1
|
Kazanietz MG, Cooke M. Protein kinase C signaling "in" and "to" the nucleus: Master kinases in transcriptional regulation. J Biol Chem 2024; 300:105692. [PMID: 38301892 PMCID: PMC10907189 DOI: 10.1016/j.jbc.2024.105692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/03/2024] Open
Abstract
PKC is a multifunctional family of Ser-Thr kinases widely implicated in the regulation of fundamental cellular functions, including proliferation, polarity, motility, and differentiation. Notwithstanding their primary cytoplasmic localization and stringent activation by cell surface receptors, PKC isozymes impel prominent nuclear signaling ultimately impacting gene expression. While transcriptional regulation may be wielded by nuclear PKCs, it most often relies on cytoplasmic phosphorylation events that result in nuclear shuttling of PKC downstream effectors, including transcription factors. As expected from the unique coupling of PKC isozymes to signaling effector pathways, glaring disparities in gene activation/repression are observed upon targeting individual PKC family members. Notably, specific PKCs control the expression and activation of transcription factors implicated in cell cycle/mitogenesis, epithelial-to-mesenchymal transition and immune function. Additionally, PKCs isozymes tightly regulate transcription factors involved in stepwise differentiation of pluripotent stem cells toward specific epithelial, mesenchymal, and hematopoietic cell lineages. Aberrant PKC expression and/or activation in pathological conditions, such as in cancer, leads to profound alterations in gene expression, leading to an extensive rewiring of transcriptional networks associated with mitogenesis, invasiveness, stemness, and tumor microenvironment dysregulation. In this review, we outline the current understanding of PKC signaling "in" and "to" the nucleus, with significant focus on established paradigms of PKC-mediated transcriptional control. Dissecting these complexities would allow the identification of relevant molecular targets implicated in a wide spectrum of diseases.
Collapse
Affiliation(s)
- Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| |
Collapse
|
2
|
|
3
|
Vallvé-Juanico J, Suárez-Salvador E, Castellví J, Ballesteros A, Taylor HS, Gil-Moreno A, Santamaria X. Aberrant expression of epithelial leucine-rich repeat containing G protein-coupled receptor 5-positive cells in the eutopic endometrium in endometriosis and implications in deep-infiltrating endometriosis. Fertil Steril 2017; 108:858-867.e2. [PMID: 28923287 DOI: 10.1016/j.fertnstert.2017.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/25/2017] [Accepted: 08/10/2017] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To characterize leucine-rich repeat containing G protein-coupled receptor 5-positive (LGR5+) cells from the endometrium of women with endometriosis. DESIGN Prospective experimental study. SETTING University hospital/fertility clinic. PATIENT(S) Twenty-seven women with endometriosis who underwent surgery and 12 healthy egg donors, together comprising 39 endometrial samples. INTERVENTION(S) Obtaining of uterine aspirates by using a Cornier Pipelle. MAIN OUTCOMES MEASURE(S) Immunofluorescence in formalin-fixed paraffin-embedded tissue from mice and healthy and pathologic human endometrium using antibodies against LGR5, E-cadherin, and cytokeratin, and epithelial and stromal LGR5+ cells isolated from healthy and pathologic human eutopic endometrium by fluorescence-activated cell sorting and transcriptomic characterization by RNA high sequencing. RESULT(S) Immunofluorescence showed that LGR5+ cells colocalized with epithelial markers in the stroma of the endometrium only in endometriotic patients. The results from RNA high sequencing of LGR5+ cells from epithelium and stroma did not show any statistically significant differences between them. The LGR5+ versus LGR5- cells in pathologic endometrium showed 394 differentially expressed genes. The LGR5+ cells in deep-infiltrating endometriosis expressed inflammatory markers not present in the other types of the disease. CONCLUSION(S) Our results revealed the presence of aberrantly located LGR5+ cells coexpressing epithelial markers in the stromal compartment of women with endometriosis. These cells have a statistically significantly different expression profile in deep-infiltrating endometriosis in comparison with other types of endometriosis, independent of the menstrual cycle phase. Further studies are needed to elucidate their role and influence in reproductive outcomes.
Collapse
Affiliation(s)
- Júlia Vallvé-Juanico
- Department of Gynecology, IVI Barcelona S.L., Barcelona, Spain; Group of Biomedical Research in Gynecology, Vall Hebron Research Institute (VHIR) and University Hospital, Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | - Josep Castellví
- Department of Pathology, Vall d'Hebron University Hospital, Barcelona, Spain
| | | | - Hugh S Taylor
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut
| | - Antonio Gil-Moreno
- Group of Biomedical Research in Gynecology, Vall Hebron Research Institute (VHIR) and University Hospital, Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; Department of Gynecology, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Xavier Santamaria
- Department of Gynecology, IVI Barcelona S.L., Barcelona, Spain; Group of Biomedical Research in Gynecology, Vall Hebron Research Institute (VHIR) and University Hospital, Barcelona, Spain.
| |
Collapse
|
4
|
Kostyak JC, Liverani E, Kunapuli SP. PKC-epsilon deficiency alters progenitor cell populations in favor of megakaryopoiesis. PLoS One 2017; 12:e0182867. [PMID: 28783756 PMCID: PMC5544228 DOI: 10.1371/journal.pone.0182867] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 07/25/2017] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND It has long been postulated that Protein Kinase C (PKC) is an important regulator of megakaryopoiesis. Recent contributions to the literature have outlined the functions of several individual PKC isoforms with regard to megakaryocyte differentiation and platelet production. However, the exact role of PKCε remains elusive. OBJECTIVE To delineate the role of PKCε in megakaryopoiesis. APPROACH AND RESULTS We used a PKCε knockout mouse model to examine the effect of PKCε deficiency on platelet mass, megakaryocyte mass, and bone marrow progenitor cell distribution. We also investigated platelet recovery in PKCε null mice and TPO-mediated signaling in PKCε null megakaryocytes. PKCε null mice have higher platelet counts due to increased platelet production compared to WT littermate controls (p<0.05, n = 8). Furthermore, PKCε null mice have more bone marrow megakaryocyte progenitor cells than WT littermate control mice. Additionally, thrombopoietin-mediated signaling is perturbed in PKCε null mice as Akt and ERK1/2 phosphorylation are enhanced in PKCε null megakaryocytes stimulated with thrombopoietin. Finally, in response to immune-induced thrombocytopenia, PKCε null mice recovered faster and had higher rebound thrombocytosis than WT littermate control mice. CONCLUSIONS Enhanced platelet recovery could be due to an increase in megakaryocyte progenitor cells found in PKCε null mice as well as enhanced thrombopoietin-mediated signaling observed in PKCε deficient megakaryocytes. These data suggest that PKCε is a negative regulator of megakaryopoiesis.
Collapse
Affiliation(s)
- John C. Kostyak
- Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Elisabetta Liverani
- Center for Inflammation, Translational and Clinical Lung Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Satya P. Kunapuli
- Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pharmacology, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Physiology, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, United States of America
| |
Collapse
|
5
|
Mayati A, Le Vee M, Moreau A, Jouan E, Bucher S, Stieger B, Denizot C, Parmentier Y, Fardel O. Protein kinase C-dependent regulation of human hepatic drug transporter expression. Biochem Pharmacol 2015; 98:703-17. [PMID: 26462574 DOI: 10.1016/j.bcp.2015.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/07/2015] [Indexed: 12/13/2022]
Abstract
Hepatic drug transporters are now recognized as major actors of hepatobiliary elimination of drugs. Characterization of their regulatory pathways is therefore an important issue. In this context, the present study was designed to analyze the potential regulation of human hepatic transporter expression by protein kinase C (PKC) activation. Treatment by the reference PKC activator phorbol 12-myristate 13-acetate (PMA) for 48h was shown to decrease mRNA expression of various sinusoidal transporters, including OATP1B1, OATP2B1, NTCP, OCT1 and MRP3, but to increase that of OATP1B3, whereas mRNA expression of canalicular transporters was transiently enhanced (MDR1), decreased (BSEP and MRP2) or unchanged (BCRP) in human hepatoma HepaRG cells. The profile of hepatic transporter mRNA expression changes in PMA-treated HepaRG cells was correlated to that found in PMA-exposed primary human hepatocytes and was similarly observed in response to the PKC-activating marketed drug ingenol mebutate. It was associated with concomitant repression of OATP1B1 and OATP2B1 protein expression and reduction of OATP, OCT1, NTCP and MRP2 activity. The use of chemical PKC inhibitors further suggested a contribution of novel PKCs isoforms to PMA-mediated regulations of transporter mRNA expression. PMA was finally shown to cause epithelial-mesenchymal transition (EMT) in HepaRG cells and exposure to various additional EMT inducers, i.e., hepatocyte growth factor, tumor growth factor-β1 or the HNF4α inhibitor BI6015, led to transporter expression alterations highly correlated to those triggered by PMA. Taken together, these data highlight PKC-dependent regulation of human hepatic drug transporter expression, which may be closely linked to EMT triggered by PKC activation.
Collapse
Affiliation(s)
- Abdullah Mayati
- Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043 Rennes, France
| | - Marc Le Vee
- Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043 Rennes, France
| | - Amélie Moreau
- Centre de Pharmacocinétique, Technologie Servier, 25-27 Rue Eugène Vignat, 45000 Orléans, France
| | - Elodie Jouan
- Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043 Rennes, France
| | - Simon Bucher
- Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043 Rennes, France
| | - Bruno Stieger
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - Claire Denizot
- Centre de Pharmacocinétique, Technologie Servier, 25-27 Rue Eugène Vignat, 45000 Orléans, France
| | - Yannick Parmentier
- Centre de Pharmacocinétique, Technologie Servier, 25-27 Rue Eugène Vignat, 45000 Orléans, France
| | - Olivier Fardel
- Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043 Rennes, France; Pôle Biologie, Centre Hospitalier Universitaire, 2 Rue Henri Le Guilloux, 35033 Rennes, France.
| |
Collapse
|
6
|
Kostyak JC, Bhavanasi D, Liverani E, McKenzie SE, Kunapuli SP. Protein kinase C δ deficiency enhances megakaryopoiesis and recovery from thrombocytopenia. Arterioscler Thromb Vasc Biol 2014; 34:2579-85. [PMID: 25359855 DOI: 10.1161/atvbaha.114.304492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE We previously determined that protein kinase C δ (PKCδ) regulates platelet function. However, the function of PKCδ in megakaryopoiesis is unknown. APPROACH AND RESULTS Using PKCδ(-/-) and wild-type littermate mice, we found that deficiency of PKCδ caused an increase in white blood cells and platelet counts, as well as in bone marrow and splenic megakaryocytes (P<0.05). Additionally, the megakaryocyte number and DNA content were enhanced in PKCδ(-/-) mouse bone marrow after culturing with exogenous thrombopoietin compared with wild-type (P<0.05). Importantly, thrombopoietin-induced signaling was also altered with PKCδ deletion because both extracellular signal-regulated kinase and Akt308 phosphorylation were heightened in PKCδ(-/-) megakaryocytes compared with wild-type. Finally, PKCδ(-/-) mice recovered faster and had a heightened rebound thrombocytosis after thrombocytopenic challenge. CONCLUSIONS These data suggest that PKCδ is an important megakaryopoietic protein, which regulates signaling induced by thrombopoietin and represents a potential therapeutic target.
Collapse
Affiliation(s)
- John C Kostyak
- From the Sol Sherry Thrombosis Research Center (J.C.K., D.B, S.P.K.), Department of Pharmacology and Department of Physiology (S.P.K.), Temple University School of Medicine, Philadelphia, PA; and Cardeza Division of Hematology, Department of Medicine, Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (S.E.M.)
| | - Dheeraj Bhavanasi
- From the Sol Sherry Thrombosis Research Center (J.C.K., D.B, S.P.K.), Department of Pharmacology and Department of Physiology (S.P.K.), Temple University School of Medicine, Philadelphia, PA; and Cardeza Division of Hematology, Department of Medicine, Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (S.E.M.)
| | - Elisabeta Liverani
- From the Sol Sherry Thrombosis Research Center (J.C.K., D.B, S.P.K.), Department of Pharmacology and Department of Physiology (S.P.K.), Temple University School of Medicine, Philadelphia, PA; and Cardeza Division of Hematology, Department of Medicine, Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (S.E.M.)
| | - Steven E McKenzie
- From the Sol Sherry Thrombosis Research Center (J.C.K., D.B, S.P.K.), Department of Pharmacology and Department of Physiology (S.P.K.), Temple University School of Medicine, Philadelphia, PA; and Cardeza Division of Hematology, Department of Medicine, Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (S.E.M.)
| | - Satya P Kunapuli
- From the Sol Sherry Thrombosis Research Center (J.C.K., D.B, S.P.K.), Department of Pharmacology and Department of Physiology (S.P.K.), Temple University School of Medicine, Philadelphia, PA; and Cardeza Division of Hematology, Department of Medicine, Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (S.E.M.).
| |
Collapse
|
7
|
Kostyak JC, Kunapuli SP. PKCθ is dispensable for megakaryopoiesis. Platelets 2014; 26:610-1. [PMID: 24955517 DOI: 10.3109/09537104.2014.926474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- John C Kostyak
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine , Philadelphia, PA , USA
| | | |
Collapse
|
8
|
Shyu YC, Lee TL, Chen X, Hsu PH, Wen SC, Liaw YW, Lu CH, Hsu PY, Lu MJ, Hwang J, Tsai MD, Hwang MJ, Chen JR, Shen CKJ. Tight regulation of a timed nuclear import wave of EKLF by PKCθ and FOE during Pro-E to Baso-E transition. Dev Cell 2014; 28:409-22. [PMID: 24576425 DOI: 10.1016/j.devcel.2014.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Revised: 11/24/2013] [Accepted: 01/13/2014] [Indexed: 11/28/2022]
Abstract
Erythropoiesis is a highly regulated process during which BFU-E are differentiated into RBCs through CFU-E, Pro-E, PolyCh-E, OrthoCh-E, and reticulocyte stages. Uniquely, most erythroid-specific genes are activated during the Pro-E to Baso-E transition. We show that a wave of nuclear import of the erythroid-specific transcription factor EKLF occurs during the Pro-E to Baso-E transition. We further demonstrate that this wave results from a series of finely tuned events, including timed activation of PKCθ, phosphorylation of EKLF at S68 by P-PKCθ(S676), and sumoylation of EKLF at K74. The latter EKLF modifications modulate its interactions with a cytoplasmic ankyrin-repeat-protein FOE and importinβ1, respectively. The role of FOE in the control of EKLF nuclear import is further supported by analysis of the subcellular distribution patterns of EKLF in FOE-knockout mice. This study reveals the regulatory mechanisms of the nuclear import of EKLF, which may also be utilized in the nuclear import of other factors.
Collapse
Affiliation(s)
- Yu-Chiau Shyu
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Beitou, Taipei 112, Taiwan, ROC; Department of Education and Research, Taipei City Hospital, Da'an, Taipei 103, Taiwan, ROC; Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC.
| | - Tung-Liang Lee
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Xin Chen
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Pang-Hung Hsu
- The Genomics Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Shau-Ching Wen
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Yi-Wei Liaw
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Chi-Huan Lu
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Po-Yen Hsu
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Mu-Jie Lu
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - JauLang Hwang
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC
| | - Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Ming-Jing Hwang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Jim-Ray Chen
- Department of Pathology, Keelung Chang Gung Memorial Hospital, Anle, Keelung 204, Taiwan, ROC; College of Medicine, Chang Gung University, Kwei-Shan, Taoyuan 259, Taiwan, ROC
| | - Che-Kun James Shen
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC.
| |
Collapse
|
9
|
Machlus KR, Thon JN, Italiano JE. Interpreting the developmental dance of the megakaryocyte: a review of the cellular and molecular processes mediating platelet formation. Br J Haematol 2014; 165:227-36. [PMID: 24499183 DOI: 10.1111/bjh.12758] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Platelets are essential for haemostasis, and thrombocytopenia (platelet counts <150 × 10(9) /l) is a major clinical problem encountered across a number of conditions, including immune thrombocytopenic purpura, myelodysplastic syndromes, chemotherapy, aplastic anaemia, human immunodeficiency virus infection, complications during pregnancy and delivery, and surgery. Circulating blood platelets are specialized cells that function to prevent bleeding and minimize blood vessel injury. Platelets circulate in their quiescent form, and upon stimulation, activate to release their granule contents and spread on the affected tissue to create a physical barrier that prevents blood loss. The current model of platelet formation states that large progenitor cells in the bone marrow, called megakaryocytes, release platelets by extending long, branching processes, designated proplatelets, into sinusoidal blood vessels. This review will focus on different factors that impact megakaryocyte development, proplatelet formation and platelet release. It will highlight recent studies on thrombopoeitin-dependent megakaryocyte maturation, endomitosis and granule formation, cytoskeletal contributions to proplatelet formation, the role of apoptosis, and terminal platelet formation and release.
Collapse
Affiliation(s)
- Kellie R Machlus
- Hematology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | | | | |
Collapse
|
10
|
Tsirimonaki E, Fedonidis C, Pneumaticos SG, Tragas AA, Michalopoulos I, Mangoura D. PKCε signalling activates ERK1/2, and regulates aggrecan, ADAMTS5, and miR377 gene expression in human nucleus pulposus cells. PLoS One 2013; 8:e82045. [PMID: 24312401 PMCID: PMC3842981 DOI: 10.1371/journal.pone.0082045] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 10/29/2013] [Indexed: 12/25/2022] Open
Abstract
The protein kinase C (PKC) signaling, a major regulator of chondrocytic differentiation, has been also implicated in pathological extracellular matrix remodeling, and here we investigate the mechanism of PKCε-dependent regulation of the chondrocytic phenotype in human nucleus pulposus (NP) cells derived from herniated disks. NP cells from each donor were successfully propagated for 25+ culture passages, with remarkable tolerance to repeated freeze-and-thaw cycles throughout long-term culturing. More specifically, after an initial downregulation of COL2A1, a stable chondrocytic phenotype was attested by the levels of mRNA expression for aggrecan, biglycan, fibromodulin, and lumican, while higher expression of SOX-trio and Patched-1 witnessed further differentiation potential. NP cells in culture also exhibited a stable molecular profile of PKC isoforms: throughout patient samples and passages, mRNAs for PKC α, δ, ε, ζ, η, ι, and µ were steadily detected, whereas β, γ, and θ were not. Focusing on the signalling of PKCε, an isoform that may confer protection against degeneration, we found that activation with the PKCε-specific activator small peptide ψεRACK led sequentially to a prolonged activation of ERK1/2, increased abundance of the early gene products ATF, CREB1, and Fos with concurrent silencing of transcription for Ki67, and increases in mRNA expression for aggrecan. More importantly, ψεRACK induced upregulation of hsa-miR-377 expression, coupled to decreases in ADAMTS5 and cleaved aggrecan. Therefore, PKCε activation in late passage NP cells may represent a molecular basis for aggrecan availability, as part of an PKCε/ERK/CREB/AP-1-dependent transcriptional program that includes upregulation of both chondrogenic genes and microRNAs. Moreover, this pathway should be considered as a target for understanding the molecular mechanism of IVD degeneration and for therapeutic restoration of degenerated disks.
Collapse
Affiliation(s)
| | | | - Spiros G. Pneumaticos
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- Department of Orthopedics, Athens Medical School, University of Athens, Athens, Greece
| | | | | | - Dimitra Mangoura
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- * E-mail:
| |
Collapse
|
11
|
Williams CM, Harper MT, Poole AW. PKCα negatively regulates in vitro proplatelet formation and in vivo platelet production in mice. Platelets 2013; 25:62-8. [PMID: 23402219 DOI: 10.3109/09537104.2012.761686] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Proplatelet formation is a part of the intricate process by which platelets are generated by their precursor cell, the megakaryocyte. The processes that drive megakaryocyte maturation and platelet production are however still not well understood. The protein kinase C (PKC) family of serine/threonine kinases has been demonstrated as an important regulator of megakaryocyte maturation and proplatelet formation, but little investigation has been made on the individual isoforms. We have previously shown, in mouse models, that PKCα plays a vital role in regulating platelet function, so in this study we aimed to investigate the role of PKCα in megakaryocyte function using the same Prkca(-)(/)(-) mice. We assessed the role of global PKC and specifically PKCα in proplatelet formation in vitro, analyzed polyploidy in Prkca(-)(/)(-)-derived megakaryocytes and followed platelet recovery in platelet-depleted Prkca(-)(/)(-) mice. We show reduced proplatelet formation in the presence of global PKC blockade. However, in the presence of a selective classical PKC isoform inhibitor, Go6976, proplatelet formation was conversely enhanced. PKCα null megakaryocytes also showed enhanced proplatelet formation, as well as a shift to greater polyploidy. In vivo, platelet production was enhanced in response to experimentally induced immune thrombocytopenia. In conclusion, our data indicate that classical PKC isoforms, and more specifically PKCα, are negative regulators of proplatelet formation. PKCα appears to negatively regulate endomitosis, with the enhanced polyploidy observed in Prkca(-)(/)(-)-derived megakaryocytes. In vivo, these observations may culminate in the observed ability of Prkca(-)(/)(-) mice to recover more rapidly from a thrombocytopenic insult.
Collapse
Affiliation(s)
- Christopher M Williams
- School of Physiology and Pharmacology, Bristol Heart Institute, Bristol Platelet Group, Medical Sciences Building, University of Bristol, University Walk , Bristol, BS8 1TD , UK
| | | | | |
Collapse
|
12
|
Gilboa-Geffen A, Hartmann G, Soreq H. Stressing hematopoiesis and immunity: an acetylcholinesterase window into nervous and immune system interactions. Front Mol Neurosci 2012; 5:30. [PMID: 22448158 PMCID: PMC3305920 DOI: 10.3389/fnmol.2012.00030] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 02/22/2012] [Indexed: 01/08/2023] Open
Abstract
Hematopoietic stem cells (HSCs) differentiate and generate all blood cell lineages while maintaining self-renewal ability throughout life. Systemic responses to stressful insults, either psychological or physical exert both stimulating and down-regulating effects on these dynamic members of the immune system. Stress-facilitated division and re-oriented differentiation of progenitor cells modifies hematopoietic cell type composition, while enhancing cytokine production and promoting inflammation. Inversely, stress-induced increases in the neurotransmitter acetylcholine (ACh) act to mitigate inflammatory response and regain homeostasis. This signaling process is terminated when ACh is hydrolyzed by acetylcholinesterase (AChE). Alternative splicing, which is stress-modified, changes the composition of AChE variants, modifying their terminal sequences, susceptibility for microRNA suppression, and sub-cellular localizations. Intriguingly, the effects of stress and AChE variants on hematopoietic development and inflammation in health and disease are both subject to small molecule as well as oligonucleotide-mediated manipulations in vitro and in vivo. The therapeutic agents can thus be targeted to the enzyme protein, its encoding mRNA transcripts, or the regulator microRNA-132, opening new venues for therapeutic interference with multiple nervous and immune system diseases.
Collapse
Affiliation(s)
- Adi Gilboa-Geffen
- The Edmond and Lily Safra Center for Brain Sciences and the Institute of Life Sciences, The Hebrew University of Jerusalem Jerusalem, Israel
| | | | | |
Collapse
|
13
|
Jalagadugula G, Mao G, Kaur G, Dhanasekaran DN, Rao AK. Platelet protein kinase C-theta deficiency with human RUNX1 mutation: PRKCQ is a transcriptional target of RUNX1. Arterioscler Thromb Vasc Biol 2011; 31:921-7. [PMID: 21252065 DOI: 10.1161/atvbaha.110.221879] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Mutations in the hematopoietic transcription factor RUNX1 cause thrombocytopenia and impaired platelet function. In a patient with a heterozygous mutation in RUNX1, we have described decreased platelet pleckstrin phosphorylation and protein kinase C- (PKC-, gene PRKCQ) associated with thrombocytopenia, impaired platelet aggregation, and dense granule secretion. Little is known regarding regulation of PKC- in megakaryocytes and platelets. We have addressed the hypothesis that PRKCQ is a direct transcriptional target of RUNX1. METHODS AND RESULTS In a chromatin immunoprecipitation assay using megakaryocytic cells, there was RUNX1 binding in vivo to PRKCQ promoter region -1225 to -1056 bp containing a RUNX1 consensus site ACCGCA at -1088 to -1069 bp; an electrophoretic mobility shift assay showed RUNX1 binding to the specific site. In RUNX1 overexpression studies, PKC- protein expression and promoter activity were enhanced; mutation of RUNX1 site showed decreased activity even with RUNX1 overexpression. Lastly, PRKCQ promoter activity and PKC- protein were decreased by short interfering RNA knockdown of RUNX1. CONCLUSIONS Our results provide the first evidence that PRKCQ is regulated at the transcriptional level by RUNX1 in megakaryocytic cells and a mechanism for PKC- deficiency associated with RUNX1 haplodeficiency.
Collapse
Affiliation(s)
- Gauthami Jalagadugula
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | | | | | | | | |
Collapse
|
14
|
Redig AJ, Sassano A, Majchrzak-Kita B, Katsoulidis E, Liu H, Altman JK, Fish EN, Wickrema A, Platanias LC. Activation of protein kinase C{eta} by type I interferons. J Biol Chem 2009; 284:10301-14. [PMID: 19211565 DOI: 10.1074/jbc.m807254200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Type I interferons (IFNs) are cytokines with diverse biological properties, including antiviral, growth inhibitory, and immunomodulatory effects. Although several signaling pathways are activated during engagement of the type I IFN receptor and participate in the induction of IFN responses, the mechanisms of generation of specific signals for distinct biological effects remain to be elucidated. We provide evidence that a novel member of the protein kinase C (PKC) family of proteins is rapidly phosphorylated and activated during engagement of the type I IFN receptor. In contrast to other members of the PKC family that are also regulated by IFN receptors, PKCeta does not regulate IFN-inducible transcription of interferon-stimulated genes or generation of antiviral responses. However, its function promotes cell cycle arrest and is essential for the generation of the suppressive effects of IFNalpha on normal and leukemic human myeloid (colony-forming unit-granulocyte macrophage) bone marrow progenitors. Altogether, our studies establish PKCeta as a unique element in IFN signaling that plays a key and essential role in the generation of the regulatory effects of type I IFNs on normal and leukemic hematopoiesis.
Collapse
Affiliation(s)
- Amanda J Redig
- Robert H. Lurie Comprehensive Cancer Center and Division of Hematology/Oncology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Gobbi G, Mirandola P, Sponzilli I, Micheloni C, Malinverno C, Cocco L, Vitale M. Timing and Expression Level of Protein Kinase Cε Regulate the Megakaryocytic Differentiation of Human CD34 Cells. Stem Cells 2009; 25:2322-9. [PMID: 17569788 DOI: 10.1634/stemcells.2006-0839] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Protein kinase C (PKC)-mediated intracellular signaling participates in several key steps of hematopoietic cell differentiation. The epsilon isoform of PKC has been associated with erythroid differentiation as well as with the early phases of megakaryocytic (MK) lineage commitment. Here, we worked on the hypothesis that PKCepsilon expression levels might be modulated during MK differentiation, with a specific role in the early as well as in the late phases of thrombopoiesis. We demonstrate that--at variance with the erythroid lineage development--PKCepsilon is completely downmodulated in TPO-induced CD34 cells from day 6 onward. The forced expression of PKCepsilon in the late phases of MK differentiation delays the phenotypic differentiation of progenitors likely via Bcl-xL upregulation. Moreover, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), known as a negative regulator of early erythroid expansion, is not apoptogenic for thrombopoietin-induced CD34 cells, but rather accelerates their maturation. However, PKCepsilon levels negatively interfere also with the effects of TRAIL in MK differentiation. PKCepsilon can therefore be considered a signaling intermediate whose expression levels are finely tuned, with a virtually opposite kinetic, in erythroid versus megakaryocytic lineages, to adequately respond to the signaling requirements of the specific hematopoietic lineage.
Collapse
Affiliation(s)
- Giuliana Gobbi
- Department of Anatomy, Pharmacology & Forensic Medicine, Human Anatomy Section, University of Parma, Ospedale Maggiore, Via Gramsci, 14, I-43100 Parma, Italy
| | | | | | | | | | | | | |
Collapse
|
16
|
Li X, Meng H, Chen BD. Differentiation-Associated Expression of Conventional Protein Kinase C Isoforms in Primary Cultures of Bone Marrow Cells Induced by M-CSF and G-CSF. ACTA ACUST UNITED AC 2009; 1:47-55. [PMID: 20535245 DOI: 10.5099/aj090100047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Protein kinase C (PKC) -associated signal pathway plays crucial roles in regulation of cell growth, differentiation and apoptosis. The present study focuses on conventional PKC (cPKC) expression and its regulation in primary cultures of bone marrow cells induced to undergo macrophage/granulocyte differentiation by macrophage colony-stimulating factor (M-CSF) or granular colony-stimulating factor (G-CSF). By performing western blot analysis with pan anti-PKC antibodies, we found that PKC is transiently induced by M-CSF, reaching a maximum level by day 2, and then declines and diminishes by day 9 in primary culture of bone marrow cells. In contrast, the expression of PKC along G-CSF induced granulocytic differentiation of bone marrow stem cells is low and increases gradually. Reverse transcription-PCR (RT-PCR) assay was utilized to investigate the expression of PKC isoforms. PKC-alpha is constitutively expressed in bone marrow cells independently of hematopoietic growth factors in cultures. PKC-gamma mRNA is undetectable. Similarly, the expression of PKC-beta is transiently induced by M-CSF, yet steadily increased by G-CSF, in agreement with results obtained from PKC protein expression. Furthermore, gel-shift assay showed that the activation of NF-kappaB is transiently induced by M-CSF but not by G-CSF. These data suggest that PKC expression is involved in both macrophage and granulocyte differentiation by bone marrow committed stem cells. Yet, NF-kappaB activation is only detected in macrophage and not granulocyte differentiation. Thus, we conclude that the PKC-mediated signaling pathway is distinctly involved in bone-marrow cell differentiation induced by M-CSF and G-CSF.
Collapse
Affiliation(s)
- Xiaohua Li
- Barbara Ann Karmanos Cancer Institute, and Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201
| | | | | |
Collapse
|
17
|
PDGF receptor activation induces p120-catenin phosphorylation at serine 879 via a PKCalpha-dependent pathway. Exp Cell Res 2009; 315:39-49. [PMID: 18950621 PMCID: PMC2925109 DOI: 10.1016/j.yexcr.2008.09.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/08/2008] [Accepted: 09/15/2008] [Indexed: 12/14/2022]
Abstract
p120-catenin (p120) is required for cadherin stability and is thought to have a central role in modulating cell-cell adhesion. Several lines of evidence suggest that S/T phosphorylation may regulate p120 activity, but the upstream kinases involved have not been established, nor has a discreet measurable function been assigned to an individual site. To approach these issues, we have generated p120 phospho-specific monoclonal antibodies to several individual phosphorylation sites and are using them to pinpoint upstream kinases and signaling pathways that control p120 activity. Protein Kinase C (PKC) has been implicated as a signaling intermediate in several cadherin-associated cellular activities. Signaling events that activate PKC induce rapid phosphorylation at p120 Serine 879 (S879), suggesting that p120 activity is regulated, in part, by one or more PKC isoforms. Here, we find that physiologic activation of a G-protein coupled receptor (i.e., endothelin receptor), as well as several Receptor Tyrosine Kinases, induce rapid and robust p120 phosphorylation at S879, suggesting that these pathways crosstalk to cadherin complexes via p120. Using Va2 cells and PDGF stimulation, we show for the first time that PDGFR-mediated phosphorylation at this site is dependent on PKCalpha, a conventional PKC isoform implicated previously in disruption of adherens junctions.
Collapse
|
18
|
Wu TT, Hsieh YH, Hsieh YS, Liu JY. Reduction of PKC alpha decreases cell proliferation, migration, and invasion of human malignant hepatocellular carcinoma. J Cell Biochem 2008; 103:9-20. [PMID: 17486587 DOI: 10.1002/jcb.21378] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Protein kinase C (PKC) superfamily play key regulatory roles on the development of cancer. However, the exact role of these enzymes in human hepatocellular carcinoma (HCC) has not been well established. Using the RT-PCR and Western blotting to analyze the levels of PKC isoforms mRNA and protein in the five different differentiated hepatoma cell lines, we found that PKC alpha was highly expressed in the poor-differentiated HCC cell lines (SK-Hep-1 and HA22T/VGH) as compared with that in the well-differentiated HCC cell lines (PLC/PRF/5, Hep3B, and HepG2). When treated with PKC alpha antisense oligonucleotides (ODN), both HA22T/VGH and SK-Hep-1 cells lines showed the reduction of PKC alpha expression, as well as a deceleration in the growth rate and in the level of cyclin D1, but the increase in the levels of p53 and p21(WAF1/CIP1). Moreover, the reduction of PKC alpha expression also inhibited the migratory and invasive potential of both HA22T/VGH and SK-Hep-1 cells lines, and revealed a down-regulation of several migration/invasion-related genes (MMP-1, u-PA, u-PAR, and FAK). These phenomenon were also confirmed by DNA-based small interfering RNA (siRNA) PKC alpha and PKC alpha/beta specific inhibitor Go6976. Thus, the results indicated that PKC alpha may be associated with regulation of cell proliferation/migration/invasion in human poorly differentiated HCC cells, suggesting a role for the PKC alpha in the malignant progression of human HCC.
Collapse
Affiliation(s)
- Trang-Tiau Wu
- Department of Surgery, School of Medicine, College of Medicine, Chung Shan Medical University, Taichung 402, Taiwan
| | | | | | | |
Collapse
|
19
|
Di Baldassarre A, Di Rico M, Di Noia A, Bonfini T, Iacone A, Marchisio M, Miscia S, Alfani E, Migliaccio AR, Stamatoyannopoulos G, Migliaccio G. Protein kinase Calpha is differentially activated during neonatal and adult erythropoiesis and favors expression of a reporter gene under the control of the (A)gamma globin-promoter in cellular models of hemoglobin switching. J Cell Biochem 2007; 101:411-24. [PMID: 17212360 DOI: 10.1002/jcb.21189] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
PKCalpha was found to be expressed (mRNA and protein) throughout the in vitro maturation of primary human erythroblasts but its activity (phosphorylation levels and nuclear localization) was consistently higher in cells derived from human neonatal rather than adult blood. Since the gamma/gamma + beta globin expression ratio represented the major difference between neonatal and adult erythroblasts (58 +/- 12 vs. 7 +/- 3, respectively), we tested the hypothesis that PKCalpha might affect gamma-globin expression by measuring the levels of (A)gamma- or beta-promoter-driven reporter activity in erythroid cells stably (GM979) or transiently (K562, primary adult and neonatal erythroblasts) transfected with a dual microLCRbetaprRluc(A)gammaprFluc reporter in the presence of transient expression of either the constitutively active (sPKCalpha) or catalytically inactive (iPKCalpha) PKCalpha. As further control, GM979 cells were incubated with the PKC inhibitor rottlerin (30 microM). In all the cells analyzed, sPKCalpha significantly increased (by two- to sixfold) the levels of luciferase activity driven by the (A)gamma-promoter and the (A)gamma-F/((A)gamma-F + 2beta-R) expression ratio. In GM979 cells, rottlerin inhibited (by 50%) the (A)gamma-driven luciferase activity and the (A)gamma-F/((A)gamma-F + 2beta-R) expression ratio. These results suggest that different PKC isoforms may exert ontogenetic-specific functions in erythropoiesis and that modulation of PKCalpha might affect the activity of (A)gamma-promoter-driven reporters.
Collapse
|
20
|
Wu TT, Hsieh YH, Wu CC, Hsieh YS, Huang CY, Liu JY. Overexpression of protein kinase C alpha mRNA in human hepatocellular carcinoma: a potential marker of disease prognosis. Clin Chim Acta 2007; 382:54-8. [PMID: 17459358 DOI: 10.1016/j.cca.2007.03.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 03/16/2007] [Accepted: 03/19/2007] [Indexed: 11/30/2022]
Abstract
BACKGROUND Members of the protein kinase C (PKC) isoenzyme family play a central role in the tumorigenesis of several tissues. However, little is known about subtype specific intracellular expression of PKC in human hepatocellular carcinomas. METHODS We investigated PKC isoforms mRNA expression in 42 HCC specimens using reverse transcription polymerase chain reaction analysis, and the correlation between PKC isoforms expression and clinicopathologic parameters. RESULTS We found that PKCalpha, PKCdelta and PKCiota mRNA were significantly increased in HCCs as compared to the corresponding non-cancerous liver tissues. PKCalpha expression also significantly correlated with tumor size (P<0.05) and TNM stage (P<0.05), but PKCdelta and PKCiota did not. The log-rank analysis revealed that patients with higher PKCalpha mRNA expression in the HCC tissues had significantly shorter survival rate than patients with lower PKCalpha mRNA expression (P<0.01). CONCLUSIONS Our results suggested that the PKCalpha may be a prognostic factor for the survival of patients with HCC.
Collapse
Affiliation(s)
- Trang-Tiau Wu
- Department of Surgery, School of Medicine, Medical College, Chung Shan Medical University, Taichung, Taiwan
| | | | | | | | | | | |
Collapse
|
21
|
Pick M, Perry C, Lapidot T, Guimaraes-Sternberg C, Naparstek E, Deutsch V, Soreq H. Stress-induced cholinergic signaling promotes inflammation-associated thrombopoiesis. Blood 2006; 107:3397-406. [PMID: 16380450 DOI: 10.1182/blood-2005-08-3240] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
AbstractTo study the role of the stress-induced “readthrough” acetylcholinesterase splice variant, AChE-R, in thrombopoiesis, we used transgenic mice overexpressing human AChE-R (TgR). Increased AChE hydrolytic activity in the peripheral blood of TgR mice was associated with increased thrombopoietin levels and platelet counts. Bone marrow (BM) progenitor cells from TgR mice presented an elevated capacity to produce mixed (GEMM) and megakaryocyte (Mk) colonies, which showed intensified labeling of AChE-R and its interacting proteins RACK1 and PKC. When injected with bacterial lipopolysaccharide (LPS), parent strain FVB/N mice, but not TgR mice, showed reduced platelet counts. Therefore, we primed human CD34+ cells with the synthetic ARP26 peptide, derived from the cleavable C-terminus of AChE-R prior to transplantation, into sublethally irradiated NOD/SCID mice. Engraftment of human cells (both CD45+ and CD41+ Mk) was significantly increased in mice that received ARP26-primed CD34+ human cells versus mice that received fresh nonprimed CD34+ human cells. Moreover, ARP26 induced polyploidization and proplatelet shedding in human MEG-01 promegakaryotic cells, and human platelet engraftment increased following ex vivo expansion of ARP26-treated CD34+ cells as compared to cells expanded with thrombopoietin and stem cell factor. Our findings implicate AChE-R in thrombopoietic recovery, suggesting new therapeutic modalities for supporting platelet production.
Collapse
Affiliation(s)
- Marjorie Pick
- Department of Hematology, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | | | | | | | | | | | | |
Collapse
|
22
|
Uziel O, Fenig E, Nordenberg J, Beery E, Reshef H, Sandbank J, Birenbaum M, Bakhanashvili M, Yerushalmi R, Luria D, Lahav M. Imatinib mesylate (Gleevec) downregulates telomerase activity and inhibits proliferation in telomerase-expressing cell lines. Br J Cancer 2005; 92:1881-91. [PMID: 15870711 PMCID: PMC2361771 DOI: 10.1038/sj.bjc.6602592] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Imatinib mesylate (IM) is a tyrosine kinase inhibitor, which inhibits phosphorylation of downstream proteins involved in BCR-ABL signal transduction. It has proved beneficial in treating patients with chronic myeloid leukaemia (CML). In addition, IM demonstrates activity against malignant cells expressing c-kit and platelet-derived growth factor receptor (PDGF-R). The activity of IM in the blastic crisis of CML and against various myeloma cell lines suggests that this drug may also target other cellular components. In the light of the important role of telomerase in malignant transformation, we evaluated the effect of IM on telomerase activity (TA) and regulation in various malignant cell lines. Imatinib mesylate caused a dose-dependent inhibition of TA (up to 90% at a concentration of 15 μM IM) in c-kit-expressing SK-N-MC (Ewing sarcoma), SK-MEL-28 (melanoma), RPMI 8226 (myeloma), MCF-7 (breast cancer) and HSC 536/N (Fanconi anaemia) cells as well as in ba/F3 (murine pro-B cells), which do not express c-kit, BCR-ABL or PDGF-R. Imatinib mesylate did not affect the activity of other DNA polymerases. Inhibition of TA was associated with 50% inhibition of proliferation. The inhibition of proliferation was associated with a decrease in the S-phase of the cell cycle and an accumulation of cells in the G2/M phase. No apoptosis was observed. Inhibition of TA was caused mainly by post-translational modifications: dephosphorylation of AKT and, to a smaller extent, by early downregulation of hTERT (the catalytic subunit of the enzyme) transcription. Other steps of telomerase regulation were not affected by IM. This study demonstrates an additional cellular target of IM, not necessarily mediated via known tyrosine kinases, that causes inhibition of TA and cell proliferation.
Collapse
Affiliation(s)
- O Uziel
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - E Fenig
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
- Institute of Oncology, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - J Nordenberg
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - E Beery
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - H Reshef
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - J Sandbank
- Institute of Pathology, Assaf Harofeh Medical Center, Zerifin, Israel
| | - M Birenbaum
- Institute of Pathology, Assaf Harofeh Medical Center, Zerifin, Israel
| | - M Bakhanashvili
- Division of Infectious Diseases, Sheba Medical Center, Tel-Hashomer, Israel
| | - R Yerushalmi
- Institute of Oncology, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - D Luria
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
| | - M Lahav
- Felsenstein Medical Research Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
- Medicine A, Rabin Medical Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva, Israel
- Department of Medicine A, Rabin Medical Center, Beilinson Campus, Sackler School of Medicine, Tel Aviv University, Petah-Tikva 49100, Israel. E-mail:
| |
Collapse
|
23
|
Ahmed S, Shibazaki M, Takeuchi T, Kikuchi H. Protein kinase C? activity is involved in the 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced signal transduction pathway leading to apoptosis in L-MAT, a human lymphoblastic T-cell line. FEBS J 2005; 272:903-15. [PMID: 15691325 DOI: 10.1111/j.1742-4658.2004.04519.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The aromatic hydrocarbon receptor (AhR)-dependent pathway involved in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity has been studied extensively, but the AhR-independent molecular mechanism has not. In previous studies we found that the AhR is not expressed in L-MAT, a human lymphoblastic T-cell line. In this report, we provide the following evidence that the protein kinase C (PKC)theta activity is functionally involved in the AhR-independent signal transduction mechanism that participates in the TCDD-induced L-MAT cell apoptosis. First, only rottlerin, a novel PKC (nPKC)-selective inhibitor, blocked the apoptosis completely, in a dose-dependent manner. Second, PKCtheta was the major nPKC isoform (compared to PKCdelta) expressed in the L-MAT cell line. Third, a cell-permeable myristoylated PKCtheta pseudosubstrate peptide inhibitor also blocked the apoptosis completely, in a dose-dependent manner. Fourth, both rottlerin and myristoylated PKCtheta pseudosubstrate peptide inhibitor completely inhibited PKCtheta kinase activity in vitro at doses that effectively blocked TCDD-induced L-MAT cell apoptosis. TCDD treatment induced a time-dependent activation of nPKC kinase activity in L-MAT cells, and moreover, TCDD induced a translocation of PKCtheta from the cytosolic fraction to the particulate fraction in L-MAT cells. Finally, transient over-expression of a dominant negative PKCtheta (a kinase-dead mutant, K/R 409) in L-MAT cells conferred significant protection against TCDD-induced apoptosis.
Collapse
Affiliation(s)
- Sohel Ahmed
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | | | | | | |
Collapse
|
24
|
van Baal J, de Widt J, Divecha N, van Blitterswijk WJ. Translocation of diacylglycerol kinase theta from cytosol to plasma membrane in response to activation of G protein-coupled receptors and protein kinase C. J Biol Chem 2005; 280:9870-8. [PMID: 15632189 DOI: 10.1074/jbc.m409301200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates the second messenger diacylglycerol (DAG) to phosphatidic acid. We previously identified DGK as one of nine mammalian DGK isoforms and reported on its regulation by interaction with RhoA and by translocation to the plasma membrane in response to noradrenaline. Here, we have investigated how the localization of DGK, fused to green fluorescent protein, is controlled upon activation of G protein-coupled receptors in A431 cells. Extracellular ATP, bradykinin, or thrombin induced DGK translocation from the cytoplasm to the plasma membrane within 2-6 min. This translocation, independent of DGK activity, was preceded by protein kinase C (PKC) translocation and was blocked by PKC inhibitors. Conversely, activation of PKC by 12-O-tetradecanoylphorbol-13-acetate induced DGK translocation. Membrane-permeable DAG (dioctanoylglycerol) also induced DGK translocation but in a PKC (staurosporin)-independent fashion. Mutations in the cysteine-rich domains of DGK abrogated its hormone- and DAG-induced translocation, suggesting that these domains are essential for DAG binding and DGK recruitment to the membrane. We show that DGK interacts selectively with and is phosphorylated by PKCepsilon and -eta and that peptide agonist-induced selective activation of PKCepsilon directly leads to DGK translocation. Our data are consistent with the concept that hormone-induced PKC activation regulates the intracellular localization of DGK, which may be important in the negative regulation of PKCepsilon and/or PKCeta activity.
Collapse
Affiliation(s)
- Jürgen van Baal
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | | | | | | |
Collapse
|
25
|
Vijapurkar U, Fischbach N, Shen W, Brandts C, Stokoe D, Lawrence HJ, Largman C. Protein kinase C-mediated phosphorylation of the leukemia-associated HOXA9 protein impairs its DNA binding ability and induces myeloid differentiation. Mol Cell Biol 2004; 24:3827-37. [PMID: 15082777 PMCID: PMC387750 DOI: 10.1128/mcb.24.9.3827-3837.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
HOXA9 expression is a common feature of acute myeloid leukemia, and high-level expression is correlated with poor prognosis. Moreover, HOXA9 overexpression immortalizes murine marrow progenitors that are arrested at a promyelocytic stage of differentiation when cultured and causes leukemia in recipient mice following transplantation of HOXA9 expressing bone marrow. The molecular mechanisms underlying the physiologic functions and transforming properties of HOXA9 are poorly understood. This study demonstrates that HOXA9 is phosphorylated by protein kinase C (PKC) and casein kinase II and that PKC mediates phosphorylation of purified HOXA9 on S204 as well as on T205, within a highly conserved consensus sequence, in the N-terminal region of the homeodomain. S204 in the endogenous HOXA9 protein was phosphorylated in PLB985 myeloid cells, as well as in HOXA9-immortalized murine marrow cells. This phosphorylation was enhanced by phorbol ester, a known inducer of PKC, and was inhibited by a specific PKC inhibitor. PKC-mediated phosphorylation of S204 decreased HOXA9 DNA binding affinity in vitro and the ability of the endogenous HOXA9 to form cooperative DNA binding complexes with PBX. PKC inhibition significantly reduced the phorbol-ester induced differentiation of the PLB985 hematopoietic cell line as well as HOXA9-immortalized murine bone marrow cells. These data suggest that phorbol ester-induced myeloid differentiation is in part due to PKC-mediated phosphorylation of HOXA9, which decreases the DNA binding of the homeoprotein.
Collapse
Affiliation(s)
- Ulka Vijapurkar
- Department of Medicine, University of California VA Medical Center, San Francisco, California 94121, USA
| | | | | | | | | | | | | |
Collapse
|
26
|
Sun L, Mao G, Rao AK. Association of CBFA2 mutation with decreased platelet PKC-θ and impaired receptor-mediated activation of GPIIb-IIIa and pleckstrin phosphorylation: proteins regulated by CBFA2 play a role in GPIIb-IIIa activation. Blood 2004; 103:948-54. [PMID: 14525764 DOI: 10.1182/blood-2003-07-2299] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe mechanisms by which agonists activate glycoprotein (GP) IIb-IIIa function remain unclear. We have reported data on a patient with thrombocytopenia and impaired receptor-mediated aggregation, phosphorylation of pleckstrin (a protein kinase C [PKC] substrate), and activation of the GPIIb-IIIa complex. Abnormalities in hematopoietic transcription factors have been associated with thrombocytopenia and platelet dysfunction. To define the molecular mechanisms, we amplified from patient platelet RNA exons 3 to 6 of core-binding factor A2 (CBFA2) cDNA, which encompasses the DNA-binding Runt domain; a 13-nucleotide (nt) deletion was found (796-808 nt). The gDNA revealed a heterozygous mutation (G>T) in intron 3 at the splice acceptor site for exon 4, leading to a frameshift with premature termination in the Runt domain. On immunoblotting, platelet CBFA2, PKC-θ, albumin, and IgG were decreased, but pleckstrin, PKC-α, -βI, -βII, -η, -ϵ, -δ, and -ζ, and fibrinogen were normal. Our conclusions are that (1) CBFA2 mutation is associated with not only thrombocytopenia, but also impaired platelet protein phosphorylation and GPIIb-IIIa activation; (2) proteins regulated by CBFA2 are required for inside-out signal transduction-dependent activation of GPIIb-IIIa; and (3) we have documented the first deficiency of a human PKC isozyme (PKC-θ), suggesting a major role of this isozyme in platelet production and function. (Blood. 2004;103:948-954)
Collapse
Affiliation(s)
- Liansheng Sun
- Division of Hematology and Thromboembolic Diseases, Temple University School of Medicine, 3400 N Broad St, OMS 300, Philadelphia, PA 19140, USA
| | | | | |
Collapse
|
27
|
Lee SW, Kwak HB, Chung WJ, Cheong H, Kim HH, Lee ZH. Participation of protein kinase C beta in osteoclast differentiation and function. Bone 2003; 32:217-27. [PMID: 12667549 DOI: 10.1016/s8756-3282(02)00976-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Protein kinase C (PKC) proteins have been shown to be involved in diverse cellular responses of various cell types. In experiments to identify genes regulated during osteoclast differentiation by a cDNA microarray approach, we found that the gene expression of PKC-betaII was upregulated in differentiated cells. Reverse transcription-polymerase chain reaction and Western blotting analyses also showed an increase in PKC-betaI as well as PKC-betaII during osteoclast formation in mouse bone marrow cell cultures in the presence of macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL). Use of an antisense oligonucleotide to PKC-betaII resulted in a reduction in the RANKL-driven osteoclastogenesis. Pharmacological intervention with PKC-beta activity by the specific inhibitor CG53353 suppressed cellular differentiation and fusion processes during osteoclastogenesis and inhibited bone-resorbing function of mature osteoclasts. PKC-beta inhibition abolished the ERK and MEK activation by macrophage-colony stimulating factor and RANKL in osteoclast precursor cells whereas the cytokine-induced NF-kappaB activation was not hampered by the PKC-beta inhibition. Our findings indicate that PKC-beta has a role in regulation of osteoclast formation and function potentially by participating in the ERK signaling pathway of M-CSF and RANKL.
Collapse
Affiliation(s)
- S W Lee
- National Research Laboratory for Bone Metabolism, Chosun University, Gwangju 501-759, South Korea
| | | | | | | | | | | |
Collapse
|
28
|
Szyper-Kravitz M, Uziel O, Shapiro H, Radnay J, Katz T, Rowe JM, Lishner M, Lahav M. Granulocyte colony-stimulating factor administration upregulates telomerase activity in CD34+ haematopoietic cells and may prevent telomere attrition after chemotherapy. Br J Haematol 2003; 120:329-36. [PMID: 12542495 DOI: 10.1046/j.1365-2141.2003.04043.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hematopoietic reconstitution could be associated with premature ageing of the transplanted cells and a high frequency of myelodysplastic syndrome and secondary leukaemia. Telomere length decreases with cell divisions and age, and at a crucial length it is associated with chromosomal instability and cell senescence. Telomerase is a reverse transcriptase enzyme that adds nucleotides to chromosomal ends. Most somatic cells lack telomerase activity yet haematopoietic stem cells retain low levels of telomerase. Some studies have found that chemotherapy and stem cell transplantation lead to the accelerated shortening of telomere length. As granulocyte colony-stimulating factor (G-CSF) is routinely used in the mobilization of stem cells for transplantation, we evaluated its effects on telomerase activity and regulation, and on telomere dynamics, in normal donors and selected lymphoma patients. Administration of G-CSF increased telomerase activity in CD34+ haematopoietic cells compared with controls. In marrow-derived CD34+ cells, telomerase activity increased sevenfold, compared with a 14-fold increase in peripheral-blood-mobilized CD34+ cells. A parallel increase in the expression of human telomerase enzyme reverse transcriptase RNA and protein kinase C alpha occurred. In addition, G-CSF administration to five lymphoma patients after consecutive courses of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy, resulted in telomere length preservation or elongation, as opposed to marked attrition in patients who did not receive growth factors. We conclude that the in vivo administration of G-CSF prevents or attenuates telomere attrition associated with chemotherapy administration. This attenuation may contribute to the preservation of telomere integrity inG-CSF-primed transplanted stem cells.
Collapse
|
29
|
Darley RL, Pearn L, Omidvar N, Sweeney M, Fisher J, Phillips S, Hoy T, Burnett AK. Protein kinase C mediates mutant N-Ras-induced developmental abnormalities in normal human erythroid cells. Blood 2002; 100:4185-92. [PMID: 12393454 DOI: 10.1182/blood-2002-05-1358] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RAS mutations are one of the most frequent molecular abnormalities associated with myeloid leukemia and preleukemia, yet there is a poor understanding of how they contribute to the pathogenesis of these conditions. Here, we describe the consequences of ectopic mutant N-Ras (N-Ras*) expression on normal human erythropoiesis. We show that during early (erythropoietin [EPO]-independent) erythropoiesis, N-Ras* promoted the amplification of a phenotypically primitive but functionally defective subpopulation of CD34(+) erythroblasts. N-Ras* also up-regulated the expression of megakaryocyte antigens on human erythroblasts. Although early erythroblasts expressing N-Ras* were able to respond to erythropoietin and generate mature progeny, this occurred with greatly reduced efficiency, probably explaining the poor colony growth characteristics of these cells. We further report that this oncogene promoted the expression and activation of protein kinase C (PKC) and that the effects of N-Ras* on erythropoiesis could be abrogated or attenuated by inhibition of PKC. Similarly, the effects of this oncogene could be partially mimicked by treatment with PKC agonist. Together, these data suggest that expression of N-Ras* is able to subvert the normal developmental cues that regulate erythropoiesis by activating PKC. This gives rise to phenotypic and functional abnormalities commonly observed in preleukemia, suggesting a direct link between RAS mutations and the pathogenesis of preleukemia.
Collapse
Affiliation(s)
- Richard L Darley
- Leukaemia Research Fund Differentiation Group, Department of Haematology, University of Wales College of Medicine, Cardiff, United Kingdom.
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Moraczewski J, Nowotniak A, Wróbel E, Castagna M, Gautron J, Martelly I. Differential changes in protein kinase C associated with regeneration of rat extensor digitorum longus and soleus muscles. Int J Biochem Cell Biol 2002; 34:938-49. [PMID: 12007632 DOI: 10.1016/s1357-2725(02)00014-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We used a model of crush-induced regeneration in rat in order to characterize biochemically and histologically the implication of protein kinase C (PKC) in muscle repair after damage. In this model, slow soleus and fast extensor digitorum longus (EDL) muscle regeneration proceed differently. PKC activity has been assayed in regenerating muscles and their intact contralateral during the first 14 days following crushing. Degeneration (myolysis) occurring shortly after crush was associated with a marked down-regulation of the enzyme in both wound muscles and notable increase in the corresponding contralateral muscles. Muscle fiber reconstruction in EDL was associated with a rise in PKC activity which peaked at day 7 in regenerating muscle where it was twice higher than in intact muscle. At variance, muscle PKC activity in soleus increased slower than that of EDL and reached later intact level. Western blot analysis and immunohistochemical studies of representative members of the three PKC subfamilies were performed. All the isoform tested were much less expressed in regenerating than in control intact muscles suggesting that the overall PKC activity in regenerating muscles was more activable than in controls. We have shown that PKC isoforms were sequentially expressed during regeneration in both muscle types. PKC theta; being present the earliest, then delta, epsilon and alpha and finally zeta, beta and eta. Some isoforms were differentially expressed according muscle type. PKC delta being more expressed in soleus whereas beta and eta appeared earlier in EDL. Histochemical studies have revealed that the isoforms were differently localized in muscle tissue and that fiber regeneration was associated with PKC alpha translocation from sarcoplasma to sarcolemma. Together these data have shown that multiple PKC isoforms are implicated in the regenerative process acting at different in times and location and suggesting that individual isoform may fulfill distinct functions.
Collapse
Affiliation(s)
- J Moraczewski
- Faculty of Biology, Department of Cytology, University of Warsaw, Miecznikowa 1, Warsaw, Poland.
| | | | | | | | | | | |
Collapse
|
31
|
Mansat-De Mas V, de Thonel A, Gaulin V, Demur C, Laurent G, Quillet-Mary A. Protein kinase C-zeta overexpression induces erythroid phenotype in the monocytic leukaemia cell line U937. Br J Haematol 2002; 118:646-53. [PMID: 12139760 DOI: 10.1046/j.1365-2141.2002.03625.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies have established that protein kinase C-zeta (PKC-zeta) is critical for neuronal cell differentiation. However, the role of PKC-zeta in haematopoietic cell differentiation is less clear. In this study, we have investigated the influence of PKC-zeta overexpression on the phenotype of the human monocytic U937 leukaemic cells. In two PKC-zeta-overexpressing clones (U937 zetaJ and U937 zetaB), PKC-zeta expression levels and activity were three to fourfold higher, and the enzyme accumulated both in the cytoplasm and in the nucleus compared with U937 control cells. PKC-zeta-overexpressing U937 cells exhibited an erythroid phenotype characterized by high levels of glycophorin A, cell haemoglobinization, increased GATA-1 transcripts and protein expression, compared with controls. Immunoprecipitation studies revealed that GATA-1 protein was constitutively phosphorylated in PKC-zeta-overexpressing cells. Moreover, GATA-1 did not interact with PKC-zeta but interacted with ERK1, which was constitutively activated and accumulated in the nucleus of U937 zetaJ. However, ERK1 phosphorylation inhibition by PD098059 did not influence either GATA-1 phosphorylation or GATA-1/ERK1 interaction. Collectively, these results suggest a model in which PKC-zeta induces MEK-dependent ERK1 activation, ERK1 translocation to the nucleus, GATA-1/ERK1 interaction and ERK1-independent GATA-1 phosphorylation resulting in GATA-1 accumulation. To conclude, this study provides evidence for the role of PKC-zeta in erythroid gene regulation.
Collapse
Affiliation(s)
- Véronique Mansat-De Mas
- Institut National de la Santé et de la Recherche Médicale (INSERM) E9910, Institut Claudius Régaud, 20 Rue du pont Saint-Pierre, 31052 Toulouse Cedex, France.
| | | | | | | | | | | |
Collapse
|
32
|
Faulkner NE, Hilfinger JM, Markovitz DM. Protein phosphatase 2A activates the HIV-2 promoter through enhancer elements that include the pets site. J Biol Chem 2001; 276:25804-12. [PMID: 11320078 DOI: 10.1074/jbc.m006454200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Human immunodeficiency virus type 2 (HIV-2) gene expression is regulated by upstream promoter elements, including the peri-Ets (pets) site, which mediate enhancer stimulation following treatment with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). We previously showed that the oncoprotein DEK binds to the pets site in a site-specific manner. In this report, we show that binding to the HIV-2 pets site is modulated by treatment of U937 monocytic cells with TPA, an activator of protein kinase C. TPA treatment resulted in a reduction in the levels of DEK and the formation of a faster migrating pets complex in gel shift assays. We show further that the actions of TPA on pets binding can be duplicated by phosphatase treatment of nuclear proteins and is blocked with okadaic acid, a protein phospatase-2A (PP2A) inhibitor. Finally, we demonstrate that ectopic expression of the catalytic domain of PP2A can activate the HIV-2 enhancer/promoter alone or in synergy with TPA, an effect mediated in part through the pets site. These results suggest that, through an interaction with the protein kinase C pathway, PP2A is strongly involved in regulating HIV-2 enhancer-mediated transcription. This is a consequence of its effects on DEK expression and binding to the pets site, as well as its effects on other promoter elements. These findings have implications not only for HIV-2 transcription but also for multiple cellular processes involving DEK or PP2A.
Collapse
Affiliation(s)
- N E Faulkner
- Department of Internal Medicine, Division of Infectious Diseases, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0640, USA
| | | | | |
Collapse
|
33
|
Dolznig H, Boulmé F, Stangl K, Deiner EM, Mikulits W, Beug H, Müllner EW. Establishment of normal, terminally differentiating mouse erythroid progenitors: molecular characterization by cDNA arrays. FASEB J 2001; 15:1442-4. [PMID: 11387251 DOI: 10.1096/fj.00-0705fje] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- H Dolznig
- Institute of Medical Biochemistry, Division of Molecular Biology, Vienna Biocenter, A-1030 Vienna, Austria
| | | | | | | | | | | | | |
Collapse
|