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Bui S, Mejia I, Díaz B, Wang Y. Adaptation of the Golgi Apparatus in Cancer Cell Invasion and Metastasis. Front Cell Dev Biol 2021; 9:806482. [PMID: 34957124 PMCID: PMC8703019 DOI: 10.3389/fcell.2021.806482] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
The Golgi apparatus plays a central role in normal cell physiology by promoting cell survival, facilitating proliferation, and enabling cell-cell communication and migration. These roles are partially mediated by well-known Golgi functions, including post-translational modifications, lipid biosynthesis, intracellular trafficking, and protein secretion. In addition, accumulating evidence indicates that the Golgi plays a critical role in sensing and integrating external and internal cues to promote cellular homeostasis. Indeed, the unique structure of the mammalian Golgi can be fine-tuned to adapt different Golgi functions to specific cellular needs. This is particularly relevant in the context of cancer, where unrestrained proliferation and aberrant survival and migration increase the demands in Golgi functions, as well as the need for Golgi-dependent sensing and adaptation to intrinsic and extrinsic stressors. Here, we review and discuss current understanding of how the structure and function of the Golgi apparatus is influenced by oncogenic transformation, and how this adaptation may facilitate cancer cell invasion and metastasis.
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Affiliation(s)
- Sarah Bui
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Isabel Mejia
- Department of Internal Medicine, Division of Medical Hematology and Oncology, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States
| | - Begoña Díaz
- Department of Internal Medicine, Division of Medical Hematology and Oncology, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, United States.,David Geffen School of Medicine and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, United States.,Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States
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Santos J, Dolai S, O’Rourke MB, Liu F, Padula MP, Molloy MP, Milthorpe BK. Quantitative Proteomic Profiling of Small Molecule Treated Mesenchymal Stem Cells Using Chemical Probes. Int J Mol Sci 2020; 22:ijms22010160. [PMID: 33375241 PMCID: PMC7795898 DOI: 10.3390/ijms22010160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/04/2022] Open
Abstract
The differentiation of human adipose derived stem cells toward a neural phenotype by small molecules has been a vogue topic in the last decade. The characterization of the produced cells has been explored on a broad scale, examining morphological and specific surface protein markers; however, the lack of insight into the expression of functional proteins and their interactive partners is required to further understand the extent of the process. The phenotypic characterization by proteomic profiling allows for a substantial in-depth analysis of the molecular machinery induced and directing the cellular changes through the process. Herein we describe the temporal analysis and quantitative profiling of neural differentiating human adipose-derived stem cells after sub-proteome enrichment using a bisindolylmaleimide chemical probe. The results show that proteins enriched by the Bis-probe were identified reproducibly with 133, 118, 126 and 89 proteins identified at timepoints 0, 1, 6 and 12, respectively. Each temporal timepoint presented several shared and unique proteins relative to neural differentiation and their interactivity. The major protein classes enriched and quantified were enzymes, structural and ribosomal proteins that are integral to differentiation pathways. There were 42 uniquely identified enzymes identified in the cells, many acting as hubs in the networks with several interactions across the network modulating key biological pathways. From the cohort, it was found by gene ontology analysis that 18 enzymes had direct involvement with neurogenic differentiation.
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Affiliation(s)
- Jerran Santos
- Advanced Tissue Engineering and Stem Cell Biology Group, School of Life Sciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;
- School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;
- Correspondence:
| | - Sibasish Dolai
- Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, NSW 2109, Australia; (S.D.); (F.L.); (M.P.M.)
| | - Matthew B. O’Rourke
- Northern Clinical School, Bowel Cancer & Biomarker Lab, Faculty of Medicine and Health, The University of Sydney, Lvl 8, Kolling Instiute, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia;
| | - Fei Liu
- Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, NSW 2109, Australia; (S.D.); (F.L.); (M.P.M.)
| | - Matthew P. Padula
- School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;
- Proteomics Core Facility, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia
| | - Mark P. Molloy
- Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, NSW 2109, Australia; (S.D.); (F.L.); (M.P.M.)
- Northern Clinical School, Bowel Cancer & Biomarker Lab, Faculty of Medicine and Health, The University of Sydney, Lvl 8, Kolling Instiute, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia;
| | - Bruce K. Milthorpe
- Advanced Tissue Engineering and Stem Cell Biology Group, School of Life Sciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;
- School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia;
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Regulating Apoptosis by Degradation: The N-End Rule-Mediated Regulation of Apoptotic Proteolytic Fragments in Mammalian Cells. Int J Mol Sci 2018; 19:ijms19113414. [PMID: 30384441 PMCID: PMC6274719 DOI: 10.3390/ijms19113414] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/24/2018] [Accepted: 10/27/2018] [Indexed: 12/13/2022] Open
Abstract
A pivotal hallmark of some cancer cells is the evasion of apoptotic cell death. Importantly, the initiation of apoptosis often results in the activation of caspases, which, in turn, culminates in the generation of proteolytically-activated protein fragments with potentially new or altered roles. Recent investigations have revealed that the activity of a significant number of the protease-generated, activated, pro-apoptotic protein fragments can be curbed via their selective degradation by the N-end rule degradation pathways. Of note, previous work revealed that several proteolytically-generated, pro-apoptotic fragments are unstable in cells, as their destabilizing N-termini target them for proteasomal degradation via the N-end rule degradation pathways. Remarkably, previous studies also showed that the proteolytically-generated anti-apoptotic Lyn kinase protein fragment is targeted for degradation by the UBR1/UBR2 E3 ubiquitin ligases of the N-end rule pathway in chronic myeloid leukemia cells. Crucially, the degradation of cleaved fragment of Lyn by the N-end rule counters imatinib resistance in these cells, implicating a possible linkage between the N-end rule degradation pathway and imatinib resistance. Herein, we highlight recent studies on the role of the N-end rule proteolytic pathways in regulating apoptosis in mammalian cells, and also discuss some possible future directions with respect to apoptotic proteolysis signaling.
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Holmgren C, Cornmark L, Lønne GK, Masoumi KC, Larsson C. Molecular characterization of protein kinase C delta (PKCδ)-Smac interactions. BMC BIOCHEMISTRY 2016; 17:11. [PMID: 27216037 PMCID: PMC4877760 DOI: 10.1186/s12858-016-0065-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 05/17/2016] [Indexed: 12/12/2022]
Abstract
Background Protein kinase C δ (PKCδ) is known to be an important regulator of apoptosis, having mainly pro- but also anti-apoptotic effects depending on context. In a previous study, we found that PKCδ interacts with the pro-apoptotic protein Smac. Smac facilitates apoptosis by suppressing inhibitor of apoptosis proteins (IAPs). We previously established that the PKCδ-Smac complex dissociates during induction of apoptosis indicating a functional importance. Because the knowledge on the molecular determinants of the interaction is limited, we aimed at characterizing the interactions between PKCδ and Smac. Results We found that PKCδ binds directly to Smac through its regulatory domain. The interaction is enhanced by the PKC activator TPA and seems to be independent of PKCδ catalytic activity since the PKC kinase inhibitor GF109203X did not inhibit the interaction. In addition, we found that C1 and C2 domains from several PKC isoforms have Smac-binding capacity. Conclusions Our data demonstrate that the Smac-PKCδ interaction is direct and that it is facilitated by an open conformation of PKCδ. The binding is mediated via the PKCδ regulatory domain and both the C1 and C2 domains have Smac-binding capacity. With this study we thereby provide molecular information on an interaction between two apoptosis-regulating proteins.
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Affiliation(s)
- Christian Holmgren
- Lund University, Translational Cancer Research, Medicon Village, Building 404:C3, SE-22363, Lund, Sweden
| | - Louise Cornmark
- Lund University, Translational Cancer Research, Medicon Village, Building 404:C3, SE-22363, Lund, Sweden
| | - Gry Kalstad Lønne
- Lund University, Translational Cancer Research, Medicon Village, Building 404:C3, SE-22363, Lund, Sweden
| | | | - Christer Larsson
- Lund University, Translational Cancer Research, Medicon Village, Building 404:C3, SE-22363, Lund, Sweden.
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Mishra S, Vinayak M. Role of ellagic acid in regulation of apoptosis by modulating novel and atypical PKC in lymphoma bearing mice. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 15:281. [PMID: 26276710 PMCID: PMC4536603 DOI: 10.1186/s12906-015-0810-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 08/07/2015] [Indexed: 12/15/2022]
Abstract
Background Protein kinase C regulates various cellular processes including cell proliferation, cell adhesion, apoptosis, angiogenesis, invasion, and metastasis. Activation of different PKC isozymes results in distinct cellular responses. Novel PKCs are mainly involved in apoptotic process. Atypical PKC subfamily plays a critical role in cell proliferation and apoptosis, cell differentiation and motility. However, Atypical PKCs show contradictory regulation in different tissues or cancer cells. The mechanism of diversified effects is not well explored. Antioxidant ellagic acid shows hepatoprotective, anti-carcinogenic and anti-mutagenic properties. Present study is focused to analyze the effect of ellagic acid on novel and atypical isozymes of PKC in regulation of PKC-mediated apoptosis in liver of lymphoma bearing mice. Implication of ellagic acid treatment to DL mice was analyzed on caspase-3 mediated apoptosis via PKCδ induced activation; and on maintenance of adequate supply of energy during cancer growth. Methods 15–20 weeks old adult DL mice were divided into four groups (n = 6). Group 2, 3, 4 were treated with different doses of ellagic acid (40 mg/kg, 60 mg/kg and 80 mg/kg bw). The mice were sacrificed after 19 days of treatment and liver was used for study. The effect of ellagic acid was determined on expression of novel and atypical PKC isozymes. Apoptotic potentiality of ellagic acid was checked on activities of caspase-3 and PKCδ in terms of their catalytic fragments. Aerobic glycolysis was monitored by LDH activity, especially activity of LDH A. Results Ellagic acid treatment caused up regulation of expression of almost all novel and atypical PKC isozymes. Activities of PKCδ and caspase-3 were enhanced by ellagic acid, however activities of total LDH and LDH-A were inhibited. Conclusion The results show that ellagic acid promotes apoptosis in lymphoma bearing mice via novel and atypical PKCs which involves PKCδ induced caspase-3 activation; and inhibition of glycolytic pathway.
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Cole TR, Igumenova TI. Expression and purification of the N-terminal regulatory domain of Protein Kinase C for biophysical studies. Protein Expr Purif 2015; 110:14-21. [PMID: 25582765 DOI: 10.1016/j.pep.2014.12.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/20/2014] [Accepted: 12/25/2014] [Indexed: 11/25/2022]
Abstract
We report the protocol for heterologous expression and purification of the N-terminal regulatory region of two Protein Kinase C (PKC)(1) isozymes, one conventional and one novel. Previous studies of these domains relied almost exclusively on the fusion constructs with high-molecular-weight solubility fusion partners such as GST and MBP. We developed experimental procedures that enabled us to overcome challenges associated with the amphiphilic character of the regulatory domain and generate sufficient quantities of fusion partner-free proteins for biophysical work. The key features of the protocol are the identity of the cleavable fusion partner, expression conditions, growth medium additives, introduction of mutation/solubility tags, and incorporation of osmolytes. The protein yields are sufficient for cost-effective production of isotopically enriched proteins for NMR work and biophysical studies in general. Our work opens up an avenue for the structural studies of these challenging proteins with high amphiphilic character.
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Affiliation(s)
- Taylor R Cole
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, TX 77843, USA
| | - Tatyana I Igumenova
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, TX 77843, USA.
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Fabian J, Lodrini M, Oehme I, Schier MC, Thole TM, Hielscher T, Kopp-Schneider A, Opitz L, Capper D, von Deimling A, Wiegand I, Milde T, Mahlknecht U, Westermann F, Popanda O, Roels F, Hero B, Berthold F, Fischer M, Kulozik AE, Witt O, Deubzer HE. GRHL1 acts as tumor suppressor in neuroblastoma and is negatively regulated by MYCN and HDAC3. Cancer Res 2014; 74:2604-16. [PMID: 24419085 DOI: 10.1158/0008-5472.can-13-1904] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuroblastoma is an embryonic solid tumor of neural crest origin and accounts for 11% of all cancer-related deaths in children. Novel therapeutic strategies are therefore urgently required. MYCN oncogene amplification, which occurs in 20% of neuroblastomas, is a hallmark of high risk. Here, we aimed to exploit molecular mechanisms that can be pharmacologically addressed with epigenetically modifying drugs, such as histone deacetylase (HDAC) inhibitors. Grainyhead-like 1 (GRHL1), a gene critical for Drosophila neural development, belonged to the genes most strongly responding to HDAC inhibitor treatment of neuroblastoma cells in a genome-wide screen. An increase in the histone H4 pan-acetylation associated with its promoter preceded transcriptional activation. Physically adjacent, HDAC3 and MYCN colocalized to the GRHL1 promoter and repressed its transcription. High-level GRHL1 expression in primary neuroblastomas correlated on transcriptional and translational levels with favorable patient survival and established clinical and molecular markers for favorable tumor biology, including lack of MYCN amplification. Enforced GRHL1 expression in MYCN-amplified neuroblastoma cells with low endogenous GRHL1 levels abrogated anchorage-independent colony formation, inhibited proliferation, and retarded xenograft growth in mice. GRHL1 knockdown in MYCN single-copy cells with high endogenous GRHL1 levels promoted colony formation. GRHL1 regulated 170 genes genome-wide, and most were involved in pathways regulated during neuroblastomagenesis, including nervous system development, proliferation, cell-cell adhesion, cell spreading, and cellular differentiation. In summary, the data presented here indicate a significant role of HDAC3 in the MYCN-mediated repression of GRHL1 and suggest drugs that block HDAC3 activity and suppress MYCN expression as promising candidates for novel treatment strategies of high-risk neuroblastoma.
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Affiliation(s)
- Johannes Fabian
- Authors' Affiliations: Clinical Cooperation Unit Pediatric Oncology; Departments of Biostatistics and Tumor Genetics; Clinical Cooperation Unit Neuropathology; Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ); Departments of Neuropathology and Pediatric Hematology and Oncology, University of Heidelberg, Heidelberg; Transcriptome Analysis Laboratory, University of Goettingen, Goettingen; St. Lukas Klinik Solingen, Solingen; Department of Pediatric Hematology and Oncology; and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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Jiang Q, Wang L, Guan Y, Xu H, Niu Y, Han L, Wei YP, Lin L, Chu J, Wang Q, Yang Y, Pei L, Wang JZ, Tian Q. Golgin-84-associated Golgi fragmentation triggers tau hyperphosphorylation by activation of cyclin-dependent kinase-5 and extracellular signal-regulated kinase. Neurobiol Aging 2013; 35:1352-63. [PMID: 24368089 DOI: 10.1016/j.neurobiolaging.2013.11.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 09/23/2013] [Accepted: 11/24/2013] [Indexed: 12/16/2022]
Abstract
Tau hyperphosphorylation is a critical event in Alzheimer's disease, in which the neuronal Golgi fragmentation occurs earlier than tau hyperphosphorylation. However, the intrinsic link between Golgi impairment and tau pathology is missing. By electron microscopy and western blotting, we observed in the present study that the neuronal Golgi fragmentation was increased age-dependently with a correlated tau hyperphosphorylation in the brains of C57BL/6 mice aged from 4 to 16 months. Simultaneously, golgin-84 and Golgi reassembly stacking protein 65, 2 important Golgi matrix proteins, were decreased in the brains of elder mice. Further studies in HEK293/tau cells showed that Golgi-disturbing agents, brefeldin A and nocodazole induced tau hyperphosphorylation. Knockdown of golgin-84, not Golgi reassembly stacking protein 65, by small interfering RNA was sufficient to induce tau hyperphosphorylation, while over-expressing golgin-84 arrested the brefeldin A-induced Golgi fragmentation and tau hyperphosphorylation. Finally, we demonstrated that cyclin-dependent kinase-5 and extracellular signal-regulated kinase were activated after golgin-84 knockdown, and simultaneous inhibition of these kinases abolished the golgin-84 deficit-induced tau hyperphosphorylation. These data suggest Golgi fragmentation could be an upstream event triggering tau hyperphosphorylation through golgin-84 deficit-induced activation of cyclin-dependent kinase-5 and extracellular signal-regulated kinase.
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Affiliation(s)
- Qian Jiang
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Present address: Department of Dermatology, The First Hospital of Wuhan, Wuhan, China
| | - Lu Wang
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Guan
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Xu
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Niu
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li Han
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Ping Wei
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li Lin
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiang Chu
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qun Wang
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Yang
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lei Pei
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian-Zhi Wang
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Qing Tian
- Department of Pathology and Pathophysiology, Ultrastructural Pathology Center, Key Laboratory of Neurological Disease of National Education Ministry and Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Regulation of Golgi signaling and trafficking by the KDEL receptor. Histochem Cell Biol 2013; 140:395-405. [DOI: 10.1007/s00418-013-1130-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2013] [Indexed: 12/31/2022]
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Fassl A, Tagscherer KE, Richter J, Berriel Diaz M, Alcantara Llaguno SR, Campos B, Kopitz J, Herold-Mende C, Herzig S, Schmidt MHH, Parada LF, Wiestler OD, Roth W. Notch1 signaling promotes survival of glioblastoma cells via EGFR-mediated induction of anti-apoptotic Mcl-1. Oncogene 2012; 31:4698-708. [PMID: 22249262 DOI: 10.1038/onc.2011.615] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Notch1-mediated signaling pathway has a central role in the maintenance of neural stem cells and contributes to growth and progression of glioblastomas, the most frequent malignant brain tumors in adults. Here, we demonstrate that the Notch1 receptor promotes survival of glioblastoma cells by regulation of the anti-apoptotic Mcl-1 protein. Notch1-dependent regulation of Mcl-1 occurs cell type dependent at a transcriptional or post-translational level and is mediated by the induction of epidermal growth factor receptor (EGFR). Inhibition of the Notch1 pathway overcomes apoptosis resistance and sensitizes glioblastoma cells to apoptosis induced by ionizing radiation, the death ligand TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) or the Bcl-2/Bcl-XL inhibitor ABT-737. In conclusion, targeting Notch1 might represent a promising novel strategy in the treatment of glioblastomas.
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Affiliation(s)
- A Fassl
- Molecular Tumor Pathology, DKFZ, Heidelberg, Germany
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Wang H, Xiao L, Kazanietz MG. p23/Tmp21 associates with protein kinase Cdelta (PKCdelta) and modulates its apoptotic function. J Biol Chem 2011; 286:15821-31. [PMID: 21454541 DOI: 10.1074/jbc.m111.227991] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
There is emerging evidence that C1 domains, motifs originally identified in PKC isozymes and responsible for binding of phorbol esters and diacylglycerol, interact with the Golgi/endoplasmic reticulum protein p23 (Tmp21). In this study, we investigated whether PKCδ, a kinase widely implicated in apoptosis and inhibition of cell cycle progression, associates with p23 and determined the potential functional implications of this interaction. Using a yeast two-hybrid approach, we found that the PKCδ C1b domain associates with p23 and identified two key residues (Asp(245) and Met(266)) implicated in this interaction. Interestingly, silencing p23 from LNCaP prostate cancer cells using RNAi markedly enhanced PKCδ-dependent apoptosis and activation of PKCδ downstream effectors ROCK and JNK by phorbol 12-myristate 13-acetate. Moreover, translocation of PKCδ to the plasma membrane by phorbol 12-myristate 13-acetate was enhanced in p23-depleted LNCaP cells. Notably, a PKCδ mutant that failed to interact with p23 triggered a strong apoptotic response when expressed in LNCaP cells. In summary, our data compellingly support the concept that C1 domains have dual roles both in lipid and protein associations and provide strong evidence that p23 acts as an anchoring protein that retains PKCδ at the perinuclear region, thus limiting the availability of this kinase for activation in response to stimuli.
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Affiliation(s)
- HongBin Wang
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
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12
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Abstract
The protein processing and trafficking function of the Golgi is intimately linked to multiple intracellular signaling pathways. Assembly of Golgi trafficking structures and lipid sorting at the Golgi complex is controlled and coordinated by specific phosphoinositide kinases and phosphatases. The intra-Golgi transport machinery is also regulated by kinases belonging to several functionally distinct families, for example, MAP kinase signaling is required for mitotic disassembly of the Golgi. However, the Golgi plays an additional, prominent role in compartmentalizing other signaling cascades that originate at the plasma membrane or at other organelles. This article summarizes recent advances in our understanding of the signaling network that converges at the Golgi.
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Affiliation(s)
- Peter Mayinger
- Division of Nephrology and Hypertension and Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR 97239, USA.
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Tan F, Ghosh S, Mbeunkui F, Thomas R, Weiner JA, Ofori-Acquah SF. Essential role for ALCAM gene silencing in megakaryocytic differentiation of K562 cells. BMC Mol Biol 2010; 11:91. [PMID: 21126364 PMCID: PMC3003670 DOI: 10.1186/1471-2199-11-91] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 12/02/2010] [Indexed: 01/12/2023] Open
Abstract
Background Activated leukocyte cell adhesion molecule (ALCAM/CD166) is expressed by hematopoietic stem cells. However, its role in hematopoietic differentiation has not previously been defined. Results In this study, we show that ALCAM expression is silenced in erythromegakaryocytic progenitor cell lines. In agreement with this finding, the ALCAM promoter is occupied by GATA-1 in vivo, and a cognate motif at -850 inhibited promoter activity in K562 and MEG-01 cells. Gain-of-function studies showed that ALCAM clusters K562 cells in a process that requires PKC. Induction of megakaryocytic differentiation in K562 clones expressing ALCAM activated PKC-δ and triggered apoptosis. Conclusions There is a lineage-specific silencing of ALCAM in bi-potential erythromegakaryocytic progenitor cell lines. Marked apoptosis of ALCAM-expressing K562 clones treated with PMA suggests that aberrant ALCAM expression in erythromegakaryocytic progenitors may contribute to megakaryocytopenia.
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Affiliation(s)
- Fang Tan
- Department of Pediatrics, Aflac Cancer Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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Nazarenko I, Jenny M, Keil J, Gieseler C, Weisshaupt K, Sehouli J, Legewie S, Herbst L, Weichert W, Darb-Esfahani S, Dietel M, Schäfer R, Ueberall F, Sers C. Atypical protein kinase C zeta exhibits a proapoptotic function in ovarian cancer. Mol Cancer Res 2010; 8:919-34. [PMID: 20501645 DOI: 10.1158/1541-7786.mcr-09-0358] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Intracellular signaling governed by serine/threonine kinases comprises the molecular interface between cell surface receptors and the nuclear transcriptional machinery. The protein kinase C (PKC) family members are involved in the control of many signaling processes directing cell proliferation, motility, and survival. Here, we examined a role of different PKC isoenzymes in protein phosphatase 2A (PP2A) and HRSL3 tumor suppressor-dependent cell death induction in the ovarian carcinoma cell line OVCAR-3. Phosphorylation and activity of PKC isoenzymes were measured in response to PP2A or phosphoinositide 3-kinase inhibition or HRSL3 overexpression. These experiments indicated a regulation of PKC, epsilon, zeta, and iota through PP2A and/or HRSL3, but not of PKCalpha and beta. Using isoform-specific peptide inhibitors and overexpression approaches, we verified a contribution to PP2A- and HRLS3-dependent apoptosis only for PKCzeta, suggesting a proapoptotic function of this kinase. We observed a significant proportion of human ovarian carcinomas expressing high levels of PKCzeta, which correlated with poor prognosis. Primary ovarian carcinoma cells isolated from patients also responded to okadaic acid treatment with increased phosphorylation of PKCzeta and apoptosis induction. Thus, our data indicate a contribution of PKCzeta in survival control in ovarian carcinoma cells and suggest that upregulation or activation of tyrosine kinase receptors in this tumor might impinge onto apoptosis control through the negative regulation of the atypical PKCzeta.
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Affiliation(s)
- Irina Nazarenko
- Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Hermann von Helmholtz Platz 1, Eggenstein-Leopoldshafen, Germany.
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15
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Lønne GK, Masoumi KC, Lennartsson J, Larsson C. Protein kinase Cdelta supports survival of MDA-MB-231 breast cancer cells by suppressing the ERK1/2 pathway. J Biol Chem 2009; 284:33456-65. [PMID: 19833733 DOI: 10.1074/jbc.m109.036186] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mechanisms that mediate apoptosis resistance are attractive therapeutic targets for cancer. Protein kinase Cdelta (PKCdelta) is considered a pro-apoptotic factor in many cell types. In breast cancer, however, it has shown both pro-survival and pro-apoptotic effects. Here, we report for the first time that down-regulation of PKCdelta per se leads to apoptosis of MDA-MB-231 cells. Inhibition of MEK1/2 by either PD98059 or U0126 suppressed the induction of apoptosis of PKCdelta-depleted MDA-MB-231 cells but did not support survival of MCF-7 or MDA-MB-468 cells. Basal ERK1/2 phosphorylation was substantially higher in MDA-MB-231 cells than in the other cell lines. PKCdelta depletion led to even higher ERK1/2 phosphorylation levels and also to lower expression levels of the ERK1/2 phosphatase MKP3. Depletion of MKP3 led to apoptosis and higher levels of ERK1/2 phosphorylation, suggesting that this may be a mechanism mediating the effect of PKCdelta down-regulation. However, PKCdelta silencing also induced increased MEK1/2 phosphorylation, indicating that PKCdelta regulates ERK1/2 phosphorylation both upstream and downstream. Moreover, PKCdelta silencing led to increased levels of the E3 ubiquitin ligase Nedd4, which is a potential regulator of MKP3, because down-regulation led to increased MKP3 levels. Our results highlight PKCdelta as a potential target for therapy of breast cancers with high activity of the ERK1/2 pathway.
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Affiliation(s)
- Gry Kalstad Lønne
- Center for Molecular Pathology, Department of Laboratory Medicine, Lund University, and Malmö University Hospital, Sweden
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16
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Masuoka HC, Mott J, Bronk SF, Werneburg NW, Akazawa Y, Kaufmann SH, Gores GJ. Mcl-1 degradation during hepatocyte lipoapoptosis. J Biol Chem 2009; 284:30039-48. [PMID: 19734538 DOI: 10.1074/jbc.m109.039545] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The mechanisms of free fatty acid-induced lipoapoptosis are incompletely understood. Here we demonstrate that Mcl-1, an anti-apoptotic member of the Bcl-2 family, was rapidly degraded in hepatocytes in response to palmitate and stearate by a proteasome-dependent pathway. Overexpression of a ubiquitin-resistant Mcl-1 mutant in Huh-7 cells attenuated palmitate-mediated Mcl-1 loss and lipoapoptosis; conversely, short hairpin RNA-targeted knockdown of Mcl-1 sensitized these cells to lipoapoptosis. Palmitate-induced Mcl-1 degradation was attenuated by the novel protein kinase C (PKC) inhibitor rottlerin. Of the two human novel PKC isozymes, PKCdelta and PKC, only activation of PKC was observed by phospho-immunoblot analysis. As compared with Jurkat cells, a smaller PKC polypeptide and mRNA were expressed in hepatocytes consistent with an alternative splice variant. Short hairpin RNA-mediated knockdown of PKC reduced Mcl-1 degradation and lipoapoptosis. Likewise, genetic deletion of Pkc also attenuated Mcl-1 degradation and cytotoxicity by palmitate in primary hepatocytes. During treatment with palmitate, rottlerin inhibited phosphorylation of Mcl-1 at Ser(159), a phosphorylation site previously implicated in Mcl-1 turnover. Consistent with these results, an Mcl-1 S159A mutant was resistant to degradation and improved cell survival during palmitate treatment. Collectively, these results implicate PKC-dependent destabilization of Mcl-1 as a mechanism contributing to hepatocyte lipoapoptosis.
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Affiliation(s)
- Howard C Masuoka
- Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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17
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Passalacqua M, Pedrazzi M, Sparatore B, Patrone M, Pontremoli S, Melloni E. Functional role of the charge at the T538 residue in the control of protein kinase Cθ. Arch Biochem Biophys 2009; 481:202-9. [DOI: 10.1016/j.abb.2008.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 11/04/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
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18
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Reyland ME. Protein kinase C isoforms: Multi-functional regulators of cell life and death. Front Biosci (Landmark Ed) 2009; 14:2386-99. [PMID: 19273207 DOI: 10.2741/3385] [Citation(s) in RCA: 207] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The protein kinase C (PKC) family consists of 10 related serine/threonine protein kinases some of which are critical regulators of cell proliferation, survival and cell death. While early studies relied on broad spectrum chemical activators or inhibitors of this family, the generation of isoform specific tools has greatly facilitated our understanding of the contribution of specific PKC isoforms to cell proliferation and apoptosis. These studies suggest that PKC-alpha, PKC-epsilon, and the atypical PKC's, PKC-lambda/iota and PKC-zeta, preferentially function to promote cell proliferation and survival, while the novel isoform, PKC-delta is an important regulator of apoptosis. The essential role of this kinase family in both cell survival and apoptosis suggests that specific isoforms may function as molecular sensors, promoting cell survival or cell death depending on environmental cues. Given their central role in cell and tissue homeostasis, it is not surprising that the expression or activity of some of these kinases is altered in human diseases, particularly cancer.
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Affiliation(s)
- Mary E Reyland
- Department of Craniofacial Biology, University of Colorado Health Sciences Center, Aurora, CO 80045, USA.
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19
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Abstract
Protein kinase C (PKC) isoforms comprise a family of lipid-activated enzymes that have been implicated in a wide range of cellular functions. PKCs are modular enzymes comprised of a regulatory domain (that contains the membrane-targeting motifs that respond to lipid cofactors, and in the case of some PKCs calcium) and a relatively conserved catalytic domain that binds ATP and substrates. These enzymes are coexpressed and respond to similar stimulatory agonists in many cell types. However, there is growing evidence that individual PKC isoforms subserve unique (and in some cases opposing) functions in cells, at least in part as a result of isoform-specific subcellular compartmentalization patterns, protein-protein interactions, and posttranslational modifications that influence catalytic function. This review focuses on the structural basis for differences in lipid cofactor responsiveness for individual PKC isoforms, the regulatory phosphorylations that control the normal maturation, activation, signaling function, and downregulation of these enzymes, and the intra-/intermolecular interactions that control PKC isoform activation and subcellular targeting in cells. A detailed understanding of the unique molecular features that underlie isoform-specific posttranslational modification patterns, protein-protein interactions, and subcellular targeting (i.e., that impart functional specificity) should provide the basis for the design of novel PKC isoform-specific activator or inhibitor compounds that can achieve therapeutically useful changes in PKC signaling in cells.
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Affiliation(s)
- Susan F Steinberg
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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20
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Basu A, Persaud SD, Sivaprasad U. Manipulation of PKC isozymes by RNA interference and inducible expression of PKC constructs. Methods Enzymol 2008; 446:141-57. [PMID: 18603120 DOI: 10.1016/s0076-6879(08)01608-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein kinase C (PKC), a family of serine/threonine kinases, plays an important role in apoptosis. Several members of the PKC family act as substrates for caspases. In addition, PKCs can also regulate caspase activation and cell death by apoptosis. The cleavage of PKCs separates the regulatory domain from the catalytic domain. The full-length, the catalytic domain, and the regulatory domain of PKC family members may have distinct function in apoptosis. Delineating the role of protein kinase C (PKC) isozymes in apoptosis has been challenging because of the lack of selective inhibitors of PKC isozymes and difficulty in generating stable cell lines expressing pro-apoptotic PKC isozymes. In this chapter, we describe the use of RNA interference (siRNA) technology and tetracycline-inducible expression of PKC isozymes to study their function in apoptosis.
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Affiliation(s)
- Alakananda Basu
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, USA
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21
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Sunesson L, Hellman U, Larsson C. Protein kinase Cepsilon binds peripherin and induces its aggregation, which is accompanied by apoptosis of neuroblastoma cells. J Biol Chem 2008; 283:16653-64. [PMID: 18408015 DOI: 10.1074/jbc.m710436200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A hallmark of the afflicted nervous tissue in amyotrophic lateral sclerosis is the presence of protein aggregates, which to a large extent contain the intermediate filament protein peripherin. Here we show that activation of protein kinase C (PKC) or overexpression of PKCepsilon induces the aggregation of peripherin in cultured neuroblastoma cells with elevated amounts of peripherin. The formation of aggregates was coupled to an increased apoptosis, suggesting a functional link between these events. Both induction of aggregates and apoptosis were suppressed in cells that had been transfected with small interfering RNAs targeting PKCepsilon. PKCepsilon and peripherin associate as shown by co-immunoprecipitation, and the interaction is dependent on and mediated by the C1b domain of PKCepsilon. The interaction was specific for PKCepsilon since corresponding structures from other isoforms did not co-precipitate peripherin, with the exception for PKCeta and -, which pulled down minute amounts. PKCepsilon interacts with vimentin through the same structures but does not induce its aggregation. When the PKCepsilon C1b domain is expressed in neuroblastoma cells together with peripherin, both phorbol ester-induced peripherin aggregation and apoptosis are abolished, supporting a model in which PKCepsilon through its interaction with peripherin facilitates its aggregation and subsequent cell death. These events may be prevented by expressing molecules that bind peripherin at the same site as PKCepsilon.
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Affiliation(s)
- Lovisa Sunesson
- Center for Molecular Pathology, Lund University, Entrance 78, 3rd floor, Malmö University Hospital, UMAS SE-205 02 Malmö
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22
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Protein kinase C epsilon activates lens mitochondrial cytochrome c oxidase subunit IV during hypoxia. Exp Eye Res 2008; 86:226-34. [DOI: 10.1016/j.exer.2007.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2007] [Revised: 09/26/2007] [Accepted: 10/27/2007] [Indexed: 11/22/2022]
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23
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Ran R, Pan R, Lu A, Xu H, Davis RR, Sharp FR. A novel 165-kDa Golgin protein induced by brain ischemia and phosphorylated by Akt protects against apoptosis. Mol Cell Neurosci 2007; 36:392-407. [PMID: 17888676 DOI: 10.1016/j.mcn.2007.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 07/18/2007] [Accepted: 07/30/2007] [Indexed: 01/02/2023] Open
Abstract
A cDNA encoding a novel protein was cloned from ischemic rat brain and found to be homologous to testis Mea-2 Golgi-associated protein (Golga3). The sequence predicted a 165-kDa protein, and in vitro translated protein exhibited a molecular mass of 165-170 kDa. Because brain ischemia induced the mRNA, and the protein localized to the Golgi apparatus, this protein was designated Ischemia-Inducible Golgin Protein 165 (IIGP165). In HeLa cells, serum and glucose deprivation-induced caspase-dependent cleavage of the IIGP165 protein, after which the IIGP165 fragments translocated to the nucleus. The C-terminus of IIGP165, which contains a LXXLL motif, appears to function as a transcriptional co-regulator. Akt co-localizes with IIGP165 protein in the Golgi in vivo, and phosphorylates IIGP165 on serine residues 345 and 134. Though transfection of IIGP165 cDNA alone does not protect HeLa cells from serum deprivation or Brefeldin-A-triggered cell death, co-transfection of both Akt and IIGP165 cDNA or combined IIGP165-transfection with PDGF treatment significantly protects HeLa cells better than either treatment alone. These data show that Akt phosphorylation of IIGP165 protects against apoptotic cell death, and add to evidence that the Golgi apparatus also plays a role in regulating apoptosis.
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Affiliation(s)
- Ruiqiong Ran
- M.I.N.D. Institute and Department of Neurology, University of California at Davis Medical Center, University of California at Davis, Sacramento, CA 95817, USA.
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24
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Takahashi H, Namiki H. Mechanism of membrane redistribution of protein kinase C by its ATP-competitive inhibitors. Biochem J 2007; 405:331-40. [PMID: 17373912 PMCID: PMC1904528 DOI: 10.1042/bj20070299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ATP-competitive inhibitors of PKC (protein kinase C) such as the bisindolylmaleimide GF 109203X, which interact with the ATP-binding site in the PKC molecule, have also been shown to affect several redistribution events of PKC. However, the reason why these inhibitors affect the redistribution is still controversial. In the present study, using immunoblot analysis and GFP (green fluorescent protein)-tagged PKC, we showed that, at commonly used concentrations, these ATP-competitive inhibitors alone induced redistribution of DAG (diacylglycerol)-sensitive PKCalpha, PKCbetaII, PKCdelta and PKCepsilon, but not atypical PKCzeta, to the endomembrane or the plasma membrane. Studies with deletion and point mutants showed that the DAG-sensitive C1 domain of PKC was required for membrane redistribution by these inhibitors. Furthermore, membrane redistribution was prevented by the aminosteroid PLC (phospholipase C) inhibitor U-73122, although an ATP-competitive inhibitor had no significant effect on acute DAG generation. Immunoblot analysis showed that an ATP-competitive inhibitor enhanced cell-permeable DAG analogue- or phorbol-ester-induced translocation of endogenous PKC. Furthermore, these inhibitors also enhanced [3H]phorbol 12,13-dibutyrate binding to the cytosolic fractions from PKCalpha-GFP-overexpressing cells. These results clearly demonstrate that ATP-competitive inhibitors cause redistribution of DAG-sensitive PKCs to membranes containing endogenous DAG by altering the DAG sensitivity of PKC and support the idea that the inhibitors destabilize the closed conformation of PKC and make the C1 domain accessible to DAG. Most importantly, our findings provide novel insights for the interpretation of studies using ATP-competitive inhibitors, and, especially, suggest caution about the interpretation of the relationship between the redistribution and kinase activity of PKC.
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Affiliation(s)
- Hideyuki Takahashi
- Department of Biology, School of Education, Waseda University, Shinjuku-ku, Tokyo 169-0051, Japan.
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25
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Kheifets V, Mochly-Rosen D. Insight into intra- and inter-molecular interactions of PKC: design of specific modulators of kinase function. Pharmacol Res 2007; 55:467-76. [PMID: 17580120 PMCID: PMC2834269 DOI: 10.1016/j.phrs.2007.04.014] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 03/16/2007] [Accepted: 04/16/2007] [Indexed: 01/23/2023]
Abstract
Protein kinase C (PKC) is a family of kinases that are critical in many cellular events. These enzymes are activated by lipid-derived second messengers, are dependent on binding to negatively charged phospholipids and some members also require calcium to attain full activation. The interaction with lipids and calcium activators is mediated by binding to the regulatory domains C1 and C2. In addition, many protein-protein interactions between PKC and other proteins have been described. These include interactions with adaptor proteins, substrates and cytoskeletal elements. Regulation of the interactions between PKC, small molecules and other proteins is essential for signal transduction to occur. Finally, a number of auto-inhibitory intra-molecular protein-protein interactions have also been identified in PKC. This chapter focuses on mapping the sites for many of these inter- and intra-molecular interactions and how this information may be used to generate selective inhibitors and activators of PKC signaling.
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Affiliation(s)
- Viktoria Kheifets
- Department of Chemical and Systems Biology, Stanford University School of Medicine, CCSR, Rm 3145A, 269 Campus Drive, Stanford, CA 94305-5174, USA
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26
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Ling M, Sunesson L, Larsson C. Comparison of the PKCalpha and the PKCepsilon C1b domains: identification of residues critical for PKCepsilon-mediated neurite induction. J Mol Biol 2007; 368:951-65. [PMID: 17382347 DOI: 10.1016/j.jmb.2007.02.073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 02/12/2007] [Accepted: 02/16/2007] [Indexed: 11/15/2022]
Abstract
We showed earlier that over-expression of protein kinase C (PKC) epsilon induces neurite outgrowth. The effect is mediated by a region (PKCepsilonPSC1V3) encompassing the pseudosubstrate, the two C1 domains and part of the V3 region, and is independent of the catalytic activity of the enzyme. In this region, residues immediately N-terminal of the C1b domain are crucial for neurite outgrowth. However, in this study we show that the PKCepsilon C1b domain itself is necessary for neurite induction, since a mutant in which the PKCepsilon C1b domain has been replaced with the C1b domain from PKCalpha, PKCepsilonPSC1a(alphaC1b)V3 lacks neurite-inducing capacity. The molecular basis for the importance of the PKCepsilon C1b domain was investigated by mutation studies of the PKCalpha C1b domain. Point mutations were done in the PKCalpha C1b domain of the PKCepsilonPSC1a(alphaC1b)V3 construct, in which the PKCalpha residues were mutated into the corresponding residues in PKCepsilon. This highlighted residues in the C-terminal part of the primary sequence of the C1b domain, located in the base of the C1b domain, as important for neurite outgrowth. The mutations S48P, D32K and L49N all influenced neurite induction positively. Furthermore, the mutation of L49N alone was sufficient to make PKCepsilonPSC1a(alphaC1b)V3 neuritogenic in phorbol ester-stimulated cells, and mutation of this residue in full-length PKCepsilon into the corresponding residue in PKCalpha, N291L reduced the neurite-inducing effect of PKCepsilon. In conclusion, we have identified residues in the PKCepsilon C1b domain, in particular Asn49, that are essential for neurite outgrowth.
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Affiliation(s)
- Mia Ling
- Lund University, Department of Laboratory Medicine, Malmö University Hospital, Malmö, Sweden
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27
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Gallegos LL, Kunkel MT, Newton AC. Targeting Protein Kinase C Activity Reporter to Discrete Intracellular Regions Reveals Spatiotemporal Differences in Agonist-dependent Signaling. J Biol Chem 2006; 281:30947-56. [PMID: 16901905 DOI: 10.1074/jbc.m603741200] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase C (PKC) family members transduce an abundance of diverse intracellular signals. Here we address the role of spatial and temporal segregation in signal specificity by measuring the activity of endogenous PKC at defined intracellular locations in real time in live cells. We targeted a genetically encoded fluorescence resonance energy transfer-based reporter for PKC activity, C kinase activity reporter (CKAR) (Violin, J. D., Zhang, J., Tsien, R. Y., and Newton, A. C. (2003) J. Cell Biol. 161, 899-909), to the plasma membrane, Golgi, cytosol, mitochondria, or nucleus by fusing appropriate targeting sequences to the NH2 or COOH terminus of CKAR. Measuring the phosphorylation of the reporter in the presence of PKC inhibitors, activators, and/or phosphatase inhibitors shows that activity at each region is under differential control by phosphatase activity; nuclear activity is completely suppressed by phosphatases, whereas membrane-associated activity is the least suppressed by phosphatases. UTP stimulation of endogenous P2Y receptors in COS 7 cells reveals spatiotemporally divergent PKC responses. Imaging the second messengers Ca2+ and diacylglycerol (DAG) reveal that PKC activity at each location is driven by an initial spike in Ca2+, followed by location-specific diacylglycerol generation. In response to UTP, phosphorylation of GolgiCKAR was sustained the longest, driven by the persistence of DAG, whereas phosphorylation of CytoCKAR was of the shortest duration, driven by high phosphatase activity. Our data reveal that the magnitude and duration of PKC signaling is location-specific and controlled by the level of phosphatase activity and persistence of DAG at each location.
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Affiliation(s)
- Lisa L Gallegos
- Department of Pharmacology, University of California at San Diego, La Jolla, California 92093, USA
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28
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Sallese M, Pulvirenti T, Luini A. The physiology of membrane transport and endomembrane-based signalling. EMBO J 2006; 25:2663-73. [PMID: 16763561 PMCID: PMC1500860 DOI: 10.1038/sj.emboj.7601172] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 05/05/2006] [Indexed: 01/01/2023] Open
Abstract
Some of the important open questions concerning the physiology of the secretory pathway relate to its homeostasis. Secretion involves a number of separate compartments for which their transport activities should be precisely cross-coordinated to avoid gross imbalances in the trafficking system. Moreover, the membrane fluxes across these compartments should be able to adapt to environmental 'requests' and to respond to extracellular signals. How is this regulation effected? Here, we consider evidence that endomembrane-based signalling cascades that are similar in organization to those used at the plasma membrane coordinate membrane traffic. If this is the case, this would also represent a model for a more general inter-organelle signalling network for functionally interconnecting different intracellular activities, a necessity for the maintenance of cellular homeostasis and to express harmonic global cellular responses.
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Affiliation(s)
- Michele Sallese
- Laboratory of Membrane Traffic, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Teodoro Pulvirenti
- Laboratory of Membrane Traffic, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
| | - Alberto Luini
- Laboratory of Membrane Traffic, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy
- Laboratory of Membrane Traffic, Department of Cell Biology and Oncology, Consorzio Mario, Negri Sud, Santa Maria Imbaro, Chieti 66030, Italy. Tel.: +39 0872 570355; Fax: +39 0872 570412; E-mail:
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29
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Corbalán-García S, Gómez-Fernández JC. Protein kinase C regulatory domains: the art of decoding many different signals in membranes. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:633-54. [PMID: 16809062 DOI: 10.1016/j.bbalip.2006.04.015] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 04/27/2006] [Accepted: 04/28/2006] [Indexed: 11/29/2022]
Abstract
Protein kinase C (PKC) is a member of a family of Ser/Thr phosphotransferases that are involved in many cellular signaling pathways. These enzymes possess two regulatory domains, C1 and C2, that are the targets of different second messengers. The purpose of this review is to describe in molecular terms the diverse mechanisms of activation of PKCs in the light of very significant advances made in this field over recent years. The role of some critical amino acid residues concerning activation of the enzymes and their location within known structures of isolated domains will be presented. For example, the recently deduced 3D structures of the C2 domains show that these domains can additionally act as PtdIns(4,5)P(2)-binding or phosphotyrosine-binding modules depending on the isoenzyme. All these capacities to play different roles in the cell wide web of signals underline the notion that we are dealing with a multifunctional family of enzymes which, after 30 years of investigation, we are just beginning to understand.
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Affiliation(s)
- Senena Corbalán-García
- Dpto. de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de Murcia, Apdo. 4021, E-30100 Murcia, Spain.
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30
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Jackson A, Sedaghat K, Minerds K, James C, Tiberi M. Opposing effects of phorbol-12-myristate-13-acetate, an activator of protein kinase C, on the signaling of structurally related human dopamine D1 and D5 receptors. J Neurochem 2006; 95:1387-400. [PMID: 16313517 DOI: 10.1111/j.1471-4159.2005.03476.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The 'cross-talk' between different types of neurotransmitters through second messenger pathways represents a major regulatory mechanism in neuronal function. We investigated the effects of activation of protein kinase C (PKC) on cAMP-dependent signaling by structurally related human D1-like dopaminergic receptors. Human embryonic kidney 293 (HEK293) cells expressing D1 or D5 receptors were pretreated with phorbol-12-myristate-13-acetate (PMA), a potent activator of PKC, followed by analysis of dopamine-mediated receptor activation using whole cell cAMP assays. Unpredictably, PKC activation had completely opposite effects on D1 and D5 receptor signaling. PMA dramatically augmented agonist-evoked D1 receptor signaling, whereas constitutive and dopamine-mediated D5 receptor activation were rapidly blunted. RT-PCR and immunoblotting analyses showed that phorbol ester-regulated PKC isozymes (conventional: alpha, betaI, betaII, gamma; novel: delta, epsilon, eta, theta) and protein kinase D (PKCmicro) are expressed in HEK293 cells. PMA appears to mediate these contrasting effects through the activation of Ca2+-independent novel PKC isoforms as revealed by specific inhibitors, bisindolylmaleimide I, Gö6976, and Gö6983. The finding that cross-talk between PKC and cAMP pathways can produce such opposite outcomes following the activation of structurally similar D1-like receptor subtypes is novel and further strengthens the view that D1 and D5 receptors serve distinct functions in the mammalian nervous and endocrine systems.
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Affiliation(s)
- Adele Jackson
- Ottawa Health Research Institute, Ottawa Hospital (Civic Campus), and Department of Medicine/Cellular and Molecular Medicine/Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
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31
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Kopecky-Bromberg SA, Martinez-Sobrido L, Palese P. 7a protein of severe acute respiratory syndrome coronavirus inhibits cellular protein synthesis and activates p38 mitogen-activated protein kinase. J Virol 2006; 80:785-93. [PMID: 16378980 PMCID: PMC1346853 DOI: 10.1128/jvi.80.2.785-793.2006] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
It was recently shown that the 7a protein of severe acute respiratory syndrome coronavirus induces biochemical changes associated with apoptosis. In this study, the mechanism by which the 7a protein induces apoptosis was examined. The 7a protein was tested for the ability to inhibit cellular gene expression because several proapoptotic viral proteins with this function have previously been identified. 7a protein inhibited expression of luciferase from an mRNA construct that specifically measures translation, whereas inhibitors of transcription and nucleocytoplasmic transport did not. The inhibition of translation and other cellular processes of gene expression have been associated with the induction of a stress response in cells. Western blot analysis using phosphospecific antibodies indicated that 7a protein activated p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal protein kinase/stress-activated protein kinase. Taken together, these data indicate that the induction of apoptosis by the 7a protein may be related to its ability to inhibit cellular translation and activate p38 MAPK.
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7a protein of severe acute respiratory syndrome coronavirus inhibits cellular protein synthesis and activates p38 mitogen-activated protein kinase. J Virol 2005. [PMID: 16378980 DOI: 10.1128/jvi.80.2.785‐793.2006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
It was recently shown that the 7a protein of severe acute respiratory syndrome coronavirus induces biochemical changes associated with apoptosis. In this study, the mechanism by which the 7a protein induces apoptosis was examined. The 7a protein was tested for the ability to inhibit cellular gene expression because several proapoptotic viral proteins with this function have previously been identified. 7a protein inhibited expression of luciferase from an mRNA construct that specifically measures translation, whereas inhibitors of transcription and nucleocytoplasmic transport did not. The inhibition of translation and other cellular processes of gene expression have been associated with the induction of a stress response in cells. Western blot analysis using phosphospecific antibodies indicated that 7a protein activated p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal protein kinase/stress-activated protein kinase. Taken together, these data indicate that the induction of apoptosis by the 7a protein may be related to its ability to inhibit cellular translation and activate p38 MAPK.
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Maissel A, Marom M, Shtutman M, Shahaf G, Livneh E. PKCeta is localized in the Golgi, ER and nuclear envelope and translocates to the nuclear envelope upon PMA activation and serum-starvation: C1b domain and the pseudosubstrate containing fragment target PKCeta to the Golgi and the nuclear envelope. Cell Signal 2005; 18:1127-39. [PMID: 16242915 DOI: 10.1016/j.cellsig.2005.09.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 09/09/2005] [Indexed: 11/27/2022]
Abstract
Protein kinase C (PKC) represents a family of serin/threonine kinases, playing a central role in the regulation of cell growth, differentiation and transformation. These enzymes differ in their primary structure, biochemical properties, tissue distribution and subcellular localization. The specific cellular functions of PKC isoforms are largely controlled by their localization. PKCeta, a member of the novel subfamily, is expressed predominantly in epithelial tissues. However, not much is known with respect to its mechanism of activation and regulation. Our recent studies suggest its role in cell cycle control. Here we show that PKCeta is localized at the Golgi apparatus, ER and the nuclear envelope. Furthermore, using GFP-fusion proteins of the different functional domains of PKCeta we deciphered the specific structural domains of the protein responsible for its apparent localization. We show that the cysteine-rich repeat C1b is responsible for its Golgi localization, while for its presence at the ER/nuclear envelope the pseudosubstrate containing fragment coupled to the C1 domain is required. In response to short-term activation by PMA we show translocation of PKCeta to the plasma membrane and the nuclear envelope. We demonstrate that the C1b is sufficient for its translocation to the plasma membrane. Interestingly, accumulation of PKCeta at the nuclear envelope also occurred in response to serum-starvation. It should be noted that interaction of PKCeta with the cyclin E/Cdk2 complex at the perinuclear region was recently reported by us in response to serum-starvation. Thus, our studies demonstrate translocation of PKCeta to the nuclear envelope, and suggest that the spatial regulation of PKCeta could be important for its cellular functions including effects on cell cycle control and involvement in tumor promotion.
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Affiliation(s)
- Adva Maissel
- Department of Microbiology and Immunology, Faculty of Health Sciences and the Cancer Research Center, Ben Gurion University, Beer Sheva 84105, Israel
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Okhrimenko H, Lu W, Xiang C, Ju D, Blumberg PM, Gomel R, Kazimirsky G, Brodie C. Roles of Tyrosine Phosphorylation and Cleavage of Protein Kinase Cδ in Its Protective Effect Against Tumor Necrosis Factor-related Apoptosis Inducing Ligand-induced Apoptosis. J Biol Chem 2005; 280:23643-52. [PMID: 15774464 DOI: 10.1074/jbc.m501374200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Protein kinase Cdelta (PKCdelta) regulates cell apoptosis in a cell- and stimulus-specific manner. Here, we studied the role of PKCdelta in the apoptotic effect of TRAIL in glioma cells. We found that transfection of the cells with a PKCdelta kinase-dead mutant (K376R) or with a small interfering RNA targeting the PKCdelta mRNA increased the apoptotic effect of tumor necrosis factor-related apoptosis inducing ligand (TRAIL), whereas overexpression of PKCdelta decreased it. PKCdelta acted downstream of caspase 8 and upstream of cytochrome c release from the mitochondria. TRAIL induced cleavage of PKCdelta within 2-3 h of treatment, which was abolished by caspase 3, 8, and 9 inhibitors. The cleavage of PKCdelta was essential for its protective effect because overexpression of a caspase-resistant mutant (PKCdeltaD327A) did not protect glioma cells from TRAIL-induced apoptosis but rather increased it. TRAIL induced translocation of PKCdelta to the perinuclear region and the endoplasmic reticulum and phosphorylation of PKCdelta on tyrosine 155. Using a PKCdeltaY155F mutant, we found that the phosphorylation of PKCdelta on tyrosine 155 was essential for the cleavage of PKCdelta in response to TRAIL and for its translocation to the endoplasmic reticulum. In addition, phosphorylation of PKCdelta on tyrosine 155 was necessary for the activation of AKT in response to TRAIL. Our results indicate that PKCdelta protects glioma cells from the apoptosis induced by TRAIL and implicate the phosphorylation of PKCdelta on tyrosine 155 and its cleavage as essential factors in the anti-apoptotic effect of PKCdelta.
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Affiliation(s)
- Hana Okhrimenko
- Gonda (Goldschmied) Medical Diagnosis Research Center, Faculty of Life-Sciences, Bar-Ilan University, Ramat-Gan, Israel 52900
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Ling M, Trollér U, Zeidman R, Stensman H, Schultz A, Larsson C. Identification of conserved amino acids N-terminal of the PKC epsilon C1b domain crucial for protein kinase C epsilon-mediated induction of neurite outgrowth. J Biol Chem 2005; 280:17910-9. [PMID: 15718244 DOI: 10.1074/jbc.m412036200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that protein kinase C (PKC) epsilon can induce neurite outgrowth independently of its catalytic activity via a region encompassing its C1 domains. In this study we aimed at identifying specific amino acids in this region crucial for induction of neurite outgrowth. Deletion studies demonstrated that only 4 amino acids N-terminal and 20 residues C-terminal of the C1 domains are necessary for neurite induction. The corresponding regions from all other novel isoforms but not from PKCalpha were also neuritogenic. Further mutation studies indicated that amino acids immediately N-terminal of the C1a domain are important for plasma membrane localization and thereby for neurite induction. Addition of phorbol ester made this construct neurite-inducing. However, mutation of amino acids flanking the C1b domain reduced the neurite-inducing capacity even in the presence of phorbol esters. Sequence alignment highlighted an 8-amino acid-long sequence N-terminal of the C1b domain that is conserved in all novel PKC isoforms. Specifically, we found that mutations of either Phe-237, Val-239, or Met-241 in PKCepsilon completely abolished the neurite-inducing capacity of PKCepsilon C1 domains. Phorbol ester treatment could not restore neurite induction but led to a plasma membrane translocation. Furthermore, if 12 amino acids were included N-terminal of the C1b domain, the C1a domain was dispensable for neurite induction. In conclusion, we have identified a highly conserved sequence N-terminal of the C1b domain that is crucial for neurite induction by PKCepsilon, indicating that this motif may be critical for some morphological effects of PKC.
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Affiliation(s)
- Mia Ling
- Lund University, Molecular Medicine, Malmö University Hospital, 205 02 Malmö, Sweden
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Stensman H, Raghunath A, Larsson C. Autophosphorylation Suppresses Whereas Kinase Inhibition Augments the Translocation of Protein Kinase Cα in Response to Diacylglycerol. J Biol Chem 2004; 279:40576-83. [PMID: 15277524 DOI: 10.1074/jbc.m405560200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have seen that protein kinase Calpha (PKCalpha) is transiently translocated to the plasma membrane by carbachol stimulation of neuroblastoma cells. This is induced by the Ca2+ increase, and PKCalpha does not respond to diacylglycerol (DAG). The unresponsiveness is dependent on structures in the catalytic domain of PKCalpha. This study was designed to investigate if and how the kinase activity and autophosphorylation are involved in regulating the translocation. PKCalpha enhanced green fluorescent protein translocation was studied in living neuroblastoma cells by confocal microscopy. Carbachol stimulation induced a transient translocation of PKCalpha to the plasma membrane and a sustained translocation of kinase-dead PKCalpha. In cells treated with the PKC inhibitor GF109203X, wild-type PKCalpha also showed a sustained translocation. The same effects were seen with PKCbetaI, PKCbetaII, and PKCdelta. Only kinase-dead and not wild-type PKCalpha translocated in response to 1,2-dioctanoylglycerol. To examine whether autophosphorylation regulates relocation to the cytosol, the autophosphorylation sites in PKCalpha were mutated to glutamate, to mimic phosphorylation, or alanine, to mimic the non-phosphorylated protein. After stimulation with carbachol, glutamate mutants behaved like wild-type PKCalpha, whereas alanine mutants behaved like kinase-dead PKCalpha. When the alanine mutants were treated with 1,2-dioctanoylglycerol, all cells showed a sustained translocation of the protein. However, neither carbachol nor GF109203X had any major effects on the level of autophosphorylation, and GF109203X potentiated the translocation of the glutamate mutants. We, therefore, hypothesize that 1) autophosphorylation of PKCalpha limits its sensitivity to DAG and 2) that kinase inhibitors augment the DAG sensitivity of PKCalpha, perhaps by destabilizing the closed conformation.
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Affiliation(s)
- Helena Stensman
- Lund University, Molecular Medicine, Entrance 78, 3rd Floor, Malmö University Hospital, 205 02 Malmö, Sweden
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Schultz A, Larsson C. Ceramide influences neurite outgrowth and neuroblastoma cell apoptosis regulated by novel protein kinase C isoforms. J Neurochem 2004; 89:1427-35. [PMID: 15189345 DOI: 10.1111/j.1471-4159.2004.02431.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously seen that protein kinase C (PKC) epsilon induces neurite outgrowth and that PKCdelta and PKCtheta elicit apoptosis in neuroblastoma cells. In this study we investigate the effects of cell-permeable C(2)-ceramide on these events in SK-N-BE(2) neuroblastoma cells. C(2)-ceramide abolishes neurite formation induced by overexpression of PKCepsilon and, in cells overexpressing PKCdelta or PKCtheta, ceramide treatment leads to apoptosis. Exposure to C(2)-ceramide also suppressed neurite outgrowth induced by retinoic acid, but ceramide did not abrogate neurite induction by treatment with the ROCK inhibitor Y-27632, demonstrating that C(2)-ceramide is not a general inhibitor of neurite outgrowth. The neurite-suppressing effect occurs independently of cell-death. Furthermore, C(2)-ceramide relocated PKCepsilon and the isolated regulatory domain of PKCepsilon from the cytosol to the perinuclear region. In contrast, neither the localization of PKCdelta nor of PKCtheta was affected by C(2)-ceramide. Taken together, the data indicate that the neurite-inhibiting effect of C(2)-ceramide treatment may be caused by a re-localization of PKCepsilon and thus identify a functional consequence of ceramide effects on PKCepsilon localization.
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Affiliation(s)
- Anna Schultz
- Molecular Medicine, Lund University, 205-02 Malmö, Sweden
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Schultz A, Ling M, Larsson C. Identification of an amino acid residue in the protein kinase C C1b domain crucial for its localization to the Golgi network. J Biol Chem 2004; 279:31750-60. [PMID: 15145947 DOI: 10.1074/jbc.m313017200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase C (PKC) isoforms have been reported to be targeted to the Golgi complex via their C1 domains. We have shown recently that the regulatory domain of PKC induces apoptosis in neuroblastoma cells and that this effect is correlated to Golgi localization via the C1b domain. This study was designed to identify specific residues in the C1 domains that mediate Golgi localization. We demonstrate that the isolated C1b domains from PKCalpha, -delta, -epsilon, -eta, and - are targeted to the Golgi complex, whereas the corresponding C1a domains localize throughout the cell. Sequence alignment showed that amino acid residues corresponding to Glu-246 and Met-267 in PKC are conserved among C1b but absent from C1a domains. Mutation of Met-267, but not of Glu-246, to glycine abolished the Golgi localization of the isolated C1b domain and the regulatory domain of PKC. The mutated PKC regulatory domain constructs lacking Golgi localization were unable to induce apoptosis, suggesting a direct correlation between Golgi localization and apoptotic activity of PKC regulatory domain. Mutation of analogous residues in the C1b domain of PKCepsilon abrogated its Golgi localization, demonstrating that this effect is not restricted to one PKC isoform. The abolished Golgi localization did not affect neurite induction by PKCepsilon. However, the PKCepsilon mutant did not relocate to the Golgi network in response to ceramide and ceramide did not suppress the neurite-inducing capacity of the protein. Thus, the specific mutations in the C1b domain influence both the localization and function of full-length PKCepsilon.
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Affiliation(s)
- Anna Schultz
- Department of Laboratory Medicine, Molecular Medicine, Lund University, 205 02 Malmö, Sweden
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Sparatore B, Passalacqua M, Pedrazzi M, Ledda S, Patrone M, Gaggero D, Pontremoli S, Melloni E. Role of the kinase activation loop on protein kinase C theta activity and intracellular localisation. FEBS Lett 2003; 554:35-40. [PMID: 14596910 DOI: 10.1016/s0014-5793(03)01073-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Multiple protein kinase C (PKC) theta species, identified in an erythroleukaemia cell line, have been characterised in terms of their molecular properties and intracellular distribution. PKCthetas localised in the detergent-soluble cell fraction have an Mr of 76 kDa (theta-76) and contain Thr538 or pThr538 in the kinase activation loop. In contrast, PKCthetas localised in the Golgi complex have an Mr of 85 kDa (theta-85) and, although unphosphorylated at Thr538, are catalytically active. Strikingly, only theta-76 species which are unphosphorylated at Thr538 can undergo autocatalytic conversion to theta-85. Moreover, a Thr538-->Ala PKCtheta mutant is constitutively localised in the Golgi complex, confirming that changes in the phosphorylation state of this residue play a pivotal role in the overall control of catalytic properties and localisation of this kinase.
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Affiliation(s)
- Bianca Sparatore
- Department of Experimental Medicine, Biochemistry Section, University of Genoa, Viale Benedetto XV, 16132 Genoa, Italy.
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