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Structural aspects of the MHC expression control system. Biophys Chem 2022; 284:106781. [PMID: 35228036 PMCID: PMC8941990 DOI: 10.1016/j.bpc.2022.106781] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/04/2022] [Accepted: 02/13/2022] [Indexed: 12/11/2022]
Abstract
The major histocompatibility complex (MHC) spans innate and adaptive immunity by presenting antigenic peptides to CD4+ and CD8+ T cells. Multiple transcription factors form an enhanceosome complex on the MHC promoter and recruit transcriptional machinery to activate gene transcription. Immune signals such as interferon-γ (IFN-γ) control MHC level by up-regulating components of the enhanceosome complex. As MHC plays crucial roles in immune regulation, alterations in the MHC enhanceosome structure will alter the pace of rapid immune responses at the transcription level and lead to various diseases related to the immune system. In this review, we discuss the current understanding of the MHC enhanceosome, with a focus on the structures of MHC enhanceosome components and the molecular basis of MHC enhanceosome assembly.
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Vijayan S, Sidiq T, Yousuf S, van den Elsen PJ, Kobayashi KS. Class I transactivator, NLRC5: a central player in the MHC class I pathway and cancer immune surveillance. Immunogenetics 2019; 71:273-282. [PMID: 30706093 DOI: 10.1007/s00251-019-01106-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 01/10/2019] [Indexed: 12/19/2022]
Abstract
Major histocompatibility complex (MHC) class I and class II molecules play critical roles in the activation of the adaptive immune system by presenting antigens to CD8+ and CD4+ T cells, respectively. Although it has been well known that CIITA (MHC class II transactivator), an NLR (nucleotide-binding domain, leucine-rich-repeat containing) protein, as a master regulator of MHC class II gene expression, the mechanism of MHC class I gene transactivation was unclear. Recently, another NLR protein, NLRC5 (NLR family, CARD domain-containing 5), was identified as an MHC class I transactivator (CITA). NLRC5 is a critical regulator for the transcriptional activation of MHC class I genes and other genes involved in the MHC class I antigen presentation pathway. CITA/NLRC5 plays a crucial role in human cancer immunity through the recruitment and activation of tumor killing CD8+ T cells. Here, we discuss the molecular function and mechanism of CITA/NLRC5 in the MHC class I pathway and its role in cancer.
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Affiliation(s)
- Saptha Vijayan
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, TX, 77843, USA
| | - Tabasum Sidiq
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, TX, 77843, USA
| | - Suhail Yousuf
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, TX, 77843, USA
| | - Peter J van den Elsen
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.,Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Koichi S Kobayashi
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, TX, 77843, USA. .,Department of Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
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3
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Xu Z, Cheng K, Li X, Yang J, Xu S, Cao X, Hu X, Xie W, Yuan L, Ambrose M, Chen G, Mi H, Luo D. Transcriptional and Post-transcriptional Modulation of SQU and KEW Activities in the Control of Dorsal-Ventral Asymmetric Flower Development in Lotus japonicus. MOLECULAR PLANT 2016; 9:722-736. [PMID: 26854849 DOI: 10.1016/j.molp.2016.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 01/16/2016] [Accepted: 01/30/2016] [Indexed: 06/05/2023]
Abstract
In Papilionoideae legume, Lotus japonicus, the development of dorsal-ventral (DV) asymmetric flowers is mainly controlled by two TB1/CYCLOIDEA/PCF (TCP) genes, SQUARED STANDARD (SQU) and KEELED WINGS IN LOTUS (KEW), which determine dorsal and lateral identities, respectively. However, the molecular basis of how these two highly homologous genes orchestrate their diverse functions remains unclear. Here, we analyzed their expression levels, and investigated the transcriptional activities of SQU and KEW. We demonstrated that SQU possesses both activation and repression activities, while KEW acts only as an activator. They form homo- and heterodimers, and then collaboratively regulate their expression at the transcription level. Furthermore, we identified two types of post-transcriptional modifications, phosphorylation and ATP/GTP binding, both of which could affect their transcriptional activities. Mutations in ATP/GTP binding motifs of SQU and KEW lead to failure of phosphorylation, and transgenic plants bearing the mutant proteins display defective DV asymmetric flower development, indicating that the two conjugate modifications are essential for their diverse functions. Altogether, SQU and KEW activities are precisely modulated at both transcription and post-transcription levels, which might link DV asymmetric flower development to different physiological status and/or signaling pathways.
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Affiliation(s)
- Zhiyong Xu
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China; Modality of LFIA, Research and Application Marketing, Healthcare Group of General Electric, China Technology Park, Shanghai 201203, China
| | - Kai Cheng
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xin Li
- Laboratory Center of Life Sciences, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jun Yang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Shilei Xu
- Laboratory of Cancer Cell Biology, Tianjin Medical University Cancer Hospital and Institute, Tianjin 300060, China
| | - Xiangling Cao
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiaohe Hu
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Ling Yuan
- Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY 40546, USA
| | - Mike Ambrose
- Department of Crop Genetics, John Innes Centre, Colney, Norwich NR4 7UH, UK
| | - Genyun Chen
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Da Luo
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
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4
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Neerincx A, Castro W, Guarda G, Kufer TA. NLRC5, at the Heart of Antigen Presentation. Front Immunol 2013; 4:397. [PMID: 24319445 PMCID: PMC3837245 DOI: 10.3389/fimmu.2013.00397] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/07/2013] [Indexed: 01/25/2023] Open
Abstract
Nucleotide-binding domain and leucine-rich repeat containing receptors (NLRs) are intracellular proteins mainly involved in pathogen recognition, inflammatory responses, and cell death. Until recently, the function of the family member NLR caspase recruitment domain (CARD) containing 5 (NLRC5) has been a matter of debate. It is now clear that NLRC5 acts as a transcriptional regulator of the major-histocompatibility complex class I. In this review we detail the development of our understanding of NLRC5 function, discussing both the accepted and the controversial aspects of NLRC5 activity. We give insight into the molecular mechanisms, and the potential implications, of NLRC5 function in health and disease.
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Affiliation(s)
- Andreas Neerincx
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne , Cologne , Germany
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Kobayashi KS, van den Elsen PJ. NLRC5: a key regulator of MHC class I-dependent immune responses. Nat Rev Immunol 2013; 12:813-20. [PMID: 23175229 DOI: 10.1038/nri3339] [Citation(s) in RCA: 256] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The expression of MHC class I molecules is crucial for the initiation and regulation of adaptive immune responses against pathogens. NOD-, LRR- and CARD-containing 5 (NLRC5) was recently identified as a specific transactivator of MHC class I genes (CITA). NLRC5 and the master regulator for MHC class II genes, class II transactivator (CIITA), interact with similar MHC promoter-bound factors. Here, we provide a broad overview of the molecular mechanisms behind MHC class I transcription and the role of the class I transactivator NLRC5 in MHC class I-dependent immune responses.
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Affiliation(s)
- Koichi S Kobayashi
- Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M Health Science Center, College Station, Texas 77843, USA.
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6
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Inostroza-Nieves Y, Venkatraman P, Zavala-Ruiz Z. Role of Sug1, a 19S proteasome ATPase, in the transcription of MHC I and the atypical MHC II molecules, HLA-DM and HLA-DO. Immunol Lett 2012; 147:67-74. [PMID: 22771340 DOI: 10.1016/j.imlet.2012.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/09/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
Abstract
The 19S proteasome regulatory particle plays a critical role in cellular proteolysis. However, emerging evidence suggests roles for 19S proteasome subunits in regulating yeast and mammalian transcription. It has been previously shown that Sug1 is important for the transcription of MHC II molecules. We report here that Sug1 also has a role in regulating transcription of class I MHC and the MHC II-like molecules, HLA-DM and HLA-DO. Reduction of Sug1 expression causes a decrease in the transcription of MHC I and MHC II-like molecules. In addition, we show that association of Sug1 with MHC promoters is followed by the recruitment of the CREB-binding protein (CBP) and the class II transactivator (CIITA). Reduction of Sug1 expression is accompanied by decreased recruitment of CBP and CIITA to the MHC promoters and decreased histone H3 acetylation in these promoters. These studies suggest that Sug1 plays a critical role in transcription of MHC class I, and the MHC class II-like molecules, HLA-DM and HLA-DO.
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Affiliation(s)
- Yaritza Inostroza-Nieves
- Department of Biochemistry, University of Puerto Rico, Medical Sciences Campus, San Juan, PR, USA
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Mo J, Boyle JP, Howard CB, Monie TP, Davis BK, Duncan JA. Pathogen sensing by nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is mediated by direct binding to muramyl dipeptide and ATP. J Biol Chem 2012; 287:23057-67. [PMID: 22549783 PMCID: PMC3391102 DOI: 10.1074/jbc.m112.344283] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 04/11/2012] [Indexed: 11/07/2022] Open
Abstract
Nucleotide binding and oligomerization domain-containing protein 2 (NOD2/Card15) is an intracellular protein that is involved in the recognition of bacterial cell wall-derived muramyl dipeptide. Mutations in the gene encoding NOD2 are associated with inherited inflammatory disorders, including Crohn disease and Blau syndrome. NOD2 is a member of the nucleotide-binding domain and leucine-rich repeat-containing protein gene (NLR) family. Nucleotide binding is thought to play a critical role in signaling by NLR family members. However, the molecular mechanisms underlying signal transduction by these proteins remain largely unknown. Mutations in the nucleotide-binding domain of NOD2 have been shown to alter its signal transduction properties in response to muramyl dipeptide in cellular assays. Using purified recombinant protein, we now demonstrate that NOD2 binds and hydrolyzes ATP. Additionally, we have found that the purified recombinant protein is able to bind directly to muramyl dipeptide and can associate with known NOD2-interacting proteins in vitro. Binding of NOD2 to muramyl dipeptide and homo-oligomerization of NOD2 are enhanced by ATP binding, suggesting a model of the molecular mechanism for signal transduction that involves binding of nucleotide followed by binding of muramyl dipeptide and oligomerization of NOD2 into a signaling complex. These findings set the stage for further studies into the molecular mechanisms that underlie detection of muramyl dipeptide and assembly of NOD2-containing signaling complexes.
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Affiliation(s)
- Jinyao Mo
- From the Department of Medicine, Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina 27599-7030
| | - Joseph P. Boyle
- the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Tom P. Monie
- the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Beckley K. Davis
- the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295, and
| | - Joseph A. Duncan
- From the Department of Medicine, Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina 27599-7030
- the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295, and
- the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365
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Meissner TB, Li A, Liu YJ, Gagnon E, Kobayashi KS. The nucleotide-binding domain of NLRC5 is critical for nuclear import and transactivation activity. Biochem Biophys Res Commun 2012; 418:786-91. [PMID: 22310711 DOI: 10.1016/j.bbrc.2012.01.104] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 01/23/2012] [Indexed: 11/15/2022]
Abstract
Major histocompatibility complex (MHC) class I and class II are crucial for the function of the human adaptive immune system. A member of the NLR (nucleotide-binding domain, leucine-rich repeat) protein family, NLRC5, has recently been identified as a transcriptional regulator of MHC class I and related genes. While a 'master regulator' of MHC class II genes, CIITA, has long been known, NLRC5 specifically associates with and transactivates the proximal promoters of MHC class I genes. In this study, we analyzed the molecular requirements of NLRC5 nuclear import and transactivation activity. We show that NLRC5-mediated MHC class I gene induction requires an intact nuclear localization signal and nuclear distribution of NLRC5. In addition, we find that the nucleotide-binding domain (NBD) of NLRC5 is critical not only for nuclear translocation but also for the transactivation of MHC class I genes. Changing the cellular localization of NLRC5 is likely to immediately impact MHC class I expression as well as MHC class I-mediated antigen presentation. NLRC5 may thus provide a promising target for the modulation of MHC class I antigen presentation, especially in the setting of transplant medicine.
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Affiliation(s)
- Torsten B Meissner
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, MA 02215, United States
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Meissner TB, Li A, Kobayashi KS. NLRC5: a newly discovered MHC class I transactivator (CITA). Microbes Infect 2011; 14:477-84. [PMID: 22209772 DOI: 10.1016/j.micinf.2011.12.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 12/09/2011] [Accepted: 12/12/2011] [Indexed: 02/07/2023]
Abstract
Major histocompatibility complex (MHC) class I and class II are crucial for the function of the human adaptive immune system. An NLR protein, CIITA (MHC class II transactivator), is a master regulator of MHC class II gene expression as well as of some of the genes involved in MHC class II antigen presentation. It has recently been discovered that another member of the NLR protein family, NLRC5, transcriptionally activates MHC class I genes, and thus acts as "CITA" (MHC class I transactivator), a counterpart to CIITA. In addition to MHC class I genes, NLRC5 can induce the expression of β2M, TAP1 and LMP2, essential components of MHC class I antigen presentation. These findings indicate that NLRC5 and CIITA are transcriptional regulators that orchestrate the concerted expression of critical components in the MHC class I and MHC class II pathways, respectively.
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Affiliation(s)
- Torsten B Meissner
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Dana 1420A, Boston, MA 02215, United States
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Atianand MK, Harton JA. Uncoupling of Pyrin-only protein 2 (POP2)-mediated dual regulation of NF-κB and the inflammasome. J Biol Chem 2011; 286:40536-47. [PMID: 21976665 DOI: 10.1074/jbc.m111.274290] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Activation of transcription factor NF-κB and inflammasome-directed caspase-1 cleavage of IL-1β are key processes in the inflammatory response to pathogen or host-derived signals. Pyrin-only proteins (POPs) are restricted to Old World monkeys, apes, and humans and have previously been shown to impair inflammasome assembly and/or NF-κB p65 transcriptional activity in transfected epithelial cells. However, the biological role of POP2 and the molecular basis for its observed functions are not well understood. In this report we demonstrate that POP2 regulates TNFα and IL-1β responses in human monocytic THP-1 cells and in stable transfectants of mouse J774A.1 macrophages. Deletion analysis of POP2 revealed that the first α-helix (residues 1-19) is necessary and sufficient for both inflammasome and NF-κB inhibitory functions. Further, key acidic residues Glu(6), Asp(8), and Glu(16), believed critical for Pyrin/Pyrin domain interaction, are important for inflammasome inhibition. Moreover, these mutations did not reduce the effect of POP2 upon NF-κB, indicating that the inflammasome and NF-κB inhibitory properties of POP2 can be uncoupled mechanistically. Collectively, these data demonstrate that POP2 acts as a regulator of inflammatory signals and exerts its two known functions through distinct modalities employed by its first α-helix.
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Affiliation(s)
- Maninjay K Atianand
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208, USA
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NLR family member NLRC5 is a transcriptional regulator of MHC class I genes. Proc Natl Acad Sci U S A 2010; 107:13794-9. [PMID: 20639463 DOI: 10.1073/pnas.1008684107] [Citation(s) in RCA: 317] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
MHC class I plays a critical role in the immune defense against viruses and tumors by presenting antigens to CD8 T cells. An NLR protein, class II transactivator (CIITA), is a key regulator of MHC class II gene expression that associates and cooperates with transcription factors in the MHC class II promoter. Although CIITA also transactivates MHC class I gene promoters, loss of CIITA in humans and mice results in the severe reduction of only MHC class II expression, suggesting that additional mechanisms regulate the expression of MHC class I. Here, we identify another member of the NLR protein family, NLRC5, as a transcriptional regulator of MHC class I genes. Similar to CIITA, NLRC5 is an IFN-gamma-inducible nuclear protein, and the expression of NLRC5 resulted in enhanced MHC class I expression in lymphoid as well as epithelial cell lines. Using chromatin immunoprecipitation and reporter gene assays, we show that NLRC5 associates with and activates the promoters of MHC class I genes. Furthermore, we show that the IFN-gamma-induced up-regulation of MHC class I requires NLRC5, because knockdown of NLRC5 specifically impaired the expression of MHC class I. In addition to MHC class I genes, NLRC5 also induced the expression of beta2-microglobulin, transporter associated with antigen processing, and large multifunctional protease, which are essential for MHC class I antigen presentation. Our results suggest that NLRC5 is a transcriptional regulator, orchestrating the concerted expression of critical components in the MHC class I pathway.
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Porter KA, Kelley LN, George A, Harton JA, Duus KM. Class II transactivator (CIITA) enhances cytoplasmic processing of HIV-1 Pr55Gag. PLoS One 2010; 5:e11304. [PMID: 20585587 PMCID: PMC2892040 DOI: 10.1371/journal.pone.0011304] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 05/26/2010] [Indexed: 11/18/2022] Open
Abstract
Background The Pr55gag (Gag) polyprotein of HIV serves as a scaffold for virion assembly and is thus essential for progeny virion budding and maturation. Gag localizes to the plasma membrane (PM) and membranes of late endosomes, allowing for release of infectious virus directly from the cell membrane and/or upon exocytosis. The host factors involved in Gag trafficking to these sites are largely unknown. Upon activation, CD4+ T cells, the primary target of HIV infection, express the class II transcriptional activator (CIITA) and therefore the MHC class II isotype, HLA-DR. Similar to Gag, HLA-DR localizes to the PM and at the membranes of endosomes and specialized vesicular MHC class II compartments (MIICs). In HIV producer cells, transient HLA-DR expression induces intracellular Gag accumulation and impairs virus release. Methodology/Principal Findings Here we demonstrate that both stable and transient expression of CIITA in HIV producer cells does not induce HLA-DR-associated intracellular retention of Gag, but does increase the infectivity of virions. However, neither of these phenomena is due to recapitulation of the class II antigen presentation pathway or CIITA-mediated transcriptional activation of virus genes. Interestingly, we demonstrate that CIITA, apart from its transcriptional effects, acts cytoplasmically to enhance Pr160gag-pol (Gag-Pol) levels and thereby the viral protease and Gag processing, accounting for the increased infectivity of virions from CIITA-expressing cells. Conclusions/Significance This study demonstrates that CIITA enhances HIV Gag processing, and provides the first evidence of a novel, post-transcriptional, cytoplasmic function for a well-known transactivator.
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Affiliation(s)
- Kristen A. Porter
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Lauren N. Kelley
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Annette George
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Jonathan A. Harton
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Karen M. Duus
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
- * E-mail:
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Voong LN, Slater AR, Kratovac S, Cressman DE. Mitogen-activated protein kinase ERK1/2 regulates the class II transactivator. J Biol Chem 2008; 283:9031-9. [PMID: 18245089 PMCID: PMC2431044 DOI: 10.1074/jbc.m706487200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 01/31/2008] [Indexed: 01/12/2023] Open
Abstract
The expression of major histocompatibility class II genes is necessary for proper antigen presentation and induction of an immune response. This expression is initiated by the class II transactivator, CIITA. The establishment of the active form of CIITA is controlled by a series of post-translational events, including GTP binding, ubiquitination, and dimerization. However, the role of phosphorylation is less clearly defined as are the consequences of phosphorylation on CIITA activity and the identity of the kinases involved. In this study we show that the extracellular signal-regulated kinases 1 and 2 (ERK1/2) interact directly with CIITA, targeting serine residues in the amino terminus of the protein, including serine 288. Inhibition of this phosphorylation by dominant-negative forms of ERK or by treatment of cells with the ERK inhibitor PD98059 resulted in the increase in CIITA-mediated gene expression from a class II promoter, enhanced the nuclear concentration of CIITA, and impaired its ability to bind to the nuclear export factor, CRM1. In contrast, inhibition of ERK1/2 activity had little effect on serine-to-alanine mutant forms of CIITA. These data suggest a model whereby ERK1/2-mediated phosphorylation of CIITA down-regulates CIITA activity by priming it for nuclear export, thus providing a means for cells to tightly regulate the extent of antigen presentation.
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Affiliation(s)
- Lilien N Voong
- Department of Biology, Sarah Lawrence College, 1 Mead Way, Bronxville, NY 10708, USA
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