551
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Sanz MJ, Cortijo J, Morcillo EJ. PDE4 inhibitors as new anti-inflammatory drugs: effects on cell trafficking and cell adhesion molecules expression. Pharmacol Ther 2005; 106:269-97. [PMID: 15922015 DOI: 10.1016/j.pharmthera.2004.12.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2004] [Indexed: 01/15/2023]
Abstract
Phosphodiesterase 4 (PDE4) is a major cyclic AMP-hydrolyzing enzyme in inflammatory and immunomodulatory cells. The wide range of inflammatory mechanisms under control by PDE4 points to this isoenzyme as an attractive target for new anti-inflammatory drugs. Selective inhibitors of PDE4 have demonstrated a broad spectrum of anti-inflammatory activities including the inhibition of cellular trafficking and microvascular leakage, cytokine and chemokine release from inflammatory cells, reactive oxygen species production, and cell adhesion molecule expression in a variety of in vitro and in vivo experimental models. The initially detected side effects, mainly nausea and emesis, appear at least partially overcome by the 'second generation' PDE4 inhibitors, some of which like roflumilast and cilomilast are in the later stages of clinical development for treatment of chronic obstructive pulmonary disease. These new drugs may also offer opportunities for treatment of other inflammatory diseases.
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Affiliation(s)
- María Jesús Sanz
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Avenida Blasco Ibáñez 15, E-46010 Valencia, Spain
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552
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Ariga M, Neitzert B, Nakae S, Mottin G, Bertrand C, Pruniaux MP, Jin SLC, Conti M. Nonredundant function of phosphodiesterases 4D and 4B in neutrophil recruitment to the site of inflammation. THE JOURNAL OF IMMUNOLOGY 2005; 173:7531-8. [PMID: 15585880 DOI: 10.4049/jimmunol.173.12.7531] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neutrophils have been implicated in the pathogenesis of many inflammatory lung diseases, including chronic obstructive pulmonary disease and asthma. With this study, we investigated how disruption of cAMP signaling impacts the function of neutrophil recruitment to the lung. Four genes code for type 4 phosphodiesterases (PDE4s), enzymes critical for regulation of cAMP levels and cell signaling. Ablation of two of these genes, PDE4B and PDE4D, but not PDE4A, has profound effects on neutrophil function. In a paradigm of mouse lung injury induced by endotoxin inhalation, the number of neutrophils recovered in the bronchoalveolar lavage was markedly decreased in PDE4D(-/-) and PDE4B(-/-) mice 4 and 24 h after exposure to LPS. Acute PDE4 inhibition with rolipram had additional inhibitory effects on neutrophil migration in PDE4B(-/-) and, to a lesser extent, PDE4D(-/-) mice. This decreased neutrophil recruitment occurred without major changes in chemokine accumulation in bronchoalveolar lavage, suggesting a dysfunction intrinsic to neutrophils. This hypothesis was confirmed by investigating the expression of adhesion molecules on the surface of neutrophils and chemotaxis in vitro. CD18 expression was decreased after ablation of both PDE4B and PDE4D, whereas CD11 expression was not significantly affected. Chemotaxis in response to KC and macrophage inflammatory protein-2 was markedly reduced in PDE4B(-/-) and PDE4D(-/-) neutrophils. The effect of PDE4 ablation on chemotaxis was comparable, but not additive, to the effects of acute PDE4 inhibition with rolipram. These data demonstrate that PDE4B and PDE4D play complementary, but not redundant, roles in the control of neutrophil function.
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MESH Headings
- 3',5'-Cyclic-AMP Phosphodiesterases/antagonists & inhibitors
- 3',5'-Cyclic-AMP Phosphodiesterases/deficiency
- 3',5'-Cyclic-AMP Phosphodiesterases/genetics
- 3',5'-Cyclic-AMP Phosphodiesterases/physiology
- Animals
- Cell Adhesion/genetics
- Cell Adhesion/immunology
- Chemokines/biosynthesis
- Chemotaxis, Leukocyte/genetics
- Chemotaxis, Leukocyte/immunology
- Cyclic Nucleotide Phosphodiesterases, Type 4
- Disease Models, Animal
- Enzyme Inhibitors/administration & dosage
- Inflammation/enzymology
- Inflammation/genetics
- Inflammation/immunology
- Lipopolysaccharides/administration & dosage
- Lung/enzymology
- Lung/immunology
- Lung/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neutrophil Infiltration/genetics
- Neutrophil Infiltration/immunology
- Pulmonary Disease, Chronic Obstructive/enzymology
- Pulmonary Disease, Chronic Obstructive/genetics
- Pulmonary Disease, Chronic Obstructive/immunology
- Rolipram/administration & dosage
- Tumor Necrosis Factor-alpha/biosynthesis
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Affiliation(s)
- Miyako Ariga
- Division of Reproductive Biology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA 94305, USA
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553
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Viste K, Kopperud RK, Christensen AE, Døskeland SO. Substrate enhances the sensitivity of type I protein kinase a to cAMP. J Biol Chem 2005; 280:13279-84. [PMID: 15691833 DOI: 10.1074/jbc.m413065200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The functional significance of the presence of two major (types I and II) isoforms of the cAMP-dependent protein kinase (PKA) is still enigmatic. The present study showed that peptide substrate enhanced the activation of PKA type I at low, physiologically relevant concentrations of cAMP through competitive displacement of the regulatory RI subunit. The effect was similar whether the substrate was a short peptide or the physiological 60-kDa protein tyrosine hydroxylase. In contrast, substrate failed to affect the cAMP-sensitivity of PKA type II. Size exclusion chromatography confirmed that substrate acted to physically enhance the dissociation of the RIalpha and Calpha subunits of PKA type I, but not the RIIalpha and Calpha subunits of PKA type II. Substrate availability can therefore fine-tune the activation of PKA type I by cAMP, but not PKA type II. The cAMP-dissociated RII and C subunits of PKA type II reassociated much faster than the PKA type I subunits in the presence of substrate peptide. This suggests that only PKA type II is able to rapidly reverse its activation after a burst of cAMP when exposed to high substrate concentration. We propose this as a possible reason why PKA type II is preferentially found in complexes with substrates undergoing rapid phosphorylation cycles.
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Affiliation(s)
- Kristin Viste
- Department of Biomedicine, Section for Anatomy and Cell Biology, University of Bergen, Jonas Lies Vei 91, N-5009 Bergen and Haukeland University Hospital, N-5021 Bergen, Norway
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554
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Abdulla D, Renton KW. Beta-adrenergic receptor modulation of the LPS-mediated depression in CYP1A activity in astrocytes. Biochem Pharmacol 2005; 69:741-50. [PMID: 15710352 DOI: 10.1016/j.bcp.2004.11.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Accepted: 11/25/2004] [Indexed: 11/19/2022]
Abstract
CYP1A1 and 1A2, two important P450 isoforms in the brain that metabolize many endogenous and exogenous substrates, are downregulated during central nervous system (CNS) inflammation. The stimulation of beta-adrenergic receptors has been demonstrated to be anti-inflammatory in many cell types, leading us to hypothesize that stimulation of beta-adrenergic receptors could prevent the downregulation in CYP1A1 and 1A2 activity in an in vitro model of CNS inflammation. Isoproterenol, a general beta(1)/beta(2) receptor agonist, and clenbuterol, a specific beta(2) receptor agonist, were both able to prevent the LPS-induced downregulation in CYP1A1/2 activity in astrocytes. The involvement of beta-adrenergic receptors was confirmed using the general beta(1)/beta(2) receptor antagonist propranolol, which was able to abrogate the protection conferred by isoproterenol and clenbuterol in astrocytes treated with LPS. The isoproterenol and clenbuterol mediated protective effect on the LPS-induced downregulation in CYP1A activity was a cyclic AMP (cAMP) dependent process, since forskolin was able to mimic the protective effect. Isoproterenol and clenbuterol may also prevent the LPS-induced downregulation in CYP1A activity through changes in TNF alpha expression. Despite a slight reduction in the LPS-induced nuclear translocation of the p65 subunit of NF-kappa B, isoproterenol and clenbuterol had no effect on the DNA binding ability of this transcription factor, indicating that the beta-adrenergic protective effects on CYP1A activity occurred independent of changes in NF-kappa B activity. The results presented in this paper reveal that beta-adrenergic receptor stimulation can modulate cytochrome P450 activity in an in vitro model of CNS inflammation by a cAMP mediated pathway.
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Affiliation(s)
- Dalya Abdulla
- Department of Pharmacology, Dalhousie University, Sir Charles Tupper Medical Building, Halifax, NS, Canada B3H 4H7
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555
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Sastri M, Barraclough DM, Carmichael PT, Taylor SS. A-kinase-interacting protein localizes protein kinase A in the nucleus. Proc Natl Acad Sci U S A 2005; 102:349-54. [PMID: 15630084 PMCID: PMC544310 DOI: 10.1073/pnas.0408608102] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The genetic variability and covalent modifications associated with the amino terminus of the protein kinase A (PKA) catalytic (C) subunit suggest that it may contribute to protein-protein interactions and/or localization. By using a yeast two-hybrid screen, we identified a PKA-interacting protein (AKIP1) that binds to the amino terminus (residues 1-39) of the C subunit of PKA. The interaction was localized to the A helix (residues 14-39) of the C subunit and to the carboxyl terminus of AKIP1. AKIP1 thus defines the amino-terminal A helix of PKA as a protein interaction motif. In normal breast (Hs 578 Bst) and HeLa cells, AKIP1 is present in the nucleus as speckles. A nuclear localization signal (Arg-14 and Arg-15) was identified. Upon stimulation with forskolin, HeLa cells expressing AKIP1 accumulated higher levels of the endogenous C subunit in the nucleus. Deletion of the carboxyl terminus of AKIP1 or overexpression of residues 1-39 of the C subunit abolished nuclear localization of the activated endogenous C subunit. Thus, AKIP1 describes a PKA-interacting protein that can contribute to localization by a mechanism that is distinct from A-kinase anchoring proteins that interact with the regulatory subunits.
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Affiliation(s)
- Mira Sastri
- The Howard Hughes Medical Institute and Departments of Chemistry and Biochemistry and Pharmacology, University of California at San Diego, La Jolla, CA 92093-0654, USA
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556
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Linden R, Martins RAP, Silveira MS. Control of programmed cell death by neurotransmitters and neuropeptides in the developing mammalian retina. Prog Retin Eye Res 2004; 24:457-91. [PMID: 15845345 DOI: 10.1016/j.preteyeres.2004.10.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has long been known that a barrage of signals from neighboring and connecting cells, as well as components of the extracellular matrix, control cell survival. Given the extensive repertoire of retinal neurotransmitters, neuromodulators and neurotrophic factors, and the exhuberant interconnectivity of retinal interneurons, it is likely that various classes of released neuroactive substances may be involved in the control of sensitivity to retinal cell death. The aim of this article is to review evidence that neurotransmitters and neuropeptides control the sensitivity to programmed cell death in the developing retina. Whereas the best understood mechanism of execution of cell death is that of caspase-mediated apoptosis, current evidence shows that not only there are many parallel pathways to apoptotic cell death, but non-apoptotic programs of execution of cell death are also available, and may be triggered either in isolation or combined with apoptosis. The experimental data show that many upstream signaling pathways can modulate cell death, including those dependent on the second messengers cAMP-PKA, calcium and nitric oxide. Evidence for anterograde neurotrophic control is provided by a variety of models of the central nervous system, and the data reviewed here indicate that an early function of certain neurotransmitters, such as glutamate and dopamine, as well as neuropeptides such as pituitary adenylyl cyclase-activating polypeptide and vasoactive intestinal peptide is the trophic support of cell populations in the developing retina. This may have implications both regarding the mechanisms of retinal organogenesis, as well as pathological conditions leading to retinal dystrophies and to dysfunctional cellular behavior.
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Affiliation(s)
- Rafael Linden
- Centro de Ciencias da Saude, Instituto de Biofísica da UFRJ, Cidade Universitária, bloco G, Rio de Janeiro 21949-900, Brazil.
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557
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Carlisle Michel J, Dodge K, Wong W, Mayer N, Langeberg L, Scott J. PKA-phosphorylation of PDE4D3 facilitates recruitment of the mAKAP signalling complex. Biochem J 2004; 381:587-92. [PMID: 15182229 PMCID: PMC1133866 DOI: 10.1042/bj20040846] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Revised: 06/03/2004] [Accepted: 06/08/2004] [Indexed: 11/17/2022]
Abstract
mAKAP (muscle-selective A-kinase-anchoring protein) co-ordinates a cAMP-sensitive negative-feedback loop comprising PKA (cAMP-dependent protein kinase) and the cAMP-selective PDE4D3 (phosphodiesterase 4D3). In vitro and cellular experiments demonstrate that PKA-phosphorylation of PDE4D3 on Ser-13 increases the affinity of PDE4D3 for mAKAP. Our data suggest that activation of mAKAP-anchored PKA enhances the recruitment of PDE4D3, allowing for quicker signal termination.
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Affiliation(s)
- Jennifer J. Carlisle Michel
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
| | - Kimberly L. Dodge
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
| | - Wei Wong
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
| | - Nicole C. Mayer
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
| | - Lorene K. Langeberg
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
| | - John D. Scott
- Howard Hughes Medical Institute and Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, U.S.A
- To whom correspondence should be addressed (e-mail )
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558
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Galán-Caridad JM, Calabokis M, Uzcanga G, Aponte F, Bubis J. Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi. Mem Inst Oswaldo Cruz 2004; 99:845-54. [PMID: 15761601 DOI: 10.1590/s0074-02762004000800011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Trypanosoma evansi contains protein kinases capable of phosphorylating endogenous substrates with apparent molecular masses in the range between 20 and 205 kDa. The major phosphopolypeptide band, pp55, was predominantly localized in the particulate fraction. Anti-alpha and anti-beta tubulin monoclonal antibodies recognized pp55 by Western blot analyses, suggesting that this band corresponds to phosphorylated tubulin. Inhibition experiments in the presence of emodin, heparin, and 2,3-bisphosphoglycerate indicated that the parasite tubulin kinase was a casein kinase 2 (CK2)-like activity. GTP, which can be utilized instead of ATP by CK2, stimulated rather than inactivated the phosphorylation of tubulin in the parasite homogenate and particulate fraction. However, GTP inhibited the cytosolic CK2 responsible for phosphorylating soluble tubulin and other soluble substrates. Casein and two selective peptide substrates, P1 (RRKDLHDDEEDEAMSITA) for casein kinase (CK1) and P2 (RRRADDSDDDDD) for CK2, were recognized as substrates in T. evansi. While the enzymes present in the soluble fraction predominantly phosphorylated P1, P2 was preferentially labeled in the particulate fractions. These results demonstrated the existence of CK1-like and CK2-like activities primarily located in the parasite cytosolic and membranous fractions, respectively. Histone II-A and kemptide (LRRASVA) also behaved as suitable substrates, implying the existence of other Ser/Thr kinases in T. evansi. Cyclic AMP only increased the phosphorylation of histone II-A and kemptide in the cytosol, demonstrating the existence of soluble cAMP-dependent protein kinase-like activities in T. evansi. However, no endogenous substrates for this enzyme were identified in this fraction. Further evidences were obtained by using PKI (6-22), a reported inhibitor of the catalytic subunit of mammalian cAMP-dependent protein kinases, which specifically hindered the cAMP-dependent phosphorylation of histone II-A and kemptide in the parasite soluble fraction. Since the sum of the values obtained in the parasite cytosolic and particulate fractions were always higher than the values observed in the total T. evansi lysate, the kinase activities examined here appeared to be inhibited in the original extract.
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Affiliation(s)
- José Manuel Galán-Caridad
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89,000, Valle de Sartenejas, Baruta, Caracas 1081-A, Venezuela
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559
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Humphries KM, Deal MS, Taylor SS. Enhanced dephosphorylation of cAMP-dependent protein kinase by oxidation and thiol modification. J Biol Chem 2004; 280:2750-8. [PMID: 15533936 DOI: 10.1074/jbc.m410242200] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The catalytic subunit of cAMP-dependent protein kinase (PKA) is phosphorylated at threonine 197 and serine 338. Phosphorylation of threonine 197, located in the activation loop, is required for coordinating the active site conformation and optimal enzymatic activity. However, this phosphorylation has not been widely appreciated as a regulatory site because of the apparent constitutive nature of the phosphorylation and the general resistance of the kinase to phosphatase treatment. We demonstrate here that the observed resistance of the catalytic subunit to dephosphorylation is due, in part, to the presence of the highly nucleophilic cysteine 199 located proximal to the phosphate on threonine 197. Experiments performed in vitro demonstrated that mutation (cysteine 199 to alanine), oxidation, such as by glutathionylation or internal disulfide bond formation, or alkylation of the C-subunit enhanced its ability to be dephosphorylated. Furthermore, rephosphorylation of reduced C-subunit by PDK1 created a cycle whereby the inactive kinase could be reactivated. To demonstrate that thiol modification of PKA can lead to enhanced dephosphorylation in vivo, PC12 cells were treated with N-ethylmaleimide (NEM). Such treatment resulted in complete PKA inactivation and dephosphorylation of threonine 197. This effect of NEM was contingent upon prior treatment of the cells with PKA activators, demonstrating the resistance of the holoenzyme to thiol alkylation-mediated dephosphorylation. Our results also demonstrated that NEM treatment of PC12 cells enhanced the dephosphorylation of the protein kinase Calpha activation loop, suggesting a common mechanism of regulation among members of the AGC family of kinases.
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Affiliation(s)
- Kenneth M Humphries
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry and Department of Pharmacology, The University of California, San Diego, La Jolla, California 92093-0654, USA
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560
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Abrahamsen H, Baillie G, Ngai J, Vang T, Nika K, Ruppelt A, Mustelin T, Zaccolo M, Houslay M, Taskén K. TCR- and CD28-mediated recruitment of phosphodiesterase 4 to lipid rafts potentiates TCR signaling. THE JOURNAL OF IMMUNOLOGY 2004; 173:4847-58. [PMID: 15470025 DOI: 10.4049/jimmunol.173.8.4847] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ligation of the TCR along with the coreceptor CD28 is necessary to elicit T cell activation in vivo, whereas TCR triggering alone does not allow a full T cell response. Upon T cell activation of human peripheral blood T cells, we found that the majority of cAMP was generated in T cell lipid rafts followed by activation of protein kinase A. However, upon TCR and CD28 coligation, beta-arrestin in complex with cAMP-specific phosphodiesterase 4 (PDE4) was recruited to lipid rafts which down-regulated cAMP levels. Whereas inhibition of protein kinase A increased TCR-induced immune responses, inhibition of PDE4 blunted T cell cytokine production. Conversely, overexpression of either PDE4 or beta-arrestin augmented TCR/CD28-stimulated cytokine production. We show here for the first time that the T cell immune response is potentiated by TCR/CD28-mediated recruitment of PDE4 to lipid rafts, which counteracts the local, TCR-induced production of cAMP. The specific recruitment of PDE4 thus serves to abrogate the negative feedback by cAMP which is elicited in the absence of a coreceptor stimulus.
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561
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Rochais F, Vandecasteele G, Lefebvre F, Lugnier C, Lum H, Mazet JL, Cooper DMF, Fischmeister R. Negative feedback exerted by cAMP-dependent protein kinase and cAMP phosphodiesterase on subsarcolemmal cAMP signals in intact cardiac myocytes: an in vivo study using adenovirus-mediated expression of CNG channels. J Biol Chem 2004; 279:52095-105. [PMID: 15466415 DOI: 10.1074/jbc.m405697200] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracardiac cAMP levels are modulated by hormones and neuromediators with specific effects on contractility and metabolism. To understand how the same second messenger conveys different information, mutants of the rat olfactory cyclic nucleotide-gated (CNG) channel alpha-subunit CNGA2, encoded into adenoviruses, were used to monitor cAMP in adult rat ventricular myocytes. CNGA2 was not found in native myocytes but was strongly expressed in infected cells. In whole cell patch-clamp experiments, the forskolin analogue L-858051 (L-85) elicited a non-selective, Mg2+ -sensitive current observed only in infected cells, which was thus identified as the CNG current (ICNG). The beta-adrenergic agonist isoprenaline (ISO) also activated ICNG, although the maximal efficiency was approximately 5 times lower than with L-85. However, ISO and L-85 exerted a similar maximal increase of the L-type Ca2+ current. The use of a CNGA2 mutant with a higher sensitivity for cAMP indicated that this difference is caused by the activation of a localized fraction of CNG channels by ISO. cAMP-dependent protein kinase (PKA) blockade with H89 or PKI, or phosphodiesterase (PDE) inhibition with IBMX, dramatically potentiated ISO- and L-85-stimulated ICNG. A similar potentiation of beta-adrenergic stimulation occurred when PDE4 was blocked, whereas PDE3 inhibition had a smaller effect (by 2-fold). ISO and L-85 increased total PDE3 and PDE4 activities in cardiomyocytes, although this effect was insensitive to H89. However, in the presence of IBMX, H89 had no effect on ISO stimulation of ICNG. This study demonstrates that subsarcolemmal cAMP levels are dynamically regulated by a negative feedback involving PKA stimulation of subsarcolemmal cAMP-PDE.
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Affiliation(s)
- Francesca Rochais
- Laboratoire de Cardiologie Cellulaire et Moléculaire, INSERM U-446, Université Paris-Sud, Faculté de Pharmacie, F-92296 Chātenay-Malabry, France
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562
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Nikolaev VO, Bünemann M, Hein L, Hannawacker A, Lohse MJ. Novel Single Chain cAMP Sensors for Receptor-induced Signal Propagation. J Biol Chem 2004; 279:37215-8. [PMID: 15231839 DOI: 10.1074/jbc.c400302200] [Citation(s) in RCA: 559] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
cAMP is a universal second messenger of many G-protein-coupled receptors and regulates a wide variety of cellular events. cAMP exerts its effects via cAMP-dependent protein kinase (PKA), cAMP-gated ion channels, and two isoforms of exchange protein directly activated by cAMP (Epac). Here we report the development of novel fluorescent indicators for cAMP based on the cAMP-binding domains of Epac and PKA. Fluorescence resonance energy transfer between variants of green fluorescent protein (enhanced cyan fluorescent protein and enhanced yellow fluorescent protein) fused directly to the cAMP-binding domains was used to analyze spatial and temporal aspects of cAMP-signaling in different cells. In contrast to previously developed PKA-based indicators, these probes are comprised of only a single binding site lacking cooperativity, catalytic properties, and interactions with other proteins and thereby allow us to easily image free intracellular cAMP and rapid signaling events. Rapid beta-adrenergic receptor-induced cAMP signals were observed to travel with high speed ( approximately 40 microm/s) throughout the entire cell body of hippocampal neurons and peritoneal macrophages. The developed indicators could be ubiquitously applied to studying cAMP, its physiological role and spatio-temporal regulation.
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Affiliation(s)
- Viacheslav O Nikolaev
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacherstrasse 9, D-97078 Würzburg, Germany
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563
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Ostrom RS, Insel PA. The evolving role of lipid rafts and caveolae in G protein-coupled receptor signaling: implications for molecular pharmacology. Br J Pharmacol 2004; 143:235-45. [PMID: 15289291 PMCID: PMC1575337 DOI: 10.1038/sj.bjp.0705930] [Citation(s) in RCA: 302] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 05/26/2004] [Accepted: 06/01/2004] [Indexed: 11/09/2022] Open
Abstract
The many components of G-protein-coupled receptor (GPCR) signal transduction provide cells with numerous combinations with which to customize their responses to hormones, neurotransmitters, and pharmacologic agonists. GPCRs function as guanine nucleotide exchange factors for heterotrimeric (alpha, beta, gamma) G proteins, thereby promoting exchange of GTP for GDP and, in turn, the activation of 'downstream' signaling components. Recent data indicate that individual cells express mRNA for perhaps over 100 different GPCRs (out of a total of nearly a thousand GPCR genes), several different combinations of G-protein subunits, multiple regulators of G-protein signaling proteins (which function as GTPase activating proteins), and various isoforms of downstream effector molecules. The differential expression of such protein combinations allows for modulation of signals that are customized for a specific cell type, perhaps at different states of maturation or differentiation. In addition, in the linear arrangement of molecular interactions involved in a given GPCR-G-protein-effector pathway, one needs to consider the localization of receptors and post-receptor components in subcellular compartments, microdomains, and molecular complexes, and to understand the movement of proteins between these compartments. Co-localization of signaling components, many of which are expressed at low overall concentrations, allows cells to tailor their responses by arranging, or spatially organizing in unique and kinetically favorable ways, the molecules involved in GPCR signal transduction. This review focuses on the role of lipid rafts and a subpopulation of such rafts, caveolae, as a key spatial compartment enriched in components of GPCR signal transduction. Recent data suggest cell-specific patterns for expression of those components in lipid rafts and caveolae. Such domains likely define functionally important, cell-specific regions of signaling by GPCRs and drugs active at those GPCRs.
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Affiliation(s)
- Rennolds S Ostrom
- Department of Pharmacology and the Vascular Biology Center of Excellence, University of Tennessee Health Science Center, Memphis, TN 38163, U.S.A
| | - Paul A Insel
- Department of Pharmacology, 0636, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0636, U.S.A
- Department of Medicine, 0636, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0636, U.S.A
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564
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Carnegie GK, Smith FD, McConnachie G, Langeberg LK, Scott JD. AKAP-Lbc Nucleates a Protein Kinase D Activation Scaffold. Mol Cell 2004; 15:889-99. [PMID: 15383279 DOI: 10.1016/j.molcel.2004.09.015] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 07/06/2004] [Accepted: 07/09/2004] [Indexed: 12/30/2022]
Abstract
The transmission of cellular signals often proceeds through multiprotein complexes where enzymes are positioned in proximity to their upstream activators and downstream substrates. In this report we demonstrate that the A-kinase anchoring protein AKAP-Lbc assembles an activation complex for the lipid-dependent enzyme protein kinase D (PKD). Using a combination of biochemical, enzymatic, and immunofluorescence techniques, we show that the anchoring protein contributes to PKD activation in two ways: it recruits an upstream kinase PKCeta and coordinates PKA phosphorylation events that release activated protein kinase D. Thus, AKAP-Lbc synchronizes PKA and PKC activities in a manner that leads to the activation of a third kinase. This configuration illustrates the utility of kinase anchoring as a mechanism to constrain the action of broad-spectrum enzymes.
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Affiliation(s)
- Graeme K Carnegie
- Howard Hughes Medical Institute, Vollum Institute, Oregon Health and Sciences University, Portland, OR 97239, USA
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565
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Nolan MA, Babcock DF, Wennemuth G, Brown W, Burton KA, McKnight GS. Sperm-specific protein kinase A catalytic subunit Calpha2 orchestrates cAMP signaling for male fertility. Proc Natl Acad Sci U S A 2004; 101:13483-8. [PMID: 15340140 PMCID: PMC518783 DOI: 10.1073/pnas.0405580101] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
An unusual cAMP signaling system mediates many of the events that prepare spermatozoa to meet the egg. Its components include the atypical, bicarbonate-stimulated, sperm adenylyl cyclase and a cAMP-dependent protein kinase (PKA) with the unique catalytic subunit termed Calpha(2) or C(s). We generated mice that lack Calpha(2) to determine its importance in the events downstream of cAMP production. Male Calpha(2) null mice produce normal numbers of sperm that swim spontaneously in vitro. Thus, Calpha(2) has no required role in formation of a functional flagellum or the initiation of motility. In contrast, we find that Calpha(2) is required for bicarbonate to speed the flagellar beat and facilitate Ca(2+) entry channels. In addition, Calpha(2) is needed for the protein tyrosine phosphorylation that occurs late in the sequence of sperm maturation and for a negative feedback control of cAMP production, revealed here. Consistent with these specific defects in several important sperm functions, Calpha(2) null males are infertile despite normal mating behavior. These results define several crucial roles of PKA in sperm cell biology, bringing together both known and unique PKA-mediated events that are necessary for male fertility.
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Affiliation(s)
- Michael A Nolan
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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Bundey RA, Insel PA. Discrete intracellular signaling domains of soluble adenylyl cyclase: camps of cAMP? Sci Signal 2004; 2004:pe19. [PMID: 15126677 DOI: 10.1126/stke.2312004pe19] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Soluble adenylyl cyclase can function in the nucleus, defining a nuclear microdomain of adenosine 3',5'-monophosphate (cAMP) signaling. Bundey and Insel discuss the evidence for discrete signaling microdomains of cAMP, including the nucleus and caveolae, and conclude that such microdomains may be defined by the localized, subcellular expression of adenylyl cyclase isoforms.
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Affiliation(s)
- Richard A Bundey
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, San Diego, CA 92037-0636, USA.
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567
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Henn V, Edemir B, Stefan E, Wiesner B, Lorenz D, Theilig F, Schmitt R, Vossebein L, Tamma G, Beyermann M, Krause E, Herberg FW, Valenti G, Bachmann S, Rosenthal W, Klussmann E. Identification of a novel A-kinase anchoring protein 18 isoform and evidence for its role in the vasopressin-induced aquaporin-2 shuttle in renal principal cells. J Biol Chem 2004; 279:26654-65. [PMID: 15037626 DOI: 10.1074/jbc.m312835200] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Arginine vasopressin (AVP) increases the water permeability of renal collecting duct principal cells by inducing the fusion of vesicles containing the water channel aquaporin-2 (AQP2) with the plasma membrane (AQP2 shuttle). This event is initiated by activation of vasopressin V2 receptors, followed by an elevation of cAMP and the activation of protein kinase A (PKA). The tethering of PKA to subcellular compartments by protein kinase A anchoring proteins (AKAPs) is a prerequisite for the AQP2 shuttle. During the search for AKAP(s) involved in the shuttle, a new splice variant of AKAP18, AKAP18delta, was identified. AKAP18delta functions as an AKAP in vitro and in vivo. In the kidney, it is mainly expressed in principal cells of the inner medullary collecting duct, closely resembling the distribution of AQP2. It is present in both the soluble and particulate fractions derived from renal inner medullary tissue. Within the particulate fraction, AKAP18delta was identified on the same intracellular vesicles as AQP2 and PKA. AVP not only recruited AQP2, but also AKAP18delta to the plasma membrane. The elevation of cAMP caused the dissociation of AKAP18delta and PKA. The data suggest that AKAP18delta is involved in the AQP2 shuttle.
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Affiliation(s)
- Volker Henn
- Forschungsinstitut fur Molekulare Pharmakologie, Campus Berlin-Buch, Robert-Rossle-Strasse 10, 13125 Berlin, Germany
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568
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Noda Y, Sasaki S. Molecular Mechanisms and Drug Development in Aquaporin Water Channel Diseases: Molecular Mechanism of Water Channel Aquaporin-2 Trafficking. J Pharmacol Sci 2004; 96:249-54. [PMID: 15539762 DOI: 10.1254/jphs.fmj04004x2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Targeted positioning of water channel aquaporin-2 (AQP2) strictly regulates body water homeostasis. Trafficking of AQP2 to the apical membrane is critical for the reabsorption of water in renal collecting ducts. Besides the cAMP-mediated effect of vasopressin on AQP2 trafficking to the apical membrane, other signaling cascades also induce this sorting. Recently, AQP2-binding proteins that directly regulate this trafficking have been uncovered: SPA-1, a GTPase-activating protein (GAP) for Rap1, and cytoskeletal protein actin. This review summarizes recent advances related to the trafficking mechanism of AQP2 and its defect causing nephrogenic diabetes insipidus (NDI).
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Affiliation(s)
- Yumi Noda
- Department of Nephrology, Graduate School, Tokyo Medical and Dental University, Japan.
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