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Hong F, Yang Y, Chen B, Li P, Wang G, Jiang Y. Protein kinase C-θ knockout decreases serum IL-10 levels and inhibits insulin secretion from islet β cells. Islets 2021; 13:24-31. [PMID: 33719858 PMCID: PMC8018435 DOI: 10.1080/19382014.2021.1890963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Various subtypes of protein kinase C (PKC) are expressed in islet β cells and regulate β cell proliferation and survival. PKC-θ is distributed in the immune system and promotes the secretion of IL-10, which manifests a critical role in the onset of diabetes, by the immune cells. However, the role of PKC-θ in islets has not been concerned. In the present study, we investigated the role of PKC-θ in the protection of islet β cells and insulin secretion. Fasting glucose and insulin measurement, glucose tolerant test, immunofluorescence, and ELISA were conducted to study the influence of PKC-θ knockout on islet β cell survival and function, and explore the mechanism underlying this regulation. PKC-θ knockout mice at 2 weeks manifested normal serum insulin levels, glucose tolerance, and β cell mass. Knockout mice at 8 weeks show decreased β cell mass, but manifested normal insulin levels and glucose tolerance. Knockout mice at 16 weeks manifested impaired glucose tolerance, β cell mass, and decreased glucose stimulated insulin secretion. Furthermore, knockout mice manifested decreased serum IL-10 level compared with normal mice since 2 weeks. IL-10 injection into knockout mice improved glucose tolerance, serum insulin level, and reduced β cell mass, and IL-10 administration into cultured pancreatic tissue increased glucose stimulated insulin secretion. PKC-θ knockout decreases the secretion of IL-10, reduces β cell mass and insulin secretion in pancreatic islets. The present study illuminates the critical role of PKC-θ in protecting the survival and function of islet β cells.
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Affiliation(s)
- Feng Hong
- School of Preclinical Medicine, Wannan Medical College, Wuhu, China
- Hong Feng School of Preclinical Medicine, Wannan Medical College; No.22 Wenchang West Road, Wuhu 241002, China
| | - Yang Yang
- School of Preclinical Medicine, Wannan Medical College, Wuhu, China
| | - Baiyi Chen
- School of Preclinical Medicine, Wannan Medical College, Wuhu, China
| | - Peng Li
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Guoguang Wang
- School of Preclinical Medicine, Wannan Medical College, Wuhu, China
- CONTACT Yuxin Jiang School of Medicine, Jiaxing University, No.118 Jiahang Road, Jiaxing 341001, China
| | - Yuxin Jiang
- College of Medicine, Jiaxing University, Jiaxing, China
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Xie J, Han X, Zhao C, Canonigo-Balancio AJ, Yates JR, Li Y, Lillemeier BF, Altman A. Phosphotyrosine-dependent interaction between the kinases PKCθ and Zap70 promotes proximal TCR signaling. Sci Signal 2019; 12:12/577/eaar3349. [PMID: 30992398 DOI: 10.1126/scisignal.aar3349] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Protein kinase C-θ (PKCθ) is an important component of proximal T cell receptor (TCR) signaling. We previously identified the amino-terminal C2 domain of PKCθ as a phosphotyrosine (pTyr)-binding domain. Using a mutant form of PKCθ that cannot bind pTyr (PKCθHR2A), we showed that pTyr binding by PKCθ was required for TCR-induced T cell activation, proliferation, and TH2 cell differentiation but not for T cell development. Using tandem mass spectrometry and coimmunoprecipitation, we identified the kinase ζ-associated protein kinase of 70 kDa (Zap70) as a binding partner of the PKCθ pTyr-binding pocket. Tyr126 of Zap70 directly bound to PKCθ, and the interdomain B residues Tyr315 and Tyr319 were indirectly required for binding to PKCθ, reflecting their role in promoting the open conformation of Zap70. PKCθHR2A-expressing CD4+ T cells displayed defects not only in known PKCθ-dependent signaling events, such as nuclear factor κB (NF-κB) activation and TH2 cell differentiation, but also in full activation of Zap70 itself and in the activating phosphorylation of linker of activation of T cells (LAT) and phospholipase C-γ1 (PLCγ1), signaling proteins that are traditionally considered to be activated independently of PKC. These findings demonstrate that PKCθ plays an important role in a positive feedback regulatory loop that modulates TCR-proximal signaling and, moreover, provide a mechanistic explanation for earlier reports that documented an important role for PKCθ in T cell Ca2+ signaling. This PKCθ-Zap70 interaction could potentially serve as a promising and highly selective immunosuppressive drug target in autoimmunity and organ transplantation.
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Affiliation(s)
- Jiji Xie
- Division of Cell Biology, La Jolla Institute for Immunology, La Jolla, CA 92037, USA
| | - Xuemei Han
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Chensi Zhao
- State Key Laboratory for Biocontrol, School of Life Science, Sun Yat-sen University, Guangzhou 510006, China
| | | | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yingqiu Li
- State Key Laboratory for Biocontrol, School of Life Science, Sun Yat-sen University, Guangzhou 510006, China
| | - Björn F Lillemeier
- Nomis Center for Immunobiology and Microbial Pathogenesis & Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Immunology, La Jolla, CA 92037, USA.
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Ozay EI, Gonzalez-Perez G, Torres JA, Vijayaraghavan J, Lawlor R, Sherman HL, Garrigan DT, Burnside AS, Osborne BA, Tew GN, Minter LM. Intracellular Delivery of Anti-pPKCθ (Thr538) via Protein Transduction Domain Mimics for Immunomodulation. Mol Ther 2016; 24:2118-2130. [PMID: 27633441 DOI: 10.1038/mt.2016.177] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 09/07/2016] [Indexed: 12/12/2022] Open
Abstract
Targeting cellular proteins with antibodies, to better understand cellular signaling pathways in the context of disease modulation, is a fast-growing area of investigation. Humanized antibodies are increasingly gaining attention for their therapeutic potential, but the collection of cellular targets is limited to those secreted from cells or expressed on the cell surface. This approach leaves a wealth of intracellular proteins unexplored as putative targets for antibody binding. Protein kinase Cθ (PKCθ) is essential to T cell activation, proliferation, and differentiation, and its phosphorylation at specific residues is required for its activity. Here we report on the design, synthesis, and characterization of a protein transduction domain mimic capable of efficiently delivering an antibody against phosphorylated PKCθ (Thr538) into human peripheral mononuclear blood cells and altering expression of downstream indicators of T cell activation and differentiation. We used a humanized, lymphocyte transfer model of graft-versus-host disease, to evaluate the durability of protein transduction domain mimic:Anti-pPKCθ modulation, when delivered into human peripheral mononuclear blood cells ex vivo. We demonstrate that protein transduction domain mimic:Antibody complexes can be readily introduced with high efficacy into hard-to-transfect human peripheral mononuclear blood cells, eliciting a biological response sufficient to alter disease progression. Thus, protein transduction domain mimic:Antibody delivery may represent an efficient ex vivo approach to manipulating cellular responses by targeting intracellular proteins.
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Affiliation(s)
- E Ilker Ozay
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Gabriela Gonzalez-Perez
- Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Columbia University, New York, New York, USA
| | - Joe A Torres
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Jyothi Vijayaraghavan
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Rebecca Lawlor
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Heather L Sherman
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Daniel T Garrigan
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Amy S Burnside
- Institute for Applied Life Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Barbara A Osborne
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA.,Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Gregory N Tew
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA.,Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA.,Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Lisa M Minter
- Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA.,Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
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Tan Y, AlKhamees B, Jia D, Li L, Couture JF, Figeys D, Jinushi M, Wang L. MFG-E8 Is Critical for Embryonic Stem Cell-Mediated T Cell Immunomodulation. Stem Cell Reports 2015; 5:741-752. [PMID: 26455415 PMCID: PMC4649138 DOI: 10.1016/j.stemcr.2015.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 02/03/2023] Open
Abstract
The molecules and mechanisms pertinent to the low immunogenicity of undifferentiated embryonic stem cells (ESCs) remain poorly understood. Here, we provide evidence that milk fat globule epidermal growth factor 8 (MFG-E8) is a vital mediator in this phenomenon and directly suppresses T cell immune responses. MFG-E8 is enriched in undifferentiated ESCs but diminished in differentiated ESCs. Upregulation of MFG-E8 in ESCs increases the successful engraftment of both undifferentiated and differentiated ESCs across major histocompatibility complex barriers. MFG-E8 suppresses T cell activation/proliferation and inhibits Th1, Th2, and Th17 subpopulations while increasing regulatory T cell subsets. Neutralizing MFG-E8 substantially abrogates these effects, whereas addition of recombinant MFG-E8 to differentiated ESCs restores immunosuppression. Furthermore, we provide the evidence that MFG-E8 suppresses T cell activation and regulates T cell polarization by inhibiting PKCθ phosphorylation through the α3/5βV integrin receptor. Our findings offer an approach to facilitate transplantation acceptance. MFG-E8 is enriched in undifferentiated but diminished in differentiated ESCs MFG-E8 promotes allogeneic engraftment of ESC-derived tissues across the MHC barrier ESC-produced MFG-E8 inhibits Th1/Th2/Th17 while promoting regulatory T cells MFG-E8 modulates T cell polarization via inhibiting PKCθ phosphorylation
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Affiliation(s)
- Yuan Tan
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Bodour AlKhamees
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Deyong Jia
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Li Li
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Jean-François Couture
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Daniel Figeys
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Masahisa Jinushi
- Institute for Advanced Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjiku-ku, Tokyo 160-8582, Japan.
| | - Lisheng Wang
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.
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Abstract
Activating as well as inhibitory circuits tightly regulate T-cell activation thresholds and effector differentiation processes enabling proper immune response outcomes. Recently, an additional molecular link between T-cell receptor signalling and CD4⁺ Th17 cell skewing has been reported, namely that protein kinase C (PKC) θ critically regulates Th17/Th1 phenotypic differentiation and plasticity in CD4⁺ T-cells by selectively acting as a 'reprogramming element' that suppresses Th1-typical genes during Th17-mediated immune activation in order to stabilize a Th17 cell phenotype.
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Abstract
The protein kinases C (PKCs) are a family of serine/threonine kinases involved in regulating multiple essential cellular processes such as survival, proliferation, and differentiation. Of particular interest is the novel, calcium-independent PKCθ which plays a central role in immune responses. PKCθ shares structural similarities with other PKC family members, mainly consisting of an N-terminal regulatory domain and a C-terminal catalytic domain tethered by a hinge region. This isozyme, however, is unique in that it translocates to the immunological synapse between a T cell and an antigen-presenting cell (APC) upon T cell receptor-peptide MHC recognition. Thereafter, PKCθ interacts physically and functionally with downstream effectors to mediate T cell activation and differentiation, subsequently leading to inflammation. PKCθ-specific perturbations have been identified in several diseases, most notably autoimmune disorders, and hence the modulation of its activity presents an attractive therapeutic intervention. To that end, many inhibitors of PKCs and PKCθ have been developed and tested in preclinical and clinical studies. And although selectivity remains a challenge, results are promising for the future development of effective PKCθ inhibitors that would greatly advance the treatment of several T-cell mediated diseases.
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Fukahori H, Chida N, Maeda M, Tasaki M, Kawashima T, Matsuoka H, Suzuki K, Ishikawa T, Tanaka A, Higashi Y. Effect of AS2521780, a novel PKCθ selective inhibitor, on T cell-mediated immunity. Eur J Pharmacol 2014; 745:217-22. [DOI: 10.1016/j.ejphar.2014.10.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/23/2014] [Accepted: 10/28/2014] [Indexed: 01/29/2023]
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Verstrepen L, Beyaert R. Receptor proximal kinases in NF-κB signaling as potential therapeutic targets in cancer and inflammation. Biochem Pharmacol 2014; 92:519-29. [PMID: 25449604 DOI: 10.1016/j.bcp.2014.10.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 10/30/2014] [Accepted: 10/30/2014] [Indexed: 01/12/2023]
Abstract
Many signaling pathways leading to activation of transcription factors and gene expression are characterized by phosphorylation events mediated by specific kinases. The transcription factor NF-κB plays a key role in multiple cellular processes, including immune signaling, inflammation, development, proliferation and survival. Dysregulated NF-κB activation is associated with autoimmunity, chronic inflammation and cancer. Activation of NF-κB requires IκB kinase (IKK)α or β, the activity of which is regulated via phosphorylation by specific IKK kinases and by autophosphorylation. Receptor specificity is further obtained by the use of multiple upstream receptor proximal kinases. We review the identities of several IKK regulatory kinases as well as the proposed molecular mechanisms. In addition, we discuss the potential for therapeutic targeting of some of these kinases in the context of inflammatory diseases and cancer.
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Affiliation(s)
- Lynn Verstrepen
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Rudi Beyaert
- Inflammation Research Center, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
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9
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Yan W, Xu R, Ma LL, Han W, Geevarghese SK, Williams PE, Sciammas R, Chong AS, Yin DP. B cells assist allograft rejection in the deficiency of protein kinase c-theta. Transpl Int 2013; 26:919-27. [PMID: 23841454 DOI: 10.1111/tri.12143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/29/2013] [Accepted: 06/10/2013] [Indexed: 11/28/2022]
Abstract
We have previously shown that mice deficient in protein kinase C theta (PKCθ) have the ability to reject cardiac allografts, but are susceptible to tolerance induction. Here we tested role of B cells in assisting alloimmune responses in the absence of PKCθ. Mouse cardiac allograft transplantations were performed from Balb/c (H-2d) to PKCθ knockout (PKCθ(-/-)), PKCθ and B cell double-knockout (PBDK, H-2b) mice and wild-type (WT) C57BL/6 (H-2b) mice. PBDK mice spontaneously accepted the allografts with the inhibition of NF-κB activation in the donor cardiac allograft. Anti-B cell antibody (rituximab) significantly delayed allograft rejection in PKCθ(-/-), but not in WT mice. Co-transfer of PKCθ(-/-) T plus PKCθ(-/-) B cells or primed sera triggered allograft rejection in Rag1(-/-) mice, and only major histocompatibility complex class II-enriched B cells, but not class I-enriched B cells, were able to promote rejection. This, together with the inability of PKCθ(-/-) and CD28(-/-) double-deficient (PCDK) mice to acutely reject allografts, suggested that an effective cognate interaction between PKCθ(-/-) T and B cells for acute rejection is CD28 molecule dependent. We conclude that T-B cell interactions synergize with PKCθ(-/-) T cells to mediate acute allograft rejection.
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Affiliation(s)
- Wenwei Yan
- Division of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Rational design, synthesis and QSAR study of vasorelaxant active 3-pyridinecarbonitriles incorporating 1H-benzimidazol-2-yl function. Eur J Med Chem 2013; 63:14-21. [DOI: 10.1016/j.ejmech.2013.01.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 01/20/2013] [Accepted: 01/24/2013] [Indexed: 11/23/2022]
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Kim YD, Kwon MS, Na BR, Kim HR, Lee HS, Jun CD. Swiprosin-1 Expression Is Up-Regulated through Protein Kinase C-θ and NF-κB Pathway in T Cells. Immune Netw 2013; 13:55-62. [PMID: 23700395 PMCID: PMC3659256 DOI: 10.4110/in.2013.13.2.55] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/15/2013] [Accepted: 02/21/2013] [Indexed: 12/01/2022] Open
Abstract
Swiprosin-1 exhibits the highest expression in CD8+ T cells and immature B cells and has been proposed to play a role in lymphocyte biology through actin remodeling. However, regulation of swiprosin-1 gene expression is poorly understood. Here we report that swiprosin-1 is up-regulated in T cells by PKC pathway. Targeted inhibition of the specific protein kinase C (PKC) isotypes by siRNA revealed that PKC-θ is involved in the expression of swiprosin-1 in the human T cells. In contrast, down-regulation of swiprosin-1 by A23187 or ionomycin suggests that calcium-signaling plays a negative role. Interestingly, swiprosin-1 expression is only reduced by treatment with NF-κB inhibitors but not by NF-AT inhibitor, suggesting that the NF-κB pathway is critical for regulation of swiprosin-1 expression. Collectively, these results suggest that swiprosin-1 is a PKC-θ-inducible gene and that it may modulate the late phase of T cell activation after antigen challenge.
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Affiliation(s)
- Young-Dae Kim
- School of Life Sciences, Immune Synapse Research Center and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
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Yan Zhang E, Kong KF, Altman A. The yin and yang of protein kinase C-theta (PKCθ): a novel drug target for selective immunosuppression. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2013; 66:267-312. [PMID: 23433459 PMCID: PMC3903317 DOI: 10.1016/b978-0-12-404717-4.00006-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Protein kinase C-theta (PKCθ) is a protein kinase C (PKC) family member expressed predominantly in T lymphocytes, and extensive studies addressing its function have been conducted. PKCθ is the only T cell-expressed PKC that localizes selectively to the center of the immunological synapse (IS) following conventional T cell antigen stimulation, and this unique localization is essential for PKCθ-mediated downstream signaling. While playing a minor role in T cell development, early in vitro studies relying, among others, on the use of PKCθ-deficient (Prkcq(-/-)) T cells revealed that PKCθ is required for the activation and proliferation of mature T cells, reflecting its importance in activating the transcription factors nuclear factor kappa B, activator protein-1, and nuclear factor of activated T cells, as well as for the survival of activated T cells. Upon subsequent analysis of in vivo immune responses in Prkcq(-/-) mice, it became clear that PKCθ has a selective role in the immune system: it is required for experimental Th2- and Th17-mediated allergic and autoimmune diseases, respectively, and for alloimmune responses, but is dispensable for protective responses against pathogens and for graft-versus-leukemia responses. Surprisingly, PKCθ was recently found to be excluded from the IS of regulatory T cells and to negatively regulate their suppressive function. These attributes of PKCθ make it an attractive target for catalytic or allosteric inhibitors that are expected to selectively suppress harmful inflammatory and alloimmune responses without interfering with beneficial immunity to infections. Early progress in developing such drugs is being made, but additional studies on the role of PKCθ in the human immune system are urgently needed.
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Affiliation(s)
| | | | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA
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Michalczyk I, Sikorski AF, Kotula L, Junghans RP, Dubielecka PM. The emerging role of protein kinase Cθ in cytoskeletal signaling. J Leukoc Biol 2012. [PMID: 23192428 DOI: 10.1189/jlb.0812371] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cytoskeletal rearrangements often occur as the result of transduction of signals from the extracellular environment. Efficient awakening of this powerful machinery requires multiple activation and deactivation steps, which usually involve phosphorylation or dephosphorylation of different signaling units by kinases and phosphatases, respectively. In this review, we discuss the signaling characteristics of one of the nPKC isoforms, PKCθ, focusing on PKCθ-mediated signal transduction to cytoskeletal elements, which results in cellular rearrangements critical for cell type-specific responses to stimuli. PKCθ is the major PKC isoform present in hematopoietic and skeletal muscle cells. PKCθ plays roles in T cell signaling through the IS, survival responses in adult T cells, and T cell FasL-mediated apoptosis, all of which involve cytoskeletal rearrangements and relocation of this enzyme. PKCθ has been linked to the regulation of cell migration, lymphoid cell motility, and insulin signaling and resistance in skeletal muscle cells. Additional roles were suggested for PKCθ in mitosis and cell-cycle regulation. Comprehensive understanding of cytoskeletal regulation and the cellular "modus operandi" of PKCθ holds promise for improving current therapeutic applications aimed at autoimmune diseases.
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Affiliation(s)
- Izabela Michalczyk
- Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
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14
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Zeng L, Webster SV, Newton PM. The biology of protein kinase C. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:639-61. [PMID: 22453963 DOI: 10.1007/978-94-007-2888-2_28] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review gives a basic introduction to the biology of protein kinase C, one of the first calcium-dependent kinases to be discovered. We review the structure and function of protein kinase C, along with some of the substrates of individual isoforms. We then review strategies for inhibiting PKC in experimental systems and finally discuss the therapeutic potential of targeting PKC. Each aspect is covered in summary, with links to detailed resources where appropriate.
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Affiliation(s)
- Lily Zeng
- School of Medicine, University of California, San Francisco, CA, USA
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15
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Isakov N, Altman A. PKC-theta-mediated signal delivery from the TCR/CD28 surface receptors. Front Immunol 2012; 3:273. [PMID: 22936936 PMCID: PMC3425079 DOI: 10.3389/fimmu.2012.00273] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 08/09/2012] [Indexed: 12/23/2022] Open
Abstract
Protein kinase C-theta (PKCθ) is a key enzyme in T lymphocytes, where it plays an important role in signal transduction downstream of the activated T cell antigen receptor (TCR) and the CD28 costimulatory receptor. Interest in PKCθ as a potential drug target has increased following recent findings that PKCθ is essential for harmful inflammatory responses mediated by Th2 (allergies) and Th17 (autoimmunity) cells as well as for graft-versus-host disease (GvHD) and allograft rejection, but is dispensable for beneficial responses such as antiviral immunity and graft-versus-leukemia (GvL) response. TCR/CD28 engagement triggers the translocation of the cytosolic PKCθ to the plasma membrane (PM), where it localizes at the center of the immunological synapse (IS), which forms at the contact site between an antigen-specific T cell and antigen-presenting cells (APC). However, the molecular basis for this unique localization, and whether it is required for its proper function have remained unresolved issues until recently. Our recent study resolved these questions by demonstrating that the unique V3 (hinge) domain of PKCθ and, more specifically, a proline-rich motif within this domain, is essential and sufficient for its localization at the IS, where it is anchored to the cytoplasmic tail of CD28 via an indirect mechanism involving Lck protein tyrosine kinase (PTK) as an intermediate. Importantly, the association of PKCθ with CD28 is essential not only for IS localization, but also for PKCθ-mediated activation of downstream signaling pathways, including the transcription factors NF-κB and NF-AT, which are essential for productive T cell activation. Hence, interference with formation of the PKCθ-Lck-CD28 complex provides a promising basis for the design of novel, clinically useful allosteric PKCθ inhibitors. An additional recent study demonstrated that TCR triggering activates the germinal center kinase (GSK)-like kinase (GLK) and induces its association with the SLP-76 adaptor at the IS, where GLK phosphorylates the activation loop of PKCθ, converting it into an active enzyme. This recent progress, coupled with the need to study the biology of PKCθ in human T cells, is likely to facilitate the development of PKCθ-based therapeutic modalities for T cell-mediated diseases.
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Affiliation(s)
- Noah Isakov
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences and the Cancer Research Center, Ben-Gurion University of the Negev Beer Sheva, Israel
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16
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Sun Z. Intervention of PKC-θ as an immunosuppressive regimen. Front Immunol 2012; 3:225. [PMID: 22876242 PMCID: PMC3410430 DOI: 10.3389/fimmu.2012.00225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 07/10/2012] [Indexed: 01/04/2023] Open
Abstract
PKC-θ is selectively enriched in T cells and specifically translocates to immunological synapse where it mediates critical T cell receptor signals required for T cell activation, differentiation, and survival. T cells deficient in PKC-θ are defective in their ability to differentiate into inflammatory effector cells that mediate actual immune responses whereas, their differentiation into regulatory T cells (Treg) that inhibits the inflammatory T cells is enhanced. Therefore, the manipulation of PKC-θ activity can shift the ratio between inflammatory effector T cells and inhibitory Tregs, to control T cell-mediated immune responses that are responsible for autoimmunity and allograft rejection. Indeed, PKC-θ-deficient mice are resistant to the development of several Th2 and Th17-dependent autoimmune diseases and are defective in mounting alloimmune responses required for rejection of transplanted allografts and graft-versus-host disease. Selective inhibition of PKC-θ is therefore considered as a potential treatment for prevention of autoimmune diseases and allograft rejection.
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Affiliation(s)
- Zuoming Sun
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA, USA
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17
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Weist BM, Hernandez JB, Walsh CM. Loss of DRAK2 signaling enhances allogeneic transplant survival by limiting effector and memory T cell responses. Am J Transplant 2012; 12:2220-7. [PMID: 22494341 PMCID: PMC3396732 DOI: 10.1111/j.1600-6143.2012.04056.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Here, we demonstrate that loss of DRAK2 signaling significantly promotes the acceptance of allogeneic engraftment in two separate transplant models without promoting generalized immunosuppression. Drak2-/- T cells failed to reject allogeneic tumors, and were defective in rejecting Balb/C allogeneic skin grafts on C57BL6/J recipients. A significant fraction of alloreactive Drak2-/- T cells underwent apoptosis following activation, whereas enforced expression of Bcl-xL in Drak2-/- T cells restored allograft rejection. Formation of allogeneic memory was also greatly hampered in T cells lacking the Drak2 gene. Adoptive transfer of memory T cells from Drak2-/- mice failed to promote the rejection of allogeneic tumors, and such cells led to significantly delayed rejection of skin allografts in the Balb/C->C57BL/6J model. Costimulatory blockade by in vivo administration of Cytotoxic T-Lymphocyte Antigen 4 fusion protein (CTLA4-Ig) synergized with the DRAK2 deficiency and led to long-term allogeneic skin graft acceptance. Overall, these results demonstrate that DRAK2 plays an important role in primary and memory T cell responsiveness to allografts. Because previous studies have demonstrated that a loss of DRAK2 does not negatively impact antiviral immunity, the studies here underscore the potential utility of pharmacological blockade of DRAK2 to achieve transplant maintenance without the imposition of generalized immunosuppression.
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Affiliation(s)
- Brian M. Weist
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900
- Institute for Immunology, University of California, Irvine, California 92697
| | - Jeniffer B. Hernandez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900
- Institute for Immunology, University of California, Irvine, California 92697
| | - Craig M. Walsh
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900
- Institute for Immunology, University of California, Irvine, California 92697
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18
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Kwon MJ, Ma J, Ding Y, Wang R, Sun Z. Protein kinase C-θ promotes Th17 differentiation via upregulation of Stat3. THE JOURNAL OF IMMUNOLOGY 2012; 188:5887-97. [PMID: 22586032 DOI: 10.4049/jimmunol.1102941] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although protein kinase C-θ (PKC-θ)-deficient mice are resistant to the induction of Th17-dependent experimental autoimmune encephalomyelitis, the function of PKC-θ in Th17 differentiation remains unknown. In this article, we show that purified, naive CD4 PKC-θ(-/-) T cells were defective in Th17 differentiation, whereas Th1 and Th2 differentiation appeared normal. Activation of PKC-θ with PMA promoted Th17 differentiation in wild type (WT) but not PKC-θ(-/-) T cells. Furthermore, PKC-θ(-/-) T cells had notably lower levels of Stat3, a transcription factor required for Th17 differentiation, and PMA markedly stimulated the expression of Stat3 in WT but not PKC-θ(-/-) T cells. In contrast, activation of Stat4 and Stat6, which are critical for Th1 and Th2 differentiation, was normal in PKC-θ(-/-) T cells. Forced expression of Stat3 significantly increased Th17 differentiation in PKC-θ(-/-) T cells, suggesting that reduced Stat3 levels were responsible for impaired Th17 differentiation, and that Stat3 lies downstream of PKC-θ. Constitutively active PKC-θ, or WT PKC-θ activated by either PMA or TCR cross-linking, stimulated expression of a luciferase reporter gene driven by the Stat3 promoter. PKC-θ-mediated activation of the Stat3 promoter was inhibited by dominant-negative AP-1 and IκB kinase-β, but stimulated by WT AP-1 and IκB kinase-β, suggesting that PKC-θ stimulates Stat3 transcription via the AP-1 and NF-κB pathways. Lastly, conditions favoring Th17 differentiation induced the highest activation level of PKC-θ. Altogether, the data indicate that PKC-θ integrates the signals from TCR signaling and Th17 priming cytokines to upregulate Stat3 via NF-κB and AP-1, resulting in the stimulation of Th17 differentiation.
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Affiliation(s)
- Myung-Ja Kwon
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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19
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Ma J, Ding Y, Fang X, Wang R, Sun Z. Protein kinase C-θ inhibits inducible regulatory T cell differentiation via an AKT-Foxo1/3a-dependent pathway. THE JOURNAL OF IMMUNOLOGY 2012; 188:5337-47. [PMID: 22539794 DOI: 10.4049/jimmunol.1102979] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Protein kinase C (PKC)-θ has been shown to be a critical TCR signaling molecule that promotes the activation and differentiation of naive T cells into inflammatory effector T cells. In this study, we demonstrate that PKC-θ-mediated signals inhibit inducible regulatory T cell (iTreg) differentiation via an AKT-Foxo1/3A pathway. TGF-β-induced iTreg differentiation was enhanced in PKC-θ(-/-) T cells or wild-type cells treated with a specific PKC-θ inhibitor, but was inhibited by the PKC-θ activator PMA, or by CD28 crosslinking, which enhances PKC-θ activation. PKC-θ(-/-) T cells had reduced activity of the AKT kinase, and the expression of a constitutively active form of AKT in PKC-θ(-/-) T cells restored the ability to inhibit iTreg differentiation. Furthermore, knockdown or overexpression of the AKT downstream targets Foxo1 and Foxo3a was found to inhibit or promote iTreg differentiation in PKC-θ(-/-) T cells accordingly, indicating that the AKT-Foxo1/3A pathway is responsible for the inhibition of iTreg differentiation of iTregs downstream of PKC-θ. We conclude that PKC-θ is able to control T cell-mediated immune responses by shifting the balance between the differentiation of effector T cells and inhibitory Tregs.
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Affiliation(s)
- Jian Ma
- Division of Immunology, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
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20
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Wang R, Xie H, Huang Z, Shang W, Sun Z. Developing and activated T cell survival depends on differential signaling pathways to regulate anti-apoptotic Bcl-x(L). Clin Dev Immunol 2011; 2012:632837. [PMID: 22235227 PMCID: PMC3253460 DOI: 10.1155/2012/632837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 11/07/2011] [Indexed: 12/22/2022]
Abstract
Survival of T cells in both the central and peripheral immune system determines its ultimate function in the regulation of immune responses. In the thymus, developing T cells undergo positive and negative selection to generate a T cell repertoire that responds to foreign, but not self, antigens. During T cell development, the T cell receptor α chain is rearranged. However, the first round of rearrangement may fail, which triggers another round of α chain rearrangement until either successful positive selection or cell death occurs. Thus, the lifespan of double positive (CD4(+)CD8(+); DP) thymocytes determines how many rounds of α chain rearrangement can be carried out and influences the likelihood of completing positive selection. The anti-apoptotic protein Bcl-x(L) is the ultimate effector regulating the survival of CD4(+)CD8(+) thymocytes subject to the selection process, and the deletion of Bcl-x(L) leads to premature apoptosis of thymocytes prior to the completion of the developmental process. In addition to its critical function in the thymus, Bcl-x(L) also regulates the survival of peripheral T cells. Upon engagement with antigens, T cells are activated and differentiated into effectors. Activated T cells upregulate Bcl-x(L) to enhance their own survival. Bcl-x(L)-mediated survival is required for the generation of effectors that carry out the actual immune responses. In the absence of Bcl-x(L), mature T cells undergo apoptosis prior to the completion of the differentiation process to become effector cells. Therefore, Bcl-x(L) ensures the survival of both developing and peripheral T cells, which is essential for a functional immune system.
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Affiliation(s)
- Ruiqing Wang
- Division of Immunology, Beckman Research Institute of the City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, CA 91010, USA
| | - Huimin Xie
- Department of Microbiology and Immunology, Medical School of the University of Illinois, Chicago, IL 60612, USA
| | - Zhaofeng Huang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Weirong Shang
- Department of Gynecology and Obstetrics, Emory University School of Medicine, 550 Peachtree Street, Suite 1800, Atlanta, GA 30308, USA
| | - Zuoming Sun
- Division of Immunology, Beckman Research Institute of the City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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21
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Molinero LL, Alegre ML. Role of T cell-nuclear factor κB in transplantation. Transplant Rev (Orlando) 2011; 26:189-200. [PMID: 22074783 DOI: 10.1016/j.trre.2011.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/17/2011] [Accepted: 07/12/2011] [Indexed: 11/30/2022]
Abstract
Nuclear factor (NF) κB is a pleiotropic transcription factor that is ubiquitously expressed. After transplantation of solid organs, NF-κB in the graft is activated within a few hours as a consequence of ischemia/reperfusion and then again after a few days in intragraft infiltrating cells during the process of acute allograft rejection. In the present article, we review the components of the NF-κB pathway, their mechanisms of activation, and their role in T cell and antigen-presenting cell activation and differentiation and in solid organ allograft rejection. Targeted inhibition of NF-κB in selected cell types may promote graft survival with fewer adverse effects compared with global immunosuppressive therapies.
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Affiliation(s)
- Luciana L Molinero
- Department of Medicine, Section of Rheumatology, The University of Chicago, Chicago, IL 60637, USA.
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22
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Zanin-Zhorov A, Dustin ML, Blazar BR. PKC-θ function at the immunological synapse: prospects for therapeutic targeting. Trends Immunol 2011; 32:358-63. [PMID: 21733754 DOI: 10.1016/j.it.2011.04.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 12/16/2022]
Abstract
Protein kinase C (PKC)-θ regulates conventional effector T (Teff) cell function. Since this initial finding, it has become clear that the role of PKC-θ in T cells is complex. PKC-θ plays a central role in Teff cell activation and survival, and negatively regulates stability of the immunological synapse (IS). Recent studies demonstrated that PKC-θ is required for the development of natural CD4(+)Foxp3(+) regulatory T (Treg) cells, and mediates negative regulation of Treg cell function. Here, we examine the role of PKC-θ in the IS, evidence for its distinct localization in Treg cells and the therapeutic implications of inhibiting PKC-θ in Teff cells, to reduce effector function, and in Treg cells, to increase suppressor function, for the prevention and treatment of autoimmune and alloimmune disease states.
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Affiliation(s)
- Alexandra Zanin-Zhorov
- Molecular Pathogenesis Program, Helen and Martin Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
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23
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Valenzuela JO, Iclozan C, Hossain MS, Prlic M, Hopewell E, Bronk CC, Wang J, Celis E, Engelman RW, Blazar BR, Bevan MJ, Waller EK, Yu XZ, Beg AA. PKCtheta is required for alloreactivity and GVHD but not for immune responses toward leukemia and infection in mice. J Clin Invest 2009; 119:3774-86. [PMID: 19907075 DOI: 10.1172/jci39692] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Accepted: 09/16/2009] [Indexed: 12/12/2022] Open
Abstract
When used as therapy for hematopoietic malignancies, allogeneic BM transplantation (BMT) relies on the graft-versus-leukemia (GVL) effect to eradicate residual tumor cells through immunologic mechanisms. However, graft-versus-host disease (GVHD), which is initiated by alloreactive donor T cells that recognize mismatched major and/or minor histocompatibility antigens and cause severe damage to hematopoietic and epithelial tissues, is a potentially lethal complication of allogeneic BMT. To enhance the therapeutic potential of BMT, we sought to find therapeutic targets that could inhibit GVHD while preserving GVL and immune responses to infectious agents. We show here that T cell responses triggered in mice by either Listeria monocytogenes or administration of antigen and adjuvant were relatively well preserved in the absence of PKC isoform theta (PKCtheta), a key regulator of TCR signaling. In contrast, PKCtheta was required for alloreactivity and GVHD induction. Furthermore, absence of PKCtheta raised the threshold for T cell activation, which selectively affected alloresponses. Most importantly, PKCtheta-deficient T cells retained the ability to respond to virus infection and to induce GVL effect after BMT. These findings suggest PKCtheta is a potentially unique therapeutic target required for GVHD induction but not for GVL or protective responses to infectious agents.
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Optimization of 5-phenyl-3-pyridinecarbonitriles as PKCθ inhibitors. Bioorg Med Chem Lett 2009; 19:3623-6. [DOI: 10.1016/j.bmcl.2009.04.126] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 04/24/2009] [Accepted: 04/24/2009] [Indexed: 11/15/2022]
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25
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Gruber T, Hermann-Kleiter N, Pfeifhofer-Obermair C, Lutz-Nicoladoni C, Thuille N, Letschka T, Barsig J, Baudler M, Li J, Metzler B, Nüsslein-Hildesheim B, Wagner J, Leitges M, Baier G. PKC theta cooperates with PKC alpha in alloimmune responses of T cells in vivo. Mol Immunol 2009; 46:2071-9. [PMID: 19356803 DOI: 10.1016/j.molimm.2009.02.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 02/16/2009] [Accepted: 02/17/2009] [Indexed: 12/15/2022]
Abstract
The physiological roles of PKC alpha and PKC theta were defined in T cell immune functions downstream of the antigen receptor. To investigate the hypothesis that both PKC isotypes may have overlapping functions, we generated mice lacking both genes. We find that PKC alpha(-/-)/theta(-/-) animals have additive T cell response defects in comparison to animals carrying single mutations in these genes. Our studies demonstrate that the activities of PKC alpha and PKC theta converge to regulate both IL-2 cytokine responses and T cell intrinsic alloreactivity in vivo. Mechanistically, this PKC alpha/theta crosstalk primarily affects the NFAT transactivation pathway in T lymphocytes, as observed by decreased phosphorylation of Ser-9 on GSK3 beta, reduced nuclear translocation and DNA binding of NFAT in isolated PKC alpha(-/-)/theta(-/-) CD3(+) T cells. This additive defect proved to be of physiological relevance, because PKC alpha(-/-)/theta(-/-) mice demonstrated significantly prolonged allograft survival in heart transplantation experiments, whereas both PKC alpha(-/-) and PKC theta(-/-) mice showed only minimal graft prolongation when compared to wild type controls. While PKC theta appears to be the rate-limiting PKC isotype mediating T lymphocyte activation, we here provide genetic evidence that PKC alpha and PKC theta have overlapping functions in alloimmunoreactivity in vivo and both PKC theta and PKC alpha isotypes must be targeted to prevent organ allograft rejection.
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Affiliation(s)
- Thomas Gruber
- Department for Medical Genetics, Molecular and Clinical Pharmacology, Medical University Innsbruck, Austria
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26
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Baier G, Wagner J. PKC inhibitors: potential in T cell-dependent immune diseases. Curr Opin Cell Biol 2009; 21:262-7. [DOI: 10.1016/j.ceb.2008.12.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 12/30/2008] [Indexed: 10/21/2022]
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27
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Wang L, Xiang Z, Ma LL, Chen Z, Gao X, Sun Z, Williams P, Chari RS, Yin DP. Deficiency of Protein Kinase C-Theta Facilitates Tolerance Induction. Transplantation 2009; 87:507-16. [DOI: 10.1097/tp.0b013e318195fd36] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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28
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Second generation 4-(4-methyl-1H-indol-5-ylamino)-2-phenylthieno[2,3-b]pyridine-5-carbonitrile PKCθ inhibitors. Bioorg Med Chem Lett 2009; 19:766-9. [DOI: 10.1016/j.bmcl.2008.12.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/04/2008] [Accepted: 12/04/2008] [Indexed: 12/17/2022]
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