1
|
D'Amico AE, Wong AC, Zajd CM, Zhang X, Murali A, Trebak M, Lennartz MR. PKC-ε regulates vesicle delivery and focal exocytosis for efficient IgG-mediated phagocytosis. J Cell Sci 2021; 134:jcs258886. [PMID: 34622926 PMCID: PMC8627556 DOI: 10.1242/jcs.258886] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 09/27/2021] [Indexed: 11/20/2022] Open
Abstract
Protein kinase C (PKC)-ε is required for membrane addition during IgG-mediated phagocytosis, but its role in this process is ill defined. Here, we performed high-resolution imaging, which reveals that PKC-ε exits the Golgi and enters phagosomes on vesicles that then fuse. TNF and PKC-ε colocalize at the Golgi and on vesicles that enter the phagosome. Loss of PKC-ε and TNF delivery upon nocodazole treatment confirmed vesicular transport on microtubules. That TNF+ vesicles were not delivered in macrophages from PKC-ε null mice, or upon dissociation of the Golgi-associated pool of PKC-ε, implies that Golgi-tethered PKC-ε is a driver of Golgi-to-phagosome trafficking. Finally, we established that the regulatory domain of PKC-ε is sufficient for delivery of TNF+ vesicles to the phagosome. These studies reveal a novel role for PKC-ε in focal exocytosis - its regulatory domain drives Golgi-derived vesicles to the phagosome, whereas catalytic activity is required for their fusion. This is one of the first examples of a PKC requirement for vesicular trafficking and describes a novel function for a PKC regulatory domain. This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Anna E. D'Amico
- Albany Medical College, 47 New Scotland Ave MC-165, Albany, NY 12208, USA
| | - Alexander C. Wong
- Albany Medical College, 47 New Scotland Ave MC-165, Albany, NY 12208, USA
| | - Cheryl M. Zajd
- Albany Medical College, 47 New Scotland Ave MC-165, Albany, NY 12208, USA
| | - Xuexin Zhang
- Penn State College of Medicine, 500 University Dr., Hershey, PA 17033, USA
| | - Ananya Murali
- Albany Medical College, 47 New Scotland Ave MC-165, Albany, NY 12208, USA
| | - Mohamed Trebak
- University of Pittsburgh School of Medicine, 2550 Terrace Street, Pittsburgh, PA 15231, USA
| | | |
Collapse
|
2
|
The PKC universe keeps expanding: From cancer initiation to metastasis. Adv Biol Regul 2020; 78:100755. [PMID: 33017725 DOI: 10.1016/j.jbior.2020.100755] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 02/08/2023]
Abstract
Classical and novel protein kinase C (PKC) isozymes (c/nPKCs), members of the PKC family that become activated by the lipid second messenger diacylglycerol (DAG) and phorbol esters, exert a myriad of cellular effects that impact proliferative and motile cellular responses. While c/nPKCs have been indisputably associated with tumor promotion, their roles exceed by far their sole involvement as promoter kinases. Indeed, this original dogma has been subsequently redefined by the introduction of several new concepts: the identification of tumor suppressing roles for c/nPKCs, and their participation in early and late stages of carcinogenesis. This review dives deep into the intricate roles of c/nPKCs in cancer initiation as well as in the different stages of the metastatic cascade, with great emphasis in their involvement in cancer cell motility via regulation of small Rho GTPases, the production of extracellular matrix (ECM)-degrading proteases, and the epithelial-to-mesenchymal transition (EMT) program required for the acquisition of highly invasive traits. Here, we highlight functional interplays between either PKCα or PKCε and mesenchymal features that may ultimately contribute to anticancer drug resistance in cellular and animal models. We also introduce the novel hypothesis that c/nPKCs may be implicated in the control of immune evasion through the regulation of immune checkpoint protein expression. In summary, dissecting the colossal complexity of c/nPKC signaling in the wide spectrum of cancer progression may bring new opportunities for the development of meaningful tools aiding for cancer prognosis and therapy.
Collapse
|
3
|
Isakov N. Protein kinase C (PKC) isoforms in cancer, tumor promotion and tumor suppression. Semin Cancer Biol 2017; 48:36-52. [PMID: 28571764 DOI: 10.1016/j.semcancer.2017.04.012] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/22/2017] [Accepted: 04/25/2017] [Indexed: 12/27/2022]
Abstract
The AGC family of serine/threonine kinases (PKA, PKG, PKC) includes more than 60 members that are critical regulators of numerous cellular functions, including cell cycle and differentiation, morphogenesis, and cell survival and death. Mutation and/or dysregulation of AGC kinases can lead to malignant cell transformation and contribute to the pathogenesis of many human diseases. Members of one subgroup of AGC kinases, the protein kinase C (PKC), have been singled out as critical players in carcinogenesis, following their identification as the intracellular receptors of phorbol esters, which exhibit tumor-promoting activities. This observation attracted the attention of researchers worldwide and led to intense investigations on the role of PKC in cell transformation and the potential use of PKC as therapeutic drug targets in cancer diseases. Studies demonstrated that many cancers had altered expression and/or mutation of specific PKC genes. However, the causal relationships between the changes in PKC gene expression and/or mutation and the direct cause of cancer remain elusive. Independent studies in normal cells demonstrated that activation of PKC is essential for the induction of cell activation and proliferation, differentiation, motility, and survival. Based on these observations and the general assumption that PKC isoforms play a positive role in cell transformation and/or cancer progression, many PKC inhibitors have entered clinical trials but the numerous attempts to target PKC in cancer has so far yielded only very limited success. More recent studies demonstrated that PKC function as tumor suppressors, and suggested that future clinical efforts should focus on restoring, rather than inhibiting, PKC activity. The present manuscript provides some historical perspectives on the tumor promoting function of PKC, reviewing some of the observations linking PKC to cancer progression, and discusses the role of PKC in the pathogenesis of cancer diseases and its potential usage as a therapeutic target.
Collapse
Affiliation(s)
- Noah Isakov
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences and the Cancer Research Center, Ben Gurion University of the Negev, P.O.B. 653, Beer Sheva 84105, Israel.
| |
Collapse
|
4
|
Hanes CM, D'Amico AE, Ueyama T, Wong AC, Zhang X, Hynes WF, Barroso MM, Cady NC, Trebak M, Saito N, Lennartz MR. Golgi-Associated Protein Kinase C-ε Is Delivered to Phagocytic Cups: Role of Phosphatidylinositol 4-Phosphate. THE JOURNAL OF IMMUNOLOGY 2017; 199:271-277. [PMID: 28539432 DOI: 10.4049/jimmunol.1700243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/28/2017] [Indexed: 11/19/2022]
Abstract
Protein kinase C-ε (PKC-ε) at phagocytic cups mediates the membrane fusion necessary for efficient IgG-mediated phagocytosis. The C1B and pseudosubstrate (εPS) domains are necessary and sufficient for this concentration. C1B binds diacylglycerol; the docking partner for εPS is unknown. Liposome assays revealed that the εPS binds phosphatidylinositol 4-phosphate (PI4P) and PI(3,5)P2 Wortmannin, but not LY294002, inhibits PKC-ε concentration at cups and significantly reduces the rate of phagocytosis. As Wortmannin inhibits PI4 kinase, we hypothesized that PI4P mediates the PKC-ε concentration at cups and the rate of phagocytosis. PKC-ε colocalizes with the trans-Golgi network (TGN) PI4P reporter, P4M, suggesting it is tethered at the TGN. Real-time imaging of GFP-PKC-ε-expressing macrophages revealed a loss of Golgi-associated PKC-ε during phagocytosis, consistent with a Golgi-to-phagosome translocation. Treatment with PIK93, a PI4 kinase inhibitor, reduces PKC-ε at both the TGN and the cup, decreases phagocytosis, and prevents the increase in capacitance that accompanies membrane fusion. Finally, expression of the Golgi-directed PI4P phosphatase, hSac1-K2A, recapitulates the PIK93 phenotype, confirming that Golgi-associated PI4P is critical for efficient phagocytosis. Together these data are consistent with a model in which PKC-ε is tethered to the TGN via an εPS-PI4P interaction. The TGN-associated pool of PKC-ε concentrates at the phagocytic cup where it mediates the membrane fusion necessary for phagocytosis. The novelty of these data lies in the demonstration that εPS binds PI4P and PI(3,5)P2 and that PI4P is necessary for PKC-ε localization at the TGN, its translocation to the phagocytic cup, and the membrane fusion required for efficient Fc [γ] receptor-mediated phagocytosis.
Collapse
Affiliation(s)
- Cheryl M Hanes
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208
| | - Anna E D'Amico
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208
| | - Takehiko Ueyama
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Alexander C Wong
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - W Frederick Hynes
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, NY 12203; and
| | - Margarida M Barroso
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY 12208
| | - Nathaniel C Cady
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, NY 12203; and
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Naoaki Saito
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Michelle R Lennartz
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, NY 12208;
| |
Collapse
|
5
|
Protein Kinase C Epsilon Cooperates with PTEN Loss for Prostate Tumorigenesis through the CXCL13-CXCR5 Pathway. Cell Rep 2017; 19:375-388. [PMID: 28402859 DOI: 10.1016/j.celrep.2017.03.042] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 02/01/2017] [Accepted: 03/13/2017] [Indexed: 11/22/2022] Open
Abstract
PKCε, an oncogenic member of the PKC family, is aberrantly overexpressed in epithelial cancers. To date, little is known about functional interactions of PKCε with other genetic alterations, as well as the effectors contributing to its tumorigenic and metastatic phenotype. Here, we demonstrate that PKCε cooperates with the loss of the tumor suppressor Pten for the development of prostate cancer in a mouse model. Mechanistic analysis revealed that PKCε overexpression and Pten loss individually and synergistically upregulate the production of the chemokine CXCL13, which involves the transcriptional activation of the CXCL13 gene via the non-canonical nuclear factor κB (NF-κB) pathway. Notably, targeted disruption of CXCL13 or its receptor, CXCR5, in prostate cancer cells impaired their migratory and tumorigenic properties. In addition to providing evidence for an autonomous vicious cycle driven by PKCε, our studies identified a compelling rationale for targeting the CXCL13-CXCR5 axis for prostate cancer treatment.
Collapse
|
6
|
Gutierrez-Uzquiza A, Lopez-Haber C, Jernigan DL, Fatatis A, Kazanietz MG. PKCε Is an Essential Mediator of Prostate Cancer Bone Metastasis. Mol Cancer Res 2015; 13:1336-46. [PMID: 26023164 DOI: 10.1158/1541-7786.mcr-15-0111] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/20/2015] [Indexed: 11/16/2022]
Abstract
UNLABELLED The bone is a preferred site for metastatic homing of prostate cancer cells. Once prostate cancer patients develop skeletal metastases, they eventually succumb to the disease; therefore, it is imperative to identify key molecular drivers of this process. This study examines the involvement of protein kinase C epsilon (PKCε), an oncogenic protein that is abnormally overexpressed in human tumor specimens and cell lines, on prostate cancer cell bone metastasis. PC3-ML cells, a highly invasive prostate cancer PC3 derivative with bone metastatic colonization properties, failed to induce skeletal metastatic foci upon inoculation into nude mice when PKCε expression was silenced using shRNA. Interestingly, while PKCε depletion had only marginal effects on the proliferative, adhesive, and migratory capacities of PC3-ML cells in vitro or in the growth of xenografts upon s.c. inoculation, it caused a significant reduction in cell invasiveness. Notably, PKCε was required for transendothelial cell migration (TEM) as well as for the growth of PC3-ML cells in a bone biomimetic environment. At a mechanistic level, PKCε depletion abrogates the expression of IL1β, a cytokine implicated in skeletal metastasis. Taken together, PKCε is a key factor for driving the formation of bone metastasis by prostate cancer cells and is a potential therapeutic target for advanced stages of the disease. IMPLICATIONS This study uncovers an important new function of PKCε in the dissemination of cancer cells to the bone; thus, highlighting the promising potential of this oncogenic kinase as a therapeutic target for skeletal metastasis.
Collapse
Affiliation(s)
- Alvaro Gutierrez-Uzquiza
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cynthia Lopez-Haber
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Danielle L Jernigan
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Alessandro Fatatis
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania. Program in Biology of Prostate Cancer, Sidney Kimmel Cancer Center, Philadelphia, Pennsylvania
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
| |
Collapse
|
7
|
Garg R, Benedetti LG, Abera MB, Wang H, Abba M, Kazanietz MG. Protein kinase C and cancer: what we know and what we do not. Oncogene 2014; 33:5225-37. [PMID: 24336328 DOI: 10.1038/onc.2013.524] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/20/2013] [Accepted: 10/20/2013] [Indexed: 02/08/2023]
Abstract
Since their discovery in the late 1970s, protein kinase C (PKC) isozymes represent one of the most extensively studied signaling kinases. PKCs signal through multiple pathways and control the expression of genes relevant for cell cycle progression, tumorigenesis and metastatic dissemination. Despite the vast amount of information concerning the mechanisms that control PKC activation and function in cellular models, the relevance of individual PKC isozymes in the progression of human cancer is still a matter of controversy. Although the expression of PKC isozymes is altered in multiple cancer types, the causal relationship between such changes and the initiation and progression of the disease remains poorly defined. Animal models developed in the last years helped to better understand the involvement of individual PKCs in various cancer types and in the context of specific oncogenic alterations. Unraveling the enormous complexity in the mechanisms by which PKC isozymes have an impact on tumorigenesis and metastasis is key for reassessing their potential as pharmacological targets for cancer treatment.
Collapse
Affiliation(s)
- R Garg
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - L G Benedetti
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M B Abera
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - H Wang
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Abba
- Centro de Investigaciones Inmunológicas Básicas y Aplicadas (CINIBA), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M G Kazanietz
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
8
|
Ong ST, Freeley M, Skubis-Zegadło J, Fazil MHUT, Kelleher D, Fresser F, Baier G, Verma NK, Long A. Phosphorylation of Rab5a protein by protein kinase Cϵ is crucial for T-cell migration. J Biol Chem 2014; 289:19420-34. [PMID: 24872409 DOI: 10.1074/jbc.m113.545863] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Rab GTPases control membrane traffic and receptor-mediated endocytosis. Within this context, Rab5a plays an important role in the spatial regulation of intracellular transport and signal transduction processes. Here, we report a previously uncharacterized role for Rab5a in the regulation of T-cell motility. We show that Rab5a physically associates with protein kinase Cϵ (PKCϵ) in migrating T-cells. After stimulation of T-cells through the integrin LFA-1 or the chemokine receptor CXCR4, Rab5a is phosphorylated on an N-terminal Thr-7 site by PKCϵ. Both Rab5a and PKCϵ dynamically interact at the centrosomal region of migrating cells, and PKCϵ-mediated phosphorylation on Thr-7 regulates Rab5a trafficking to the cell leading edge. Furthermore, we demonstrate that Rab5a Thr-7 phosphorylation is functionally necessary for Rac1 activation, actin rearrangement, and T-cell motility. We present a novel mechanism by which a PKCϵ-Rab5a-Rac1 axis regulates cytoskeleton remodeling and T-cell migration, both of which are central for the adaptive immune response.
Collapse
Affiliation(s)
- Seow Theng Ong
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland
| | - Michael Freeley
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland
| | - Joanna Skubis-Zegadło
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland, Department of Applied Pharmacy and Bioengineering, Medical University of Warsaw, 02-091 Warsaw, Poland
| | | | - Dermot Kelleher
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637553, Faculty of Medicine, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom, and
| | - Friedrich Fresser
- the Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Gottfried Baier
- the Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Navin Kumar Verma
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637553,
| | - Aideen Long
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland,
| |
Collapse
|
9
|
Claro S, Oshiro MEM, Mortara RA, Paredes-Gamero EJ, Pereira GJS, Smaili SS, Ferreira AT. γ-Rays-generated ROS induce apoptosis via mitochondrial and cell cycle alteration in smooth muscle cells. Int J Radiat Biol 2014; 90:914-27. [DOI: 10.3109/09553002.2014.911988] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
10
|
PKC ε Phosphorylates and Mediates the Cell Membrane Localization of RhoA. ISRN ONCOLOGY 2013; 2013:329063. [PMID: 24191200 PMCID: PMC3804392 DOI: 10.1155/2013/329063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/18/2013] [Indexed: 11/17/2022]
Abstract
Protein kinase Cε (PKCε) signals through RhoA to modulate cell invasion and motility. In this study, the multifaceted interaction between PKCε and RhoA was defined. Phosphopeptide mapping revealed that PKCε phosphorylates RhoA at T127 and S188. Recombinant PKCε bound to recombinant RhoA in the absence of ATP indicating that the association between PKCε and RhoA does not require an active ATP-docked PKCε conformation. Activation of PKCε resulted in a dramatic coordinated translocation of PKCε and RhoA from the cytoplasm to the cell membrane using time-lapse fluorescence microscopy. Stoichiometric FRET analysis revealed that the molecular interaction between PKCε and RhoA is a biphasic event, an initial peak at the cytoplasm and a gradual prolonged increase at the cell membrane for the entire time-course (12.5 minutes). These results suggest that the PKCε-RhoA complex is assembled in the cytoplasm and subsequently recruited to the cell membrane. Kinase inactive (K437R) PKCε is able to recruit RhoA to the cell membrane indicating that the association between PKCε and RhoA is proximal to the active catalytic site and perhaps independent of a PKCε-RhoA phosphorylation event. This work demonstrates, for the first time, that PKCε phosphorylates and modulates the cell membrane translocation of RhoA.
Collapse
|
11
|
Zhang X, Li D, Li M, Ye M, Ding L, Cai H, Fu D, Lv Z. MicroRNA-146a targets PRKCE to modulate papillary thyroid tumor development. Int J Cancer 2013; 134:257-67. [PMID: 23457043 DOI: 10.1002/ijc.28141] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/14/2013] [Indexed: 12/21/2022]
Abstract
MicroRNAs are single-stranded noncoding RNAs composed of approximately 22 nucleotides that suppress gene expression by selectively binding via base-pairing to the complementary 3'-untranslated region (3'-UTR) of messenger RNA transcripts. Protein kinase C epsilon (PKCε) is an important modulating member of the transducing Ras/Raf-1 signal pathway; a computational search revealed miR-146a putatively binds to the 3'-UTR of the PRKCE gene, and thus decreasing PKCε expression. Moreover, PKCε inhibits mitochondrial apoptosis and is associated with the Bcl family. However, it has been previously reported that miR-146a expression in papillary thyroid carcinoma (PTC) is slightly elevated. Thus, we hypothesized that because miR-146a expression depends on nuclear factor kappaB (NF-κB) activation and NF-κB expression is elevated in PTC, miR-146a is potentially upregulated in PTC via negative feedback of NF-κB, and thus suppressing PKCε expression. In our study, we investigated whether overexpression of miR-146a, a tumor-suppressing-miR, in PTC cells decreases cell survival and induces apoptosis. Luciferase reporter assay analysis confirmed the direct binding of miR-146a and PRKCE 3'-UTR. Specific overexpression of exogenous miR-146a significantly decreased PKCε levels in PTC cell line NPA-187 and increased apoptosis. Additionally, using stably expressing miR-146a thyroid carcinoma cells to establish subcutaneous tumors, the tumor growth exhibited significant inhibition. Our study confirmed the tumor-suppressing role of miR-146a in thyroid carcinoma cells and contributes to the knowledge regarding modulation of Ras/Raf-1 signal transduction and apoptosis via PKCε targeted by miR-146a in PTC; moreover, our findings confirmed that miR-146a is involved in the feedback system of the classical NF-κB signal pathway in PTC.
Collapse
Affiliation(s)
- Xiaoping Zhang
- Department of Nuclear Medicine, Shanghai 10th People's Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Wood TR, Chow RY, Hanes CM, Zhang X, Kashiwagi K, Shirai Y, Trebak M, Loegering DJ, Saito N, Lennartz MR. PKC-ε pseudosubstrate and catalytic activity are necessary for membrane delivery during IgG-mediated phagocytosis. J Leukoc Biol 2013; 94:109-22. [PMID: 23670290 DOI: 10.1189/jlb.1212634] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In RAW 264.7 cells, PKC-ε regulates FcγR-mediated phagocytosis. BMDM behave similarly; PKC-ε concentrates at phagosomes and internalization are reduced in PKC-ε⁻/⁻ cells. Two questions were asked: what is the role of PKC-ε? and what domains are necessary for PKC-ε concentration? Function was studied using BMDM and frustrated phagocytosis. On IgG surfaces, PKC-ε⁻/⁻ macrophages spread less than WT. Patch-clamping revealed that the spreading defect is a result of the failure of PKC-ε⁻/⁻ macrophages to add membrane. The defect is specific for FcγR ligation and can be reversed by expression of full-length (but not the isolated RD) PKC-ε in PKC-ε⁻/⁻ BMDM. Thus, PKC-ε function in phagocytosis requires translocation to phagosomes and the catalytic domain. The expression of chimeric PKC molecules in RAW cells identified the εPS as necessary for PKC-ε targeting. When placed into (nonlocalizing) PKC-δ, εPS was sufficient for concentration, albeit to a lesser degree than intact PKC-ε. In contrast, translocation of δ(εPSC1B) resembled that of WT PKC-ε. Thus, εPS and εC1B cooperate for optimal phagosome targeting. Finally, cells expressing εK437W were significantly less phagocytic than their PKC-ε-expressing counterparts, blocked at the pseudopod-extension phase. In summary, we have shown that εPS and εC1B are necessary and sufficient for targeting PKC-ε to phagosomes, where its catalytic activity is required for membrane delivery and pseudopod extension.
Collapse
Affiliation(s)
- Tiffany R Wood
- Centers for Cell Biology and Cancer Researchnces, Albany Medical College, Albany, New York, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Caino MC, Lopez-Haber C, Kissil JL, Kazanietz MG. Non-small cell lung carcinoma cell motility, rac activation and metastatic dissemination are mediated by protein kinase C epsilon. PLoS One 2012; 7:e31714. [PMID: 22384062 PMCID: PMC3288050 DOI: 10.1371/journal.pone.0031714] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 01/17/2012] [Indexed: 11/18/2022] Open
Abstract
Background Protein kinase C (PKC) ε, a key signaling transducer implicated in mitogenesis, survival, and cancer progression, is overexpressed in human primary non-small cell lung cancer (NSCLC). The role of PKCε in lung cancer metastasis has not yet been established. Principal Findings Here we show that RNAi-mediated knockdown of PKCε in H358, H1299, H322, and A549 NSCLC impairs activation of the small GTPase Rac1 in response to phorbol 12-myristate 13-acetate (PMA), serum, or epidermal growth factor (EGF). PKCε depletion markedly impaired the ability of NSCLC cells to form membrane ruffles and migrate. Similar results were observed by pharmacological inhibition of PKCε with εV1-2, a specific PKCε inhibitor. PKCε was also required for invasiveness of NSCLC cells and modulated the secretion of extracellular matrix proteases and protease inhibitors. Finally, we found that PKCε-depleted NSCLC cells fail to disseminate to lungs in a mouse model of metastasis. Conclusions Our results implicate PKCε as a key mediator of Rac signaling and motility of lung cancer cells, highlighting its potential as a therapeutic target.
Collapse
Affiliation(s)
- M Cecilia Caino
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | | | | | | |
Collapse
|
14
|
Ziv-Av A, Taller D, Attia M, Xiang C, Lee HK, Cazacu S, Finniss S, Kazimirsky G, Sarid R, Brodie C. RTVP-1 expression is regulated by SRF downstream of protein kinase C and contributes to the effect of SRF on glioma cell migration. Cell Signal 2011; 23:1936-43. [PMID: 21777672 DOI: 10.1016/j.cellsig.2011.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 07/04/2011] [Indexed: 01/13/2023]
Abstract
Gliomas are characterized by increased infiltration into the surrounding normal brain tissue. We recently reported that RTVP-1 is highly expressed in gliomas and plays a role in the migration of these cells, however the regulation of RTVP-1 expression in these cells is not yet described. In this study we examined the role of PKC in the regulation of RTVP-1 expression and found that PMA and overexpression of PKCα and PKCε increased the expression of RTVP-1, whereas PKCδ exerted an opposite effect. Using the MatInspector software, we identified a SRF binding site on the RTVP-1 promoter. Chromatin immunoprecipitation (ChIP) assay revealed that SRF binds to the RTVP-1 promoter in U87 cells, and that this binding was significantly increased in response to serum addition. Moreover, silencing of SRF blocked the induction of RTVP-1 expression in response to serum. We found that overexpression of PKCα and PKCε increased the activity of the RTVP-1 promoter and the binding of SRF to the promoter. In contrast, overexpression of PKCδ blocked the increase in RTVP-1 expression in response to serum and the inhibitory effect of PKCδ was abrogated in cells expressing a SRFT160A mutant. SRF regulated the migration of glioma cells and its effect was partially mediated by RTVP-1. We conclude that RTVP-1 is a PKC-regulated gene and that this regulation is at least partly mediated by SRF. Moreover, RTVP-1 plays a role in the effect of SRF on glioma cell migration.
Collapse
Affiliation(s)
- Amotz Ziv-Av
- The Mina and Everard Goodman Faculty of Life-Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
The epsilon isoform of protein kinase C (PKCepsilon) has important roles in the function of the cardiac, immune and nervous systems. As a result of its diverse actions, PKCepsilon is the target of active drug-discovery programmes. A major research focus is to identify signalling cascades that include PKCepsilon and the substrates that PKCepsilon regulates. In the present review, we identify and discuss those proteins that have been conclusively shown to be direct substrates of PKCepsilon by the best currently available means. We will also describe binding partners that anchor PKCepsilon near its substrates. We review the consequences of substrate phosphorylation and discuss cellular mechanisms by which target specificity is achieved. We begin with a brief overview of the biology of PKCepsilon and methods for substrate identification, and proceed with a discussion of substrate categories to identify common themes that emerge and how these may be used to guide future studies.
Collapse
|
16
|
Gorin MA, Pan Q. Protein kinase C epsilon: an oncogene and emerging tumor biomarker. Mol Cancer 2009; 8:9. [PMID: 19228372 PMCID: PMC2647895 DOI: 10.1186/1476-4598-8-9] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 02/19/2009] [Indexed: 12/30/2022] Open
Abstract
Members of the protein kinase C (PKC) family have long been studied for their contributions to oncogenesis. Among the ten different isoforms of this family of serine/threonine kinases, protein kinase Cε (PKCε) is one of the best understood for its role as a transforming oncogene. In vitro, overexpression of PKCε has been demonstrated to increase proliferation, motility, and invasion of fibroblasts or immortalized epithelial cells. In addition, xenograft and transgenic animal models have clearly shown that overexpression of PKCε is tumorigenic resulting in metastatic disease. Perhaps most important in implicating the epsilon isoform in oncogenesis, PKCε has been found to be overexpressed in tumor-derived cell lines and histopathological tumor specimens from various organ sites. Combined, this body of work provides substantial evidence implicating PKCε as a transforming oncogene that plays a crucial role in establishing an aggressive metastatic phenotype. Reviewed here is the literature that has led to the current understanding of PKCε as an oncogene. Moreover, this review focuses on the PKCε-mediated signaling network for cell motility and explores the interaction of PKCε with three major PKCε signaling nodes: RhoA/C, Stat3 and Akt. Lastly, the emerging role of PKCε as a tumor biomarker is discussed.
Collapse
Affiliation(s)
- Michael A Gorin
- University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | | |
Collapse
|
17
|
Caino MC, Meshki J, Kazanietz MG. Hallmarks for senescence in carcinogenesis: novel signaling players. Apoptosis 2009; 14:392-408. [DOI: 10.1007/s10495-009-0316-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
18
|
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.
Collapse
Affiliation(s)
- Mary E Reyland
- Department of Craniofacial Biology, University of Colorado Health Sciences Center, Aurora, CO 80045, USA.
| |
Collapse
|
19
|
Akita Y. Protein kinase Cε: multiple roles in the function of, and signaling mediated by, the cytoskeleton. FEBS J 2008; 275:3995-4004. [DOI: 10.1111/j.1742-4658.2008.06557.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
20
|
Huang L, Cheng HC, Isom R, Chen CS, Levine RA, Pauli BU. Protein kinase Cepsilon mediates polymeric fibronectin assembly on the surface of blood-borne rat breast cancer cells to promote pulmonary metastasis. J Biol Chem 2008; 283:7616-27. [PMID: 18184652 DOI: 10.1074/jbc.m705839200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Malignant breast cancer cells that have entered the blood circulation from primary mammary fat pad tumors or are grown in end-over-end suspension culture assemble a characteristic, multi-globular polymeric fibronectin (polyFn) coat on their surfaces. Surface polyFn is critical for pulmonary metastasis, presumably by facilitating lung vascular arrest via endothelial dipeptidylpeptidase IV (CD26). Here, we show that cell-surface polyFn assembly is initiated by the state of suspension, is dependent upon the synthesis and secretion of cellular Fn, and is augmented in a dose- and time-dependent manner by plasma Fn. PolyFn assembly is regulated by protein kinase Cepsilon (PKCepsilon), which translocates rapidly and in increasing amounts from the cytosol to the plasma membrane and is phosphorylated. PolyFn assembly is impeded by select inhibitors of this kinase, i.e. bisindolylmaleimide I, Ro-32-0432, Gö6983, and Rottlerin, by the phorbol 12-myristate 13-acetate-mediated and time-dependent loss of PKCepsilon protein and decreased plasma membrane translocation, and more specifically, by stable transfection of lung-metastatic MTF7L breast cancer cells with small interfering RNA-PKCepsilon and dominant-negative PKCepsilon constructs (e.g. RD-PKCepsilon). The inability to assemble a cell surface-associated polyFn coat by knockdown of endogenous Fn or PKCepsilon impedes cancer cells from metastasis to the lungs. The present studies identify a novel regulatory mechanism for polyFn assembly on blood-borne breast cancer cells and depict its effect on pulmonary metastasis.
Collapse
Affiliation(s)
- Lynn Huang
- Cancer Cell Biology Laboratories, Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
| | | | | | | | | | | |
Collapse
|
21
|
D’Souza T, Indig FE, Morin PJ. Phosphorylation of claudin-4 by PKCepsilon regulates tight junction barrier function in ovarian cancer cells. Exp Cell Res 2007; 313:3364-75. [PMID: 17678893 PMCID: PMC2034282 DOI: 10.1016/j.yexcr.2007.06.026] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 06/15/2007] [Accepted: 06/28/2007] [Indexed: 11/27/2022]
Abstract
Claudin proteins belong to a large family of transmembrane proteins essential to the formation and maintenance of tight junctions (TJs). In ovarian cancer, TJ protein claudin-4 is frequently overexpressed and may have roles in survival and invasion, but the molecular mechanisms underlying its regulation are poorly understood. In this report, we show that claudin-4 can be phosphorylated by protein kinase C (PKC) at Thr189 and Ser194 in ovarian cancer cells and overexpression of a claudin-4 mutant protein mimicking the phosphorylated state results in the disruption of the barrier function. Furthermore, upon phorbol ester-mediated PKC activation of OVCA433 cells, TJ strength is decreased and claudin-4 localization is altered. Analyses using PKC inhibitors and siRNA suggest that PKCepsilon, an isoform typically expressed in ovarian cancer cells, may be important in the TPA-mediated claudin-4 phosphorylation and weakening of the TJs. Furthermore, immunofluorescence studies showed that claudin-4 and PKCepsilon are co-localized at the TJs in these cells. The modulation of claudin-4 activity by PKCepsilon may not only provide a mechanism for disrupting TJ function in ovarian cancer, but may also be important in the regulation of TJ function in normal epithelial cells.
Collapse
Affiliation(s)
- Theresa D’Souza
- Laboratory of Cellular and Molecular Biology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Fred E. Indig
- Research Resources Branch, National Institute on Aging, MD 21224, USA
| | - Patrice J. Morin
- Laboratory of Cellular and Molecular Biology, National Institute on Aging, Baltimore, MD 21224, USA
- Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA
- *Correspondence: Patrice J. Morin, Laboratory of Cellular and Molecular Biology, Gerontology Research Center, NIA, NIH, 5600 Nathan Shock Drive, Baltimore MD 21224. Tel. 410 558 8506; Fax: 410 558 8386;
| |
Collapse
|
22
|
Wheeler DL, Li Y, Verma AK. Protein Kinase C Epsilon Signals Ultraviolet Light-induced Cutaneous Damage and Development of Squamous Cell Carcinoma Possibly Through Induction of Specific Cytokines in a Paracrine Mechanism¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2005.tb01516.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
23
|
Basu A, Sivaprasad U. Protein kinase Cepsilon makes the life and death decision. Cell Signal 2007; 19:1633-42. [PMID: 17537614 PMCID: PMC1986651 DOI: 10.1016/j.cellsig.2007.04.008] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 04/23/2007] [Indexed: 12/20/2022]
Abstract
Cancer is caused by dysregulation in cellular signaling systems that control cell proliferation, differentiation and cell death. Protein kinase C (PKC), a family of serine/threonine kinases, plays an important role in the growth factor signal transduction pathway. PKCepsilon, however, is the only PKCepsilon isozyme that has been considered as an oncogene. It can contribute to malignancy by enhancing cell proliferation or by inhibiting cell death. This review focuses on how PKCepsilon collaborates with other signaling pathways, such as Ras/Raf/ERK and Akt, to regulate cell survival and cell death. We have also discussed how PKCepsilon mediates its antiapoptotic signal by altering the level or function of pro- and antiapoptotic Bcl-2 family members.
Collapse
Affiliation(s)
- Alakananda Basu
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
| | | |
Collapse
|
24
|
Abstract
Almost three decades after the discovery of protein kinase C (PKC), we still have only a partial understanding of how this family of serine/threonine kinases is involved in tumour promotion. PKC isozymes - effectors of diacylglycerol (DAG) and the main targets of phorbol-ester tumour promoters - have important roles in cell-cycle regulation, cellular survival, malignant transformation and apoptosis. How do PKC isozymes regulate these diverse cellular processes and what are their contributions to carcinogenesis? Moreover, what is the contribution of all phorbol-ester effectors, which include PKCs and small G-protein regulators? We now face the challenge of dissecting the relative contribution of each DAG signal to cancer progression.
Collapse
Affiliation(s)
- Erin M Griner
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics (ITMAT), University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA
| | | |
Collapse
|
25
|
Pan Q, Bao LW, Kleer CG, Sabel MS, Griffith KA, Teknos TN, Merajver SD. Protein kinase C epsilon is a predictive biomarker of aggressive breast cancer and a validated target for RNA interference anticancer therapy. Cancer Res 2005; 65:8366-71. [PMID: 16166314 DOI: 10.1158/0008-5472.can-05-0553] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumor metastasis is the major cause of morbidity and mortality in patients with breast cancer. It is critical to identify metastasis enabling genes and understand how they are responsible for inducing specific aspects of the metastatic phenotype to allow for improved clinical detection and management. Protein kinase C epsilon (PKC epsilon), a member of a family of serine/threonine protein kinases, is a transforming oncogene that has been reported to be involved in cell invasion and motility. In this study, we investigated the role of PKC epsilon in breast cancer development and progression. High-density tissue microarray analysis showed that PKC epsilon protein was detected in 73.6% (106 of 144) of primary tumors from invasive ductal breast cancer patients. Increasing PKC epsilon staining intensity was associated with high histologic grade (P = 0.0206), positive Her2/neu receptor status (P = 0.0419), and negative estrogen (P = 0.0026) and progesterone receptor status (P = 0.0008). Kaplan-Meier analyses showed that PKC epsilon was significantly associated with poorer disease-free and overall survival (log-rank, P = 0.0478 and P = 0.0414, respectively). RNA interference of PKC epsilon in MDA-MB231 cells, an aggressive breast cancer cell line with elevated PKC epsilon levels, resulted in a cell phenotype that was significantly less proliferative, invasive, and motile than the parental or the control RNA interference transfectants. Moreover, in vivo tumor growth of small interfering RNA-PKC epsilon MDA-MB231 clones was retarded by a striking 87% (P < 0.05) and incidence of lung metastases was inhibited by 83% (P < 0.02). PKC epsilon-deficient clones were found to have lower RhoC GTPase protein levels and activation. Taken together, these results revealed that PKC epsilon plays a critical and causative role in promoting an aggressive metastatic breast cancer phenotype and as a target for anticancer therapy.
Collapse
MESH Headings
- Animals
- Biomarkers, Tumor/biosynthesis
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Breast Neoplasms/enzymology
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Breast Neoplasms/therapy
- Carcinoma, Ductal, Breast/enzymology
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/pathology
- Carcinoma, Ductal, Breast/therapy
- Cell Growth Processes/physiology
- Cell Line, Tumor
- Disease-Free Survival
- Female
- Humans
- Mice
- Mice, Nude
- Predictive Value of Tests
- Protein Kinase C-epsilon/antagonists & inhibitors
- Protein Kinase C-epsilon/biosynthesis
- Protein Kinase C-epsilon/genetics
- Protein Kinase C-epsilon/metabolism
- RNA Interference
- RNA, Small Interfering/genetics
- Xenograft Model Antitumor Assays
- ras Proteins
- rho GTP-Binding Proteins/metabolism
- rhoC GTP-Binding Protein
Collapse
Affiliation(s)
- Quintin Pan
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan Health System, Ann Arbor, Michigan 48109, USA.
| | | | | | | | | | | | | |
Collapse
|
26
|
Jerdeva GV, Yarber FA, Trousdale MD, Rhodes CJ, Okamoto CT, Dartt DA, Hamm-Alvarez SF. Dominant-negative PKC-epsilon impairs apical actin remodeling in parallel with inhibition of carbachol-stimulated secretion in rabbit lacrimal acini. Am J Physiol Cell Physiol 2005; 289:C1052-68. [PMID: 15930141 PMCID: PMC1414898 DOI: 10.1152/ajpcell.00546.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the involvement of PKC-epsilon in apical actin remodeling in carbachol-stimulated exocytosis in reconstituted rabbit lacrimal acinar cells. Lacrimal acinar PKC-epsilon cosedimented with actin filaments in an actin filament binding assay. Stimulation of acini with carbachol (100 microM, 2-15 min) significantly (P < or = 0.05) increased PKC-epsilon recovery with actin filaments in two distinct biochemical assays, and confocal fluorescence microscopy showed a significant increase in PKC-epsilon association with apical actin in stimulated acini as evidenced by quantitative colocalization analysis. Overexpression of dominant-negative (DN) PKC-epsilon in lacrimal acini with replication-defective adenovirus (Ad) resulted in profound alterations in apical and basolateral actin filaments while significantly inhibiting carbachol-stimulated secretion of bulk protein and beta-hexosaminidase. The chemical inhibitor GF-109203X (10 microM, 3 h), which inhibits PKC-alpha, -beta, -delta, and -epsilon, also elicited more potent inhibition of carbachol-stimulated secretion relative to Gö-6976 (10 microM, 3 h), which inhibits only PKC-alpha and -beta. Transduction of lacrimal acini with Ad encoding syncollin-green fluorescent protein (GFP) resulted in labeling of secretory vesicles that were discharged in response to carbachol stimulation, whereas cotransduction of acini with Ad-DN-PKC-epsilon significantly inhibited carbachol-stimulated release of syncollin-GFP. Carbachol also increased the recovery of secretory component in culture medium, whereas Ad-DN-PKC-epsilon transduction suppressed its carbachol-stimulated release. We propose that DN-PKC-epsilon alters lacrimal acinar apical actin remodeling, leading to inhibition of stimulated exocytosis and transcytosis.
Collapse
Affiliation(s)
| | | | | | - Christopher J. Rhodes
- University of Southern California, Los Angeles CA; Pacific Northwest Research Institute, Seattle WA; and
| | | | | | - Sarah F. Hamm-Alvarez
- Departments of Pharmaceutical Sciences
- Ophthalmology and
- Physiology and Biophysics
- Address correspondence to: Sarah F. Hamm-Alvarez, Ph. D., Department of Pharmaceutical Sciences, USC School of Pharmacy, 1985 Zonal Avenue, Los Angeles CA 90033, 323-442-1445 O, 323-442-1390 F,
| |
Collapse
|
27
|
Wheeler DL, Li Y, Verma AK. Protein Kinase C Epsilon Signals Ultraviolet Light-induced Cutaneous Damage and Development of Squamous Cell Carcinoma Possibly Through Induction of Specific Cytokines in a Paracrine Mechanism¶. Photochem Photobiol 2005. [DOI: 10.1562/2004-08-12-ra-271.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
28
|
Heckman CA, Urban JM, Cayer M, Li Y, Boudreau N, Barnes J, Plummer HK, Hall C, Kozma R, Lim L. Novel p21-activated kinase-dependent protrusions characteristically formed at the edge of transformed cells. Exp Cell Res 2004; 295:432-47. [PMID: 15093742 DOI: 10.1016/j.yexcr.2003.12.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2003] [Revised: 12/10/2003] [Indexed: 11/20/2022]
Abstract
During long-term culture, certain lines become neoplastic while accumulating changes in cell shape. Early and late cell populations have characteristic shape phenotypes that have been quantified by computerized assay. Phenotypes are determined from variables describing three-dimensional aspects of the subcellular distribution of mass. The features of cells can be recognized by use of latent factors, which are theoretical variables based on the covariance of the primary variables. Factor #7 represented a cell edge feature different from filopodia. We studied the morphological characteristics and morphogenesis of the feature. Brief exposure of cells from rat tracheal epithelium to phorbol 12-myristate 13-acetate (PMA) enhanced #7 values. The time to reach maximal #7 values was prolonged if PMA was administered with calcium ionophore or lysophosphatidic acid (LPA). Factor #7 was elevated during periods of ruffling suppression and stress fiber reorganization. Cells showing high #7 values were examined by scanning electron microscopy (SEM) and found to exhibit strap-shaped and cupola-shaped projections. Because RhoA regulates stress fiber formation, we sought to perturb #7 features by introducing dominant-acting negative and positive constructs of RhoA, RhoA-N19, and RhoA-V14. Neither affected #7 values. Although overexpression of the kinase inhibitory domain of p21-activated kinase 1 (PAK) had no effect on #7 values, they were affected by overexpression of a domain binding PAK-interacting guanine nucleotide exchange factor (PIX). Because a PAK-PIX complex is implicated in the remodeling of focal complexes (FCs) and recycling of PAK to the cytoplasm, the results implicate a component of FCs in the formation of #7 features. The data suggested that feature formation is driven by activated Cdc42-binding kinase (ACK) and Rac. Moreover, they suggested that the #7 protrusions are neurite-like structures and that their development involves FC regulation.
Collapse
Affiliation(s)
- C A Heckman
- Department of Biological Sciences and Center for Microscopy and Microanalysis, Bowling Green State University, Bowling Green, OH 43403, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|