1
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Peart LA, Draper M, Tarasov AI. The impact of GLP-1 signalling on the energy metabolism of pancreatic islet β-cells and extrapancreatic tissues. Peptides 2024; 178:171243. [PMID: 38788902 DOI: 10.1016/j.peptides.2024.171243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Glucagon-like peptide-1 signalling impacts glucose homeostasis and appetite thereby indirectly affecting substrate availability at the whole-body level. The incretin canonically produces an insulinotropic effect, thereby lowering blood glucose levels by promoting the uptake and inhibiting the production of the sugar by peripheral tissues. Likewise, GLP-1 signalling within the central nervous system reduces the appetite and food intake, whereas its gastric effect delays the absorption of nutrients, thus improving glycaemic control and reducing the risk of postprandial hyperglycaemia. We review the molecular aspects of the GLP-1 signalling, focusing on its impact on intracellular energy metabolism. Whilst the incretin exerts its effects predominantly via a Gs receptor, which decodes the incretin signal into the elevation of intracellular cAMP levels, the downstream signalling cascades within the cell, acting on fast and slow timescales, resulting in an enhancement or an attenuation of glucose catabolism, respectively.
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Affiliation(s)
- Leah A Peart
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Matthew Draper
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
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2
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Chen Z, Zhai J, Ma J, Chen P, Lin W, Zhang W, Xiong J, Zhang C, Wei H. Melatonin-Primed Mesenchymal Stem Cells-Derived Small Extracellular Vesicles Alleviated Neurogenic Erectile Dysfunction by Reversing Phenotypic Modulation. Adv Healthc Mater 2023; 12:e2203087. [PMID: 36652551 DOI: 10.1002/adhm.202203087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/10/2023] [Indexed: 01/19/2023]
Abstract
Erectile dysfunction (ED) is an adverse side effect of pelvic surgery with no effective treatment. In this study, it is explored whether melatonin could improve the therapeutic effects of small extracellular vesicles (sEVs), derived from mesenchymal stem cells (MSCs), on cavernous nerve injury (CNI) ED, and the underlying mechanisms are investigated. The sEVs from melatonin-pretreated MSCs (MT-EVs) and MSCs (NC-EVs) are isolated and applied to CNI ED. Transplantation of MT-EVs remarkably increases erectile function and reduces phenotypic modulation in CNI ED rats. The therapeutic effects of MT-EVs are superior to those of NC-EVs. Sequencing implies that miR-10a-3p is enriched in MT-EVs, and directly targets the protein kinase inhibitor α (PKIA). After the suppression of miR-10a-3p, the therapeutic actions of MT-EVs are abolished, but are rescued by PKIA. Similarly, RhoA/ROCK is inhibited by MT-EVs, but this action is reversed by suppressing miR-10a-3p, accompanied by corresponding changes in PKIA. In conclusion, transplantation of MT-EVs could significantly alleviate CNI ED. MT-EVs may relieve the phenotypic modulation of the corpora cavernosum smooth muscle cells via the miR-10a-3p/PKIA/RhoA/ROCK signaling axis. These nanovesicles should be potential therapeutic vectors or bioactive materials for CNI ED.
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Affiliation(s)
- Zehong Chen
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Jiancheng Zhai
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Jiahui Ma
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Peng Chen
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Weishun Lin
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Weipeng Zhang
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Jiaming Xiong
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Chaowei Zhang
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
| | - Hongbo Wei
- Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Tianhe Road 600, Guangzhou, 510630, China
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3
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Peng GE, von Zastrow M. A Live-Cell Imaging Assay for Nuclear Entry of cAMP-Dependent Protein Kinase Catalytic Subunits Stimulated by Endogenous GPCR Activation. Methods Mol Biol 2022; 2483:339-349. [PMID: 35286686 DOI: 10.1007/978-1-0716-2245-2_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nuclear entry of cAMP-dependent protein kinase catalytic subunits is typically inferred from changes in net protein amount or kinase activity in the nucleus. Previous methods to directly assess nuclear entry require kinase subunit overexpression and/or supraphysiological cAMP elevation. We describe a method to detect nuclear entry of catalytic subunits expressed at an endogenous level in living cells, stimulated by cAMP in a physiological range, and in real time.
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Affiliation(s)
- Grace E Peng
- Program in Cell Biology, University of California, San Francisco, San Francisco, CA, USA
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Mark von Zastrow
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA.
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA.
- Quantitative Biology Institute, University of California, San Francisco, San Francisco, CA, USA.
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4
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Liu C, Ke P, Zhang J, Zhang X, Chen X. Protein Kinase Inhibitor Peptide as a Tool to Specifically Inhibit Protein Kinase A. Front Physiol 2020; 11:574030. [PMID: 33324237 PMCID: PMC7723848 DOI: 10.3389/fphys.2020.574030] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/02/2020] [Indexed: 12/13/2022] Open
Abstract
The protein kinase enzyme family plays a pivotal role in almost every aspect of cellular function, including cellular metabolism, division, proliferation, transcription, movement, and survival. Protein kinase A (PKA), whose activation is triggered by cyclic adenosine monophosphate (cAMP), is widely distributed in various systems and tissues throughout the body and highly related to pathogenesis and progression of various kinds of diseases. The inhibition of PKA activation is essential for the study of PKA functions. Protein kinase inhibitor peptide (PKI) is a potent, heat-stable, and specific PKA inhibitor. It has been demonstrated that PKI can block PKA-mediated phosphorylase activation. Since then, researchers have a lot of knowledge about PKI. PKI is considered to be the most effective and specific method to inhibit PKA and is widely used in related research. In this review, we will first introduce the knowledge on the activation of PKA and mechanisms related on the inhibitory effects of PKI on PKA. Then, we will compare PKI-mediated PKA inhibition vs. several popular methods of PKA inhibition.
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Affiliation(s)
- Chong Liu
- Department of Pharmacology, Second Military Medical University, Shanghai, China
| | - Ping Ke
- Department of Pharmacology, Second Military Medical University, Shanghai, China
| | - Jingjing Zhang
- Department of Pharmacology, Second Military Medical University, Shanghai, China
| | - Xiaoying Zhang
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA, United States
| | - Xiongwen Chen
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA, United States
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5
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Olivieri C, Wang Y, Li GC, V S M, Kim J, Stultz BR, Neibergall M, Porcelli F, Muretta JM, Thomas DDT, Gao J, Blumenthal DK, Taylor SS, Veglia G. Multi-state recognition pathway of the intrinsically disordered protein kinase inhibitor by protein kinase A. eLife 2020; 9:e55607. [PMID: 32338601 PMCID: PMC7234811 DOI: 10.7554/elife.55607] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/27/2020] [Indexed: 12/17/2022] Open
Abstract
In the nucleus, the spatiotemporal regulation of the catalytic subunit of cAMP-dependent protein kinase A (PKA-C) is orchestrated by an intrinsically disordered protein kinase inhibitor, PKI, which recruits the CRM1/RanGTP nuclear exporting complex. How the PKA-C/PKI complex assembles and recognizes CRM1/RanGTP is not well understood. Using NMR, SAXS, fluorescence, metadynamics, and Markov model analysis, we determined the multi-state recognition pathway for PKI. After a fast binding step in which PKA-C selects PKI's most competent conformations, PKI folds upon binding through a slow conformational rearrangement within the enzyme's binding pocket. The high-affinity and pseudo-substrate regions of PKI become more structured and the transient interactions with the kinase augment the helical content of the nuclear export sequence, which is then poised to recruit the CRM1/RanGTP complex for nuclear translocation. The multistate binding mechanism featured by PKA-C/PKI complex represents a paradigm on how disordered, ancillary proteins (or protein domains) are able to operate multiple functions such as inhibiting the kinase while recruiting other regulatory proteins for nuclear export.
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Affiliation(s)
- Cristina Olivieri
- Department of Biochemistry, Molecular Biology, and Biophysics, University of MinnesotaMinneapolisUnited States
| | - Yingjie Wang
- Department of Chemistry and Supercomputing Institute, University of MinnesotaMinneapolisUnited States
- Shenzhen Bay LaboratoryShenzhenChina
| | - Geoffrey C Li
- Department of Chemistry and Supercomputing Institute, University of MinnesotaMinneapolisUnited States
| | - Manu V S
- Department of Biochemistry, Molecular Biology, and Biophysics, University of MinnesotaMinneapolisUnited States
| | - Jonggul Kim
- Department of Chemistry and Supercomputing Institute, University of MinnesotaMinneapolisUnited States
| | | | | | | | - Joseph M Muretta
- Department of Biochemistry, Molecular Biology, and Biophysics, University of MinnesotaMinneapolisUnited States
| | - David DT Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of MinnesotaMinneapolisUnited States
| | - Jiali Gao
- Department of Chemistry and Supercomputing Institute, University of MinnesotaMinneapolisUnited States
- Laboratory of Computational Chemistry and Drug Design, Peking University Shenzhen Graduate SchoolShenzhenChina
| | - Donald K Blumenthal
- Department of Pharmacology and Toxicology, University of UtahSalt Lake CityUnited States
| | - Susan S Taylor
- Department of Chemistry and Biochemistry and Pharmacology, University of California, San DiegoLa JollaUnited States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of MinnesotaMinneapolisUnited States
- Department of Chemistry and Supercomputing Institute, University of MinnesotaMinneapolisUnited States
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6
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Swimming regulations for protein kinase A catalytic subunit. Biochem Soc Trans 2020; 47:1355-1366. [PMID: 31671183 DOI: 10.1042/bst20190230] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/05/2019] [Accepted: 09/10/2019] [Indexed: 11/17/2022]
Abstract
cAMP-dependent protein kinase (PKA) plays a central role in important biological processes including synaptic plasticity and sympathetic stimulation of the heart. Elevations of cAMP trigger release of PKA catalytic (C) subunits from PKA holoenzymes, thereby coupling cAMP to protein phosphorylation. Uncontrolled C subunit activity, such as occurs in genetic disorders in which regulatory subunits are depleted, is pathological. Anchoring proteins that associate with PKA regulatory subunits are important for localising PKA activity in cells. However, anchoring does not directly explain how unrestrained 'free swimming' of C subunits is avoided following C subunit release. In this review, I discuss new mechanisms that have been posited to account for this old problem. One straightforward explanation is that cAMP does not trigger C subunit dissociation but instead activates intact PKA holoenzymes whose activity is restrained through anchoring. A comprehensive comparison of observations for and against cAMP-activation of intact PKA holoenzymes does not lend credence to this mechanism. Recent measurements have revealed that PKA regulatory subunits are expressed at very high concentrations, and in large molar excess relative to C subunits. I discuss the implications of these skewed PKA subunit concentrations, before considering how phosphorylation of type II regulatory subunits and myristylation of C subunits are likely to contribute to controlling C subunit diffusion and recapture in cells. Finally, I speculate on future research directions that may be pursued on the basis of these emerging mechanisms.
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7
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Rizk-Rabin M, Chaoui-Ibadioune S, Vaczlavik A, Ribes C, Polak M, Ragazzon B, Bertherat J. Link between steroidogenesis, the cell cycle, and PKA in adrenocortical tumor cells. Mol Cell Endocrinol 2020; 500:110636. [PMID: 31678420 DOI: 10.1016/j.mce.2019.110636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 10/09/2019] [Accepted: 10/26/2019] [Indexed: 02/04/2023]
Abstract
Adrenocortical tumors (ACTs) frequently cause steroid excess and present cell-cycle dysregulation. cAMP/PKA signaling is involved in steroid synthesis and play a role in cell-cycle regulation. We investigated, by cell synchronization in the different phases of the cell-cycle, the control of steroidogenesis and the contribution of PKA in adrenocortical cells (H295R and culture of primary pigmented nodular adrenocortical disease cells). Cells showed increased steroidogenesis and a maximal PKA activity at G2 phase, and a reduction at G1 phase. PRKACA overexpression, or cAMP stimulation, enhanced PKA activity and induced steroidogenesis in all synchronized groups but is not sufficient to drive cell-cycle progression. PRKAR1A inactivation enhanced PKA activity and induced STAR gene expression, only in cells in G1, and triggered cell-cycle progression in all groups. These findings provide evidence for a tight association between steroidogenesis and cell-cycle in ACTs. Moreover, PRKAR1A is essential for mediating the function of PKA activity on both steroidogenesis and cell-cycle progression in adrenocortical cells.
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Affiliation(s)
- Marthe Rizk-Rabin
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France.
| | | | - Anna Vaczlavik
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France
| | - Christopher Ribes
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France
| | - Michel Polak
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France; Hopital Necker Enfants Maladies, Department of Endocrinology, Paris, France
| | - Bruno Ragazzon
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France
| | - Jerôme Bertherat
- Institut Cochin, U1016, CNRS (UMR 8104), Université Paris Descartes, Paris, France; Hôpital Cochin, Department of Endocrinology. Center for Rare Adrenal Diseases, Paris, France
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8
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Averill AM, Rehman HT, Charles JW, Dinh TA, Danyal K, Verschraegen CF, Stein GS, Dostmann WR, Ramsey JE. Inhibition of the chimeric DnaJ-PKAc enzyme by endogenous inhibitor proteins. J Cell Biochem 2019; 120:13783-13791. [PMID: 30938854 DOI: 10.1002/jcb.28651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 01/16/2019] [Indexed: 12/22/2022]
Abstract
The chimeric DnaJ-PKAc enzymeresulting from an approximately 400-kb deletion of chromosome 19 is a primary contributor to the oncogenic transformation that occurs in fibrolamellar hepatocellular carcinoma, also called fibrolamellar carcinoma (FLC). This oncogenic deletion juxtaposes exon 1 of the DNAJB1 heat shock protein gene with exon 2 of the PRKACA gene encoding the protein kinase A catalytic subunit, resulting in DnaJ-PKAc fusion under the transcriptional control of the DNAJB1 promoter. The expression of DnaJ-PKAc is approximately 10 times that of wild-type (wt) PKAc catalytic subunits, causing elevated and dysregulated kinase activity that contributes to oncogenic transformation. In normal cells, PKAc activity is regulated by a group of endogenous proteins, termed protein kinase inhibitors (PKI) that competitively inhibit PKAc and assist with the nuclear export of the enzyme. Currently, it is scarcely known whether interactions with PKI are perturbed in DnaJ-PKAc. In this report, we survey existing data sets to assess the expression levels of the various PKI isoforms that exist in humans to identify those that are candidates to encounter DnaJ-PKAc in both normal liver and FLC tumors. We then compare inhibition profiles of wtPKAc and DnaJ-PKAc against PKI and demonstrate that extensive structural homology in the active site clefts of the two enzymes confers similar kinase activities and inhibition by full-length PKI and PKI-derived peptides.
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Affiliation(s)
- April M Averill
- Department of Microbiology and Molecular Genetics, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Hibba Tul Rehman
- Division of Hematology and Oncology, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont.,University of Vermont Cancer Center, Burlington, Vermont
| | - Joseph W Charles
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Timothy A Dinh
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Karamatullah Danyal
- Department of Pathology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Claire F Verschraegen
- Division of Medical Oncology, The Ohio State Comprehensive Cancer Center, Columbus, Ohio
| | - Gary S Stein
- University of Vermont Cancer Center, Burlington, Vermont.,Department of Biochemistry,, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Wolfgang R Dostmann
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Jon E Ramsey
- University of Vermont Cancer Center, Burlington, Vermont.,Department of Biochemistry,, Larner College of Medicine, University of Vermont, Burlington, Vermont
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9
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Adaptation to Endoplasmic Reticulum Stress Requires Transphosphorylation within the Activation Loop of Protein Kinases Kin1 and Kin2, Orthologs of Human Microtubule Affinity-Regulating Kinase. Mol Cell Biol 2018; 38:MCB.00266-18. [PMID: 30201804 DOI: 10.1128/mcb.00266-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/18/2018] [Indexed: 12/30/2022] Open
Abstract
Perturbations in endoplasmic reticulum (ER) homeostasis, a condition termed ER stress, activate the unfolded protein response (UPR), an intracellular network of signaling pathways. Recently, we have shown that protein kinase Kin1 and its paralog, Kin2, in the budding yeast Saccharomyces cerevisiae (orthologs of microtubule affinity-regulating kinase in humans) contribute to the UPR function. These Kin kinases contain a conserved kinase domain and an autoinhibitory kinase-associated 1 (KA1) domain separated by a long undefined domain. Here, we show that Kin1 or Kin2 protein requires minimally a kinase domain and an adjacent kinase extension region (KER) for UPR function. We also show that the functional mini-Kin2 protein is predominantly visualized inside the cells and precipitated with the cellular membrane fraction, suggesting its association with the cellular endomembrane system. Furthermore, we show that transphosphorylation of the Kin1 residue T302 and the analogous Kin2 residue T281 within the activation loop are important for full kinase activity. Collectively, our data suggest that, during ER stress, the Kin kinase domain is released from its autoinhibitory KA1 domain and is activated by transphosphorylation.
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10
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Porpora M, Sauchella S, Rinaldi L, Delle Donne R, Sepe M, Torres-Quesada O, Intartaglia D, Garbi C, Insabato L, Santoriello M, Bachmann VA, Synofzik M, Lindner HH, Conte I, Stefan E, Feliciello A. Counterregulation of cAMP-directed kinase activities controls ciliogenesis. Nat Commun 2018; 9:1224. [PMID: 29581457 PMCID: PMC5964327 DOI: 10.1038/s41467-018-03643-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/28/2018] [Indexed: 01/13/2023] Open
Abstract
The primary cilium emanates from the cell surface of growth-arrested cells and plays a central role in vertebrate development and tissue homeostasis. The mechanisms that control ciliogenesis have been extensively explored. However, the intersection between GPCR signaling and the ubiquitin pathway in the control of cilium stability are unknown. Here we observe that cAMP elevation promotes cilia resorption. At centriolar satellites, we identify a multimeric complex nucleated by PCM1 that includes two kinases, NEK10 and PKA, and the E3 ubiquitin ligase CHIP. We show that NEK10 is essential for ciliogenesis in mammals and for the development of medaka fish. PKA phosphorylation primes NEK10 for CHIP-mediated ubiquitination and proteolysis resulting in cilia resorption. Disarrangement of this control mechanism occurs in proliferative and genetic disorders. These findings unveil a pericentriolar kinase signalosome that efficiently links the cAMP cascade with the ubiquitin-proteasome system, thereby controlling essential aspects of ciliogenesis.
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Affiliation(s)
- Monia Porpora
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Simona Sauchella
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Laura Rinaldi
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Rossella Delle Donne
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Maria Sepe
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Omar Torres-Quesada
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Daniela Intartaglia
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), 80078, Italy
| | - Corrado Garbi
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Luigi Insabato
- Department of Advanced Biomedical Sciences, University Federico II, Naples, 80131, Italy
| | - Margherita Santoriello
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy
| | - Verena A Bachmann
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Matthis Synofzik
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research (HIH), University of Tübingen and German Center for Neurodegenerative Diseases (DZNE), 72076, Tübingen, Germany
| | - Herbert H Lindner
- Division of Clinical Biochemistry, Biocenter Medical University of Innsbruck, Innrain 80-82, A-6020, Innsbruck, Austria
| | - Ivan Conte
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), 80078, Italy
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Antonio Feliciello
- Department of Molecular Medicine and Medical Biotechnologies, University 'Federico II', Naples, 80131, Italy.
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11
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Wettlaufer SH, Penke LR, Okunishi K, Peters-Golden M. Distinct PKA regulatory subunits mediate PGE 2 inhibition of TGFβ-1-stimulated collagen I translation and myofibroblast differentiation. Am J Physiol Lung Cell Mol Physiol 2017; 313:L722-L731. [PMID: 28729346 DOI: 10.1152/ajplung.00131.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/27/2017] [Accepted: 07/18/2017] [Indexed: 02/02/2023] Open
Abstract
Prostaglandin E2 (PGE2), via cAMP signaling, inhibits a variety of fibroblast functions relevant to fibrogenesis. Among these are their translation of collagen I protein and their differentiation to myofibroblasts. PKA is central to these actions, with cAMP binding to regulatory (R) subunits leading to the release of catalytic subunits. Here we examined the role of specific PKAR subunit isoforms in these inhibitory actions in transforming growth factor β-1 (TGFβ-1)-stimulated human lung fibroblasts (HLFs). HLFs expressed all four R subunit isoforms. siRNA-mediated knockdown of subunits PKARIα and PKARIIα had no effect on PGE2 inhibition of either process. However, knockdown of PKARIβ selectively attenuated PGE2 inhibition of collagen I protein expression, whereas knockdown of PKARIIβ selectively attenuated PGE2 inhibition of expression of the myofibroblast differentiation marker, α-smooth muscle actin (α-SMA). cAMP analogs that selectively activate either PKARIβ or PKARIIβ exclusively inhibited collagen I synthesis or differentiation, respectively. In parallel, the PKARIβ agonist (but not a PKARIIβ agonist) reduced phosphorylation of two proteins involved in protein translation, protein kinase B (AKT) and mammalian target of rapamycin (mTOR). By contrast, the PKARIIβ agonist (but not a PKARIβ agonist) reduced levels of the differentiation-associated phosphorylated focal adhesion kinase (p-FAK) as well as the relative mRNA and protein expression of serum response factor (SRF), a transcription factor necessary for myofibroblast differentiation. Our results demonstrate that cAMP inhibition of collagen I translation and myofibroblast differentiation reflects the actions of distinct PKAR subunits.
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Affiliation(s)
- Scott H Wettlaufer
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - L Raghu Penke
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Katsuhide Okunishi
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Marc Peters-Golden
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
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12
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Dabanaka K, Chung S, Nakagawa H, Nakamura Y, Okabayashi T, Sugimoto T, Hanazaki K, Furihata M. PKIB expression strongly correlated with phosphorylated Akt expression in breast cancers and also with triple-negative breast cancer subtype. Med Mol Morphol 2012; 45:229-33. [PMID: 23224602 DOI: 10.1007/s00795-011-0565-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 09/28/2011] [Indexed: 10/27/2022]
Abstract
The cAMP-dependent protein kinase inhibitor-β (PKIB) is presumed to be one of the regulatory factors controlling the cAMP-dependent protein kinase A signaling pathway. The aim of this study was to investigate the frequency and patterns of PKIB overexpression in human breast cancer. We also examined the relationship between PKIB and phosphorylated Akt (pAkt) expression in the tumors. Using immunohistochemical techniques, we examined the expression of PKIB, ER, PR, HER2, and pAkt in 148 primary human breast carcinomas. We then analyzed the relationships between PKIB expression and that of pAkt, ER, PR, and HER2, as well as between PKIB expression and various clinicopathological characteristics. We assessed 64 and 27 cases, respectively, as positive for either PKIB or pAkt expression; 20 cases were positive for both PKIB and pAkt. We observed a significant positive correlation between the expression of PKIB and that of pAkt (P = 0.006). We showed by immunohistochemical analyses that PKIB expression was positively correlated with triple-negative breast cancers (P = 0.0004). These findings provide evidence for PKIB overexpression associated with pAkt expression. Furthermore, PKIB expression was strongly correlated with triple-negative breast cancer, suggesting that PKIB expression might contribute to the tumor behavior and development of breast cancer.
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Affiliation(s)
- Ken Dabanaka
- Department of Surgery, Kochi Medical School, Kochi 783-8505, Japan.
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13
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Pflug A, Rogozina J, Lavogina D, Enkvist E, Uri A, Engh RA, Bossemeyer D. Diversity of Bisubstrate Binding Modes of Adenosine Analogue–Oligoarginine Conjugates in Protein Kinase A and Implications for Protein Substrate Interactions. J Mol Biol 2010; 403:66-77. [DOI: 10.1016/j.jmb.2010.08.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/12/2010] [Accepted: 08/16/2010] [Indexed: 01/11/2023]
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14
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Merkle D, Hoffmann R. Roles of cAMP and cAMP-dependent protein kinase in the progression of prostate cancer: cross-talk with the androgen receptor. Cell Signal 2010; 23:507-15. [PMID: 20813184 DOI: 10.1016/j.cellsig.2010.08.017] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 08/14/2010] [Accepted: 08/20/2010] [Indexed: 01/22/2023]
Abstract
Prostate carcinomas are among the most frequently diagnosed and death causing cancers affecting males in the developed world. It has become clear that the molecular mechanisms that drive the differentiation of normal prostate cells towards neoplasia involve multiple signal transduction cascades that often overlap and interact. A critical mediator of cellular proliferation and differentiation in various cells (and cancers) is the cAMP-dependent protein kinase, also known as protein kinase A (PKA), and its activating secondary messenger, cAMP. PKA and cAMP have been shown to play critical roles in prostate carcinogenesis and are the subject of this review. In particular we will focus on the cross-talk between PKA/cAMP signaling and that of the androgen receptor.
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Affiliation(s)
- Dennis Merkle
- Philips Research, High Tech Campus, 5656AE, Eindhoven,The Netherlands.
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15
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Chung S, Furihata M, Tamura K, Uemura M, Daigo Y, Nasu Y, Miki T, Shuin T, Fujioka T, Nakamura Y, Nakagawa H. Overexpressing PKIB in prostate cancer promotes its aggressiveness by linking between PKA and Akt pathways. Oncogene 2009; 28:2849-59. [DOI: 10.1038/onc.2009.144] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Gao N, Asamitsu K, Hibi Y, Ueno T, Okamoto T. AKIP1 enhances NF-kappaB-dependent gene expression by promoting the nuclear retention and phosphorylation of p65. J Biol Chem 2008; 283:7834-43. [PMID: 18178962 DOI: 10.1074/jbc.m710285200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we have identified protein kinase A-interacting protein 1 (AKIP1) as a binding partner of NF-kappaB p65 subunit, and AKIP1 enhances the NF-kappaB-mediated gene expression. AKIP1 is a nuclear protein and known to interact with the catalytic subunit of PKA (PKAc). We identified AKIP1 by a yeast two-hybrid screen using the N terminus region of p65 as bait. The interaction between AKIP1 and p65 was confirmed by glutathione S-transferase pull-down assay in vitro and immunoprecipitation-Western blotting assay in vivo. We found that the PKAc was present in the AKIP1.p65 complex and enhanced the transcriptional activity of NF-kappaB by phosphorylating p65. In a transient luciferase assay, AKIP1 cotransfection efficiently increased the transcriptional activity of NF-kappaB induced by phorbol 12-myristate 13-acetate (PMA). When AKIP1 was knocked down by RNA interference, the PMA-mediated NF-kappaB-dependent gene expression was abolished, indicating a physiological role of AKIP1. We found that PKAc, which is maintained in an inactive form by binding to IkappaBalpha and NF-kappaB in resting cells, was activated by PMA-induced signaling and could phosphorylate p65. Overexpression of AKIP1 increased the PKAc binding to p65 and enhanced the PKAc-mediated phosphorylation of p65 at Ser-276. Interestingly, this p65 phosphorylation promoted nuclear translocation of p65 and enhanced NF-kappaB transcription. In fact, we observed that AKIP1 colocalized with p65 within the cells and appeared to retain p65 in nucleus. These findings indicate a positive role of AKIP1 in NF-kappaB signaling and suggest a novel mechanism by which AKIP1 augments the transcriptional competence of NF-kappaB.
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Affiliation(s)
- Nan Gao
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan
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17
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Role of kinase suppressor of Ras-1 in neuronal survival signaling by extracellular signal-regulated kinase 1/2. J Neurosci 2007; 27:11389-400. [PMID: 17942733 DOI: 10.1523/jneurosci.3473-07.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Scaffolding proteins including kinase suppressor of Ras-1 (KSR1) determine specificity of signaling by extracellular signal-regulated kinase 1/2 (ERK1/2), enabling it to couple diverse extracellular stimuli to various cellular responses. The scaffolding protein(s) that contributes to ERK1/2-mediated neuronal survival has not yet been identified. In cultured rat cortical neurons, BDNF activates ERK1/2 to enhance neuronal survival by suppressing DNA damage- or trophic deprivation-induced apoptosis. Here we report that in this system, BDNF increased KSR1 association with activated ERK1/2, whereas KSR1 knockdown with a short hairpin (sh) RNA reduced BDNF-mediated activation of ERK1/2 and protection against a DNA-damaging drug, camptothecin (CPT). In contrast, BDNF suppression of trophic deprivation-induced apoptosis was unaffected by shKSR1 although blocked by shERK1/2. Also, overexpression of KSR1 enhanced BDNF protection against CPT. Therefore, KSR1 is specifically involved in antigenotoxic activation of ERK1/2 by BDNF. To test whether KSR1 contributes to ERK1/2 activation by other neuroprotective stimuli, we used a cAMP-elevating drug, forskolin. In cortical neurons, ERK1/2 activation by forskolin was protein kinase A (PKA) dependent but TrkB (receptor tyrosine kinase B) independent and was accompanied by the increased association between KSR1 and active ERK1/2. Forskolin suppressed CPT-induced apoptosis in a KSR1 and ERK1/2-dependent manner. Inhibition of PKA abolished forskolin protection, whereas selective PKA activation resulted in an ERK1/2- and KSR1-mediated decrease in apoptosis. Hence, KSR1 is critical for the antiapoptotic activation of ERK1/2 by BDNF or cAMP/PKA signaling. In addition, these novel data indicate that stimulation of cAMP signaling is a candidate neuroprotective strategy to intervene against neurotoxicity of DNA-damaging agents.
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18
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Dalton GD, Dewey WL. Protein kinase inhibitor peptide (PKI): a family of endogenous neuropeptides that modulate neuronal cAMP-dependent protein kinase function. Neuropeptides 2006; 40:23-34. [PMID: 16442618 DOI: 10.1016/j.npep.2005.10.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 10/11/2005] [Indexed: 11/30/2022]
Abstract
Signal transduction cascades involving cAMP-dependent protein kinase are highly conserved among a wide variety of organisms. Given the universal nature of this enzyme it is not surprising that cAMP-dependent protein kinase plays a critical role in numerous cellular processes. This is particularly evident in the nervous system where cAMP-dependent protein kinase is involved in neurotransmitter release, gene transcription, and synaptic plasticity. Protein kinase inhibitor peptide (PKI) is an endogenous thermostable peptide that modulates cAMP-dependent protein kinase function. PKI contains two distinct functional domains within its amino acid sequence that allow it to: (1) potently and specifically inhibit the activity of the free catalytic subunit of cAMP-dependent protein kinase and (2) export the free catalytic subunit of cAMP-dependent protein kinase from the nucleus. Three distinct PKI isoforms (PKIalpha, PKIbeta, PKIgamma) have been identified and each isoform is expressed in the brain. PKI modulates neuronal synaptic activity, while PKI also is involved in morphogenesis and symmetrical left-right axis formation. In addition, PKI also plays a role in regulating gene expression induced by cAMP-dependent protein kinase. Future studies should identify novel physiological functions for endogenous PKI both in the nervous system and throughout the body. Most interesting will be the determination whether functional differences exist between individual PKI isoforms which is an intriguing possibility since these isoforms exhibit: (1) cell-type specific tissue expression patterns, (2) different potencies for the inhibition of cAMP-dependent protein kinase activity, and (3) expression patterns that are hormonally, developmentally and cell-cycle regulated. Finally, synthetic peptide analogs of endogenous PKI will continue to be invaluable tools that are used to elucidate the role of cAMP-dependent protein kinase in a variety of cellular processes throughout the nervous system and the rest of the body.
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Affiliation(s)
- George D Dalton
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980524, Richmond, VA 23298, USA.
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19
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Wiley JC, Hudson M, Kanning KC, Schecterson LC, Bothwell M. Familial Alzheimer's disease mutations inhibit gamma-secretase-mediated liberation of beta-amyloid precursor protein carboxy-terminal fragment. J Neurochem 2005; 94:1189-201. [PMID: 15992373 DOI: 10.1111/j.1471-4159.2005.03266.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cleavage of the beta-secretase processed beta-amyloid precursor protein by gamma-secretase leads to the extracellular release of Abeta42, the more amyloidogenic form of the beta-amyloid peptide, which subsequently forms the amyloid-plaques diagnostic of Alzheimer's disease. Mutations in beta-amyloid precursor protein (APP), presenilin-1 and presenilin-2 associated with familial Alzheimer's disease (FAD) increase release of Abeta42, suggesting that FAD may directly result from increased gamma-secretase activity. Here, we show that familial Alzheimer's disease mutations clustered near the sites of gamma-secretase cleavage actually decrease gamma-secretase-mediated release of the intracellular fragment of APP (CTFgamma). Concordantly, presenilin-1 mutations that result in Alzheimer's disease also decrease the release of CTFgamma. Mutagenesis of the epsilon cleavage site in APP mimicked the effects of the FAD mutations, both decreasing CTFgamma release and increasing Abeta42 production, suggesting that perturbation of this site may account for the observed decrement in gamma-secretase-mediated proteolysis of APP. As CTFgamma has been implicated in transcriptional activation, these data indicate that decreased signaling and transcriptional regulation resulting from FAD mutations in beta-amyloid precursor protein and presenilin-1 may contribute to the pathology of Alzheimer's disease.
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Affiliation(s)
- Jesse C Wiley
- Department of Physiology and Biophysics, University of Washginton, Seattle, Washington 98195, USA
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20
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Chen X, Dai JC, Orellana SA, Greenfield EM. Endogenous protein kinase inhibitor gamma terminates immediate-early gene expression induced by cAMP-dependent protein kinase (PKA) signaling: termination depends on PKA inactivation rather than PKA export from the nucleus. J Biol Chem 2004; 280:2700-7. [PMID: 15557275 DOI: 10.1074/jbc.m412558200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of many genes induced by cAMP-dependent protein kinase (PKA) signaling is rapidly terminated. Although many mechanisms contribute to regulation of PKA signaling, members of the endogenous protein kinase inhibitor (PKI) family may be particularly important for terminating nuclear PKA activity and gene expression. Here we used both siRNA and antisense knockdown strategies to examine PKA signaling activated by parathyroid hormone or the beta-adrenergic agonist, isoproterenol. We found that endogenous PKIgamma is required for efficient termination of nuclear PKA activity, transcription factor phosphorylation, and immediate-early genes. Moreover, PKIgamma is required for export of PKA catalytic subunits from the nucleus back to the cytoplasm following activation of PKA signaling because this is also inhibited by PKIgamma knockdown. Leptomycin B blocks PKA nuclear export but has little or no effect on nuclear PKA activity or immediate-early gene expression. Thus, inactivation of PKA activity in the nucleus is sufficient to terminate signaling, and nuclear export is not required. These results were the first in any cell type showing that endogenous levels of PKI regulate PKA signaling.
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Affiliation(s)
- Xin Chen
- Orthopaedics, Pediatrics, Physiology and Biophysics, and Pathology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106-5000, USA
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21
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Sharman G, Ghorbel M, Leroux M, Beaucourt S, Wong LF, Murphy D. Deciphering the mechanisms of homeostatic plasticity in the hypothalamo-neurohypophyseal system—genomic and gene transfer strategies. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 84:151-82. [PMID: 14769434 DOI: 10.1016/j.pbiomolbio.2003.11.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The hypothalamo-neurohypophyseal system (HNS) is the specialised brain neurosecretory apparatus responsible for the production of a peptide hormone, vasopressin, that maintains water balance by promoting water conservation at the level of the kidney. Dehydration evokes a massive increase in the regulated release of hormone from the HNS, and this is accompanied by a plethora of changes in morphology, electrical properties and biosynthetic and secretory activity, all of which are thought to facilitate hormone production and delivery, and hence the survival of the organism. We have adopted a functional genomic strategy to understand the activity dependent plasticity of the HNS in terms of the co-ordinated action of cellular and genetic networks. Firstly, using microarray gene-profiling technologies, we are elucidating which genes are expressed in the HNS, and how the pattern of expression changes following physiological challenge. The next step is to use transgenic rats to probe the functions of these genes in the context of the physiological integrity of the whole organism.
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Affiliation(s)
- Greig Sharman
- Molecular Neuroendocrinology Research Group, The Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK
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22
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Wong LF, Harding T, Uney J, Murphy D. cAMP-dependent protein kinase A mediation of vasopressin gene expression in the hypothalamus of the osmotically challenged rat. Mol Cell Neurosci 2004; 24:82-90. [PMID: 14550770 DOI: 10.1016/s1044-7431(03)00123-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We have tested the hypothesis that 3', 5'-cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) is involved in the regulation of the vasopressin (VP) gene in the magnocellular neurons of the paraventricular nucleus (PVN) of the osmotically challenged rat. An adenoviral vector expressing a potent peptide inhibitor of PKA, Ad.CMV.PKIalpha, was demonstrated to be highly efficient in vitro. Ad.CMV.PKIalpha was then introduced into the PVN of rats bearing a VP reporter transgene (3-VCAT-3) consisting of the VP structural gene containing an epitope reporter in exon III, flanked by 3 kb of upstream and 3 kb of downstream sequence Robust transgene expression is seen in VP neurons of the PVN, and this increases following 72 h of dehydration. Ad.CMV.PKIalpha significantly blunted 3-VCAT-3 expression in the osmotically stimulated PVN. Our evidence suggests that PKA mediates changes in VP gene expression in response to dehydration through sequences contained within the 3-VCAT-3 transgene.
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Affiliation(s)
- Liang-Fong Wong
- The University Research Centre for Neuroendocrinology, University of Bristol, Bristol Royal Infirmary, Marlborough Street, Bristol BS2 8HW, England, UK
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23
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Kopperud R, Krakstad C, Selheim F, Døskeland SO. cAMP effector mechanisms. Novel twists for an 'old' signaling system. FEBS Lett 2003; 546:121-6. [PMID: 12829247 DOI: 10.1016/s0014-5793(03)00563-5] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic AMP (cAMP) has traditionally been thought to act exclusively through cAMP-dependent protein kinase (cAPK, PKA), but a growing number of cAMP effects are not attributable to general activation of cAPK. At present, cAMP is known also to directly regulate ion channels and the ubiquitous Rap guanine exchange factors Epac 1 and 2. Adding to the sophistication of cAMP signaling is the fact that (1) the cAPK holoenzyme is incompletely dissociated even at saturating cAMP, the level of free R subunit of cAPK being able to regulate the maximal activity of cAPK, (2) cAPK activity can be modulated by oxidative glutathionylation, and (3) cAPK is anchored close to relevant substrates, other signaling enzymes, and local compartments of cAMP. Finally, we will demonstrate an example of fine-tuning of cAMP signaling through synergistic induction of neurite extensions by cAPK and Epac.
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Affiliation(s)
- Reidun Kopperud
- Department of Anatomy and Cell Biology, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
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24
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Boer AK, Drayer AL, Vellenga E. Stem cell factor enhances erythropoietin-mediated transactivation of signal transducer and activator of transcription 5 (STAT5) via the PKA/CREB pathway. Exp Hematol 2003; 31:512-20. [PMID: 12829027 DOI: 10.1016/s0301-472x(03)00075-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE To define whether the observed synergistic effects of erythropoietin (EPO) and stem cell factor (SCF) on erythroid cells can, in part, be mediated by the signal transducer and activator of transcription 5 (STAT5). METHODS STAT5 activation was examined in erythroid cell lines by analyzing the effects of EPO and SCF on STAT5 tyrosine phosphorylation, serine phosphorylation, DNA binding, and STAT5-mediated gene transactivation. RESULTS EPO induced a 5.0-fold+/-0.4-fold increase in STAT5 transactivation, which could be further enhanced by SCF. SCF pretreatment followed by EPO stimulation resulted in a 9.0-fold+/-0.9-fold increase in STAT5 transactivation, while SCF alone did not increase STAT5 transactivation. This costimulatory effect of SCF was not mediated by increased STAT5 tyrosine or serine phosphorylation or increased STAT5 DNA binding. In addition, enhanced STAT5 transactivation was independent of the phosphatidyl inositol 3-kinase and MAPK(p42/p44) pathways. Instead, the protein kinase A (PKA) inhibitor protein PKI and the PKA inhibitor H89 prevented the costimulatory SCF effect. Furthermore, the PKA target CREB showed a strongly increased and prolonged serine-133 phosphorylation after costimulation with SCF + EPO. The involvement of CREB in STAT5 transactivation was demonstrated by overexpression of serine-133-mutated CREB, which completely blocked the SCF effect. In addition, the CREB-binding protein CBP/p300 was shown to be essential for EPO- and SCF-mediated STAT5 transactivation. CONCLUSION SCF enhances the EPO-mediated STAT5 transactivation by triggering a PKA/CREB-dependent pathway.
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Affiliation(s)
- Arjen-Kars Boer
- Division of Hematology, Department of Medicine, University Hospital Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
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An extranuclear locus of cAMP-dependent protein kinase action is necessary and sufficient for promotion of spiral ganglion neuronal survival by cAMP. J Neurosci 2003. [PMID: 12574406 DOI: 10.1523/jneurosci.23-03-00777.2003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We showed previously that cAMP is a survival-promoting stimulus for cultured postnatal rat spiral ganglion neurons (SGNs) and that depolarization promotes SGN survival in part via recruitment of cAMP signaling. We here investigate the subcellular locus of cAMP prosurvival signaling. Transfection of GPKI, a green fluorescent protein (GFP)-tagged cAMP-dependent protein kinase (PKA) inhibitor, inhibits the ability of the permeant cAMP analog cpt-cAMP [8-(4-chlorophenylthio)-cAMP] to promote survival, indicating that PKA activity is necessary. Transfection of GFP-tagged PKA (GPKA) is sufficient to promote SGN survival, but restriction of GPKA to the nucleus by addition of a nuclear localization signal (GPKAnls) almost completely abrogates its prosurvival effect. In contrast, GPKA targeted to the extranuclear cytoplasm by addition of a nuclear export signal (GPKAnes) promotes SGN survival as effectively as does GPKA. Moreover, GPKI targeted to the nucleus lacks inhibitory effect on SGN survival attributable to cpt-cAMP or depolarization. These data indicate an extranuclear target of PKA for promotion of neuronal survival. Consistent with this, we find that dominant-inhibitory CREB mutants inhibit the prosurvival effect of depolarization but not that of cpt-cAMP. SGN survival is compromised by overexpression of the proapoptotic regulator Bad, previously shown to be phosphorylated in the cytoplasm by PKA. This Bad-induced apoptosis is prevented by cpt-cAMP or by cotransfection of GPKA or of GPKAnes but not of GPKAnls. Thus, cAMP prevents SGN death through a cytoplasmic as opposed to nuclear action, and inactivation of Bad proapoptotic function is a mechanism by which PKA can prevent neuronal death.
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Baillie GS, Sood A, McPhee I, Gall I, Perry SJ, Lefkowitz RJ, Houslay MD. beta-Arrestin-mediated PDE4 cAMP phosphodiesterase recruitment regulates beta-adrenoceptor switching from Gs to Gi. Proc Natl Acad Sci U S A 2003; 100:940-5. [PMID: 12552097 PMCID: PMC298705 DOI: 10.1073/pnas.262787199] [Citation(s) in RCA: 278] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2002] [Indexed: 01/08/2023] Open
Abstract
Phosphorylation of the beta(2) adrenoreceptor (beta(2)AR) by cAMP-activated protein kinase A (PKA) switches its predominant coupling from stimulatory guanine nucleotide regulatory protein (G(s)) to inhibitory guanine nucleotide regulatory protein (G(i)). beta-Arrestins recruit the cAMP-degrading PDE4 phosphodiesterases to the beta(2)AR, thus controlling PKA activity at the membrane. Here we investigate a role for PDE4 recruitment in regulating G protein switching by the beta(2)AR. In human embryonic kidney 293 cells overexpressing a recombinant beta(2)AR, stimulation with isoprenaline recruits beta-arrestins 1 and 2 as well as both PDE4D3 and PDE4D5 to the receptor and stimulates receptor phosphorylation by PKA. The PKA phosphorylation status of the beta(2)AR is enhanced markedly when cells are treated with the selective PDE4-inhibitor rolipram or when they are transfected with a catalytically inactive PDE4D mutant (PDE4D5-D556A) that competitively inhibits isoprenaline-stimulated recruitment of native PDE4 to the beta(2)AR. Rolipram and PDE4D5-D556A also enhance beta(2)AR-mediated activation of extracellular signal-regulated kinases ERK12. This is consistent with a switch in coupling of the receptor from G(s) to G(i), because the ERK12 activation is sensitive to both inhibitors of PKA (H89) and G(i) (pertussis toxin). In cardiac myocytes, the beta(2)AR also switches from G(s) to G(i) coupling. Treating primary cardiac myocytes with isoprenaline induces recruitment of PDE4D3 and PDE4D5 to membranes and activates ERK12. Rolipram robustly enhances this activation in a manner sensitive to both pertussis toxin and H89. Adenovirus-mediated expression of PDE4D5-D556A also potentiates ERK12 activation. Thus, receptor-stimulated beta-arrestin-mediated recruitment of PDE4 plays a central role in the regulation of G protein switching by the beta(2)AR in a physiological system, the cardiac myocyte.
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Affiliation(s)
- George S Baillie
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute for Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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Chen X, Dai JC, Greenfield EM. Termination of immediate-early gene expression after stimulation by parathyroid hormone or isoproterenol. Am J Physiol Cell Physiol 2002; 283:C1432-40. [PMID: 12372804 DOI: 10.1152/ajpcell.00221.2002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
cAMP/PKA signaling transiently stimulates mRNA expression of immediate-early genes, including IL-6 and c-fos. We confirmed that these mRNAs are transiently stimulated by parathyroid hormone (PTH) in ROS 17/2.8 osteoblastic cells. Consistent with the role for cAMP/PKA signaling in this response, PTH induces transient cAMP elevation, PKA activation, and cAMP-responsive element-binding protein (CREB) phosphorylation. Our goal was to determine whether termination of immediate-early gene expression is due to receptor desensitization or cAMP degradation. The approaches used were 1) inhibition of PTH receptor desensitization with G protein-coupled receptor kinase 2 (GRK2) antisense oligonucleotides or antisense plasmids, 2) sustained activation of adenyl cyclase with forskolin, and 3) inhibition of cAMP degradation with 3-isobutyl-1-methylxanthine. These experiments show that mechanisms downstream of receptor desensitization and cAMP degradation are primarily responsible for termination of PKA activity, CREB phosphorylation, and immediate-early gene expression. Similar conclusions were also obtained in response to PTH in a second osteoblastic cell line (MC3T3-E1) and in response to isoproterenol in NIH3T3 fibroblasts. This conclusion may therefore reflect a general mechanism for termination of immediate-early gene expression after induction by cAMP/PKA.
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Affiliation(s)
- Xin Chen
- Department of Orthopaedics, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106-5000, USA
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28
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Boer AK, Drayer AL, Rui H, Vellenga E. Prostaglandin-E2 enhances EPO-mediated STAT5 transcriptional activity by serine phosphorylation of CREB. Blood 2002; 100:467-73. [PMID: 12091337 DOI: 10.1182/blood.v100.2.467] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythroid colony formation in response to erythropoietin (EPO) stimulation is enhanced by costimulating the cells with prostaglandin-E2 (PGE2). The present study further analyzed the underlying mechanisms and demonstrated that EPO-mediated STAT5 transactivation in the erythroid AS-E2 cell line was enhanced 6-fold by PGE2 (10 microM), without affecting the STAT5 tyrosine phosphorylation or STAT5-DNA binding. Moreover, the PGE2-enhancing effect was independent of STAT5 serine phosphorylation. In AS-E2 cells STAT5 is constitutively phosphorylated on Ser780 (STAT5A) and EPO-dependently phosphorylated on Ser726/731 (STAT5A/STAT5B), but overexpression of STAT5 serine mutants did not affect STAT5 transactivation. In addition, PGE2 did not affect STAT5 serine phosphorylation. Instead, the stimulatory effect of PGE2 on STAT5 signaling could be mimicked by dibutyryl-cyclic adenosine monophosphate (cAMP) and the phosphodiesterase inhibitor IBMX, suggesting that the effect was mediated by cAMP. Activation of the cAMP pathway resulted in cAMP-response element binding protein (CREB) phosphorylation, which was sustained in the presence of EPO plus PGE2 and transient on EPO stimulation alone. The costimulatory effect of PGE2 on EPO-mediated STAT5 transactivation was inhibited by overexpression of serine-dead CREB or protein kinase A (PKA) inhibitor (PKI), in contrast to EPO-mediated transactivation, which was PKA independent. Furthermore, CREB-binding protein (CBP)/p300 was shown to be involved in EPO-mediated STAT5 transactivation, and a CBP mutant with increased affinity for CREB resulted in an additional enhancement of the PGE2 effect. Finally, we demonstrated that the STAT5 target genes Bcl-X, SOCS2, and SOCS3 were up-regulated by costimulation with PGE2. In summary, these studies demonstrate that PGE2 enhancement of EPO-induced STAT5 transactivation is mediated by the cAMP/PKA/CREB pathway.
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Affiliation(s)
- Arjen-Kars Boer
- Division of Hematology, Department of Medicine, University Hospital Groningen, Groningen, The Netherlands
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29
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Constantinescu A, Gordon AS, Diamond I. cAMP-dependent protein kinase types I and II differentially regulate cAMP response element-mediated gene expression: implications for neuronal responses to ethanol. J Biol Chem 2002; 277:18810-6. [PMID: 11886856 DOI: 10.1074/jbc.m112107200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown that ethanol induces translocation of cAMP-dependent protein kinase (PKA) to the nucleus, cAMP response element-binding protein (CREB) phosphorylation, and cAMP response element-mediated gene transcription in NG108-15 cells. However, little is known about which PKA types regulate this process. We show here that under basal conditions NG108-15 cells contain type I PKA (CbetaRIbeta) primarily in cytosol and type II PKA (CalphaRIIbeta) in the particulate and nuclear fractions. Antagonists of both type I and type II PKA inhibit forskolin- and ethanol-induced cAMP response element-mediated gene transcription. However, only the type II PKA antagonist inhibits forskolin-induced Calpha and ethanol-induced Calpha and RIIbeta translocation to the nucleus and CREB phosphorylation; the type I antagonist is without effect. Our data suggest that forskolin- and ethanol-induced CREB phosphorylation and gene activation are differentially mediated by the two types of PKA. We propose that type II PKA is translocated and activated in the nucleus and induces CREB phosphorylation that is necessary but not sufficient for gene transcription. By contrast, type I PKA is activated in the cytoplasm, turning on a downstream pathway that activates other transcription cofactors that interact with phosphorylated CREB to induce gene transcription.
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Affiliation(s)
- Anastasia Constantinescu
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California at San Francisco, Emeryville, California 94608, USA.
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Kopperud R, Christensen AE, Kjarland E, Viste K, Kleivdal H, Døskeland SO. Formation of inactive cAMP-saturated holoenzyme of cAMP-dependent protein kinase under physiological conditions. J Biol Chem 2002; 277:13443-8. [PMID: 11834733 DOI: 10.1074/jbc.m109869200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The complex of the subunits (RIalpha, Calpha) of cAMP-dependent protein kinase I (cA-PKI) was much more stable (K(d) = 0.25 microm) in the presence of excess cAMP than previously thought. The ternary complex of C subunit with cAMP-saturated RIalpha or RIIalpha was devoid of catalytic activity against either peptide or physiological protein substrates. The ternary complex was destabilized by protein kinase substrate. Extrapolation from the in vitro data suggested about one-fourth of the C subunit to be in ternary complex in maximally cAMP-stimulated cells. Cells overexpressing either RIalpha or RIIalpha showed decreased CRE-dependent gene induction in response to maximal cAMP stimulation. This could be explained by enhanced ternary complex formation. Modulation of ternary complex formation by the level of R subunit may represent a novel way of regulating the cAMP kinase activity in maximally cAMP-stimulated cells.
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Affiliation(s)
- Reidun Kopperud
- Department of Anatomy and Cell Biology, University of Bergen, N-5009 Bergen, Norway
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Lum H, Hao Z, Gayle D, Kumar P, Patterson CE, Uhler MD. Vascular endothelial cells express isoforms of protein kinase A inhibitor. Am J Physiol Cell Physiol 2002; 282:C59-66. [PMID: 11742798 DOI: 10.1152/ajpcell.00256.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The expression and function of the endogenous inhibitor of cAMP-dependent protein kinase (PKI) in endothelial cells are unknown. In this study, overexpression of rabbit muscle PKI gene into endothelial cells inhibited the cAMP-mediated increase and exacerbated thrombin-induced decrease in endothelial barrier function. We investigated PKI expression in human pulmonary artery (HPAECs), foreskin microvessel (HMECs), and brain microvessel endothelial cells (HBMECs). RT-PCR using specific primers for human PKI alpha, human PKI gamma, and mouse PKI beta sequences detected PKI alpha and PKI gamma mRNA in all three cell types. Sequencing and BLAST analysis indicated that forward and reverse DNA strands for PKI alpha and PKI gamma were of >96% identity with database sequences. RNase protection assays showed protection of the 542 nucleotides in HBMEC and HPAEC PKI alpha mRNA and 240 nucleotides in HBMEC, HPAEC, and HMEC PKI gamma mRNA. Western blot analysis indicated that PKI gamma protein was detected in all three cell types, whereas PKI alpha was found in HBMECs. In summary, endothelial cells from three different vascular beds express PKI alpha and PKI gamma, which may be physiologically important in endothelial barrier function.
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Affiliation(s)
- Hazel Lum
- Department of Pharmacology, Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612, USA.
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Billiard J, Grewal SS, Lukaesko L, Stork PJ, Rotwein P. Hormonal control of insulin-like growth factor I gene transcription in human osteoblasts: dual actions of cAMP-dependent protein kinase on CCAAT/enhancer-binding protein delta. J Biol Chem 2001; 276:31238-46. [PMID: 11390399 DOI: 10.1074/jbc.m103634200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-like growth factor-I (IGF-I) is essential for somatic growth and promotes bone cell replication and differentiation. IGF-I production by rat osteoblasts is stimulated by activation of cAMP-dependent protein kinase (PKA). In this report, we define two interacting PKA-regulated pathways that control IGF-I gene transcription in cultured human osteoblasts. Stimulation of cAMP led to a 12-fold increase in IGF-I mRNA and enhanced IGF-I promoter activity through a DNA response element termed HS3D and the transcription factor CCAAT/enhancer-binding protein delta (C/EBPdelta). Under basal conditions, C/EBPdelta was found in osteoblast nuclei but was transcriptionally silent. Treatment with the PKA inhibitor H-89 caused redistribution of C/EBPdelta to the cytoplasm. After hormone treatment, the catalytic subunit of PKA accumulated in osteoblast nuclei. Inhibition of active PKA with targeted nuclear expression of PKA inhibitor had no effect on the subcellular location of C/EBPdelta but prevented hormone-induced IGF-I gene activation, while cytoplasmic PKA inhibitor additionally caused the removal of C/EBPdelta from the nucleus. These results show that IGF-I gene expression is controlled in human osteoblasts by two PKA-dependent pathways. Cytoplasmic PKA mediates nuclear localization of C/EBPdelta under basal conditions, and nuclear PKA stimulates its transcriptional activity upon hormone treatment. Both mechanisms are indirect, since PKA failed to phosphorylate human C/EBPdelta in vitro.
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Affiliation(s)
- J Billiard
- Oregon Health Sciences University, Molecular Medicine Division, Department of Medicine, Portland, Oregon 97201-3098, USA
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Sekar N, Veldhuis JD. Concerted transcriptional activation of the low density lipoprotein receptor gene by insulin and luteinizing hormone in cultured porcine granulosa-luteal cells: possible convergence of protein kinase a, phosphatidylinositol 3-kinase, and mitogen-activated protein kinase signaling pathways. Endocrinology 2001; 142:2921-8. [PMID: 11416012 DOI: 10.1210/endo.142.7.8287] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Insulin and insulin-like growth factor I (IGF-I) can amplify gonadotropin-stimulated steroidogenesis by augmenting the expression of key sterol regulatory genes in ovarian cells, viz. low density lipoprotein (LDL) receptor, steroidogenic acute regulatory protein, and P450 cholesterol side-chain cleavage enzyme (CYP11A). The mechanisms underlying the foregoing bihormonal interactions are not known. Accordingly, in relation to the LDL receptor gene, the present study tests the hypothesis that insulin/IGF-I and LH can act via concerted transcriptional control of promoter expression. To this end, we transiently transfected primary monolayer cultures of porcine granulosa-luteal cells with a reporter vector containing the putative 5'-upstream full-length (pLDLR1076/luc) regulatory region (-1076 to +11 bp) of the homologous LDL receptor gene driving firefly luciferase in the presence or absence of insulin (or IGF-I) and/or LH (each 100 ng/ml). Combined exposure to LH and insulin (or IGF-I) stimulated LDL receptor transcriptional activity maximally at 4 h by 8- to 20-fold, as normalized by coexpression of Renilla luciferase. Further analysis of multiple 5'-nested deletional constructs of the LDL receptor gene promoter showed that deletion of -139 bp upstream of the transcriptional start site virtually abolished basal expression and promoter responsiveness to LH and insulin/IGF-I. In contrast, full basal activity and 60-80% of maximal monohormonal and bihormonal drive were retained by the -255 to +11 bp fragment. As LDL receptor gene expression in other tissues is negatively regulated by the abundance of intracellular free cholesterol, we assessed the impact of concomitant pretreatment of granulosa-luteal cells with an exogenous soluble sterol (25-hydroxycholesterol, 1 and 10 microM). Excess sterol markedly (50-70%) attenuated bihormonally and, in lesser measure, LH-stimulated and basal LDL receptor promoter expression, thus affirming a feedback-sensitive sterol-repressive region in this gene. Non-LH receptor-dependent agonists of protein kinase A (PKA), 8-bromo-cAMP (1 mM), and forskolin (10 microM) with or without insulin/IGF-I costimulation likewise augmented LDL receptor promoter expression with similar strong dependency on the -255 to -139 bp 5'-upstream region. To assess more specific PKA-dependent mediation of LH's contribution to combined hormonal drive, the LDL receptor (-1076 to +11 bp) reporter plasmid was cotransfected with a full-sequence rabbit muscle protein kinase inhibitor (PKI) minigene driven constitutively by a Rous sarcoma virus promoter. Expression of the latter PKA antagonist blocked transcriptional stimulation by LH alone as well as that by LH combined with insulin (or IGF-I) by 70-85% without reducing basal transcriptional activity. Transfection of a mutant inactive (Arg to Gly) Rous sarcoma virus/PKI gene confirmed the specificity of the PKI effect. To investigate the convergent role of the insulin/IGF-I effector pathway mediating bihormonal stimulation of LDL receptor promoter expression, transfected granulosa-luteal cells were pretreated for 30 min with two specific inhibitors of phophatidylinositol 3-kinase, wortmannin (100 nM) and LY 294002 (10 microM), or of mitogen-activated protein kinase kinase, PD 98059 (50 microM), U0126 (10 microM), or the latter's inactive derivative, U0124 (10 microM). Both classes of antagonists impeded the ability of insulin or IGF-I to enhance LH-stimulated LDL receptor promoter expression by 60-80%. In conclusion, the present analyses indicate that LH and insulin (or IGF-I) can up-regulate LDL receptor transcriptional activity supraadditively in porcine granulosa-luteal cells 1) via one or more agonistic cis-acting DNA regions located between -255 and -139 bp 5'- upstream of the transcriptional start site, 2) without abrogating sterol-sensitive repressive of this promoter, and 3) by way of intracellular mechanisms that include the PKA, phophatidylinositol 3-kinase, and mitogen-activated protein kinase signaling pathways.
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Affiliation(s)
- N Sekar
- Division of Endocrinology and Metabolism, Department of Internal Medicine, National Institutes of Health Specialized Cooperative Center in Reproductive Research, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA
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Clegg RA, Gardner RA, Sumathipala RN, Lavialle F, Boisgard R, Ollivier-Bousquet M. Targeting of PKA in mammary epithelial cells. Mechanisms and functional consequences. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 480:99-105. [PMID: 10959415 DOI: 10.1007/0-306-46832-8_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Targeting of protein kinases, promoting association with specific partner-molecules and localisation to particular sites within the cell, has come to be recognised as a key mechanism for attributing specificity to these enzymes. In mammary epithelial cells, the repertoire of acute regulatory roles played by cyclic AMP-dependent protein kinase (PKA) differs from that in other lipogenic cell-types. Furthermore, PKA is implicated in the regulation of mammary-specific function, mediating a tonic stimulation of the flux of newly-synthesised casein through its basal secretory pathway. Both these observations imply mammary-specific properties of either PKA targeting systems or of PKA itself. Evidence for the latter is currently lacking. Pulse-chase labelling experiments in the presence and absence of selective effectors of PKA have enabled the site(s) of action of this protein kinase on casein secretion to be localised to the early stages of the secretory pathway. Possible mechanisms are considered for the physical targeting of PKA to the membrane-enclosed components of the secretory pathway and evidence for their occurrence in mammary epithelial cells is presented.
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Affiliation(s)
- R A Clegg
- Hannah Research Institute, Ayr, Scotland, UK
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Iannicola C, Moreno S, Oliverio S, Nardacci R, Ciofi-Luzzatto A, Piacentini M. Early alterations in gene expression and cell morphology in a mouse model of Huntington's disease. J Neurochem 2000; 75:830-9. [PMID: 10899961 DOI: 10.1046/j.1471-4159.2000.0750830.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several mouse models for Huntington's disease (HD) have been produced to date. Based on differences in strain, promoter, construct, and number of glutamines, these models have provided a broad spectrum of neurological symptoms, ranging from simple increases in aggressiveness with no signs of neuropathology, to tremors and seizures in absence of degeneration, to neurological symptoms in the presence of gliosis and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling) positivity, and finally to selective striatal damage associated with electrophysiological and behavioral abnormalities. We decided to analyze the morphology of striatum and hippocampus from a mouse transgenic line obtained by microinjection of exon 1 from the HD gene after introduction of a very high number of CAG repeat units. We found a massive darkening and compacting of striatal and hippocampal neurons in affected mice, associated with a lower degree of more classical apoptotic cell condensation. We then explored whether this morphology could be explained with alterations in gene expression by hybridizing normal and affected total brain RNA to a panel of 588 known mouse cDNAs. We show that some genes are significantly and consistently up-regulated and that others are down-regulated in the affected brains. Here we discuss the possible significance of these alterations in neuronal morphology and gene expression.
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Affiliation(s)
- C Iannicola
- Department of Biology, University of Rome "Tor Vergata" Rome, Italy.
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Orellana SA, Marfella-Scivittaro C. Distinctive cyclic AMP-dependent protein kinase subunit localization is associated with cyst formation and loss of tubulogenic capacity in Madin-Darby canine kidney cell clones. J Biol Chem 2000; 275:21233-40. [PMID: 10767293 DOI: 10.1074/jbc.m001964200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polycystic kidney disease is characterized by abnormal morphological development. Mechanisms that regulate cyst development may involve multiple signaling pathways. Cyst formation by Madin-Darby canine kidney (MDCK) cells in three-dimensional culture is assumed to be cyclic AMP-dependent and due to cyclic AMP-dependent protein kinase (cAPK) activation based on pharmacological responsiveness. To determine if different cyclic AMP (cAMP) pathways are associated with morphological development, the role of cAMP in regulating morphological change was examined in MDCK clones that form tumor-like or tubular structures under basal conditions. Pharmacological cAMP pathway activators induce cyst formation and diminish formation of other structures in three clones, whereas one clone is unaffected. Tyrosine kinase-mediated morphogens have little effect. Although all clones have intact cAMP signaling pathways, each has a unique subcellular distribution of cAPK regulatory subunits. This may reflect distinct mechanisms for cAPK anchoring, allowing cAPK subtype regulation of the unique phenotypic character of each clone through preferential access to substrates. These observations suggest a molecular basis for differential cAMP responsiveness in cells that develop distinct morphological phenotypes. This evidence establishes these MDCK clones as models for understanding the mechanism and functional significance of cAPK subunit localization and may have broader implications for cystogenesis in polycystic kidney disease.
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Affiliation(s)
- S A Orellana
- Department of Pediatrics, Case Western Reserve University School of Medicine, The Rainbow Center for Childhood PKD at Rainbow Babies and Children's Hospital of the University Hospitals of Cleveland, Cleveland, Ohio, USA.
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Gangolli EA, Belyamani M, Muchinsky S, Narula A, Burton KA, McKnight GS, Uhler MD, Idzerda RL. Deficient gene expression in protein kinase inhibitor alpha Null mutant mice. Mol Cell Biol 2000; 20:3442-8. [PMID: 10779334 PMCID: PMC85637 DOI: 10.1128/mcb.20.10.3442-3448.2000] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein kinase inhibitor (PKI) is a potent endogenous inhibitor of the cyclic AMP (cAMP)-dependent protein kinase (PKA). It functions by binding the free catalytic (C) subunit with a high affinity and is also known to export nuclear C subunit to the cytoplasm. The significance of these actions with respect to PKI's physiological role is not well understood. To address this, we have generated by homologous recombination mutant mice that are deficient in PKIalpha, one of the three isoforms of PKI. The mice completely lack PKI activity in skeletal muscle and, surprisingly, show decreased basal and isoproterenol-induced gene expression in muscle. Further examination revealed reduced levels of the phosphorylated (active) form of the transcription factor CREB (cAMP response element binding protein) in the knockouts. This phenomenon stems, at least in part, from lower basal PKA activity levels in the mutants, arising from a compensatory increase in the level of the RIalpha subunit of PKA. The deficit in gene induction, however, is not easily explained by current models of PKI function and suggests that PKI may play an as yet undescribed role in PKA signaling.
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Affiliation(s)
- E A Gangolli
- Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington 98195, USA
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