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Polishchuk A, Cilleros-Mañé V, Just-Borràs L, Balanyà-Segura M, Vandellòs Pont G, Silvera Simón C, Tomàs M, Garcia N, Tomàs J, Lanuza MA. Synaptic retrograde regulation of the PKA-induced SNAP-25 and Synapsin-1 phosphorylation. Cell Mol Biol Lett 2023; 28:17. [PMID: 36869288 PMCID: PMC9985302 DOI: 10.1186/s11658-023-00431-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/09/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Bidirectional communication between presynaptic and postsynaptic components contribute to the homeostasis of the synapse. In the neuromuscular synapse, the arrival of the nerve impulse at the presynaptic terminal triggers the molecular mechanisms associated with ACh release, which can be retrogradely regulated by the resulting muscle contraction. This retrograde regulation, however, has been poorly studied. At the neuromuscular junction (NMJ), protein kinase A (PKA) enhances neurotransmitter release, and the phosphorylation of the molecules of the release machinery including synaptosomal associated protein of 25 kDa (SNAP-25) and Synapsin-1 could be involved. METHODS Accordingly, to study the effect of synaptic retrograde regulation of the PKA subunits and its activity, we stimulated the rat phrenic nerve (1 Hz, 30 min) resulting or not in contraction (abolished by µ-conotoxin GIIIB). Changes in protein levels and phosphorylation were detected by western blotting and cytosol/membrane translocation by subcellular fractionation. Synapsin-1 was localized in the levator auris longus (LAL) muscle by immunohistochemistry. RESULTS Here we show that synaptic PKA Cβ subunit regulated by RIIβ or RIIα subunits controls activity-dependent phosphorylation of SNAP-25 and Synapsin-1, respectively. Muscle contraction retrogradely downregulates presynaptic activity-induced pSynapsin-1 S9 while that enhances pSNAP-25 T138. Both actions could coordinately contribute to decreasing the neurotransmitter release at the NMJ. CONCLUSION This provides a molecular mechanism of the bidirectional communication between nerve terminals and muscle cells to balance the accurate process of ACh release, which could be important to characterize molecules as a therapy for neuromuscular diseases in which neuromuscular crosstalk is impaired.
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Affiliation(s)
- Aleksandra Polishchuk
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Marta Balanyà-Segura
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Genís Vandellòs Pont
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Carolina Silvera Simón
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Josep Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain.
| | - Maria A Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain.
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2
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Benton KC, Wheeler DS, Kurtoglu B, Ansari MBZ, Cibich DP, Gonzalez DA, Herbst MR, Khursheed S, Knorr RC, Lobner D, Maglasang JG, Rohr KE, Taylor A, Twining RC, Witt PJ, Gasser PJ. Norepinephrine activates β 1 -adrenergic receptors at the inner nuclear membrane in astrocytes. Glia 2022; 70:1777-1794. [PMID: 35589612 PMCID: PMC9276628 DOI: 10.1002/glia.24219] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 04/18/2022] [Accepted: 05/09/2022] [Indexed: 01/01/2023]
Abstract
Norepinephrine exerts powerful influences on the metabolic, neuroprotective and immunoregulatory functions of astrocytes. Until recently, all effects of norepinephrine were believed to be mediated by receptors localized exclusively to the plasma membrane. However, recent studies in cardiomyocytes have identified adrenergic receptors localized to intracellular membranes, including Golgi and inner nuclear membranes, and have shown that norepinephrine can access these receptors via transporter-mediated uptake. We recently identified a high-capacity norepinephrine transporter, organic cation transporter 3 (OCT3), densely localized to outer nuclear membranes in astrocytes, suggesting that adrenergic signaling may also occur at the inner nuclear membrane in these cells. Here, we used immunofluorescence and western blot to show that β1 -adrenergic receptors are localized to astrocyte inner nuclear membranes; that key adrenergic signaling partners are present in astrocyte nuclei; and that OCT3 and other catecholamine transporters are localized to astrocyte plasma and nuclear membranes. To test the functionality of nuclear membrane β1 -adrenergic receptors, we monitored real-time protein kinase A (PKA) activity in astrocyte nuclei using a fluorescent biosensor. Treatment of astrocytes with norepinephrine induced rapid increases in PKA activity in the nuclear compartment. Pretreatment of astrocytes with inhibitors of catecholamine uptake blocked rapid norepinephrine-induced increases in nuclear PKA activity. These studies, the first to document functional adrenergic receptors at the nuclear membrane in any central nervous system cell, reveal a novel mechanism by which norepinephrine may directly influence nuclear processes. This mechanism may contribute to previously described neuroprotective, metabolic and immunoregulatory actions of norepinephrine.
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Affiliation(s)
| | | | - Beliz Kurtoglu
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | | | - Daniel P. Cibich
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Dante A. Gonzalez
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Matthew R. Herbst
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Saema Khursheed
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Rachel C. Knorr
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Doug Lobner
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Jenree G. Maglasang
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Kayla E. Rohr
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Analisa Taylor
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Robert C. Twining
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Paul J. Witt
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
| | - Paul J. Gasser
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201
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3
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Moreno-Corona NC, Lopez-Ortega O, Flores Hermenegildo JM, Berron-Ruiz L, Rodriguez-Alba JC, Santos-Argumedo L, Lopez-Herrera G. Lipopolysaccharide-responsive beige-like anchor acts as a cAMP-dependent protein kinase anchoring protein in B cells. Scand J Immunol 2020; 92:e12922. [PMID: 32592188 DOI: 10.1111/sji.12922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 05/15/2020] [Accepted: 06/21/2020] [Indexed: 01/04/2023]
Abstract
Lipopolysaccharide (LPS)-responsive beige-like anchor (LRBA) protein was initially described as a monogenetic cause for common variable immune deficiency, a syndrome characterized by low levels of B cells, defects in memory B cell differentiation and hypogammaglobulinaemia. LRBA was identified as an LPS up-regulated gene in B cells, macrophages and T cells. LRBA weighs 320 kDa and has 2863 amino acids. Its sequence contains multiple domains, suggesting that LRBA can act as a scaffolding protein. It contains two putative binding sites for cAMP-dependent kinase (PKA) regulatory subunits, suggesting this protein can act as A-kinase anchor protein (AKAP); however, physical interactions involving LRBA and PKA have not been demonstrated to date, and functional roles for such interactions are unexplored. In this work, we investigated physical interactions involving LRBA with regulatory subunits of PKA in human B cell lines and primary human B cells. PKA is a holoenzyme composed of two regulatory subunits, which can be RIα, RIβ, RIIα or RIIβ, and two catalytic subunits, Cα or Cβ. We co-immunoprecipitated LRBA using Ramos B cell lymphoma cells and observed that LRBA interacts with RIIβ. Interestingly, St-Ht31, an inhibitory peptide that disrupts AKAP interactions with regulatory subunits, reduced the amount of interacting protein. Furthermore, in primary human B cells, LRBA was induced after CD40L and IL-4 stimulation, and under such activation, we found that LRBA interacts with RIIα and RIIβ, suggesting that LRBA acts as an AKAP and binds RII subunits. Interestingly, we also identified that LRBA interacts with activation-induced cytidine deaminase in primary B cells, suggesting that it is involved in B cell function.
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Affiliation(s)
- Nidia Carolina Moreno-Corona
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico.,Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Orestes Lopez-Ortega
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico
| | - Jose Mizael Flores Hermenegildo
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico.,Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Laura Berron-Ruiz
- Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Juan Carlos Rodriguez-Alba
- Unidad de Citometria de Flujo, Instituto de Ciencias de la Salud, Universidad Veracruzana, Xalapa, Veracruz, Mexico
| | | | - Gabriela Lopez-Herrera
- Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
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4
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Cilleros-Mañé V, Just-Borràs L, Tomàs M, Garcia N, Tomàs JM, Lanuza MA. The M 2 muscarinic receptor, in association to M 1 , regulates the neuromuscular PKA molecular dynamics. FASEB J 2020; 34:4934-4955. [PMID: 32052889 DOI: 10.1096/fj.201902113r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/23/2019] [Accepted: 01/20/2020] [Indexed: 01/13/2023]
Abstract
Muscarinic acetylcholine receptor 1 subtype (M1 ) and muscarinic acetylcholine receptor 2 subtype (M2 ) presynaptic muscarinic receptor subtypes increase and decrease, respectively, neurotransmitter release at neuromuscular junctions. M2 involves protein kinase A (PKA), although the muscarinic regulation to form and inactivate the PKA holoenzyme is unknown. Here, we show that M2 signaling inhibits PKA by downregulating Cβ subunit, upregulating RIIα/β and liberating RIβ and RIIα to the cytosol. This promotes PKA holoenzyme formation and reduces the phosphorylation of the transmitter release target synaptosome-associated protein 25 and the gene regulator cAMP response element binding. Instead, M1 signaling, which is downregulated by M2 , opposes to M2 by recruiting R subunits to the membrane. The M1 and M2 reciprocal actions are performed through the anchoring protein A kinase anchor protein 150 as a common node. Interestingly, M2 modulation on protein expression needs M1 signaling. Altogether, these results describe the dynamics of PKA subunits upon M2 muscarinic signaling in basal and under presynaptic nerve activity, uncover a specific involvement of the M1 receptor and reveal the M1 /M2 balance to activate PKA to regulate neurotransmission. This provides a molecular mechanism to the PKA holoenzyme formation and inactivation which could be general to other synapses and cellular models.
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Affiliation(s)
- Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Josep Maria Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Maria Angel Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
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5
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Rogne M, Chu DT, Küntziger TM, Mylonakou MN, Collas P, Tasken K. OPA1-anchored PKA phosphorylates perilipin 1 on S522 and S497 in adipocytes differentiated from human adipose stem cells. Mol Biol Cell 2018; 29:1487-1501. [PMID: 29688805 PMCID: PMC6014102 DOI: 10.1091/mbc.e17-09-0538] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Optic atrophy 1 (OPA1) is the A-kinase anchoring protein targeting the pool of protein kinase A (PKA) responsible for perilipin 1 phosphorylation, a gatekeeper for lipolysis. However, the involvement of OPA1-bound PKA in the downstream regulation of lipolysis is unknown. Here we show up-regulation and relocation of OPA1 from mitochondria to lipid droplets during adipocytic differentiation of human adipose stem cells. We employed various biochemical and immunological approaches to demonstrate that OPA1-bound PKA phosphorylates perilipin 1 at S522 and S497 on lipolytic stimulation. We show that the first 30 amino acids of OPA1 are essential for its lipid droplet localization as is OMA1-dependent processing. Finally, our results indicate that presence of OPA1 is necessary for lipolytic phosphorylation of downstream targets. Our results show for the first time, to our knowledge, how OPA1 mediates adrenergic control of lipolysis in human adipocytes by regulating phosphorylation of perilipin 1.
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Affiliation(s)
- Marie Rogne
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Dinh-Toi Chu
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | | | - Maria-Niki Mylonakou
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway.,Norewegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424 Oslo, Norway
| | - Kjetil Tasken
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway.,Department of Cancer Immunology, Institute of Cancer Research, Oslo University Hospital, 0424 Oslo, Norway
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6
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Weigand I, Ronchi CL, Rizk-Rabin M, Dalmazi GD, Wild V, Bathon K, Rubin B, Calebiro D, Beuschlein F, Bertherat J, Fassnacht M, Sbiera S. Differential expression of the protein kinase A subunits in normal adrenal glands and adrenocortical adenomas. Sci Rep 2017; 7:49. [PMID: 28250426 PMCID: PMC5427838 DOI: 10.1038/s41598-017-00125-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 02/08/2017] [Indexed: 11/09/2022] Open
Abstract
Somatic mutations in protein kinase A catalytic α subunit (PRKACA) were found to be causative for 30-40% of cortisol-producing adenomas (CPA) of the adrenal gland, rendering PKA signalling constitutively active. In its resting state, PKA is a stable and inactive heterotetramer, consisting of two catalytic and two regulatory subunits with the latter inhibiting PKA activity. The human genome encodes three different PKA catalytic subunits and four different regulatory subunits that are preferentially expressed in different organs. In normal adrenal glands all regulatory subunits are expressed, while CPA exhibit reduced protein levels of the regulatory subunit IIβ. In this study, we linked for the first time the loss of RIIβ protein levels to the PRKACA mutation status and found the down-regulation of RIIβ to arise post-transcriptionally. We further found the PKA subunit expression pattern of different tumours is also present in the zones of the normal adrenal cortex and demonstrate that the different PKA subunits have a differential expression pattern in each zone of the normal adrenal gland, indicating potential specific roles of these subunits in the regulation of different hormones secretion.
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Affiliation(s)
- Isabel Weigand
- Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital, University of Wuerzburg, Wuerzburg, Germany
| | - Cristina L Ronchi
- Comprehensive Cancer Center Mainfranken, University of Wuerzburg, Wuerzburg, Germany
| | - Marthe Rizk-Rabin
- Institut Cochin, INSERM U1016, CNRS UMR810, Department of Endocrinology, Reference Center for Rare Adrenal diseases, Assistance Publique Hôpiteaux de Paris, Hôpital Cochin, Descartes University, Paris, France
| | - Guido Di Dalmazi
- Medizinische Klinik and Poliklinik IV, Ludwig-Maximilians University, Munich, Germany
| | - Vanessa Wild
- Institute of Pathology, University of Wuerzburg, Wuerzburg, Germany
| | - Kerstin Bathon
- Institute of Pharmacology and Toxicology and Bioimaging Center, University of Wuerzburg, Wuerzburg, Germany
| | - Beatrice Rubin
- Endocrinology Unit, Department of Medicine, University of Padua, Padua, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bioimaging Center, University of Wuerzburg, Wuerzburg, Germany
| | - Felix Beuschlein
- Medizinische Klinik and Poliklinik IV, Ludwig-Maximilians University, Munich, Germany
| | - Jérôme Bertherat
- Institut Cochin, INSERM U1016, CNRS UMR810, Department of Endocrinology, Reference Center for Rare Adrenal diseases, Assistance Publique Hôpiteaux de Paris, Hôpital Cochin, Descartes University, Paris, France
| | - Martin Fassnacht
- Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital, University of Wuerzburg, Wuerzburg, Germany.,Comprehensive Cancer Center Mainfranken, University of Wuerzburg, Wuerzburg, Germany.,Central Laboratory, University Hospital, University of Wuerzburg, Wuerzburg, Germany
| | - Silviu Sbiera
- Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital, University of Wuerzburg, Wuerzburg, Germany. .,Comprehensive Cancer Center Mainfranken, University of Wuerzburg, Wuerzburg, Germany.
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7
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Calabokis M, González Y, Merchán A, Escalona JL, Araujo NA, Sanz-Rodríguez CE, Cywiak C, Spencer LM, Martínez JC, Bubis J. Immunological identification of a cAMP-dependent protein kinase regulatory subunit-like protein from theTrypanosoma equiperdumTeAp-N/D1 isolate. J Immunoassay Immunochem 2016; 37:485-514. [DOI: 10.1080/15321819.2016.1162799] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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8
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Type II PKAs are anchored to mature insulin secretory granules in INS-1 β-cells and required for cAMP-dependent potentiation of exocytosis. Biochimie 2016; 125:32-41. [PMID: 26898328 DOI: 10.1016/j.biochi.2016.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/13/2016] [Indexed: 11/23/2022]
Abstract
Specificity of the cAMP-dependent protein kinase (PKA) pathway relies on an extremely sophisticated compartmentalization mechanism of the kinase within a given cell, based on high-affinity binding of PKA tetramer pools to different A-Kinase Anchoring Proteins (AKAPs). We and others have previously shown that AKAPs-dependent PKA subcellular targeting is a requisite for optimal cAMP-dependent potentiation of insulin exocytosis. We thus hypothesized that a PKA pool may directly anchor to the secretory compartment to potentiate insulin exocytosis. Here, using immunofluorescence analyses combined to subcellular fractionations and purification of insulin secretory granules (ISGs), we identified discrete subpools of type II PKAs, RIIα and RIIβ PKAs, along with the catalytic subunit, physically associated with ISGs within pancreatic insulin-secreting β-cells. Ultrastructural analysis of native rodent β-cells confirmed in vivo the occurrence of PKA on dense-core ISGs. Isoform-selective disruption of binding of PKAs to AKAPs reinforced the requirement of type II PKA isoforms for cAMP potentiation of insulin exocytosis. This granular localization of PKA was of critical importance since siRNA-mediated depletion of either RIIα or RIIβ PKAs resulted in a significant reduction of cAMP-dependent potentiation of insulin release. The present work provides evidence for a previously unrecognized pool of type II PKAs physically anchored to the β-cell ISGs compartment and supports a non-redundant function for type II PKAs during cAMP potentiation of exocytosis.
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9
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Ins(1,4,5)P3 receptor type 1 associates with AKAP9 (AKAP450 variant) and protein kinase A type IIβ in the Golgi apparatus in cerebellar granule cells. Biol Cell 2012; 101:469-80. [DOI: 10.1042/bc20080184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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10
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Immunocytochemical analysis of cyclic AMP receptor proteins in the developing rat parotid gland. Arch Oral Biol 2008; 53:429-36. [PMID: 18187105 DOI: 10.1016/j.archoralbio.2007.11.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 10/23/2007] [Accepted: 11/26/2007] [Indexed: 11/20/2022]
Abstract
UNLABELLED Previous studies showed that regulatory subunits of type II cyclic AMP-dependent protein kinase (RII) are present in adult rat parotid acinar cells, and are secreted into saliva. If the synthesis and intracellular distribution of RII exhibit developmental specificity, then RII can be an indicator of secretory and regulatory activity of salivary glands. OBJECTIVE To determine the expression and distribution of RII in the rat parotid at specific ages representing defined developmental stages. METHODS Parotid glands of fetal, neonatal and adult rats were prepared for morphologic and immunocytochemical study. The cellular distribution of RII was studied using light microscopic immunogold silver staining with anti-RII, and its intracellular distribution using electron microscopic immunogold labeling. RESULTS In utero, parotid RII levels were low; 5-18 days after birth, labeling of secretory granules and cytoplasm rose to a peak, followed by a rapid decrease in both compartments at 25 days. At 60 days, granule labeling increased to levels near those at 18 days, whereas cytoplasmic labeling remained low. Nuclear labeling was highest during the first 3 weeks after birth, and then declined. CONCLUSIONS The higher nuclear and cytoplasmic labeling during the neonatal period may reflect RII involvement in acinar cell differentiation. The accumulation of RII in secretory granules is similar to the pattern of the major salivary proteins, amylase and PSP. The redistribution of RII in these compartments during development may reflect changing gene expression patterns, and may be useful for identification of genetic or metabolic abnormalities.
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11
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Kvissel AK, Ørstavik S, Eikvar S, Brede G, Jahnsen T, Collas P, Akusjärvi G, Skålhegg BS. Involvement of the catalytic subunit of protein kinase A and of HA95 in pre-mRNA splicing. Exp Cell Res 2007; 313:2795-809. [PMID: 17594903 DOI: 10.1016/j.yexcr.2007.05.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/31/2007] [Accepted: 05/01/2007] [Indexed: 11/30/2022]
Abstract
Protein kinase A (PKA) is a holoenzyme consisting of two catalytic (C) subunits bound to a regulatory (R) subunit dimer. Stimulation by cAMP dissociates the holoenzyme and causes translocation to the nucleus of a fraction of the C subunit. Apart from transcription regulation, little is known about the function of the C subunit in the nucleus. In the present report, we show that both Calpha and Cbeta are localized to spots in the mammalian nucleus. Double immunofluorescence analysis of splicing factor SC35 with the C subunit indicated that these spots are splicing factor compartments (SFCs). Using the E1A in vivo splicing assay, we found that catalytically active C subunits regulate alternative splicing and phosphorylate several members of the SR-protein family of splicing factors in vitro. Furthermore, nuclear C subunits co-localize with the C subunit-binding protein homologous to AKAP95, HA95. HA95 also regulates E1A alternative splicing in vivo, apparently through its N-terminal domain. Localization of the C subunit to SFCs and the E1A splicing pattern were unaffected by cAMP stimulation. Our findings demonstrate that the nuclear PKA C subunit co-locates with HA95 in SFCs and regulates pre-mRNA splicing, possibly through a cAMP-independent mechanism.
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12
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Kovo M, Kandli-Cohen M, Ben-Haim M, Galiani D, Carr DW, Dekel N. An active protein kinase A (PKA) is involved in meiotic arrest of rat growing oocytes. Reproduction 2006; 132:33-43. [PMID: 16816331 DOI: 10.1530/rep.1.00824] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Reinitiation of meiosis in meiotically competent, fully grown mammalian oocytes is governed by a fall in intraoocyte cAMP concentrations and the subsequent inactivation of protein kinase A (PKA). A similar reduction in intraoocyte cAMP concentrations in growing, meiotically incompetent rat oocytes not leading to resumption of meiosis, questions the involvement of PKA in the regulation of meiosis at this early stage of oocyte development. We examined the possibility of whether PKA activity maintains growing oocytes in meiotic arrest and further explored the mode of activation of PKA under conditions of relatively low cAMP concentrations. Our experiment demonstrated that inactivation of PKA stimulates growing rat oocytes to resume meiosis, and elevates the activity of their maturation-promoting factor (MPF). We also found that the expressions of type I and type II regulatory subunits (RI and RII) of PKA are higher in growing and fully grown oocytes, respectively. In addition, we revealed that the common 1:1 ratio between the regulatory (R) and catalytic (C) subunits of PKA is apparently not abrogated and, in accordance PKA activity in growing oocyte-cell extract is fully dependent on cAMP. Finally, we identified in growing oocytes, the A kinase anchoring protein (AKAP) 140, which was previously depicted in fully grown oocytes. We conclude that an active PKA prevents growing oocytes from resuming meiosis. Our findings further suggest that relatively high abundance of the PKAI isoform and/or its subcellular compartmentalization, through interaction with AKAP140, could possibly account for the high basal PKA activity at relatively low intraoocyte cAMP concentrations.
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Affiliation(s)
- Michal Kovo
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, 76100 Israel
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13
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Lingle WL, Lukasiewicz K, Salisbury JL. Deregulation of the centrosome cycle and the origin of chromosomal instability in cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 570:393-421. [PMID: 18727509 DOI: 10.1007/1-4020-3764-3_14] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although we have begun to tap into the mechanisms behind Boveri's initial observation that supernumerary centrosomes cause chromosome missegregation in sea urchin eggs, there is still much left to discover with regard to chromosomal instability in cancer. Many of the molecular players involved in regulation of the centrosome and cell cycles, and the coupling of the two cycles to produce a bipolar mitotic spindle have been identified. One theme that has become apparent is that cross talk and interrelatedness of the pathways serve to provide redundant mechanisms to maintain genomic integrity. In spite of this, cells occasionally fall prey to insults that initiate and maintain the chromosomal instability that results in viable malignant tumours. Deregulation of centrosome structure is an integral aspect of the origin of chromosomal instability in many cancers. There are numerous routes to centrosome amplification including: environmental insults such as ionising radiation and exposure to estrogen (Li et al., 2005); failure of cytokinesis; and activating mutations in key regulators of centrosome structure and function. There are two models for initiation of centrosome amplification (Figure 2). In the first, centrosome duplication and chromosome replication remain coupled and cells enter G2 with 4N chromosomes and duplicated centrosomes. However, these cells may fail to complete mitosis, and thus reenter G1 as tetraploid cells with amplified centrosomes. In the second, the centrosome cycle is uncoupled from chromosome replication and cells go through one or more rounds of centriole/centrosome duplication in the absence of chromosome replication. If these cells then go through chromosome replication accompanied by another round of centrosome duplication, cells complete G2 with 4N chromosomes and more than 2 centrosomes, and therefore are predisposed to generate multipolar mitotic spindles. Fragmentation of centrosomes due to ionising radiation is a variation of the second model. Once centrosome amplification is present, even in a diploid cell, that cell has the potential to yield viable aneuploid progeny. The telophase cell in Figure 3C illustrates this scenario. In a normal telophase configuration, the total number of chromosomes is 92 (resulting from the segregation of 46 pairs of chromatids), with each daughter nucleus containing 46 individual chromosomes. Based on the number of kinetochore signals present, the lower nucleus in Figure 3C has approximately 28 chromosomes, and the elongate upper nucleus has approximately 60, for a total of 88. Due to superimposition of kinetochores in this maximum projection image, 88 is an underestimate of the actual number of kinetochores and is not significantly different from the expected total of 92. A cell resulting from the lower nucleus with only around 28 chromosomes would probably not be viable, much as Boveri's experiments indicated. However, the upper nucleus with at least 60 chromosomes could be viable. This cell would enter G1 as hypotriploid (69 chromosomes = triploid) with 2 centrosomes. During S and G2, the centrosomes and chromosomes would double, and the following mitosis could be tetrapolar with a 6N chromosome content. When centrosome amplification is accompanied by permissive lapses in cell cycle checkpoints, the potential for malignant growth is present. These lapses could result from specific genetic mutations and amplifications, epigenetic gene silencing, or from massive chromosomal instability caused by the centrosome amplification. Centrosome amplification, therefore, can serve to exacerbate and/or generate genetic instabilities associated with cancers.
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Affiliation(s)
- Wilma L Lingle
- Mayo Clinic College of Medicine, Mayo Clinic Foundation, Mayo Clinic Cancer Center, Rochester, Minnesota 55905, USA
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14
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Orstavik S, Funderud A, Hafte TT, Eikvar S, Jahnsen T, Skålhegg BS. Identification and characterization of novel PKA holoenzymes in human T lymphocytes. FEBS J 2005; 272:1559-67. [PMID: 15794744 DOI: 10.1111/j.1742-4658.2005.04568.x] [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: 11/27/2022]
Abstract
Cyclic AMP-dependent protein kinase (PKA) is a holoenzyme that consists of a regulatory (R) subunit dimer and two catalytic (C) subunits that are released upon stimulation by cAMP. Immunoblotting and immunoprecipitation of T-cell protein extracts, immunofluorescence of permeabilized T cells and RT/PCR of T-cell RNA using C subunit-specific primers revealed expression of two catalytically active PKA C subunits C alpha1 (40 kDa) and C beta2 (47 kDa) in these cells. Anti-RI alpha and Anti-RII alpha immunoprecipitations demonstrated that both C alpha1 and C beta2 associate with RI alpha and RII alpha to form PKAI and PKAII holoenzymes. Moreover, Anti-C beta2 immunoprecipitation revealed that C alpha1 coimmunoprecipitates with C beta2. Addition of 8-CPT-cAMP which disrupts the PKA holoenzyme, released C alpha1 but not C beta2 from the Anti-C beta2 precipitate, indicating that C beta2 and C alpha1 form part of the same holoenzyme. Our results demonstrate for the first time that various C subunits may colocate on the same PKA holoenzyme to form novel cAMP-responsive enzymes that may mediate specific effects of cAMP.
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Affiliation(s)
- Sigurd Orstavik
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway
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15
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Abstract
The type 1alpha regulatory subunit (RIalpha) of cAMP-dependent protein kinase (PKA) (coded by the PRKAR1A gene) is the main component of type I PKA, which regulates most of the serine-threonine kinase activity catalyzed by the PKA holoenzyme in response to cAMP. Carney complex (CNC), or the complex of spotty skin pigmentation, myxomas, and endocrine overactivity, is a multiple endocrine (and not only) neoplasia syndrome that is due to PRKAR1A-inactivating mutations. The R1alpha protein and PRKAR1A mRNA have been found to be up-regulated in a series of cell lines and human and rodent neoplasms, suggesting this molecule's involvement in tumorigenesis and its potential role in cell cycle regulation, growth, and/or proliferation. Alterations in PKA activity elicit a variety of effects depending on the tissue, developmental stage, degree of differentiation, and cAMP levels. In addition, RIalpha may have functions independent of PKA. The presence of inactivating germline mutations and the loss of its wild-type allele in some CNC lesions indicate that PRKAR1A might function as a tumor suppressor gene in these tissues, but could PRKAR1A be a classic tumor suppressor gene? Probably not, and this review explains why.
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Affiliation(s)
- Ioannis Bossis
- Section on Endocrinology and Genetics, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1862, USA
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16
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Demaugre F, Philippe Y, Sar S, Pileire B, Christa L, Lasserre C, Brechot C. HIP/PAP, a C-type lectin overexpressed in hepatocellular carcinoma, binds the RII alpha regulatory subunit of cAMP-dependent protein kinase and alters the cAMP-dependent protein kinase signalling. ACTA ACUST UNITED AC 2004; 271:3812-20. [PMID: 15373827 DOI: 10.1111/j.1432-1033.2004.04302.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIP/PAP is a C-type lectin overexpressed in hepatocellular carcinoma (HCC). Pleiotropic biological activities have been ascribed to this protein, but little is known about the function of HIP/PAP in the liver. In this study, therefore, we searched for proteins interacting with HIP/PAP by screening a HCC cDNA expression library. We have identified the RII alpha regulatory subunit of cAMP-dependent protein kinase (PKA) as a partner of HIP/PAP. HIP/PAP and RII alpha were coimmunoprecipitated in HIP/PAP expressing cells. The biological relevance of the interaction between these proteins was established by demonstrating, using fractionation methods, that they are located in a same subcellular compartment. Indeed, though HIP/PAP is a protein secreted via the Golgi apparatus we showed that a fraction of HIP/PAP escaped the secretory apparatus and was recovered in the cytosol. Basal PKA activity was increased in HIP/PAP expressing cells, suggesting that HIP/PAP may alter PKA signalling. Indeed, we showed, using a thymidine kinase-luciferase reporter plasmid in which a cAMP responsive element was inserted upstream of the thymidine kinase promoter, that luciferase activity was enhanced in HIP/PAP expressing cells. Thus our findings suggest a novel mechanism for the biological activity of the HIP/PAP lectin.
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MESH Headings
- Antigens, Neoplasm/genetics
- Antigens, Neoplasm/metabolism
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Gene Library
- Golgi Apparatus
- Humans
- Immunoprecipitation
- Lectins, C-Type/genetics
- Lectins, C-Type/metabolism
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Luciferases/metabolism
- Pancreatitis-Associated Proteins
- Phosphorylation
- Signal Transduction
- Subcellular Fractions
- Thymidine Kinase/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- France Demaugre
- INSERM U370 CHU Necker Enfants Malades, 75015 Paris, France.
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17
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Ou Y, Rattner JB. The Centrosome in Higher Organisms: Structure, Composition, and Duplication. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 238:119-82. [PMID: 15364198 DOI: 10.1016/s0074-7696(04)38003-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The centrosome found in higher organisms is an organelle with a complex and dynamic architecture and composition. This organelle not only functions as a microtubule-organizing center, but also is integrated with or impacts a number of cellular processes. Defects associated with this organelle have been linked to a variety of human diseases including several forms of cancer. Here we review the emerging picture of how the structure, composition, duplication, and function of the centrosome found in higher organisms are interrelated.
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Affiliation(s)
- Young Ou
- Department of Cell Biology and Anatomy, University of Calgary 3330 Hospital Drive NW, Calgary, Alberta, Canada
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18
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Keryer G, Witczak O, Delouvée A, Kemmner WA, Rouillard D, Tasken K, Bornens M. Dissociating the centrosomal matrix protein AKAP450 from centrioles impairs centriole duplication and cell cycle progression. Mol Biol Cell 2003; 14:2436-46. [PMID: 12808041 PMCID: PMC194891 DOI: 10.1091/mbc.e02-09-0614] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Centrosomes provide docking sites for regulatory molecules involved in the control of the cell division cycle. The centrosomal matrix contains several proteins, which anchor kinases and phosphatases. The large A-Kinase Anchoring Protein AKAP450 is acting as a scaffolding protein for other components of the cell signaling machinery. We selectively perturbed the centrosome by modifying the cellular localization of AKAP450. We report that the expression in HeLa cells of the C terminus of AKAP450, which contains the centrosome-targeting domain of AKAP450 but not its coiled-coil domains or binding sites for signaling molecules, leads to the displacement of the endogenous centrosomal AKAP450 without removing centriolar or pericentrosomal components such as centrin, gamma-tubulin, or pericentrin. The centrosomal protein kinase A type II alpha was delocalized. We further show that this expression impairs cytokinesis and increases ploidy in HeLa cells, whereas it arrests diploid RPE1 fibroblasts in G1, thus further establishing a role of the centrosome in the regulation of the cell division cycle. Moreover, centriole duplication is interrupted. Our data show that the association between centrioles and the centrosomal matrix protein AKAP450 is critical for the integrity of the centrosome and for its reproduction.
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Affiliation(s)
- Guy Keryer
- Unité Mixte Recherche 144-Centre National de la Recherche Scientifique-Institut Curie, F-75248, Paris, France
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19
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MacDougall MWJ, Europe-Finner GN, Robson SC. Human myometrial quiescence and activation during gestation and parturition involve dramatic changes in expression and activity of particulate type II (RII alpha) protein kinase A holoenzyme. J Clin Endocrinol Metab 2003; 88:2194-205. [PMID: 12727975 DOI: 10.1210/jc.2002-021862] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There are substantial data indicating that components of the cAMP-signaling pathway are differentially expressed in the human myometrium during pregnancy. The effects of cAMP in most tissues and cell types are mainly modulated via protein kinase A, a heterotetrameric protein complex consisting of two regulatory (R) and two catalytic (C) subunits. In the studies presented here, we used specific antibodies in Western blotting/immunoprecipitation, RT-PCR, and functional protein kinase A (PKA) phosphorylation assays to determine the PKA holoenzymes that are expressed in the human myometrium throughout pregnancy and labor. We report that as early as the second trimester of pregnancy, there is a significant increase in expression of the regulatory RII alpha protein subunit of PKA in the myometrium. This increase in protein expression is also mirrored at the mRNA level, indicating transcriptional control throughout pregnancy, whereas during parturition both transcript and protein are significantly decreased. This increase in RII alpha protein also resulted in increased particulate PKA activity in the myometrium during gestation, which was subsequently decreased during labor. Two specific A kinase anchoring proteins, AKAP95 and AKAP79, which have high binding affinities for RII alpha subunits, were found to form complexes with myometrial RII alpha species employing immunoprecipitation assays, but their levels of expression remained uniform in all myometrial tissue samples investigated. Our findings indicate that increased particulate type II PKA activity occurs throughout pregnancy, therefore directing the cAMP quiescence signal to specific subcellular loci within myometrial smooth muscle cells including the contractile machinery at the cytoskeleton; this effect is then removed during parturition.
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Affiliation(s)
- Malcolm W J MacDougall
- Department of Obstetrics and Gynaecology, School of Surgical and Reproductive Sciences, University of Newcastle upon Tyne, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, United Kingdom
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20
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Birkeli KA, Llorente A, Torgersen ML, Keryer G, Taskén K, Sandvig K. Endosome-to-Golgi transport is regulated by protein kinase A type II alpha. J Biol Chem 2003; 278:1991-7. [PMID: 12419802 DOI: 10.1074/jbc.m209982200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Studies of RII alpha-deficient B lymphoid cells and stable transfectants expressing the type II alpha regulatory subunit (RII alpha) of cAMP-dependent protein kinase (PKA), which is targeted to the Golgi-centrosomal area, reveal that the presence of a Golgi-associated pool of PKA type II alpha mediates a change in intracellular transport of the plant toxin ricin. The transport of ricin from endosomes to the Golgi apparatus, measured as sulfation of a modified ricin (ricin sulf-1), increased in RII alpha-expressing cells when PKA was activated. However, not only endosome-to-Golgi transport, but also retrograde ricin transport to the endoplasmic reticulum (ER), measured as sulfation and N-glycosylation of another modified ricin (ricin sulf-2), seemed to be increased in cells expressing RII alpha in the presence of a cAMP analog, 8-(4-chlorophenylthio)-cAMP. Thus, PKA type II alpha seems to be involved in both endosome-to-Golgi and Golgi-to-ER transport. Because ricin, after being retrogradely transported to the ER, is translocated to the cytosol, where it inhibits protein synthesis, we also investigated the influence of RII alpha expression on ricin toxicity. In agreement with the other data obtained, 8-(4-chlorophenylthio)-cAMP and RII alpha were found to sensitize cells to ricin, indicating an increased transport of ricin to the cytosol. In conclusion, our results demonstrate that transport of ricin from endosomes to the Golgi apparatus and further to the ER is regulated by PKA type II alpha isozyme.
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Affiliation(s)
- Kim Are Birkeli
- Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway
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21
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Abstract
Cancer remains one of the leading causes of death throughout the world. One of the important reasons why conventional treatments fail is the development of resistance to therapeutics. The dual effect concept and self-defense mechanism plus the threshold theory might in part explain the development of resistance, however, the primary cause is unclear. A novel theory, 'cell brain', where, selective crystallization of the 'brain' of a cell (comprising centrosome, centrioles and the connecting filaments) occurs, may be a potential alternate approach to cancer therapy.
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Affiliation(s)
- Q Kong
- Cocid Corp, Denver, CO 80220, USA.
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22
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23
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Abstract
All malignant human tumors contain chromosomal rearrangements. Among them, the majority of solid tumors show chromosomal instability, caused by aberrations in chromosomal segregation during cell division. Chromosomal instability, defined as increased probability of formation of novel chromosomal mutations compared to that of normal or control cells, appears to be a feature of tumorigenesis in vivo and in vitro (in cancer cell lines). Several enzymatic kinases are involved in maintaining proper chromosomal segregation and regulating cell cycle progression. One such kinase, cAMP-dependent protein kinase A (PKA), has a functional role in many aspects of cell signaling, metabolism, and proliferation. In this review, we will discuss the potential participation of PKA in chromosomal stability. This role includes the association of PKA with the centrosome, microtubules, and the anaphase-promoting complex/cyclosome (ACP/C), all key aspects of proper chromosomal segregation.
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Affiliation(s)
- Ludmila Matyakhina
- Unit on Genetics & Endocrinology, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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24
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Hoover F, Kalhovde JM, Dahle MK, Skålhegg B, Taskén K, Lømo T. Electrical muscle activity pattern and transcriptional and posttranscriptional mechanisms regulate PKA subunit expression in rat skeletal muscle. Mol Cell Neurosci 2002; 19:125-37. [PMID: 11860267 DOI: 10.1006/mcne.2001.1053] [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: 11/22/2022] Open
Abstract
We have examined protein kinase A (PKA) subunit expression in adult rat skeletal muscles. Northern blots identified PKA catalytic alpha and regulatory (R) I alpha and RII alpha subunits as the major subunits expressed in slowly contracting soleus (SOL) and rapidly contracting extensor digitorum longus (EDL) muscles. In addition, the steady-state RNA levels of PKA subunit mRNAs and activities of RI alpha and RII alpha promoters are similar in SOL and EDL. These data indicate that posttranscriptional mechanisms account for the twofold differences in PKA subunit protein levels reported earlier. Electrical stimulation of denervated SOL with an EDL-like activity pattern (fast pattern) transformed SOL into an EDL-like muscle with regard to PKA protein levels. These experiments suggest that the posttranscriptional regulation is activity pattern-dependent. Denervation specifically increased RI alpha promoter activity and RI alpha mRNA levels in SOL and EDL. Further experiments indicated that the RI alpha 1a upstream sequences were activated following denervation. Direct electrical stimulation prevented the rise in RI alpha mRNA levels following denervation, demonstrating that electrical muscle activity regulates transcription.
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MESH Headings
- 5' Flanking Region/genetics
- Action Potentials/physiology
- Animals
- Cyclic AMP-Dependent Protein Kinases/genetics
- Exons/genetics
- Gene Expression Regulation, Enzymologic/physiology
- Genes, Reporter/physiology
- Male
- Muscle Contraction/physiology
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/enzymology
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/enzymology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/innervation
- Neuromuscular Junction/cytology
- Neuromuscular Junction/metabolism
- Promoter Regions, Genetic/genetics
- Protein Biosynthesis/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Long-Evans
- Rats, Wistar
- Signal Transduction/physiology
- Transcription, Genetic/physiology
- Up-Regulation/genetics
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Affiliation(s)
- Frank Hoover
- Department of Physiology, University of Oslo, Norway.
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25
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Fukuyama T, Sueoka E, Sugio Y, Otsuka T, Niho Y, Akagi K, Kozu T. MTG8 proto-oncoprotein interacts with the regulatory subunit of type II cyclic AMP-dependent protein kinase in lymphocytes. Oncogene 2001; 20:6225-32. [PMID: 11593431 DOI: 10.1038/sj.onc.1204794] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2001] [Revised: 06/16/2001] [Accepted: 07/05/2001] [Indexed: 11/09/2022]
Abstract
AML1-MTG8 chimeric oncogene is generated in acute myelogenous leukemia with t(8;21), and seems to be responsible for the pathogenesis of the disease. However, the role of MTG8 is ambiguous. Here we found that MTG8 interacted with the regulatory subunit of type II cyclic AMP-dependent protein kinase (PKA RIIalpha). The binding site of MTG8 was NHR3 domain, and that of RIIalpha was the N-terminus for interacting with PKA anchoring proteins (AKAPs). NHR3 contains a putative alpha-amphipathic helix which is characteristic in binding of AKAPs with RII. Indirect immunofluorescence microscopy showed that MTG8 and RIIalpha were overlapped at the centrosome-Golgi area in lymphocytes. These findings suggest that MTG8 may function as an AKAP at the centrosome-Golgi area in lymphocytes.
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Affiliation(s)
- T Fukuyama
- Saitama Cancer Center Research Institute, Saitama 362-0806, Japan
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26
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Carlson CR, Witczak O, Vossebein L, Labbé JC, Skålhegg BS, Keryer G, Herberg FW, Collas P, Taskén K. CDK1-mediated phosphorylation of the RIIα regulatory subunit of PKA works as a molecular switch that promotes dissociation of RIIα from centrosomes at mitosis. J Cell Sci 2001; 114:3243-54. [PMID: 11591813 DOI: 10.1242/jcs.114.18.3243] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein kinase A regulatory subunit RIIα is tightly bound to centrosomal structures during interphase through interaction with the A-kinase anchoring protein AKAP450, but dissociates and redistributes from centrosomes at mitosis. The cyclin B-p34cdc2 kinase (CDK1) has been shown to phosphorylate RIIα on T54 and this has been proposed to alter the subcellular localization of RIIα. We have made stable transfectants from an RIIα-deficient leukemia cell line (Reh) that expresses either wild-type or mutant RIIα (RIIα(T54E)). When expressed, RIIα detaches from centrosomes at mitosis and dissociates from its centrosomal location in purified nucleus-centrosome complexes by incubation with CDK1 in vitro. By contrast, centrosomal RIIα(T54E) is not redistributed at mitosis, remains mostly associated with centrosomes during all phases of the cell cycle and cannot be solubilized by CDK1 in vitro. Furthermore, RIIα is solubilized from particular cell fractions and changes affinity for AKAP450 in the presence of CDK1. D and V mutations of T54 also reduce affinity for the N-terminal RII-binding domain of AKAP450, whereas small neutral residues do not change affinity detected by surface plasmon resonance. In addition, only RIIα(T54E) interacts with AKAP450 in a RIPA-soluble extract from mitotic cells. Finally, microtubule repolymerization from mitotic centrosomes of the RIIα(T54E) transfectant is poorer and occurs at a lower frequency than that of RIIα transfectants. Our results suggest that T54 phosphorylation of RIIα by CDK1 might serve to regulate the centrosomal association of PKA during the cell cycle.
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Affiliation(s)
- C R Carlson
- Institute of Medical Biochemistry, University of Oslo, PO Box 1112 Blindern, N-0317 Oslo, Norway.
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27
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Taimi M, Breitman TR, Takahashi N. Cyclic AMP-dependent protein kinase isoenzymes in human myeloid leukemia (HL60) and breast tumor (MCF-7) cells. Arch Biochem Biophys 2001; 392:137-44. [PMID: 11469804 DOI: 10.1006/abbi.2001.2443] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Combinations of retinoic acid (RA) and cAMP mediate many biological responses in a large variety of cell types. While the basis for the apparent synergistic effects of RA and cAMP are not clearly defined, it is likely that activation of PKA by cAMP is involved. However, literature reports concerning the identity of PKA isoforms in HL60 and MCF-7 cells are conflicting. The purpose of the present investigation is to identify PKA isoforms in HL60 and MCF-7 cells. Utilization of high-performance anion-exchange liquid chromatography, immunoblotting, and 8-azido-cAMP photoaffinity binding resulted in the finding that HL60 cells contain PKA types I alpha and II alpha, while MCF-7 cells contain PKA types I alpha, II alpha, and II beta. PKA type I alpha in both HL60 and MCF-7 cells eluted from columns as two well-separated peaks. One peak eluted at a low salt concentration in agreement with previous reports. The second HL60 PKA type I alpha peak eluted at a salt concentration intermediate between that eluting the first peak and that eluting PKA type II alpha and contained approximately 62% of the total RI alpha protein. However, the second MCF-7 PKA type I alpha peak contained approximately 66% of the total RI alpha protein and co-eluted with PKA types II alpha and II beta. This "contamination" of PKA type II fractions with PKA type I has led, in some cases, to interpretations that may need reevaluation.
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Affiliation(s)
- M Taimi
- Basic Research Laboratory, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-9123, USA
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28
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Taskén KA, Collas P, Kemmner WA, Witczak O, Conti M, Taskén K. Phosphodiesterase 4D and protein kinase a type II constitute a signaling unit in the centrosomal area. J Biol Chem 2001; 276:21999-2002. [PMID: 11285255 DOI: 10.1074/jbc.c000911200] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mediation of cAMP effects by specific pools of protein kinase A (PKA) targeted to distinct subcellular domains raises the question of how inactivation of the cAMP signal is achieved locally and whether similar targeting of phosphodiesterases (PDEs) to sites of cAMP/PKA action could be observed. Here, we demonstrate that Sertoli cells of the testis contain an insoluble PDE4D3 isoform, which is shown by immunofluorescence to target to centrosomes. Staining of PDE4D and PKA shows co-localization of PDE4D with PKA-RIIalpha and RIIbeta in the centrosomal region. Co-precipitation of RII subunits and PDE4D3 from cytoskeletal extracts indicates a physical association of the two proteins. Distribution of PDE4D overlaps with that of the centrosomal PKA-anchoring protein, AKAP450, and AKAP450, PDE4D3, and PKA-RIIalpha co-immunoprecipitate. Finally, both PDE4D3 and PKA co-precipitate with a soluble fragment of AKAP450 encompassing amino acids 1710 to 2872 when co-expressed in 293T cells. Thus, a centrosomal complex that includes PDE4D and PKA constitutes a novel signaling unit that may provide accurate spatio-temporal modulation of cAMP signals.
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Affiliation(s)
- K A Taskén
- Institute of Medical Biochemistry, University of Oslo, N-0317 Oslo, Norway
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29
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Fax P, Carlson CR, Collas P, Taskén K, Esche H, Brockmann D. Binding of PKA-RIIalpha to the Adenovirus E1A12S oncoprotein correlates with its nuclear translocation and an increase in PKA-dependent promoter activity. Virology 2001; 285:30-41. [PMID: 11414803 DOI: 10.1006/viro.2001.0926] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adenovirus type 12 (Ad12) E1A12S oncoprotein utilizes the cAMP/protein kinase A (PKA) signal transduction pathway to activate expression of the viral E2 gene, the products of which are essential for viral replication. A central unsolved question is, however, whether E1A12S interacts directly with PKA in the process of promoter activation. We show here that E1A12S binds to the regulatory subunits (R) of PKA in vitro and in vivo. Interaction depends on the N-terminus and the conserved region 1 (CR1) of E1A12S. Both domains are also essential for the activation of viral E2 gene expression. Infection of cells with Ad12 leads to the cellular redistribution of RIIalpha from the cytoplasm into the nucleus. Furthermore, RIIalpha is also located in the nucleus of cells transformed by E1 of Ad12 and transient expression of E1A12S leads to the redistribution of RIIalpha into the nucleus in a N-terminus- and CR1-dependent manner. Cotransfection of E1A12S with RIIalpha results in strong activation of the E2 promoter. Based on these results we conclude that E1A12S functions as a viral A-kinase anchoring protein redistributing RIIalpha from the cytoplasm into the nucleus where it is involved in E1A12S-mediated activation of the E2 promoter.
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Affiliation(s)
- P Fax
- Institute of Molecular Biology (Cancer Research), University of Essen Medical School, Essen, Germany
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30
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Lutz W, Lingle WL, McCormick D, Greenwood TM, Salisbury JL. Phosphorylation of centrin during the cell cycle and its role in centriole separation preceding centrosome duplication. J Biol Chem 2001; 276:20774-80. [PMID: 11279195 DOI: 10.1074/jbc.m101324200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Once during each cell cycle, mitotic spindle poles arise by separation of newly duplicated centrosomes. We report here the involvement of phosphorylation of the centrosomal protein centrin in this process. We show that centrin is phosphorylated at serine residue 170 during the G(2)/M phase of the cell cycle. Indirect immunofluorescence staining of HeLa cells using a phosphocentrin-specific antibody reveals intense labeling of mitotic spindle poles during prophase and metaphase of the cell division cycle, with diminished staining of anaphase and no staining of telophase and interphase centrosomes. Cultured cells undergo a dramatic increase in centrin phosphorylation following the experimental elevation of PKA activity, suggesting that this kinase can phosphorylate centrin in vivo. Surprisingly, elevated PKA activity also resulted intense phosphocentrin antibody labeling of interphase centrosomes and in the concurrent movement of individual centrioles apart from one another. Taken together, these results suggest that centrin phosphorylation signals the separation of centrosomes at prophase and implicates centrin phosphorylation in centriole separation that normally precedes centrosome duplication.
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Affiliation(s)
- W Lutz
- Department of Biochemistry and Molecular Biology, Tumor Biology Program, Mayo Clinic Foundation, Rochester, Minnesota 55905, USA
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31
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Imaizumi-Scherrer T, Faust DM, Barradeau S, Hellio R, Weiss MC. Type I protein kinase a is localized to interphase microtubules and strongly associated with the mitotic spindle. Exp Cell Res 2001; 264:250-65. [PMID: 11262182 DOI: 10.1006/excr.2001.5164] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We show here that type I protein kinase A is localized to microtubules during the entire cell cycle in epithelial (hepatoma, cervical carcinoma) and nonepithelial (myoblast) cell lines. The association of the type Ialpha regulatory subunit is very strong in all phases of mitosis, from prophase to cytokinesis. In interphase, the association appears weaker, reflecting perhaps a more dynamic molecular interaction. This regulatory subunit appears to recruit catalytic subunits as the latter are also associated with microtubules. BW1J hepatoma cells, stably transfected with either wild-type or mutant Ialpha regulatory subunit, are enriched in aberrant mitoses with multipolar spindles and in mono- or multinucleated giant cells. This suggests that type I protein kinase A could have a role in centrosome duplication and/or segregation, sister chromatid separation, or cytokinesis.
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32
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Gupta RP, Abou-Donia MB. Enhanced activity and level of protein kinase A in the spinal cord supernatant of diisopropyl phosphorofluoridate (DFP)-treated hens. Distribution of protein kinases and phosphatases in spinal cord subcellular fractions. Mol Cell Biochem 2001; 220:15-23. [PMID: 11451376 DOI: 10.1023/a:1011010824252] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Diisopropyl phosphorofluoridate (DFP) is a type I organophosphorus compound and produces delayed neurotoxicity (OPIDN) in adult hens. A single dose of DFP (1.7 mg/kg, s.c.) produces mild ataxia in hens in 7-14 days, which develops into severe ataxia or paralysis as the disease progresses. We have previously shown altered expression of several proteins (e.g. Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) alpha-subunit, tau, tubulin, neurofilament protein (NF), vimentin, GFAP) and an immediate early gene (e.g. c-fos) in DFP-treated hens. Here we show an increase in protein kinase A (PKA) protein level and activity in the spinal cord at 1-day and 5-days time periods after DFP administration. We also determined the protein levels of protein kinase C (PKC), CaM kinase II and several phosphatases (i.e. phosphatase 1 (PP1), phosphatase 2A (PP2A), phosphatase 2B (PP2B) in the spinal cord of DFP-treated hens after 1, 5, 10, and 20 days). There was increase in CaM kinase II alpha subunit level after 10 and 20 days of treatment, and decrease in PKC level at 1-day and 20-days time periods in spinal cord mitochondria. In contrast, the cerebrum, which is resistant to DFP-induced axonal degeneration, did not show change in PKA and CaM Kinase II levels at any time period DFP post-administration. No alteration was found in the protein levels of PP1, PP2A, and PP2B at any time period. An early induction in PKA, which is an important protein kinase in signal transduction, followed by that of CaM kinase might be contributing towards the development of OPIDN in DFP-treated hens.
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Affiliation(s)
- R P Gupta
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27708, USA
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33
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Affiliation(s)
- T Küntziger
- Institut Curie, Section Recherche, UMR 144 CNRS, Paris, France
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Flaherty DB, Soria JP, Tomasiewicz HG, Wood JG. Phosphorylation of human tau protein by microtubule-associated kinases: GSK3beta and cdk5 are key participants. J Neurosci Res 2000; 62:463-72. [PMID: 11054815 DOI: 10.1002/1097-4547(20001101)62:3<463::aid-jnr16>3.0.co;2-7] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Microtubules (MTs), primarily composed of alpha and beta tubulin polymers, must often work in concert with microtubule-associated proteins (MAPs) in order to modulate their functional demands. In a mature brain neuron, one of the key MAPs that resides primarily in the axonal compartment is the tau protein. Tau, in the adult human brain, is a set of six protein isoforms, whose binding affinity to MTs can be modulated by phosphorylation. In addition to the role that phosphorylation of tau plays in the "normal" physiology of neurons, hyperphosphorylated tau is the primary component of the fibrillary pathology in Alzheimer's disease (AD). Although many protein kinases are known to phosphorylate tau in vitro, the in vivo players contributing to the hyperphosphorylation of tau remain elusive. The experiments in this study attempt to define which protein kinases and protein phosphatases reside in the associated network of microtubules, thereby being strategically positioned to influence the phosphorylation of tau. Microtubule fractions are utilized to determine which of the microtubule-associated kinases most readily impacts the phosphorylation of tau at "AD-like" sites. Results from this study indicate that PKA, CK1, GSK3beta, and cdk5 associate with microtubules. Among the MT-associated kinases, GSK3beta and cdk5 most readily contribute to the ATP-induced "AD-like" phosphorylation of tau.
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Affiliation(s)
- D B Flaherty
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Reinton N, Collas P, Haugen TB, Skâlhegg BS, Hansson V, Jahnsen T, Taskén K. Localization of a novel human A-kinase-anchoring protein, hAKAP220, during spermatogenesis. Dev Biol 2000; 223:194-204. [PMID: 10864471 DOI: 10.1006/dbio.2000.9725] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using a combination of protein kinase A type II overlay screening, rapid amplification of cDNA ends, and database searches, a contig of 9923 bp was assembled and characterized in which the open reading frame encoded a 1901-amino-acid A-kinase-anchoring protein (AKAP) with an apparent SDS-PAGE mobility of 220 kDa, named human AKAP220 (hAKAP220). The hAKAP220 amino acid sequence revealed high similarity to rat AKAP220 in the 1167 C-terminal residues, but contained 727 residues in the N-terminus not present in the reported rat AKAP220 sequence. The hAKAP220 mRNA was expressed at high levels in human testis and in isolated human pachytene spermatocytes and round spermatids. The hAKAP220 protein was present in human male germ cells and mature sperm. Immunofluorescent labeling with specific antibodies indicated that hAKAP220 was localized in the cytoplasm of premeiotic pachytene spermatocytes and in the centrosome of developing postmeiotic germ cells, while a midpiece/centrosome localization was found in elongating spermatocytes and mature sperm. The hAKAP220 protein together with a fraction of PKA types I and II and protein phosphatase I was resistant to detergent extraction of sperm tails, suggesting an association with cytoskeletal structures. In contrast, S-AKAP84/D-AKAP1, which is also present in the midpiece, was extracted under the same conditions. Anti-hAKAP220 antisera coimmunoprecipitated both type I and type II regulatory subunits of PKA in human testis lysates, indicating that hAKAP220 interacts with both classes of R subunits, either through separate or through a common binding motif(s).
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Affiliation(s)
- N Reinton
- Institute of Medical Biochemistry, University of Oslo, Oslo, N-0317, Norway
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36
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Herberg FW, Maleszka A, Eide T, Vossebein L, Tasken K. Analysis of A-kinase anchoring protein (AKAP) interaction with protein kinase A (PKA) regulatory subunits: PKA isoform specificity in AKAP binding. J Mol Biol 2000; 298:329-39. [PMID: 10764601 DOI: 10.1006/jmbi.2000.3662] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Compartmentalization of cAMP-dependent protein kinase (PKA) is in part mediated by specialized protein motifs in the dimerization domain of the regulatory (R)-subunits of PKA that participate in protein-protein interactions with an amphipathic helix region in A-kinase anchoring proteins (AKAPs). In order to develop a molecular understanding of the subcellular distribution and specific functions of PKA isozymes mediated by association with AKAPs, it is of importance to determine the apparent binding constants of the R-subunit-AKAP interactions. Here, we present a novel approach using surface plasmon resonance (SPR) to examine directly the association and dissociation of AKAPs with all four R-subunit isoforms immobilized on a modified cAMP surface with a high level of accuracy. We show that both AKAP79 and S-AKAP84/D-AKAP1 bind RIIalpha very well (apparent K(D) values of 0.5 and 2 nM, respectively). Both proteins also bind RIIbeta quite well, but with three- to fourfold lower affinities than those observed versus RIIalpha. However, only S-AKAP84/D-AKAP1 interacts with RIalpha at a nanomolar affinity (apparent K(D) of 185 nM). In comparison, AKAP95 binds RIIalpha (apparent K(D) of 5.9 nM) with a tenfold higher affinity than RIIbeta and has no detectable binding to RIalpha. Surface competition assays with increasing concentrations of a competitor peptide covering amino acid residues 493 to 515 of the thyroid anchoring protein Ht31, demonstrated that Ht31, but not a proline-substituted peptide, Ht31-P, competed binding of RIIalpha and RIIbeta to all the AKAPs examined (EC(50)-values from 6 to 360 nM). Furthermore, RIalpha interaction with S-AKAP84/D-AKAP1 was competed (EC(50) 355 nM) with the same peptide. Here we report for the first time an approach to determine apparent rate- and equilibria binding constants for the interaction of all PKA isoforms with any AKAP as well as a novel approach for characterizing peptide competitors that disrupt PKA-AKAP anchoring.
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Affiliation(s)
- F W Herberg
- Ruhr-Universität Bochum, Bochum, 44801, Germany.
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37
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Hansson V, Skålhegg BS, Taskén K. Cyclic-AMP-dependent protein kinase (PKA) in testicular cells. Cell specific expression, differential regulation and targeting of subunits of PKA. J Steroid Biochem Mol Biol 1999; 69:367-78. [PMID: 10419014 DOI: 10.1016/s0960-0760(99)00077-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
LH and FSH regulate via cyclic adenosine 3'5' cyclic monophosphate (cAMP) and cAMP-dependent protein kinase (PKA), steroid biosynthesis is Leydig and Sertoli cells, respectively. Cyclic AMP also regulates a number of different cellular processes such as cell growth and differentiation, ion channel conductivity, synaptic release of neurotransmitters, and gene transcription. The principle intracellular target for cAMP in mammalian cells is the PKA. The fact that this broad specificity protein kinase mediates a number of discrete physiological responses following cAMP engagement, has raised the question of how specificity is maintained in the cAMP/PKA system. Here we describe features of this signaling pathway that may contribute to explain how differential effects of cAMP may be contributed to features of the PKA signaling pathway.
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Affiliation(s)
- V Hansson
- Institute of Medical Biochemistry, University of Oslo, Norway
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