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The precise factors involved in the transition of the relaxed pregnant uterus to the contractile state at the onset of parturition remain unclear, but it is accepted that cAMP-generating pathways contribute to uterine relaxation. We have previously reported an increased expression of the adenylyl cyclase (AC)-stimulating protein Galphas in human myometrium during gestation, with a corresponding increase in GTP-stimulated AC activity. However, little is known about the predominating AC isoforms expressed during pregnancy. This information is important, because although all AC isoforms are stimulated by Galphas, their regulation by other signalling molecules is very different. In the present study we have identified the isoforms of AC expressed in both pregnant and non-pregnant myometrium by mRNA analysis and immunoblotting. mRNA encoding for AC I, II, III, VIII and IX was present in non-pregnant and pregnant myometrium, and in cultured myometrial cells. Differing levels of AC protein could be detected in myometrial plasma membranes, with decreased levels of Group 1 (isoforms I, III and VIII) and Group 4 (IX) ACs allied with increased levels of Group 2 (II, IV and VII) and 3 (V and VI) ACs during pregnancy. These findings imply a role for Group 2-activating pathways, e.g. G-protein betagamma-subunits and protein kinase C, in the maintenance of uterine quiescence, whilst suggesting a lesser involvement of calcium-calmodulin complex, an activator of Group 1 AC isoforms, in uterine relaxation during gestation. These data may provide an alternative pharmacological approach for the attenuation of preterm labour.
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Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
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Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
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Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
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Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
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Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
Geriatric Research, Medicine, Comprehensive Dentistry, Barshop Institute for Longevity and Aging Studies, Education and Clinical Center (182), Audie L. Murphy Division, South Texas Veterans Health Care System, 7400 Merton Minter Boulevard, San Antonio, Texas 78229, USA Departments of
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for increased hepatic fat accumulation in rodents with aging. Catecholamines acting via β-adrenergic receptors (β 1 -, β 2 -, or β 3 -AR subtypes) coupled to adenylyl cyclase and other effectors modulate important biological responses including lipid
Millennium Institute for Fundamental and Applied Biology, Santiago, Chile
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Millennium Institute for Fundamental and Applied Biology, Santiago, Chile
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Millennium Institute for Fundamental and Applied Biology, Santiago, Chile
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Millennium Institute for Fundamental and Applied Biology, Santiago, Chile
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( Nadal et al. 2001 ). Activation of signal transduction cascades by E 2 modulates diverse downstream pathways that have discrete cellular actions, including stimulation of adenylyl cyclase in breast and vascular tissues ( Aronica et al. 1994
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). In this context, the third intracellular cytoplasmic loop is involved in coupling to G proteins and activation of the adenylyl cyclase system ( Takhar et al. 1996 ). Desensitisation of the GLP-1 receptor has been correlated with C-terminal tail
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receptor to stimulate adenylyl cyclase as well as the MAP kinase pathway. Our data revealed that receptors with a deletion of the last 27 or 44 amino acids of the cytoplasmic tail conserved a similar potency and efficacy in stimulating adenylyl cyclase
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GDP for GTP, leading to its activation and dissociation from β- and γ-subunits. (III) The active, GTP-bound form of Gα s /XLα s interacts with and activates transmembrane adenylyl cyclases type I–IX, resulting in increased formation of the second
Marine Science Institute, University of Texas at Austin, 750 Channelview Drive, Port Aransas, Texas 78373, USA
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Marine Science Institute, University of Texas at Austin, 750 Channelview Drive, Port Aransas, Texas 78373, USA
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Marine Science Institute, University of Texas at Austin, 750 Channelview Drive, Port Aransas, Texas 78373, USA
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Marine Science Institute, University of Texas at Austin, 750 Channelview Drive, Port Aransas, Texas 78373, USA
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that mPRα acts as an intermediary in MIS induction of oocyte maturation in teleost fish. Recent results in human myometrial cells have shown that both mPRα and mPRβ are involved in downregulation of adenylyl cyclase activity through a pertussis toxin
Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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Department of Physiology, University of La Laguna, La Laguna, Spain
Department of Comparative Pathology, University of Córdoba, Córdoba, Spain
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from TX-treated OVX rats as well as TX-cultured anterior pituitary cells from OVX rats, this study investigated the action of E 2 on: (1) LHRH self-priming; (2) the potentiating effect of P 4 and adenylyl cyclase activator forskolin (FSK) on LHRH
Department of Cell Biology, Physiology and Immunology, University of Córdoba, Cordoba, Spain
Hospital Universitario Reina Sofia (HURS), Cordoba, Spain
CIBER de la Fisiopatología de la Obesidad y Nutrición (CIBERobn), Madrid, Spain
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inhibitors to various intracellular signaling pathways previously shown to be important in the actions of SST (adenylyl cyclase (AC), protein kinase A (PKA), phospholipase C (PLC), protein kinase C (PKC), extracellular Ca 2+ L-type channels, intracellular Ca
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Prostaglandin E(2) (PGE(2)) potently activated glycogenolysis and gluconeogenesis in isolated rockfish (Sebastes caurinus) hepatocytes. The average degree of activation for glycogenolysis was 6.4+/-0.67-fold (mean+/-S.E.M.; n=37), and could be as much as 19-fold. Analysis of dose-concentration relationships between glycogenolytic actions and PGE(2) concentrations yielded an EC(50) around 120 nM in hepatocyte suspensions and 2 nM for hepatocytes immobilized on perifusion columns. For the activation of gluconeogenesis (1.74+/-0.14-fold; n=10), the EC(50) for suspensions was 60 nM. Intracellular targets for PGE(2) actions are adenylyl cyclase, protein kinase A and glycogen phosphorylase. Concentrations of cAMP increased with increasing concentrations of PGE(2), and peaked within 2 min of hormone application. In the presence of the phosphodiesterase inhibitor, isobutyl-3-methylxanthine, peak height was increased and peak duration extended. The protein kinase A inhibitor, Rp-cAMPS, counteracted the activation of glycogenolysis by PGE(2), implying that the adenylyl cyclase/protein kinase A pathway is the most important, if not exclusive, route of message transduction. PGE(2) activated plasma membrane adenylyl cyclase and hepatocyte glycogen phosphorylase in a dose-dependent manner. The effects were specific for PGE(2); smaller degrees of activation of glycogenolysis were noted for PGE(1), 11-deoxy PGE(1), 19-R-hydroxy-PGE(2), and prostaglandins of the A, B and Falpha-series. The selective EP(2)-receptor agonist, butaprost, was as effective as PGE(2), suggesting that rockfish liver contains prostaglandin receptors pharmacologically related to the EP(2) receptors of non-hepatic tissues of mammals. Rockfish hepatocytes quickly degraded added PGE(2) (t((1/2))=17-26 min). A similar ability to degrade PGE(2) has been noted in catfish (Ameiurus nebulosus) hepatocytes, but no glycogenolytic or gluconeogenic actions of the hormone are noted for this species. We conclude that PGE(2) is an important metabolic hormone in fish liver, with cAMP-mediated actions on glycogen and glucose metabolism, and probably other pathways regulated by cAMP and protein kinase A. The constant presence of EP(2)-like receptors is a unique feature of the fish liver, with interesting implications for function and evolution of prostaglandin receptors in vertebrates.
