.1016/j.bcp.2019.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/05/2019] [Indexed: 12/13/2022]
Abstract
Adenylyl cyclases are key points for the integration of stimulatory and inhibitory G protein-coupled receptor (GPCR) signals. Adenylyl cyclase type 5 (AC5) is highly expressed in striatal medium spiny neurons (MSNs), and is known to play an important role in mediating striatal dopaminergic signaling. Dopaminergic signaling from the D1 expressing MSNs of the direct pathway, as well as the D2 expressing MSNs of the indirect pathway both function through the regulation of AC5 activity, controlling the production of the 2nd messenger cAMP, and subsequently the downstream effectors. Here, we used a newly developed cell line that used Crispr-Cas9 to eliminate the predominant adenylyl cyclase isoforms to more accurately characterize a series of AC5 gain-of-function mutations which have been identified in ADCY5-related dyskinesias. Our results demonstrate that these AC5 mutants exhibit enhanced activity to Gαs-mediated stimulation in both cell and membrane-based assays. We further show that the increased cAMP response at the membrane effectively translates into increased downstream gene transcription in a neuronal model. Subsequent analysis of inhibitory pathways show that the AC5 mutants exhibit significantly reduced inhibition following D2 dopamine receptor activation. Finally, we demonstrate that an adenylyl cyclase "P-site" inhibitor, SQ22536 may represent an effective future therapeutic mechanism by preferentially inhibiting the overactive AC5 gain-of-function mutants.
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Affiliation(s)
- T B Doyle
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States
| | - M P Hayes
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States
| | - D H Chen
- University of Washington, Department of Neurology, Seattle, WA 98195-7720, United States
| | - W H Raskind
- University of Washington, Medicine and Medical Genetics, United States; University of Washington, Psychiatry and Behavioral Sciences, Seattle, WA 98195-7720, United States; Geriatric Research, Education, and Clinical Center, Veterans Administration Puget Sound, Veterans Health Care Center, Seattle, WA 98108, United States
| | - V J Watts
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States; Purdue Institute for Integrative Neuroscience, Hall for Discovery Learning, 207 South Martin Jischke Drive, West Lafayette, IN 47907, United States; Purdue Institute for Drug Discovery, 720 Clinic Drive, West Lafayette, IN 47907, United States.
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Chaloupka JA, Bullock SA, Iourgenko V, Levin LR, Buck J. Autoinhibitory regulation of soluble adenylyl cyclase. Mol Reprod Dev 2006; 73:361-8. [PMID: 16250004 PMCID: PMC3644951 DOI: 10.1002/mrd.20409] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Soluble adenylyl cyclase is an evolutionarily conserved bicarbonate sensor that plays a crucial role in cAMP dependent processes that occur during mammalian fertilization. sAC protein is expressed at the highest levels in male germ cells, and is found to occur as one of two known isoforms: a truncated protein (sAC(t)) that consists almost exclusively of the two conserved catalytic domains (C1 and C2), and a full-length form (sAC(fl)) that contains an additional noncatalytic C-terminal region. Several studies suggested sAC(t) was more active than sAC(fl). We now demonstrate that the specific activity of sAC(t) is at least 10-fold higher than the specific activity of sAC(fl). Using deletion analysis and a novel genetic screen to identify activating mutations, we uncovered an autoinhibitory region just C-terminal to the C2 domain. Kinetic analysis of purified recombinant sAC revealed this autoinhibitory domain functions to lower the enzyme's V(max) without altering its affinity for substrate or regulation by any of the known modulators of sAC activity. Our results identify an additional regulatory mechanism specific to the sAC(fl) isoform.
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Affiliation(s)
| | | | | | - Lonny R. Levin
- Correspondence to: Lonny R. Levin, Department of Pharmacology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021.
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Clapp P, Capper AB, Taussig R. Genetic selection of regulatory mutants of mammalian adenylyl cyclases. Methods Enzymol 2002; 345:241-51. [PMID: 11665608 DOI: 10.1016/s0076-6879(02)45020-3] [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: 10/26/2022]
Abstract
Initial steps in the identification of the Gs alpha-binding site present in mammalian adenylyl cyclases can be achieved with the use of the yeast genetic system described. It must be stressed that this system serves as a means to identify mutants that are candidates; biochemical analysis of these mutants is a next and necessary step in the confirmation of these phenotypes. The system described can be readily adapted for the isolation of additional classes of mammalian adenylyl cyclase mutants including mutants with altered regulation toward forskolin, catalytic abnormalities, or enhanced sensitivities toward activators. In addition, this system can be employed for the isolation of constitutively active adenylyl cyclase mutants, or by coexpressing other adenylyl cyclase isoforms and their known regulators, mutations in the binding sites for these molecules can be elucidated.
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Affiliation(s)
- Peter Clapp
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Siebenaller JF, Garrett DJ. The effects of the deep-sea environment on transmembrane signaling. Comp Biochem Physiol B Biochem Mol Biol 2002; 131:675-94. [PMID: 11923082 DOI: 10.1016/s1096-4959(02)00027-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Membrane-associated processes may be particularly susceptible to perturbation by the high hydrostatic pressures and low temperatures of the deep ocean. Transmembrane signaling by guanyl nucleotide binding protein (G protein) coupled receptors (GPCRs) is affected at a number of steps: (1) agonist activation of the GPCR; (2) the interaction of the receptor with the heterotrimeric G protein; (3) the G protein GTPase cycle; and (4) the activation and function of the effector element, adenylyl cyclase. The effects of low temperature and high hydrostatic pressures on the A(1) adenosine receptor-inhibitory G protein (G(i))-adenylyl cyclase signaling complex were examined in teleost fishes from three families, Scorpaenidae, Macrouridae and Moridae. In a comparison of teleost fishes, rat and chicken, species with body temperatures from 1 to 40 degrees C, at atmospheric pressure, A(1) adenosine receptor agonist binding is conserved at the body temperature of the species. In the marine teleost fishes examined, increased pressure decreases agonist efficacy. There are differences among species in the effects of increased hydrostatic pressure on G protein interactions with receptors, GTP binding to G protein alpha subunits and the intrinsic GTPase activity of alpha subunits. Adenylyl cyclase activity and modulation are affected by increased pressure in all the species examined, except Antimora rostrata which was unaffected by pressure changes. At pressures approximating those which the species experience in situ adenylyl cyclase activity retains its sensitivity to modulators. To understand the physiological consequences of impaired cell signaling several prototypical human diseases are discussed.
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Affiliation(s)
- Joseph F Siebenaller
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
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Parent CA, Borleis J, Devreotes PN. Regulation of adenylyl cyclases by a region outside the minimally functional cytoplasmic domains. J Biol Chem 2002; 277:1354-60. [PMID: 11694527 DOI: 10.1074/jbc.m106430200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The highly conserved topological structure of G protein-activated adenylyl cyclases seems unnecessary because the soluble cytoplasmic domains retain regulatory and catalytic properties. Yet, we previously isolated a constitutively active mutant of the Dictyostelium discoideum adenylyl cyclase harboring a single point mutation in the region linking the cytoplasmic and membrane domains (Leu-394). We show here that multiple amino acid substitutions at Leu-394 also display constitutive activity. The constitutive activity of these mutants is not dependent on G proteins or cytosolic regulators, although some of the mutants can be activated to higher levels than wild type. Combining a constitutive mutation such as L394T with K482N, a point mutation that renders the enzyme insensitive to regulators, restores an enzyme with wild type properties of low basal activity and the capacity to be activated by G proteins. Thus regions located outside the cytoplasmic loops of adenylyl cyclases are not only important in the acquisition of an activated conformation, they also have impact on other regions within the catalytic core of the enzyme.
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Affiliation(s)
- Carole A Parent
- Department of Biological Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
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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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Hatley ME, Benton BK, Xu J, Manfredi JP, Gilman AG, Sunahara RK. Isolation and characterization of constitutively active mutants of mammalian adenylyl cyclase. J Biol Chem 2000; 275:38626-32. [PMID: 10982815 DOI: 10.1074/jbc.m007148200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A genetic screen in Saccharomyces cerevisiae identified mutations in mammalian adenylyl cyclase that activate the enzyme in the absence of G(s)alpha. Thirteen of these mutant proteins were characterized biochemically in an assay system that depends on a mixture of the two cytosolic domains (C(1) and C(2)) of mammalian adenylyl cyclases. Three mutations, I1010M, K1014N, and P1015Q located in the beta4-beta5 loop of the C(2) domain of type II adenylyl cyclase, increase enzymatic activity in the absence of activators. The K1014N mutation displays both increased maximal activity and apparent affinity for the C(1) domain of type V adenylyl cyclase in the absence of activators of the enzyme. The increased affinity of the mutant C(2) domain of adenylyl cyclase for the wild type C(1) domain was exploited to isolate a complex containing VC(1), IIC(2), and G(s)alpha-guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) in the absence of forskolin and a complex of VC(1), IIC(2), forskolin, and P-site inhibitor in the absence of G(s)alpha-GTPgammaS. The isolation of these complexes should facilitate solution of crystal structures of low activity states of adenylyl cyclase and thus determination of the mechanism of activation of the enzyme by forskolin and G(s)alpha.
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Affiliation(s)
- M E Hatley
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
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