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Abstract
Cancers undergo sequential changes to proton (H+) concentration and sensing that are consequences of the disease and facilitate its further progression. The impact of protonation state on protein activity can arise from alterations to amino acids or their titration. Indeed, many cancer-initiating mutations influence pH balance, regulation or sensing in a manner that enables growth and invasion outside normal constraints as part of oncogenic transformation. These cancer-supporting effects become more prominent when tumours develop an acidic microenvironment owing to metabolic reprogramming and disordered perfusion. The ensuing intracellular and extracellular pH disturbances affect multiple aspects of tumour biology, ranging from proliferation to immune surveillance, and can even facilitate further mutagenesis. As a selection pressure, extracellular acidosis accelerates disease progression by favouring acid-resistant cancer cells, which are typically associated with aggressive phenotypes. Although acid-base disturbances in tumours often occur alongside hypoxia and lactate accumulation, there is now ample evidence for a distinct role of H+-operated responses in key events underpinning cancer. The breadth of these actions presents therapeutic opportunities to change the trajectory of disease.
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Affiliation(s)
- Pawel Swietach
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
| | - Stine Falsig Pedersen
- Department of Biology, University of Copenhagen, University of Copenhagen, Faculty of Science, København, Denmark.
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2
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Duman JG, Blanco FA, Cronkite CA, Ru Q, Erikson KC, Mulherkar S, Saifullah AB, Firozi K, Tolias KF. Rac-maninoff and Rho-vel: The symphony of Rho-GTPase signaling at excitatory synapses. Small GTPases 2022; 13:14-47. [PMID: 33955328 PMCID: PMC9707551 DOI: 10.1080/21541248.2021.1885264] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 01/15/2023] Open
Abstract
Synaptic connections between neurons are essential for every facet of human cognition and are thus regulated with extreme precision. Rho-family GTPases, molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state, comprise a critical feature of synaptic regulation. Rho-GTPases are exquisitely controlled by an extensive suite of activators (GEFs) and inhibitors (GAPs and GDIs) and interact with many different signalling pathways to fulfill their roles in orchestrating the development, maintenance, and plasticity of excitatory synapses of the central nervous system. Among the mechanisms that control Rho-GTPase activity and signalling are cell surface receptors, GEF/GAP complexes that tightly regulate single Rho-GTPase dynamics, GEF/GAP and GEF/GEF functional complexes that coordinate multiple Rho-family GTPase activities, effector positive feedback loops, and mutual antagonism of opposing Rho-GTPase pathways. These complex regulatory mechanisms are employed by the cells of the nervous system in almost every step of development, and prominently figure into the processes of synaptic plasticity that underlie learning and memory. Finally, misregulation of Rho-GTPases plays critical roles in responses to neuronal injury, such as traumatic brain injury and neuropathic pain, and in neurodevelopmental and neurodegenerative disorders, including intellectual disability, autism spectrum disorder, schizophrenia, and Alzheimer's Disease. Thus, decoding the mechanisms of Rho-GTPase regulation and function at excitatory synapses has great potential for combatting many of the biggest current challenges in mental health.
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Affiliation(s)
- Joseph G. Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Francisco A. Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Christopher A. Cronkite
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Qin Ru
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kelly C. Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Ali Bin Saifullah
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kimberley F. Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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3
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Reverte-Salisa L, Sanyal A, Pfeifer A. Role of cAMP and cGMP Signaling in Brown Fat. Handb Exp Pharmacol 2019; 251:161-182. [PMID: 29633180 DOI: 10.1007/164_2018_117] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cold-induced activation of brown adipose tissue (BAT) is mediated by norepinephrine and adenosine that are released during sympathetic nerve activation. Both signaling molecules induce an increase in intracellular levels of 3',5'-cyclic adenosine monophosphate (cAMP) in murine and human BAT. In brown adipocytes, cAMP plays a central role, because it activates lipolysis, glucose uptake, and thermogenesis. Another well-studied intracellular second messenger is 3',5'-cyclic guanosine monophosphate (cGMP), which closely resembles cAMP. Several studies have shown that intact cGMP signaling is essential for normal adipogenic differentiation and BAT-mediated thermogenesis in mice. This chapter highlights recent observations, demonstrating the physiological significance of cyclic nucleotide signaling in BAT as well as their potential to induce browning of white adipose tissue (WAT) in mice and humans.
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Affiliation(s)
- Laia Reverte-Salisa
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Abhishek Sanyal
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany.
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4
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Zhang Q, Xiao K, Paredes JM, Mamonova T, Sneddon WB, Liu H, Wang D, Li S, McGarvey JC, Uehling D, Al-Awar R, Joseph B, Jean-Alphonse F, Orte A, Friedman PA. Parathyroid hormone initiates dynamic NHERF1 phosphorylation cycling and conformational changes that regulate NPT2A-dependent phosphate transport. J Biol Chem 2019; 294:4546-4571. [PMID: 30696771 PMCID: PMC6433080 DOI: 10.1074/jbc.ra119.007421] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/25/2019] [Indexed: 12/30/2022] Open
Abstract
Na+-H+ exchanger regulatory factor-1 (NHERF1) is a PDZ protein that scaffolds membrane proteins, including sodium-phosphate co-transport protein 2A (NPT2A) at the plasma membrane. NHERF1 is a phosphoprotein with 40 Ser and Thr residues. Here, using tandem MS analysis, we characterized the sites of parathyroid hormone (PTH)-induced NHERF1 phosphorylation and identified 10 high-confidence phosphorylation sites. Ala replacement at Ser46, Ser162, Ser181, Ser269, Ser280, Ser291, Thr293, Ser299, and Ser302 did not affect phosphate uptake, but S290A substitution abolished PTH-dependent phosphate transport. Unexpectedly, Ser290 was rapidly dephosphorylated and rephosphorylated after PTH stimulation, and we found that protein phosphatase 1α (PP1α), which binds NHERF1 through a conserved VxF/W PP1 motif, dephosphorylates Ser290 Mutating 257VPF259 eliminated PP1 binding and blunted dephosphorylation. Tautomycetin blocked PP1 activity and abrogated PTH-sensitive phosphate transport. Using fluorescence lifetime imaging (FLIM), we observed that PTH paradoxically and transiently elevates intracellular phosphate. Added phosphate blocked PP1α-mediated Ser290 dephosphorylation of recombinant NHERF1. Hydrogen-deuterium exchange MS revealed that β-sheets in NHERF1's PDZ2 domain display lower deuterium uptake than those in the structurally similar PDZ1, implying that PDZ1 is more cloistered. Dephosphorylated NHERF1 exhibited faster exchange at C-terminal residues suggesting that NHERF1 dephosphorylation precedes Ser290 rephosphorylation. Our results show that PP1α and NHERF1 form a holoenzyme and that a multiprotein kinase cascade involving G protein-coupled receptor kinase 6A controls the Ser290 phosphorylation status of NHERF1 and regulates PTH-sensitive, NPT2A-mediated phosphate uptake. These findings reveal how reversible phosphorylation modifies protein conformation and function and the biochemical mechanisms underlying PTH control of phosphate transport.
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Affiliation(s)
- Qiangmin Zhang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Kunhong Xiao
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology.,Vascular Medicine Institute, and.,Biomedical Mass Spectrometry Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - José M Paredes
- the Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, 18071-Granada, Spain
| | - Tatyana Mamonova
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - W Bruce Sneddon
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Hongda Liu
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Dawei Wang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Sheng Li
- the Department of Medicine, University of California San Diego, La Jolla, California 92093, and
| | - Jennifer C McGarvey
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - David Uehling
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Rima Al-Awar
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Babu Joseph
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | | | - Angel Orte
- the Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, 18071-Granada, Spain
| | - Peter A Friedman
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, .,Department of Structural Biology
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5
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Mugami S, Dobkin-Bekman M, Rahamim-Ben Navi L, Naor Z. Differential roles of PKC isoforms (PKCs) in GnRH stimulation of MAPK phosphorylation in gonadotrope derived cells. Mol Cell Endocrinol 2018; 463:97-105. [PMID: 28392410 DOI: 10.1016/j.mce.2017.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 12/30/2022]
Abstract
The role of protein kinase C (PKC) isoforms (PKCs) in GnRH-stimulated MAPK [ERK1/2, JNK1/2 and p38) phosphorylation was examined in gonadotrope derived cells. GnRH induced a protracted activation of ERK1/2 and a slower and more transient activation of JNK1/2 and p38MAPK. Gonadotropes express conventional PKCα and PKCβII, novel PKCδ, PKCε and PKCθ, and atypical PKC-ι/λ. The use of green fluorescent protein (GFP)-PKCs constructs revealed that GnRH induced rapid translocation of PKCα and PKCβII to the plasma membrane, followed by their redistribution to the cytosol. PKCδ and PKCε localized to the cytoplasm and Golgi, followed by the rapid redistribution by GnRH of PKCδ to the perinuclear zone and of PKCε to the plasma membrane. The use of dominant negatives for PKCs and peptide inhibitors for the receptors for activated C kinase (RACKs) has revealed differential role for PKCα, PKCβII, PKCδ and PKCε in ERK1/2, JNK1/2 and p38MAPK phosphorylation in a ligand-and cell context-dependent manner. The paradoxical findings that PKCs activated by GnRH and PMA play a differential role in MAPKs phosphorylation may be explained by persistent vs. transient redistribution of selected PKCs or redistribution of a given PKC to the perinuclear zone vs. the plasma membrane. Thus, we have identified the PKCs involved in GnRH stimulated MAPKs phosphorylation in gonadotrope derived cells. Once activated, the MAPKs will mediate the transcription of the gonadotropin subunits and GnRH receptor genes.
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Affiliation(s)
- Shany Mugami
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Masha Dobkin-Bekman
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Liat Rahamim-Ben Navi
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Zvi Naor
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel.
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6
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Gelens L, Qian J, Bollen M, Saurin AT. The Importance of Kinase-Phosphatase Integration: Lessons from Mitosis. Trends Cell Biol 2018; 28:6-21. [PMID: 29089159 DOI: 10.1016/j.tcb.2017.09.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 12/20/2022]
Abstract
Kinases and phosphatases work antagonistically to control the behaviour of individual substrate molecules. This can be incorrectly extrapolated to imply that they also work antagonistically on the signals or processes that these molecules control. In fact, in many situations kinases and phosphatases work together to positively drive signal responses. We explain how this 'cooperativity' is critical for setting the amplitude, localisation, timing, and shape of phosphorylation signals. We use mitosis to illustrate why these properties are important for controlling mitotic entry, sister chromatid cohesion, kinetochore-microtubule attachments, the spindle assembly checkpoint, mitotic spindle elongation, and mitotic exit. These examples provide a rationale to explain how complex signalling behaviour could rely on similar types of integration within many other biological processes.
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Affiliation(s)
- Lendert Gelens
- Laboratory of Dynamics in Biological Systems, Department of Cellular and Molecular Medicine, University of Leuven, 3000 Leuven, Belgium.
| | - Junbin Qian
- Laboratory of Biosignaling and Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling and Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Adrian T Saurin
- Division of Cancer Research, School of Medicine, Jacqui Wood Cancer Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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7
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Sinniah A, Yazid S, Flower RJ. The Anti-allergic Cromones: Past, Present, and Future. Front Pharmacol 2017; 8:827. [PMID: 29184504 PMCID: PMC5694476 DOI: 10.3389/fphar.2017.00827] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 10/31/2017] [Indexed: 01/10/2023] Open
Abstract
The anti-allergic cromones were originally synthesized in the 1960s by Fisons Plc, and the first drug to emerge from this program, disodium cromoglycate was subsequently marketed for the treatment of asthma and other allergic conditions. Whilst early studies demonstrated that the ability of the cromones to prevent allergic reactions was due to their 'mast cell stabilizing' properties, the exact pharmacological mechanism by which this occurred, remained a mystery. Here, we briefly review the history of these drugs, recount some aspects of their pharmacology, and discuss two new explanations for their unique actions. We further suggest how these findings could be used to predict further uses for the cromones.
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Affiliation(s)
- Ajantha Sinniah
- Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Samia Yazid
- Trio Medicines Ltd., Hammersmith Medicines Research, London, United Kingdom
| | - Roderick J Flower
- Centre for Biochemical Pharmacology, William Harvey Research Institute, St Barts and the Royal London School of Medicine, Queen Mary University of London, London, United Kingdom
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8
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Baucum AJ. Proteomic Analysis of Postsynaptic Protein Complexes Underlying Neuronal Plasticity. ACS Chem Neurosci 2017; 8:689-701. [PMID: 28211672 DOI: 10.1021/acschemneuro.7b00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Normal neuronal communication and synaptic plasticity at glutamatergic synapses requires dynamic regulation of postsynaptic molecules. Protein expression and protein post-translational modifications regulate protein interactions that underlie this organization. In this Review, we highlight data obtained over the last 20 years that have used qualitative and quantitative proteomics-based approaches to identify postsynaptic protein complexes. Herein, we describe how these proteomics studies have helped lay the foundation for understanding synaptic physiology and perturbations in synaptic signaling observed in different pathologies. We also describe emerging technologies that can be useful in these analyses. We focus on protein complexes associated with the highly abundant and functionally critical proteins: calcium/calmodulin-dependent protein kinase II, the N-methyl-d-aspartate, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors, and postsynaptic density protein of 95 kDa.
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Affiliation(s)
- Anthony J. Baucum
- Department of Biology, Stark Neurosciences
Research Institute, Indiana University-Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, Indiana 46202, United States
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9
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Zhang F, Zhang L, Qi Y, Xu H. Mitochondrial cAMP signaling. Cell Mol Life Sci 2016; 73:4577-4590. [PMID: 27233501 PMCID: PMC5097110 DOI: 10.1007/s00018-016-2282-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/25/2016] [Accepted: 05/20/2016] [Indexed: 12/19/2022]
Abstract
Cyclic adenosine 3, 5'-monophosphate (cAMP) is a ubiquitous second messenger regulating many biological processes, such as cell migration, differentiation, proliferation and apoptosis. cAMP signaling functions not only on the plasma membrane, but also in the nucleus and in organelles such as mitochondria. Mitochondrial cAMP signaling is an indispensable part of the cytoplasm-mitochondrion crosstalk that maintains mitochondrial homeostasis, regulates mitochondrial dynamics, and modulates cellular stress responses and other signaling pathways. Recently, the compartmentalization of mitochondrial cAMP signaling has attracted great attentions. This new input should be carefully taken into account when we interpret the findings of mitochondrial cAMP signaling. In this review, we summarize previous and recent progress in our understanding of mitochondrial cAMP signaling, including the components of the signaling cascade, and the function and regulation of this signaling pathway in different mitochondrial compartments.
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Affiliation(s)
- Fan Zhang
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Liping Zhang
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yun Qi
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hong Xu
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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10
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Ayres AW, Carr DW, McConnell DS, Lieberman RW, Smith GD. Expression and Intracellular Localization of Protein Phosphatases 2A and 2B, Protein Kinase A, A-Kinase Anchoring Protein (AKAP79), and Binding of the Regulatory (RII) Subunit of Protein Kinase A to AKAP79 in Human Myometrium. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/s1071-55760300136-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
| | | | | | - Richard W. Lieberman
- Oregon Health & Sciences University, Veterans Affairs Medical Center, Portland, Oregon; Reproductive Science Program; Departments of Obstetrics and Gynecology, Pathology, and Physiology and Urology, University of Michigan, Ann Arbor, Michigan
| | - Gary D. Smith
- Oregon Health & Sciences University, Veterans Affairs Medical Center, Portland, Oregon; Reproductive Science Program; Departments of Obstetrics and Gynecology, Pathology, and Physiology and Urology, University of Michigan, Ann Arbor, Michigan; University of Michigan, 6428 Med Sci 1, 1301 E. Catherine Street, Ann Arbor, MI 48109-0617
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11
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Sommese RF, Sivaramakrishnan S. Substrate Affinity Differentially Influences Protein Kinase C Regulation and Inhibitor Potency. J Biol Chem 2016; 291:21963-21970. [PMID: 27555323 DOI: 10.1074/jbc.m116.737601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 02/05/2023] Open
Abstract
The overlapping network of kinase-substrate interactions provides exquisite specificity in cell signaling pathways, but also presents challenges to our ability to understand the mechanistic basis of biological processes. Efforts to dissect kinase-substrate interactions have been particularly limited by their inherently transient nature. Here, we use a library of FRET sensors to monitor these transient complexes, specifically examining weak interactions between the catalytic domain of protein kinase Cα and 14 substrate peptides. Combining results from this assay platform with those from standard kinase activity assays yields four novel insights into the kinase-substrate interaction. First, preferential binding of non-phosphorylated versus phosphorylated substrates leads to enhanced kinase-specific activity. Second, kinase-specific activity is inversely correlated with substrate binding affinity. Third, high affinity substrates can suppress phosphorylation of their low affinity counterparts. Finally, the substrate-competitive inhibitor bisindolylmaleimide I displaces low affinity substrates more potently leading to substrate selective inhibition of kinase activity. Overall, our approach complements existing structural and biophysical approaches to provide generalizable insights into the regulation of kinase activity.
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Affiliation(s)
- Ruth F Sommese
- From the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Sivaraj Sivaramakrishnan
- From the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
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12
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Wu J, Wang J, Zeng X, Chen Y, Xia J, Wang S, Huang Z, Chen W, Shen Z. Protein phosphatase 2A regulatory subunit B56β modulates erythroid differentiation. Biochem Biophys Res Commun 2016; 478:1179-84. [PMID: 27544028 DOI: 10.1016/j.bbrc.2016.08.090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 08/16/2016] [Indexed: 11/29/2022]
Abstract
Anemia due to attenuated erythroid terminal differentiation is one of the most common hematological disorders occurring at all stages of life. We previously demonstrated that catalytic subunit α of protein phosphatase 2A (PP2Acα) modulates fetal liver erythropoiesis. However the corresponding PP2A regulatory subunit in this process remains unknown. In this study, we report that chemical inhibition of PP2A activity with okadaic acid impairs hemin-induced erythroid differentiation. Interestingly, B56 family member B56β is the only regulatory subunit whose expression is induced by both erythropoietin in fetal liver cells and hemin in erythroleukemia K562 cells. Finally, knockdown of B56β attenuates hemin-induced K562 erythroid differentiation. Collectively, our data identify B56β as the potential functional regulatory subunit of PP2A in erythroid differentiation, shedding light on new target for precise modulation of PP2A activity for treatment of anemia and related diseases.
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Affiliation(s)
- Jianping Wu
- Orthopedic Department of the Second Affiliated Hospital of Soochow University, Suzhou 215000, China
| | - Jun Wang
- Emergency Department of the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Xiansheng Zeng
- Department of Cardiology of the First Affiliated Hospital, Soochow University, Suzhou 215006, China
| | - Yueqiu Chen
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou 215006, China
| | - Jun Xia
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou 215006, China
| | - Shizhen Wang
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou 215006, China
| | - Zan Huang
- Jiangsu Province Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agriculture University, Nanjing 210000, China.
| | - Weiqian Chen
- Institute for Cardiovascular Science & Department of Cardiovascular Surgery of the First Affiliated Hospital, Soochow University, Suzhou 215006, China.
| | - Zhenya Shen
- Department of Cardiovascular Surgery of the First Affiliated Hospital & Institute for Cardiovascular Science, Soochow University, Suzhou 215006, China.
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13
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AKAP220 manages apical actin networks that coordinate aquaporin-2 location and renal water reabsorption. Proc Natl Acad Sci U S A 2016; 113:E4328-37. [PMID: 27402760 DOI: 10.1073/pnas.1607745113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Filtration through the kidney eliminates toxins, manages electrolyte balance, and controls water homeostasis. Reabsorption of water from the luminal fluid of the nephron occurs through aquaporin-2 (AQP2) water pores in principal cells that line the kidney-collecting duct. This vital process is impeded by formation of an "actin barrier" that obstructs the passive transit of AQP2 to the plasma membrane. Bidirectional control of AQP2 trafficking is managed by hormones and signaling enzymes. We have discovered that vasopressin-independent facets of this homeostatic mechanism are under the control of A-Kinase Anchoring Protein 220 (AKAP220; product of the Akap11 gene). CRISPR/Cas9 gene editing and imaging approaches show that loss of AKAP220 disrupts apical actin networks in organoid cultures. Similar defects are evident in tissue sections from AKAP220-KO mice. Biochemical analysis of AKAP220-null kidney extracts detected reduced levels of active RhoA GTPase, a well-known modulator of the actin cytoskeleton. Fluorescent imaging of kidney sections from these genetically modified mice revealed that RhoA and AQP2 accumulate at the apical surface of the collecting duct. Consequently, these animals are unable to appropriately dilute urine in response to overhydration. We propose that membrane-proximal signaling complexes constrained by AKAP220 impact the actin barrier dynamics and AQP2 trafficking to ensure water homeostasis.
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14
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Biwer LA, Taddeo EP, Kenwood BM, Hoehn KL, Straub AC, Isakson BE. Two functionally distinct pools of eNOS in endothelium are facilitated by myoendothelial junction lipid composition. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1861:671-9. [PMID: 27106139 PMCID: PMC4869716 DOI: 10.1016/j.bbalip.2016.04.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 03/10/2016] [Accepted: 04/16/2016] [Indexed: 12/21/2022]
Abstract
In resistance arteries, endothelial cells (EC) make contact with smooth muscle cells (SMC), forming myoendothelial junctions (MEJ). Endothelial nitric oxide synthase (eNOS) is present in the luminal side of the EC (apical EC) and the basal side of the EC (MEJ). To test if these eNOS pools acted in sync or separately, we co-cultured ECs and SMCs, then stimulated SMCs with phenylephrine (PE). Adrenergic activation causes inositol [1,4,5] triphosphate (IP3) to move from SMC to EC through gap junctions at the MEJ. PE increases MEJ eNOS phosphorylation (eNOS-P) at S1177, but not in EC. Conversely, we used bradykinin (BK) to increase EC calcium; this increased EC eNOS-P but did not affect MEJ eNOS-P. Inhibiting gap junctions abrogated the MEJ eNOS-P after PE, but had no effect on BK eNOS-P. Differential lipid composition between apical EC and MEJ may account for the compartmentalized eNOS-P response. Indeed, DAG and phosphatidylserine are both enriched in MEJ. These lipids are cofactors for PKC activity, which was significantly increased at the MEJ after PE. Because PKC activity also relies on endoplasmic reticulum (ER) calcium release, we used thapsigargin and xestospongin C, BAPTA, and PKC inhibitors, which caused significant decreases in MEJ eNOS-P after PE. Functionally, BK inhibited leukocyte adhesion and PE caused an increase in SMC cGMP. We hypothesize that local lipid composition of the MEJ primes PKC and eNOS-P for stimulation by PE, allowing for compartmentalized function of eNOS in the blood vessel wall.
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Affiliation(s)
- Lauren A Biwer
- Department of Molecular Physiology and Biophysics, University of Virginia, USA; Robert M. Berne Cardiovascular Research Center, University of Virginia, USA
| | - Evan P Taddeo
- Department of Pharmacology, University of Virginia, USA
| | | | - Kyle L Hoehn
- Department of Pharmacology, University of Virginia, USA; School of Biotechnology and Biomolecular Sciences, University of New South Wales, Australia
| | - Adam C Straub
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, USA; Heart, Lung, Blood and Vascular Medicine Institute; University of Pittsburgh, USA
| | - Brant E Isakson
- Department of Molecular Physiology and Biophysics, University of Virginia, USA; Robert M. Berne Cardiovascular Research Center, University of Virginia, USA.
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15
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AKAP150 participates in calcineurin/NFAT activation during the down-regulation of voltage-gated K(+) currents in ventricular myocytes following myocardial infarction. Cell Signal 2015; 28:733-40. [PMID: 26724383 DOI: 10.1016/j.cellsig.2015.12.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 12/22/2015] [Indexed: 12/19/2022]
Abstract
The Ca(2+)-responsive phosphatase calcineurin/protein phosphatase 2B dephosphorylates the transcription factor NFATc3. In the myocardium activation of NFATc3 down-regulates the expression of voltage-gated K(+) (Kv) channels after myocardial infarction (MI). This prolongs action potential duration and increases the probability of arrhythmias. Although recent studies infer that calcineurin is activated by local and transient Ca(2+) signals the molecular mechanism that underlies the process is unclear in ventricular myocytes. Here we test the hypothesis that sequestering of calcineurin to the sarcolemma of ventricular myocytes by the anchoring protein AKAP150 is required for acute activation of NFATc3 and the concomitant down-regulation of Kv channels following MI. Biochemical and cell based measurements resolve that approximately 0.2% of the total calcineurin activity in cardiomyocytes is associated with AKAP150. Electrophysiological analyses establish that formation of this AKAP150-calcineurin signaling dyad is essential for the activation of the phosphatase and the subsequent down-regulation of Kv channel currents following MI. Thus AKAP150-mediated targeting of calcineurin to sarcolemmal micro-domains in ventricular myocytes contributes to the local and acute gene remodeling events that lead to the down-regulation of Kv currents.
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16
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Turnham RE, Scott JD. Protein kinase A catalytic subunit isoform PRKACA; History, function and physiology. Gene 2015; 577:101-8. [PMID: 26687711 DOI: 10.1016/j.gene.2015.11.052] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/17/2015] [Accepted: 11/23/2015] [Indexed: 01/01/2023]
Abstract
Our appreciation of the scope and influence of second messenger signaling has its origins in pioneering work on the cAMP-dependent protein kinase. Also called protein kinase A (PKA), this holoenzyme exists as a tetramer comprised of a regulatory (R) subunit dimer and two catalytic (C) subunits. Upon binding of two molecules of the second messenger cAMP to each R subunit, a conformational change in the PKA holoenzyme occurs to release the C subunits. These active kinases phosphorylate downstream targets to propagate cAMP responsive cell signaling events. This article focuses on the discovery, structure, cellular location and physiological effects of the catalytic subunit alpha of protein kinase A (encoded by the gene PRKACA). We also explore the potential role of this essential gene as a molecular mediator of certain disease states.
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Affiliation(s)
- Rigney E Turnham
- Howard Hughes Medical Institute, Department of Pharmacology, Box 357750, University of Washington School of Medicine, 1959 Pacific St. NE, Seattle, WA 98195, United States
| | - John D Scott
- Howard Hughes Medical Institute, Department of Pharmacology, Box 357750, University of Washington School of Medicine, 1959 Pacific St. NE, Seattle, WA 98195, United States.
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17
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Lefkimmiatis K, Zaccolo M. cAMP signaling in subcellular compartments. Pharmacol Ther 2014; 143:295-304. [PMID: 24704321 PMCID: PMC4117810 DOI: 10.1016/j.pharmthera.2014.03.008] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 01/11/2023]
Abstract
In the complex microcosm of a cell, information security and its faithful transmission are critical for maintaining internal stability. To achieve a coordinated response of all its parts to any stimulus the cell must protect the information received from potentially confounding signals. Physical segregation of the information transmission chain ensures that only the entities able to perform the encoded task have access to the relevant information. The cAMP intracellular signaling pathway is an important system for signal transmission responsible for the ancestral 'flight or fight' response and involved in the control of critical functions including frequency and strength of heart contraction, energy metabolism and gene transcription. It is becoming increasingly apparent that the cAMP signaling pathway uses compartmentalization as a strategy for coordinating the large number of key cellular functions under its control. Spatial confinement allows the formation of cAMP signaling "hot spots" at discrete subcellular domains in response to specific stimuli, bringing the information in proximity to the relevant effectors and their recipients, thus achieving specificity of action. In this report we discuss how the different constituents of the cAMP pathway are targeted and participate in the formation of cAMP compartmentalized signaling events. We illustrate a few examples of localized cAMP signaling, with a particular focus on the nucleus, the sarcoplasmic reticulum and the mitochondria. Finally, we discuss the therapeutic potential of interventions designed to perturb specific cAMP cascades locally.
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Affiliation(s)
| | - Manuela Zaccolo
- Department Of Physiology, Anatomy & Genetics, University of Oxford, UK.
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18
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Dagda RK, Pien I, Wang R, Zhu J, Wang KZQ, Callio J, Banerjee TD, Dagda RY, Chu CT. Beyond the mitochondrion: cytosolic PINK1 remodels dendrites through protein kinase A. J Neurochem 2013; 128:864-77. [PMID: 24151868 DOI: 10.1111/jnc.12494] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 11/27/2022]
Abstract
The subcellular compartmentalization of kinase activity allows for regulation of distinct cellular processes involved in cell differentiation or survival. The PTEN-induced kinase 1 (PINK1), which is linked to Parkinson's disease, is a neuroprotective kinase localized to cytosolic and mitochondrial compartments. While mitochondrial targeting of PINK1 is important for its activities regulating mitochondrial homeostasis, the physiological role of the cytosolic pool of PINK1 remains unknown. Here, we demonstrate a novel role for cytosolic PINK1 in neuronal differentiation/neurite maintenance. Over-expression of wild-type PINK1, but not a catalytically inactive form of PINK1(K219M), promoted neurite outgrowth in SH-SY5Y cells and increased dendritic lengths in primary cortical and midbrain dopaminergic neurons. To identify the subcellular pools of PINK1 involved in promoting neurite outgrowth, we transiently transfected cells with PINK1 constructs designed to target PINK1 to the outer mitochondrial membrane (OMM-PINK1) or restrict PINK1 to the cytosol (ΔN111-PINK1). Both constructs blocked cell death associated with loss of endogenous PINK1. However, transient expression of ΔN111-PINK1, but not of OMM-PINK1 or ΔN111-PINK1(K219M), promoted dendrite outgrowth in primary neurons, and rescued the decreased dendritic arborization of PINK1-deficient neurons. Mechanistically, the cytosolic pool of PINK1 regulated neurite morphology through enhanced anterograde transport of dendritic mitochondria and amplification of protein kinase A-related signaling pathways. Our data support a novel role for PINK1 in regulating dendritic morphogenesis.
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Affiliation(s)
- Ruben K Dagda
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
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19
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McCole DF. Phosphatase regulation of intercellular junctions. Tissue Barriers 2013; 1:e26713. [PMID: 24868494 DOI: 10.4161/tisb.26713] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 10/03/2013] [Accepted: 10/04/2013] [Indexed: 02/06/2023] Open
Abstract
Intercellular junctions represent the key contact points and sites of communication between neighboring cells. Assembly of these junctions is absolutely essential for the structural integrity of cell monolayers, tissues and organs. Disruption of junctions can have severe consequences such as diarrhea, edema and sepsis, and contribute to the development of chronic inflammatory diseases. Cell junctions are not static structures, but rather they represent highly dynamic micro-domains that respond to signals from the intracellular and extracellular environments to modify their composition and function. This review article will focus on the regulation of tight junctions and adherens junctions by phosphatase enzymes that play an essential role in preserving and modulating the properties of intercellular junction proteins.
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Affiliation(s)
- Declan F McCole
- Division of Biomedical Sciences; University of California, Riverside; Riverside, CA USA
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20
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Schmitz-Peiffer C. The tail wagging the dog--regulation of lipid metabolism by protein kinase C. FEBS J 2013; 280:5371-83. [PMID: 23587021 DOI: 10.1111/febs.12285] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 03/19/2013] [Accepted: 04/11/2013] [Indexed: 12/12/2022]
Abstract
Upon their discovery almost 40 years ago, isoforms of the lipid-activated protein kinase C (PKC) family were initially regarded only as downstream effectors of the second messengers calcium and diacylglycerol, undergoing activation upon phospholipid hydrolysis in response to acute stimuli. Subsequently, several isoforms were found to be associated with the inhibitory effects of lipid over-supply on glucose homeostasis, especially the negative cross-talk with insulin signal transduction, observed upon accumulation of diacylglycerol in insulin target tissues. The PKC family has therefore attracted much attention in diabetes and obesity research, because intracellular lipid accumulation is strongly correlated with defective insulin action and the development of type 2 diabetes. Causal roles for various isoforms in the generation of insulin resistance have more recently been confirmed using PKC-deficient mice. However, during characterization of these animals, it became increasingly evident that the enzymes play key roles in the modulation of lipid metabolism itself, and may control the supply of lipids between tissues such as adipose and liver. Molecular studies have also demonstrated roles for PKC isoforms in several aspects of lipid metabolism, such as adipocyte differentiation and hepatic lipogenesis. While the precise mechanisms involved, especially the identities of protein substrates, are still unclear, the emerging picture suggests that the currently held view of the contribution of PKC isoforms to metabolism is an over-simplification. Although PKCs may inhibit insulin signal transduction, these enzymes are not merely downstream effectors of lipid accumulation, but in fact control the fate of fatty acids, thus the tail wags the dog.
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Affiliation(s)
- Carsten Schmitz-Peiffer
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW, Australia; St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
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21
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Vivo M, Ranieri M, Sansone F, Santoriello C, Calogero RA, Calabrò V, Pollice A, La Mantia G. Mimicking p14ARF phosphorylation influences its ability to restrain cell proliferation. PLoS One 2013; 8:e53631. [PMID: 23308265 PMCID: PMC3538741 DOI: 10.1371/journal.pone.0053631] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 12/03/2012] [Indexed: 11/29/2022] Open
Abstract
The INK4a/ARF locus on the short arm of chromosome 9 is one of the most frequently altered loci in human cancer. It is generally accepted that ARF is involved in oncogenic checkpoint pathways by sensitizing incipient cancer cells to undergo growth arrest or apoptosis through both p53-dependent and independent pathways. While intensive studies have been focused on ARF activation at the transcriptional level, only recently mechanisms governing ARF turnover have been identified. Here, we show for the first time that p14ARF is a PKC target. Prediction analysis showed many potential phosphorylation sites in PKC consensus sequences within ARF protein, and, among them, the threonine at position 8 was the most conserved. Substitution of this threonine influences both ARF stability and localization. Furthermore, a phosphomimetic ARF mutation reduces the ability to arrest cell growth although the ability to bind MDM2 and stabilize p53 result unaffected. Thus we propose that phosphorylation of ARF in both immortalized and tumor cell lines could be a mechanism to escape ARF surveillance following proliferative and oncogenic stress.
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Affiliation(s)
- Maria Vivo
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
- * E-mail: (MV); (GLM)
| | - Michela Ranieri
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
| | - Federica Sansone
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
| | - Cristina Santoriello
- Harvard Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | | | - Viola Calabrò
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
| | - Alessandra Pollice
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
| | - Girolama La Mantia
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
- * E-mail: (MV); (GLM)
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22
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O'Brien WT, Huang J, Buccafusca R, Garskof J, Valvezan AJ, Berry GT, Klein PS. Glycogen synthase kinase-3 is essential for β-arrestin-2 complex formation and lithium-sensitive behaviors in mice. J Clin Invest 2011; 121:3756-62. [PMID: 21821916 DOI: 10.1172/jci45194] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 06/15/2011] [Indexed: 12/21/2022] Open
Abstract
Lithium is the first-line therapy for bipolar disorder. However, its therapeutic target remains controversial. Candidates include inositol monophosphatases, glycogen synthase kinase-3 (GSK-3), and a β-arrestin-2/AKT/protein phosphatase 2A (β-arrestin-2/AKT/PP2A) complex that is known to be required for lithium-sensitive behaviors. Defining the direct target(s) is critical for the development of new therapies and for elucidating the molecular pathogenesis of this major psychiatric disorder. Here, we show what we believe to be a new link between GSK-3 and the β-arrestin-2 complex in mice and propose an integrated mechanism that accounts for the effects of lithium on multiple behaviors. GSK-3β (Gsk3b) overexpression reversed behavioral defects observed in lithium-treated mice and similar behaviors observed in Gsk3b+/- mice. Furthermore, immunoprecipitation of striatial tissue from WT mice revealed that lithium disrupted the β-arrestin-2/Akt/PP2A complex by directly inhibiting GSK-3. GSK-3 inhibitors or loss of one copy of the Gsk3b gene reduced β-arrestin-2/Akt/PP2A complex formation in mice, while overexpression of Gsk3b restored complex formation in lithium-treated mice. Thus, GSK-3 regulates the stability of the β-arrestin-2/Akt/PP2A complex, and lithium disrupts the complex through direct inhibition of GSK-3. We believe these findings reveal a new role for GSK-3 within the β-arrestin complex and demonstrate that GSK-3 is a critical target of lithium in mammalian behaviors.
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Affiliation(s)
- W Timothy O'Brien
- Department of Medicine, Hematology-Oncology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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23
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Yu P, Han W, Villar VAM, Li H, Arnaldo FB, Concepcion GP, Felder RA, Quinn MT, Jose PA. Dopamine D1 receptor-mediated inhibition of NADPH oxidase activity in human kidney cells occurs via protein kinase A-protein kinase C cross talk. Free Radic Biol Med 2011; 50:832-40. [PMID: 21193028 PMCID: PMC3066436 DOI: 10.1016/j.freeradbiomed.2010.12.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 12/10/2010] [Accepted: 12/17/2010] [Indexed: 12/15/2022]
Abstract
Dopamine cellular signaling via the D(1) receptor (D(1)R) involves both protein kinase A (PKA) and protein kinase C (PKC), but the PKC isoform involved has not been determined. Therefore, we tested the hypothesis that the D(1)R-mediated inhibition of NADPH oxidase activity involves cross talk between PKA and a specific PKC isoform(s). In HEK-293 cells heterologously expressing human D(1)R (HEK-hD(1)), fenoldopam, a D(1)R agonist, and phorbol 12-myristate 13-acetate (PMA), a PKC activator, inhibited oxidase activity in a time- and concentration-dependent manner. The D(1)R-mediated inhibition of oxidase activity (68.1±3.6%) was attenuated by two PKA inhibitors, H89 (10μmol/L; 88±8.1%) and Rp-cAMP (10μmol/L; 97.7±6.7%), and two PKC inhibitors, bisindolylmaleimide I (1μmol/L; 94±6%) and staurosporine (10nmol/L; 93±8%), which by themselves had no effect (n=4-8/group). The inhibitory effect of PMA (1μmol/L) on oxidase activity (73±3.2%) was blocked by H89 (100±7.8%; n=5 or 6/group). The PMA-mediated inhibition of NADPH oxidase activity was accompanied by an increase in PKCθ(S676), an effect that was also blocked by H89. Fenoldopam (1μmol/L) also increased PKCθ(S676) in HEK-hD(1) and human renal proximal tubule (RPT) cells. Knockdown of PKCθ with siRNA in RPT cells prevented the inhibitory effect of fenoldopam on NADPH oxidase activity. Our studies demonstrate for the first time that cross talk between PKA and PKCθ plays an important role in the D(1)R-mediated negative regulation of NADPH oxidase activity in human kidney cells.
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Affiliation(s)
- Peiying Yu
- Center for Molecular Physiology Research, Children's National Medical Center, Department of Pediatrics, George Washington University School of Medicine, Washington, DC 20010, USA.
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24
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Fernández-Medarde A, Santos E. The RasGrf family of mammalian guanine nucleotide exchange factors. Biochim Biophys Acta Rev Cancer 2010; 1815:170-88. [PMID: 21111786 DOI: 10.1016/j.bbcan.2010.11.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 11/14/2010] [Indexed: 12/31/2022]
Abstract
RasGrf1 and RasGrf2 are highly homologous mammalian guanine nucleotide exchange factors which are able to activate specific Ras or Rho GTPases. The RasGrf genes are preferentially expressed in the central nervous system, although specific expression of either locus may also occur elsewhere. RasGrf1 is a paternally-expressed, imprinted gene that is expressed only after birth. In contrast, RasGrf2 is not imprinted and shows a wider expression pattern. A variety of isoforms for both genes are also detectable in different cellular contexts. The RasGrf proteins exhibit modular structures composed by multiple domains including CDC25H and DHPH motifs responsible for promoting GDP/GTP exchange, respectively, on Ras or Rho GTPase targets. The various domains are essential to define their intrinsic exchanger activity and to modulate the specificity of their functional activity so as to connect different upstream signals to various downstream targets and cellular responses. Despite their homology, RasGrf1 and RasGrf2 display differing target specificities and non overlapping functional roles in a variety of signaling contexts related to cell growth and differentiation as well as neuronal excitability and response or synaptic plasticity. Whereas both RasGrfs are activatable by glutamate receptors, G-protein-coupled receptors or changes in intracellular calcium concentration, only RasGrf1 is reported to be activated by LPA, cAMP, or agonist-activated Trk and cannabinoid receptors. Analysis of various knockout mice strains has uncovered a specific functional contribution of RasGrf1 in processes of memory and learning, photoreception, control of post-natal growth and body size and pancreatic β-cell function and glucose homeostasis. For RasGrf2, specific roles in lymphocyte proliferation, T-cell signaling responses and lymphomagenesis have been described.
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25
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Dobkin-Bekman M, Rahamin-Ben Navi L, Shterntal B, Sviridonov L, Przedecki F, Naidich-Exler M, Brodie C, Seger R, Naor Z. Differential role of PKC isoforms in GnRH and phorbol 12-myristate 13-acetate activation of extracellular signal-regulated kinase and Jun N-terminal kinase. Endocrinology 2010; 151:4894-907. [PMID: 20810567 DOI: 10.1210/en.2010-0114] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH is the first key hormone of reproduction. The role of protein kinase C (PKC) isoforms in GnRH-stimulated MAPK [ERK and Jun N-terminal kinase (JNK)] was examined in the αT3-1 and LβT2 gonadotrope cells. Incubation of the cells with GnRH resulted in a protracted activation of ERK1/2 and a slower and more transient activation of JNK1/2. Gonadotropes express conventional PKCα and conventional PKCβII, novel PKCδ, novel PKCε, and novel PKCθ, and atypical PKC-ι/λ. The use of green fluorescent protein-PKC constructs revealed that GnRH induced rapid translocation of PKCα and PKCβII to the plasma membrane, followed by their redistribution to the cytosol. PKCδ and PKCε localized to the cytoplasm and Golgi, followed by the rapid redistribution by GnRH of PKCδ to the perinuclear zone and of PKCε to the plasma membrane. Interestingly, PKCα, PKCβII, and PKCε translocation to the plasma membrane was more pronounced and more prolonged in phorbol-12-myristate-13-acetate (PMA) than in GnRH-treated cells. The use of selective inhibitors and dominant-negative plasmids for the various PKCs has revealed that PKCβII, PKCδ, and PKCε mediate ERK2 activation by GnRH, whereas PKCα, PKCβII, PKCδ, and PKCε mediate ERK2 activation by PMA. Also, PKCα, PKCβII, PKCδ, and PKCε are involved in GnRH and PMA stimulation of JNK1 in a cell-context-dependent manner. We present preliminary evidence that persistent vs. transient redistribution of selected PKCs or redistribution of a given PKC to the perinuclear zone vs. the plasma membrane may dictate its selective role in ERK or JNK activation. Thus, we have described the contribution of selective PKCs to ERK and JNK activation by GnRH.
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Affiliation(s)
- Masha Dobkin-Bekman
- Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv 69978, Israel
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26
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27
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Rotman T, Etkovitz N, Spiegel A, Rubinstein S, Breitbart H. Protein kinase A and protein kinase C(alpha)/PPP1CC2 play opposing roles in the regulation of phosphatidylinositol 3-kinase activation in bovine sperm. Reproduction 2010; 140:43-56. [PMID: 20442273 DOI: 10.1530/rep-09-0314] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In order to acquire fertilization competence, spermatozoa have to undergo biochemical changes in the female reproductive tract, known as capacitation. Signaling pathways that take place during the capacitation process are much investigated issue. However, the role and regulation of phosphatidylinositol 3-kinase (PI3K) in this process are still not clear. Previously, we reported that short-time activation of protein kinase A (PRKA, PKA) leads to PI3K activation and protein kinase C(alpha)(PRKCA, PKC(alpha)) inhibition. In the present study, we found that during the capacitation PI3K phosphorylation/activation increases. PI3K activation was PRKA dependent, and down-regulated by PRKCA. PRKCA is found to be highly active at the beginning of the capacitation, conditions in which PI3K is not active. Moreover, inhibition of PRKCA causes significant activation of PI3K. Similar activation of PI3K is seen when the phosphatase PPP1 is blocked suggesting that PPP1 regulates PI3K activity. We found that during the capacitation PRKCA and PPP1CC2 (PP1gamma2) form a complex, and the two enzymes were degraded during the capacitation, suggesting that this degradation enables the activation of PI3K. This degradation is mediated by PRKA, indicating that in addition to the direct activation of PI3K by PRKA, this kinase can enhance PI3K phosphorylation indirectly by enhancing the degradation and inactivation of PRKCA and PPP1CC2.
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Affiliation(s)
- T Rotman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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28
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Abstract
Networks of signal transducers determine the conversion of environmental cues into cellular actions. Among the main players in these networks are protein kinases, which can acutely and reversibly modify protein functions to influence cellular events. One group of kinases, the protein kinase C (PKC) family, have been increasingly implicated in the organization of signal propagation, particularly in the spatial distribution of signals. Examples of where and how various PKC isoforms direct this tier of signal organization are becoming more evident.
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29
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Yazid S, Solito E, Christian H, McArthur S, Goulding N, Flower R. Cromoglycate drugs suppress eicosanoid generation in U937 cells by promoting the release of Anx-A1. Biochem Pharmacol 2009; 77:1814-26. [PMID: 19428336 PMCID: PMC2888050 DOI: 10.1016/j.bcp.2009.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 03/09/2009] [Accepted: 03/10/2009] [Indexed: 12/15/2022]
Abstract
Using biochemical, epifluorescence and electron microscopic techniques in a U937 model system, we investigated the effect of anti-allergic drugs di-sodium cromoglycate and sodium nedocromil on the trafficking and release of the anti-inflammatory protein Annexin-A1 (Anx-A1) when this was triggered by glucocorticoid (GC) treatment. GCs alone produced a rapid (within 5 min) concentration-dependent activation of PKCα/β (Protein Kinase C; EC 2.7.11.13) and phosphorylation of Anx-A1 on Ser27. Both phosphoproteins accumulated at the plasma membrane and Anx-A1 was subsequently externalised thereby inhibiting thromboxane (Tx) B2 generation. When administered alone, cromoglycate or nedocromil had little effect on this pathway however, in the presence of a fixed sub-maximal concentration of GCs, increasing amounts of the cromoglycate-like drugs caused a striking concentration-dependent enhancement of Anx-A1 and PKCα/β phosphorylation, membrane recruitment and Anx-A1 release from cells resulting in greatly enhanced inhibition of TxB2 generation. GCs also stimulated phosphatase accumulation at the plasma membrane of U937 cells. Both cromoglycate and nedocromil inhibited this enzymatic activity as well as that of a highly purified PP2A phosphatase preparation. We conclude that stimulation by the cromoglycate-like drugs of intracellular Anx-A1 trafficking and release (hence inhibition of eicosanoid release) is secondary to inhibition of a phosphatase PP2A (phosphoprotein phosphatase; EC 3.1.3.16), which probably forms part of a control loop to limit Anx-A1 release. These experiments provide a basis for a novel mechanism of action for the cromolyns, a group of drugs that have long puzzled investigators.
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Affiliation(s)
- Samia Yazid
- Biochemical Pharmacology, William Harvey Research Institute, Bart's and the London School of Medicine and Dentistry, London, UK
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30
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Kineman RD, Luque RM. Evidence that ghrelin is as potent as growth hormone (GH)-releasing hormone (GHRH) in releasing GH from primary pituitary cell cultures of a nonhuman primate (Papio anubis), acting through intracellular signaling pathways distinct from GHRH. Endocrinology 2007; 148:4440-9. [PMID: 17540720 DOI: 10.1210/en.2007-0441] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ghrelin is more effective than GHRH in stimulating GH release in normal adult humans and monkeys in vivo. This robust effect of ghrelin has been largely attributed to regulation of hypothalamic input, whereas the direct effect of ghrelin on pituitary GH release has been minimized by the observation that ghrelin has only a modest impact on GH release, compared with GHRH, in cultures prepared from human fetal pituitaries and GH-producing adenomas, as well as pituitaries from nonprimate species. However, comparable in vitro studies have not been performed to test the direct effect of ghrelin on normal adult primates. Therefore, in the present study, primary pituitary cell cultures from female baboons (Papio anubis) were used as a model system to test the direct effects of ghrelin on primate somatotrope function. In this model, both ghrelin and GHRH increased GH release in a dose-dependent fashion. Surprisingly, at maximal concentrations (10 nM), both ghrelin and GHRH elicited a robust increase in GH release (4 and 24 h, respectively), and both up-regulated GH secretagogue-receptor and GHRH-receptor mRNA levels (24 h). Combined treatment with ghrelin and GHRH resulted in an additive effect on GH release, suggesting that distinct intracellular signaling pathways are activated by each ligand, as confirmed by the use of specific inhibitors of intracellular signaling. Together, these results present the first evidence that a direct effect of ghrelin on somatotrope function may play a major role in stimulating GH release in primates.
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Affiliation(s)
- Rhonda D Kineman
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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31
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Ubersax JA, Ferrell JE. Mechanisms of specificity in protein phosphorylation. Nat Rev Mol Cell Biol 2007; 8:530-41. [PMID: 17585314 DOI: 10.1038/nrm2203] [Citation(s) in RCA: 998] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A typical protein kinase must recognize between one and a few hundred bona fide phosphorylation sites in a background of approximately 700,000 potentially phosphorylatable residues. Multiple mechanisms have evolved that contribute to this exquisite specificity, including the structure of the catalytic site, local and distal interactions between the kinase and substrate, the formation of complexes with scaffolding and adaptor proteins that spatially regulate the kinase, systems-level competition between substrates, and error-correction mechanisms. The responsibility for the recognition of substrates by protein kinases appears to be distributed among a large number of independent, imperfect specificity mechanisms.
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Affiliation(s)
- Jeffrey A Ubersax
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California 94305-5174, USA.
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32
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Celaya RB, Liscum E. Phototropins and Associated Signaling: Providing the Power of Movement in Higher Plants¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2005.tb01524.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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33
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Gilbert C, Cantin R, Barat C, Tremblay MJ. Human immunodeficiency virus type 1 replication in dendritic cell-T-cell cocultures is increased upon incorporation of host LFA-1 due to higher levels of virus production in immature dendritic cells. J Virol 2007; 81:7672-82. [PMID: 17494076 PMCID: PMC1933380 DOI: 10.1128/jvi.02810-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Dendritic cells (DCs) act as a portal for invasion by human immunodeficiency virus type-1 (HIV-1). Here, we investigated whether virion-incorporated host cell membrane proteins can affect virus replication in DC-T-cell cocultures. Using isogenic viruses either devoid of or bearing host-derived leukocyte function-associated antigen 1 (LFA-1), we showed that HIV-1 production is augmented when LFA-1-bearing virions are used compared to that for viral entities lacking this adhesion molecule. This phenomenon was observed in immature monocyte-derived DCs (IM-MDDCs) only and not in DCs displaying a mature phenotype. The increase is not due to higher virus production in responder CD4(+) T cells but rather is linked with a more important productive infection of IM-MDDCs. We provided evidence that virus-associated host LFA-1 molecules do not affect a late event in the HIV-1 life cycle but rather exert an effect on an early step in virus replication. We demonstrated that the enhancement of productive infection of IM-MDDCs that is conferred by virus-anchored host LFA-1 involves the protein kinase A (PKA) and PKC signal transduction pathways. The biological significance of this phenomenon was established by performing experiments with virus stocks produced in primary human cells and anti-LFA-1 antibodies. Together, our results indicate that the association between some virus-bound host proteins and their natural cognate ligands can modulate de novo HIV-1 production by IM-MDDCs. Therefore, the additional interactions between virus-bound host cell membrane constituents and counter receptors on the surfaces of DCs can influence HIV-1 replication in IM-MDDC-T-cell cocultures.
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Affiliation(s)
- Caroline Gilbert
- Research Center in Infectious Diseases, Laval Univeristy, Quebec, Canada
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Cai L, Marshall TW, Uetrecht AC, Schafer DA, Bear JE. Coronin 1B coordinates Arp2/3 complex and cofilin activities at the leading edge. Cell 2007; 128:915-29. [PMID: 17350576 PMCID: PMC2630706 DOI: 10.1016/j.cell.2007.01.031] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 11/13/2006] [Accepted: 01/24/2007] [Indexed: 12/24/2022]
Abstract
Actin filament formation and turnover within the treadmilling actin filament array at the leading edge of migrating cells are interdependent and coupled, but the mechanisms coordinating these two activities are not understood. We report that Coronin 1B interacts simultaneously with Arp2/3 complex and Slingshot (SSH1L) phosphatase, two regulators of actin filament formation and turnover, respectively. Coronin 1B inhibits filament nucleation by Arp2/3 complex and this inhibition is attenuated by phosphorylation of Coronin 1B at Serine 2, a site targeted by SSH1L. Coronin 1B also directs SSH1L to lamellipodia where SSH1L likely regulates Cofilin activity via dephosphorylation. Accordingly, depleting Coronin 1B increases phospho-Cofilin levels, and alters lamellipodial dynamics and actin filament architecture at the leading edge. We conclude that Coronin 1B's coordination of filament formation by Arp2/3 complex and filament turnover by Cofilin is required for effective lamellipodial protrusion and cell migration.
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Affiliation(s)
- Liang Cai
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center & Dept. of Cell and Developmental Biology
| | - Thomas W. Marshall
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center & Dept. of Cell and Developmental Biology
| | - Andrea C. Uetrecht
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center & Dept. of Cell and Developmental Biology
| | - Dorothy A. Schafer
- University of Virginia, Charlottesville, VA, Depts. of Biology and Cell Biology
| | - James E. Bear
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center & Dept. of Cell and Developmental Biology
- Corresponding Author: Phone: 919-966-5471, Fax: 919-966-3015, E-mail:
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Nazarenko I, Schäfer R, Sers C. Mechanisms of the HRSL3 tumor suppressor function in ovarian carcinoma cells. J Cell Sci 2007; 120:1393-404. [PMID: 17374643 DOI: 10.1242/jcs.000018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
HRSL3 (also known as H-REV107-1) belongs to a class II tumor suppressor gene family and is downregulated in several human tumors including ovarian carcinomas. To unravel the mechanism of HRSL3 tumor suppressor action, we performed a yeast two-hybrid screen and identified the alpha-isoform of the regulatory subunit A of protein phosphatase 2A (PR65alpha) as a new interaction partner of HRSL3. Interaction between HRSL3 and PR65alpha was confirmed in vitro and by co-immunoprecipitation in mammalian cells. We demonstrate that HRSL3 binds to the endogenous PR65alpha, thereby partially sequestering the catalytic subunit PR36 from the PR65 protein complex, and inhibiting PP2A catalytic activity. Furthermore, binding of HRSL3 to PR65 induces apoptosis in ovarian carcinoma cells in a caspase-dependent manner. Using several mutant HRSL3 constructs, we identified the N-terminal proline-rich region within the HRSL3 protein as the domain that is relevant for both binding of PR65alpha and induction of programmed cell death. This suggests that the negative impact of HRSL3 onto PP2A activity is important for the HRSL3 pro-apoptotic function and indicates a role of PP2A in survival of human ovarian carcinomas. The analysis of distinct PP2A target molecules revealed PKCzeta as being involved in HRSL3 action. These data implicate HRSL3 as a signaling regulatory molecule, which is functionally involved in the oncogenic network mediating growth and survival of ovarian cancer cells.
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Affiliation(s)
- Irina Nazarenko
- Molecular Tumor Pathology, Institute of Pathology, University Medicine Charité Berlin, Schumannstrasse 20/21, 10117 Berlin, Germany
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36
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Gilbert C, Barat C, Cantin R, Tremblay MJ. Involvement of Src and Syk Tyrosine Kinases in HIV-1 Transfer from Dendritic Cells to CD4+T Lymphocytes. THE JOURNAL OF IMMUNOLOGY 2007; 178:2862-71. [PMID: 17312130 DOI: 10.4049/jimmunol.178.5.2862] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dendritic cells (DCs) are considered as key mediators of the early events in HIV-1 infection at mucosal sites. Although several aspects of the complex interactions between DCs and HIV-1 have been elucidated, there are still basic questions that remain to be answered about DCs/HIV-1 interplay. In this study, we examined the contribution of nonreceptor TKs in the known ability of DCs to efficiently transfer HIV-1 to CD4(+) T cells in trans. Experiments performed with specific inhibitors of Src and Syk family members indicate that these tyrosine kinases (TKs) are participating to HIV-1 transfer from immature monocyte-derived DCs (IM-MDDCs) to autologous CD4(+) T cells. Experiments with IM-MDDCs transfected with small interfering RNAs targeting Lyn and Syk confirmed the importance of these nonreceptor TKs in HIV-1 transmission. The Src- and Syk-mediated effect on virus transfer was linked with infection of IM-MDDCs in cis-as monitored by quantifying integrated viral DNA and de novo virus production. The process of HIV-1 transmission from IM-MDDCs to CD4(+) T cells was unaffected following treatment with protein kinase C and protein kinase A inhibitors. These data suggest that Src and Syk TKs play a functional role in productive HIV-1 infection of IM-MDDCs. Additional work is needed to facilitate our comprehension of the various mechanisms underlying the exact contribution of Src and Syk TKs to this phenomenon.
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Affiliation(s)
- Caroline Gilbert
- Centre de Recherche en Infectiologie, Centre Hospitalier de l'Université Laval, and Faculté de Médecine, Université Laval, 2705 Boulevard Laurier, Quebec, Canada
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Belakavadi M, Prabhakar BT, Salimath BP. Purification and characterization of butyrate-induced protein phosphatase involved in apoptosis of Ehrlich ascites tumor cells. Biochim Biophys Acta Gen Subj 2007; 1770:39-47. [PMID: 17029793 DOI: 10.1016/j.bbagen.2006.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 06/19/2006] [Accepted: 07/05/2006] [Indexed: 12/01/2022]
Abstract
Short chain fatty acids including butyrate exhibit wide variety of biological effects towards cell growth, morphology and gene expression. In this report, we study the mechanism by which butyrate (BuA) modulates the expression of protein phosphatase when treated to the cells. As a model system, we used Ehrlich Ascites Tumor (EAT) cells in which BuA-treatment induces expression of a protein phosphatase enzyme. Subsequently, BuA-induced protein phosphatase has been biochemically purified and characterized. Further, pretreatment of caspase-3 inhibitor abolished the activity of BuA-induced protein phosphatase indicating the involvement of caspase-3 in the activation of BuA-induced protein phosphatase. In addition, the relationship between BuA-induced protein phosphatase and apoptosis has been verified. Activation of endonuclease-II has been shown in BuA-treated EAT cells and that activity was completely inhibited by sodium orthovanadate, a tyrosine phosphatase inhibitor suggesting that endonuclease-II may serve as a possible down-stream target for BuA-induced protein phosphatase. Together, the data suggest that activation of protein phosphatase may be an early and essential step in BuA-mediated apoptotic signaling pathway in EAT cells.
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Affiliation(s)
- Madesh Belakavadi
- Department of Applied Botany and Biotechnology, University of Mysore, Mysore-570006, India.
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Dessauge F, Cayla X, Albar JP, Fleischer A, Ghadiri A, Duhamel M, Rebollo A. Identification of PP1alpha as a caspase-9 regulator in IL-2 deprivation-induced apoptosis. THE JOURNAL OF IMMUNOLOGY 2006; 177:2441-51. [PMID: 16888006 DOI: 10.4049/jimmunol.177.4.2441] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One of the mechanisms that regulate cell death is the reversible phosphorylation of proteins. ERK/MAPK phosphorylates caspase-9 at Thr(125), and this phosphorylation is crucial for caspase-9 inhibition. Until now, the phosphatase responsible for Thr(125) dephosphorylation has not been described. Here, we demonstrate that in IL-2-proliferating cells, phosphorylated serine/threonine phosphatase type 1alpha (PP1alpha) associates with phosphorylated caspase-9. IL-2 deprivation induces PP1alpha dephosphorylation, which leads to its activation and, as a consequence, dephosphorylation and activation of caspase-9 and subsequent dissociation of both molecules. In cell-free systems supplemented with ATP caspase-9 activation is induced by addition of cytochrome c and we show that in this process PP1alpha is indispensable for triggering caspase-9 as well as caspase-3 cleavage and activation. Moreover, PP1alpha associates with caspase-9 in vitro and in vivo, suggesting that it is the phosphatase responsible for caspase-9 dephosphorylation and activation. Finally, we describe two novel phosphatase-binding sites different from the previously described PP1alpha consensus motifs, and we demonstrate that these novel sites mediate the interaction of PP1alpha with caspase-9.
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Affiliation(s)
- Frédéric Dessauge
- Laboratoire d'Immunologie Cellulaire et Tissulaire, Hôpital Pitié-Salpêtrière, Unité 543 INSERM, Bâtiment CERVI, 83 Boulevard de l'Hôpital, 75013 Paris, France
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Sim ATR, Ludowyke RI, Verrills NM. Mast cell function: regulation of degranulation by serine/threonine phosphatases. Pharmacol Ther 2006; 112:425-39. [PMID: 16790278 DOI: 10.1016/j.pharmthera.2006.04.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 04/26/2006] [Indexed: 01/28/2023]
Abstract
Mast cells play both effector and modulatory roles in a range of allergic and immune responses. The principal function of these cells is the release of inflammatory mediators from mast cells by degranulation, which involves a complex interplay of signalling molecules. Understanding the molecular architecture underlying mast cell signalling has attracted renewed interest as the capacity for therapeutic intervention through controlling mast cell degranulation is now accepted as a viable proposition. The dynamic regulation of signalling by protein phosphorylation is a well-established phenomenon and many of the early events involved in mast cell activation are well understood. Less well understood however are the events further downstream of receptor activation that allow movement of granules through the cytoskeletal barrier and docking and fusion of granules with the plasma membrane. Whilst a potential role for the protein phosphatase family of signalling enzymes in mast cell function has been accepted for some time, the evidence has largely been derived from the use of broad specificity pharmacological inhibitors and results often depend upon the experimental conditions, leading to conflicting views. In this review, we present and discuss the pharmacological and recent molecular evidence that protein phosphatases, and in particular the protein phosphatase serine/threonine phosphatase type 2A (PP2A), have major regulatory roles to play and may be potential targets for the design of new therapeutic agents.
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Affiliation(s)
- Alistair T R Sim
- School of Biomedical Sciences and Hunter Medical Research Institute, Faculty of Health, The University of Newcastle, Callaghan, NSW, Australia.
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40
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Tzircotis G, Thorne RF, Isacke CM. Directional sensing of a phorbol ester gradient requires CD44 and is regulated by CD44 phosphorylation. Oncogene 2006; 25:7401-10. [PMID: 16785995 DOI: 10.1038/sj.onc.1209724] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cancer progression is associated with enhanced directional cell migration, both of the tumour cells invading into the stroma and stromal cells infiltrating the tumour site. In cell-based assays to study directional cell migration, phorbol esters are frequently used as a chemotactic agent. However, the molecular mechanism by which these activators of protein kinase C (PKC) result in the establishment of a polarized migratory phenotype is not known. Here we show that CD44 expression is essential for chemotaxis towards a phorbol ester gradient. In an investigation of CD44 phosphorylation kinetics in resting and stimulated cells, Ser316 was identified as a novel site of phosphorylation following activation of PKC. PKC does not phosphorylate Ser316 directly, but rather mediates the activation of downstream Ser316 kinase(s). In transfection studies, a phosphorylation-deficient Ser316 mutant was shown to act in a dominant-negative fashion to impair chemotaxis mediated by endogenous CD44 in response to a phorbol ester gradient. Importantly, this mutation had no effect on random cell motility or the ability of cells to migrate directionally towards a cocktail of chemoattractants. These studies demonstrate that CD44 functions to provide directional cues to migrating cells without affecting the motility apparatus.
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Affiliation(s)
- G Tzircotis
- Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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41
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Mason CW, Swaan PW, Weiner CP. Identification of interactive gene networks: a novel approach in gene array profiling of myometrial events during guinea pig pregnancy. Am J Obstet Gynecol 2006; 194:1513-23. [PMID: 16731067 DOI: 10.1016/j.ajog.2005.12.044] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 09/02/2005] [Accepted: 12/22/2005] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The transition from myometrial quiescence to activation is poorly understood, and the analysis of array data is limited by the available data mining tools. We applied functional analysis and logical operations along regulatory gene networks to identify molecular processes and pathways underlying quiescence and activation. STUDY DESIGN We analyzed some 18,400 transcripts and variants in guinea pig myometrium at stages corresponding to quiescence and activation, and compared them to the nonpregnant (control) counterpart using a functional mapping tool, MetaCore (GeneGo, St Joseph, MI) to identify novel gene networks composed of biological pathways during mid (MP) and late (LP) pregnancy. RESULTS Genes altered during quiescence and or activation were identified following gene specific comparisons with myometrium from nonpregnant animals, and then linked to curated pathways and formulated networks. The MP and LP networks were subtracted from each other to identify unique genomic events during those periods. For example, changes 2-fold or greater in genes mediating protein biosynthesis, programmed cell death, microtubule polymerization, and microtubule based movement were noted during the transition to LP. CONCLUSION We describe a novel approach combining microarrays and genetic data to identify networks associated with normal myometrial events. The resulting insights help identify potential biomarkers and permit future targeted investigations of these pathways or networks to confirm or refute their importance.
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Affiliation(s)
- Clifford W Mason
- Department of Pharmaceutical Science, University of Maryland School of Pharmacy, Baltimore, MD, USA
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42
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Weber T, Neumann J, Meissner A, Grosse Hartlage M, Van Aken H, Hanske G, Schmitz W, Boknik P. Reduced serine–16 and threonine–17 phospholamban phosphorylation in stunning of conscious dogs. Basic Res Cardiol 2005; 101:253-60. [PMID: 16369730 DOI: 10.1007/s00395-005-0577-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 10/19/2005] [Accepted: 11/07/2005] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Cardiac stunning is the consequence of a brief cardiac ischemia. The underlying mechanism is not completely understood. METHODS Here we induced cardiac transient ischemia in conscious instrumented dogs by means of an occluder in the left anterior descending coronary artery (LAD). Contractile performance, monitored by ultrasound crystals, was reduced during and after ischemia in the LAD area. For control in the same animals cardiac performance was measured in the area of left circumflex coronary artery (Ramus circumflexus, RCx). In the RCx area, no decline in contractility was noted. Tissue was obtained from stunned LAD area and from control areas (RCx). RESULTS Phospholamban phosphorylation on both serine-16 and threonine-17 was reduced in LAD areas compared to RCx areas. Reduced phosphorylation of PLB is known to inhibit cardiac contractility. While phosphorylation of PLB was reduced, the activity of the appropriate protein phosphatases and protein kinases was not different between tissue obtained from LAD or RCx areas. CONCLUSION Reduced formation of cAMP might underlie the contractile dysfunction in myocardial stunning.
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Affiliation(s)
- Th Weber
- Klinik und Poliklinik für Anästhesiologie und Operative Intensivmedizin, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Albert-Schweitzer-Str. 33, 48149, Münster, Germany
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Crossthwaite AJ, Ciruela A, Rayner TF, Cooper DMF. A Direct Interaction between the N Terminus of Adenylyl Cyclase AC8 and the Catalytic Subunit of Protein Phosphatase 2A. Mol Pharmacol 2005; 69:608-17. [PMID: 16258073 DOI: 10.1124/mol.105.018275] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Although protein scaffolding complexes compartmentalize protein kinase A (PKA) and phosphodiesterases to optimize cAMP signaling, adenylyl cyclases, the sources of cAMP, have been implicated in very few direct protein interactions. The N termini of adenylyl cyclases are highly divergent, which hints at isoform-specific interactions. Indeed, the Ca(2+)-sensitive adenylyl cyclase 8 (AC8) contains a Ca(2+)/calmodulin binding site on the N terminus that is essential for stimulation of activity by the capacitative entry of Ca(2+) in the intact cell. Here, we have used the N terminus of AC8 as a bait in a yeast two-hybrid screen of a human embryonic kidney (HEK) 293 cell cDNA library and identified the catalytic subunit of the serine/threonine protein phosphatase 2A (PP2A(C)) as a binding partner. Confirming the highly specific nature of this novel interaction, glutathione-S-transferase fusion proteins containing the full-length N terminus of AC8 affinity precipitated catalytically active PP2A(C) from both HEK293 and mouse forebrain membranes-the latter a normal source of AC8. The scaffolding subunit of PP2A (PP2A(A); 65 kDa) was also precipitated by the N terminus of AC8, indicating that AC8 may occur in a complex with the PP2A core dimer. The interaction between the N terminus of AC8 and PP2A(C) was antagonized by Ca(2+)/calmodulin. However, PP2A(C) and Ca(2+)/calmodulin did not share identical binding specificities in the N terminus of AC8. PKA-mediated phosphorylation did not influence either calmodulin or PP2A(C) association with AC8. In addition, both PP2A(C) and AC8 occurred in lipid rafts. These findings are the first demonstration of an association between adenylyl cyclase and any downstream element of cAMP signaling.
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44
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Payvandi F, Wu L, Naziruddin SD, Haley M, Parton A, Schafer PH, Chen RS, Muller GW, Hughes CCW, Stirling DI. Immunomodulatory Drugs (IMiDs) Increase the Production of IL-2 from Stimulated T Cells by Increasing PKC-θ Activation and Enhancing the DNA-Binding Activity of AP-1 but Not NF-κB, OCT-1, or NF-AT. J Interferon Cytokine Res 2005; 25:604-16. [PMID: 16241859 DOI: 10.1089/jir.2005.25.604] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Immunomodulatory drugs (IMiDs) are orally available small molecules that potently inhibit tumor necrosis factor-alpha (TNF-alpha) production by lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (HuPBMCs) but enhance secretion of such cytokines as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) by stimulated T cells. The mechanism of cytokine regulation by IMiDs has not yet been determined. In the present study, we investigated the effects of one of the IMiDs, CC-4047 (Actimid, Celgene, Warren, NJ), on synthesis of IL-2 protein and mRNA and on the activity and expression of transcription factors. Treatment with CC-4047 enhances the secretion of IL-2 protein and the expression of IL-2 mRNA in a dose-dependent and time-dependent manner. In T cells stimulated with phorbol myristate acetate (PMA)/ionomycin, CC-4047 enhanced the DNA-binding activity of activated protein-1 (AP-1) but not NF-kappaB, Octomer-1 (OCT-1), or NFAT by 2-fold and 4-fold after an incubation time of 1 and 3 h, respectively. Luciferase reporter assays in Jurkat cells showed similar effects on transcription factor activity. Using in vitro kinase activity assays, we also showed that CC-4047 enhances the activity of protein kinase C-theta (PKC-theta) in stimulated T cells. The secreted IL-2 from HuPBMCs was shown to activate natural killer (NK) cells to lyse their target cell line K562. Taken together, our results demonstrate that the IMiDs exert their effects at least in part by activating PKC-theta and acting on AP-1 DNA-binding activity in T cells, resulting in augmented IL-2 synthesis and activation of IL- 2-dependent downstream effectors, such as NK cells.
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Affiliation(s)
- Faribourz Payvandi
- Department of Immunotherapeutics, Celgene Corporation, Summit, NJ 07901, USA.
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Ray RM, Bhattacharya S, Johnson LR. Protein Phosphatase 2A Regulates Apoptosis in Intestinal Epithelial Cells. J Biol Chem 2005; 280:31091-100. [PMID: 15994315 DOI: 10.1074/jbc.m503041200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polyamine depletion prevents apoptosis by increasing serine/threonine phosphorylation leading to either inactivation or activation of pro- and anti-apoptotic proteins, respectively. Despite evidence that protein kinases are regulators of apoptosis, a specific role for protein phosphatases in regulating cell survival has not been established. In this study, we show that polyamine depletion inhibits serine/threonine phosphatase 2A (PP2A). Inhibition of PP2A in cells depleted of polyamines correlated well with increased phosphorylation of Bad at Ser112. Bad Ser112 phosphorylation in response to tumor necrosis factor (TNF)-alpha treatment decreased with time in cells grown in control as well as those grown in the presence of alpha-difluoromethylornithine plus putrescine. However, a sustained increase in the levels of Bad Ser112 phosphorylation was maintained in response to TNF-alpha treatment in cells grown in the presence of alpha-difluoromethylornithine. Inhibition of PP2A by okadaic acid and fostriecin or PP2A small interfering RNA transfection significantly decreased TNF-alpha-induced apoptosis in control and polyamine-depleted cells. Inhibition of PP2A by okadaic acid: 1) increased Bad and Bcl-2 phosphorylation at Ser112 and Ser70, respectively; 2) increased ERK activity; 3) prevented JNK activation; 4) prevented cytochrome c release, and activation of caspases-9 and -3 in response to TNF-alpha. Inhibition of MEK1 by U0126 prevented phosphorylation of Bad at Ser112. These results indicate that polyamines regulate PP2A activity, and inhibition of PP2A in response to polyamine depletion increases steady state levels of Bad and Bcl-2 proteins and their phosphorylation and thereby prevents cytochrome c release, caspase-9, and caspase-3 activation.
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Affiliation(s)
- Ramesh M Ray
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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Lotrich FE, Pollock BG. Candidate genes for antidepressant response to selective serotonin reuptake inhibitors. Neuropsychiatr Dis Treat 2005; 1:17-35. [PMID: 18568127 PMCID: PMC2426818 DOI: 10.2147/nedt.1.1.17.52301] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) can safely and successfully treat major depression, although a substantial number of patients benefit only partially or not at all from treatment. Genetic polymorphisms may play a major role in determining the response to SSRI treatment. Nonetheless, it is likely that efficacy is determined by multiple genes, with individual genetic polymorphisms having a limited effect size. Initial studies have identified the promoter polymorphism in the gene coding for the serotonin reuptake transporter as moderating efficacy for several SSRIs. The goal of this review is to suggest additional plausible polymorphisms that may be involved in antidepressant efficacy. These include genes affecting intracellular transductional cascades; neuronal growth factors; stress-related hormones, such as corticotropin-releasing hormone and glucocorticoid receptors; ion channels and synaptic efficacy; and adaptations of monoaminergic pathways. Association analyses to examine these candidate genes may facilitate identification of patients for targeted alternative therapies. Determining which genes are involved may also assist in identifying future, novel treatments.
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Affiliation(s)
- Francis E Lotrich
- University of Pittsburgh Medical Center, Western Psychiatric Institute and Clinic, Department of Psychiatry Pittsburgh, PA, USA.
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Celaya RB, Liscum E. Phototropins and Associated Signaling: Providing the Power of Movement in Higher Plants¶. Photochem Photobiol 2005. [DOI: 10.1562/2004-08-22-ir-282.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Gangopadhyay SS, Takizawa N, Gallant C, Barber AL, Je HD, Smith TC, Luna EJ, Morgan KG. Smooth muscle archvillin: a novel regulator of signaling and contractility in vascular smooth muscle. J Cell Sci 2004; 117:5043-57. [PMID: 15383618 DOI: 10.1242/jcs.01378] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms by which protein kinase C (PKC) and extracellular-signal-regulated kinases (ERK1/2) govern smooth-muscle contractility remain unclear. Calponin (CaP), an actin-binding protein and PKC substrate, mediates signaling through ERK1/2. We report here that CaP sequences containing the CaP homology (CH) domain bind to the C-terminal 251 amino acids of smooth-muscle archvillin (SmAV), a new splice variant of supervillin, which is a known actin- and myosin-II-binding protein. The CaP-SmAV interaction is demonstrated by reciprocal yeast two-hybrid and blot-overlay assays and by colocalization in COS-7 cells. In differentiated smooth muscle, endogenous SmAV and CaP co-fractionate and co-translocate to the cell cortex after stimulation by agonist. Antisense knockdown of SmAV in tissue inhibits both the activation of ERK1/2 and contractions stimulated by either agonist or PKC activation. This ERK1/2 signaling and contractile defect is similar to that observed in CaP knockdown experiments. In A7r5 smooth-muscle cells, PKC activation by phorbol esters induces the reorganization of endogenous, membrane-localized SmAV and microfilament-associated CaP into podosome-like structures that also contain F-actin, nonmuscle myosin IIB and ERK1/2. These results indicate that SmAV contributes to the regulation of contractility through a CaP-mediated signaling pathway, involving PKC activation and phosphorylation of ERK1/2.
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Pyle WG, Solaro RJ. At the crossroads of myocardial signaling: the role of Z-discs in intracellular signaling and cardiac function. Circ Res 2004; 94:296-305. [PMID: 14976140 DOI: 10.1161/01.res.0000116143.74830.a9] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Understanding the molecular interactions among components of cardiac Z-discs and their role in signaling has become pivotal in explaining long- and short-term regulation of cardiac function. In striated muscle, the ends of the thin filaments from opposing sarcomeres overlap and are cross-linked by an elaborate array of proteins to form a highly ordered, yet dynamic network that is the Z-disc. We review here a current picture of the function and structure of the Z-disc of mammalian cardiac myocytes. We emphasize provocative findings that advance new theories about the place of cardiac Z-discs in myocardial intra- and intercellular signaling in myocardial physiology and pathology. Relatively new approaches, especially yeast two-hybrid screens, immunoprecipitation, and pull down assays, as well as immunohistochemical analysis have significantly altered previous views of the protein content of the Z-disc. These studies have generally defined domain structure and binding partners for Z-disc proteins, but the functional significance of the binding network and of the domains in cardiac cell biology remains an unfolding story. Yet, even at the present level of understanding, perceptions of potential functions of the Z-disc proteins are expanding greatly and leading to new and exciting experimental approaches toward mechanistic understanding. The theme of the following discussion of these Z-disc proteins centers on their potential to function not only as a physical anchor for myofilament and cytoskeletal proteins, but also as a pivot for reception, transduction, and transmission of mechanical and biochemical signals.
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Affiliation(s)
- W Glen Pyle
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
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Zhang X, Wu J, Fang L, Willis WD. The effects of protein phosphatase inhibitors on nociceptive behavioral responses of rats following intradermal injection of capsaicin. Pain 2004; 106:443-451. [PMID: 14659528 DOI: 10.1016/j.pain.2003.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The functions of crucial proteins in the nervous system are modulated by kinases and phosphatases which catalyze opposing reactions of phosphorylation and dephosphorylation. During spinal cord central sensitization, serine/threonine protein phosphatase 2A (PP2A) may play an important role in determining the excitability of nociceptive neurons in the spinal cord by modulating the phosphorylation state of some critical proteins. The effects of a general inhibitor of PP2A, okadaic acid (OA), and a specific inhibitor, fostriecin, on the behavioral responses of rats following capsaicin injection were investigated in this study. Hyperalgesia was initiated by injection of capsaicin into the plantar surface of the hindpaw of rats. An intrathecal catheter was previously implanted into the subarachnoid space of the spinal cord for the administration of a variety of drugs. Rats were tested for responses to mechanical stimuli using von Frey filaments of different bending forces applied at a site outside the area of injection. Responses to heat stimuli were detected from a site near the injection area. The responses were recorded before and after injection of capsaicin with the perfusion of ACSF, OA negative control, OA or fostriecin at different time points. The results demonstrated that secondary mechanical hyperalgesia and allodynia can be induced by the intradermal injection of capsaicin. Compared to administration of ACSF or the OA negative control, infusion of the phosphatase inhibitor OA or of fostriecin into the subarachnoid space enhanced the secondary mechanical hyperalgesia and allodynia by making the intradermal capsaicin-induced hyperalgesia and allodynia last longer.
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Affiliation(s)
- Xuan Zhang
- Department of Anatomy and Neuroscience, Marine Biomedical Institute, The University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1069, USA
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