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Huang S, Wang J, Zhang L, Tian S, Wang Y, Shao X, Zhou S, Yu P. Ras guanine nucleotide-releasing protein-4 promotes renal inflammatory injury in type 2 diabetes mellitus. Metabolism 2022; 131:155177. [PMID: 35218794 DOI: 10.1016/j.metabol.2022.155177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/31/2022] [Accepted: 02/18/2022] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Ras guanine nucleotide-releasing protein-4 (RasGRP4) is an activator of Ras protein, which plays significant roles in both the inflammatory response and immune activation. This study determined the role of RasGRP4 in diabetic kidney disease (DKD) progression. METHODS CRISPR/Cas9 technology was used to establish RasGRP4 knockout (KO) mice. Diabetes was induced by a high-fat diet combined with five consecutive daily intraperitoneal injections of streptozotocin (60 mg/kg) in C57BL/6J wild-type (WT) mice and RasGRP4 KO mice. Hematoxylin and eosin, periodic acid-Schiff, and Masson's trichrome staining were used to observe the histology of pathological injury. Immunohistochemical staining was used to analyze inflammatory cell infiltration. Quantitative PCR and Western blotting were used to detect the expression of inflammatory mediators and the activation of signaling pathways in renal tissues. In vitro cell co-culture experiments were performed to explore the interactions between peripheral blood mononuclear cells (PBMCs) and glomerular endothelial cells (GEnCs). RESULTS RasGRP4 KO mice developed less severe diabetic kidney injury compared to WT mice, exhibiting lower proteinuria, reduced CD3+ T lymphocyte and F4/80+ macrophage infiltration, less inflammatory mediator expression including interleukin 6, tumor necrosis alpha, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1, and lower expression levels of critical signal transduction molecules in the NLR family pyrin domain-containing 3 inflammasome and mitogen-activated protein kinase (MAPK)/nuclear factor kappa B (NF-κB) signaling pathways in the diabetic kidney. In vitro experiments showed that the adhesion function of PBMCs of RasGRP4 KO mice was reduced compared to that of WT mice. Moreover, the expression of adhesion molecules and critical signal transduction molecules in the NLRP3 inflammasome and MAPK/NF-κB signaling pathways in GEnCs was stimulated by the supernatant of PBMCs, which were derived from RasGRP4 KO mice treated with high glucose and were also significantly reduced compared to those derived from WT mice. CONCLUSION RasGRP4 promotes the inflammatory injury mediated by PBMCs in diabetes, probably by regulating the interaction between PBMCs and GEnCs and further activating the NLRP3 inflammasome and MAPK/NF-κB signaling pathways.
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Affiliation(s)
- Shuai Huang
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Junmei Wang
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Li Zhang
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Shasha Tian
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Yao Wang
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Xian Shao
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Saijun Zhou
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Pei Yu
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China.
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Benoit A, Bou-Petit E, Chou H, Lu M, Guilbert C, Luo VM, Assouline S, Morin RD, Dmitrienko S, Estrada-Tejedor R, Johnson NA, Mann KK. Mutated RAS-associating proteins and ERK activation in relapse/refractory diffuse large B cell lymphoma. Sci Rep 2022; 12:779. [PMID: 35039569 PMCID: PMC8764096 DOI: 10.1038/s41598-021-04736-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/06/2021] [Indexed: 11/16/2022] Open
Abstract
Diffuse large B cell lymphoma (DLBCL) is successfully treated with combination immuno-chemotherapy, but relapse with resistant disease occurs in ~ 40% of patients. However, little is known regarding relapsed/refractory DLBCL (rrDLBCL) genetics and alternative therapies. Based on findings from other tumors, we hypothesized that RAS-MEK-ERK signaling would be upregulated in resistant tumors, potentially correlating with mutations in RAS, RAF, or associated proteins. We analyzed mutations and phospho-ERK levels in tumor samples from rrDLBCL patients. Unlike other tumor types, rrDLBCL is not mutated in any Ras or Raf family members, despite having increased expression of p-ERK. In paired biopsies comparing diagnostic and relapsed specimens, 33% of tumors gained p-ERK expression, suggesting a role in promoting survival. We did find mutations in several Ras-associating proteins, including GEFs, GAPs, and downstream effectors that could account for increased ERK activation. We further investigated mutations in one such protein, RASGRP4. In silico modeling indicated an increased interaction between H-Ras and mutant RASGRP4. In cell lines, mutant RASGRP4 increased basal p-ERK expression and lead to a growth advantage in colony forming assays when challenged with doxorubicin. Relapsed/refractory DLBCL is often associated with increased survival signals downstream of ERK, potentially corresponding with mutations in protein controlling RAS/MEK/ERK signaling.
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Affiliation(s)
- Alexandre Benoit
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Elisabeth Bou-Petit
- Grup de Química Farmacèutica, IQS School of Engineering, Universitat Ramon Llull, Barcelona, Spain
| | - Hsiang Chou
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Melissa Lu
- Université de Montréal-Faculté de Médecine, Montreal, Canada
| | - Cynthia Guilbert
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada
| | - Vincent Mingyi Luo
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - Sarit Assouline
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada.,Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
| | - Ryan D Morin
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Svetlana Dmitrienko
- Division of Pathology, McGill University Health Centre, Montreal, QC, Canada
| | - Roger Estrada-Tejedor
- Grup de Química Farmacèutica, IQS School of Engineering, Universitat Ramon Llull, Barcelona, Spain
| | - Nathalie A Johnson
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada.,Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
| | - Koren K Mann
- Lady Davis Institute, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC, H3T 1E2, Canada. .,Division of Experimental Medicine, McGill University, Montreal, QC, Canada. .,Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada.
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Steinhoff M, Buddenkotte J, Lerner EA. Role of mast cells and basophils in pruritus. Immunol Rev 2018; 282:248-264. [DOI: 10.1111/imr.12635] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Martin Steinhoff
- Department of Dermatology and Venereology; Hamad Medical Corporation; Doha Qatar
- Translational Research Institute; Hamad Medical Corporation; Doha Qatar
- Weill Cornell Medicine-Qatar; Doha Qatar
- Medical School; Qatar University; Doha Qatar
- Department Of Dermatology and UCD Charles Institute for Translational Dermatology; University College Dublin; Dublin Ireland
| | - Jörg Buddenkotte
- Department of Dermatology and Venereology; Hamad Medical Corporation; Doha Qatar
- Translational Research Institute; Hamad Medical Corporation; Doha Qatar
| | - Ethan A. Lerner
- Cutaneous Biology Research Center; Department of Dermatology; Massachusetts General Hospital/Harvard Medical School; Charlestown MA USA
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Zhou S, Tanaka K, O’Keeffe M, Qi M, El-Assaad F, Weaver JC, Chen G, Weatherall C, Wang Y, Giannakopoulos B, Chen L, Yu D, Hamilton MJ, Wensing LA, Stevens RL, Krilis SA. CD117+ Dendritic and Mast Cells Are Dependent on RasGRP4 to Function as Accessory Cells for Optimal Natural Killer Cell-Mediated Responses to Lipopolysaccharide. PLoS One 2016; 11:e0151638. [PMID: 26982501 PMCID: PMC4794117 DOI: 10.1371/journal.pone.0151638] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/02/2016] [Indexed: 11/25/2022] Open
Abstract
Ras guanine nucleotide-releasing protein-4 (RasGRP4) is an evolutionarily conserved calcium-regulated, guanine nucleotide exchange factor and diacylglycerol/phorbol ester receptor. While an important intracellular signaling protein for CD117+ mast cells (MCs), its roles in other immune cells is less clear. In this study, we identified a subset of in vivo-differentiated splenic CD117+ dendritic cells (DCs) in wild-type (WT) C57BL/6 mice that unexpectedly contained RasGRP4 mRNA and protein. In regard to the biologic significance of these data to innate immunity, LPS-treated splenic CD117+ DCs from WT mice induced natural killer (NK) cells to produce much more interferon-γ (IFN-γ) than comparable DCs from RasGRP4-null mice. The ability of LPS-responsive MCs to cause NK cells to increase their expression of IFN-γ was also dependent on this intracellular signaling protein. The discovery that RasGRP4 is required for CD117+ MCs and DCs to optimally induce acute NK cell-dependent immune responses to LPS helps explain why this signaling protein has been conserved in evolution.
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Affiliation(s)
- Saijun Zhou
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- Laboratory of Hormones and Development (Ministry of Health), Metabolic Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, TJ, China
| | - Kumiko Tanaka
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Meredith O’Keeffe
- Dendritic Cell Research Laboratory, Immunity Vaccines and Immunisation, Burnet Institute, Prahran, Melbourne, Victoria, Australia
| | - Miao Qi
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Fatima El-Assaad
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - James C. Weaver
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- Department of Cardiology, St. George Hospital, Sydney, New South Wales, Australia
| | - Gang Chen
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Christopher Weatherall
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Ying Wang
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Bill Giannakopoulos
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Liming Chen
- Laboratory of Hormones and Development (Ministry of Health), Metabolic Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, TJ, China
| | - DeMint Yu
- Laboratory of Hormones and Development (Ministry of Health), Metabolic Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, TJ, China
| | - Matthew J. Hamilton
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
- Division of Gastroenterology, Brigham and Women’s Hospital, Boston, MA, United States of America
| | - Lislaine A. Wensing
- Departament of Immunology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Richard L. Stevens
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Steven A. Krilis
- Department of Infectious Diseases, Immunology, and Sexual Health, St. George Hospital, and the St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail:
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Han NR, Kim HM, Jeong HJ. Tryptanthrin reduces mast cell proliferation promoted by TSLP through modulation of MDM2 and p53. Biomed Pharmacother 2016; 79:71-7. [PMID: 27044814 DOI: 10.1016/j.biopha.2016.01.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 10/22/2022] Open
Abstract
BACKGROUND Atopic dermatitis (AD) results from complex interactions between mast cells and inflammatory mediators. An inflammatory mediator, thymic stromal lymphopoietin (TSLP) is known to promote mast cell proliferation through up-regulation of mouse double minute 2 (MDM2, a negative regulator of p53) and aggravate AD. In this study, we investigated whether tryptanthrin (TR, an anti-inflammatory agent) would regulate TSLP-induced mast cell proliferation and TSLP-induced a pro-inflammatory cytokine, tumor necrosis factor (TNF)-α production from mast cells. METHODS Human mast cell line (HMC-1) cells were treated with TR and stimulated with TSLP. Proliferation was measured with a bromodeoxyuridine incorporation assay. And pro- and anti-apoptotic factors were analyzed with quantitative real-time PCR, Western blot analysis, and ELISA. The mRNA expression and production of TNF-α were analyzed with quantitative real-time PCR and ELISA. RESULTS TR significantly inhibited the proliferation of HMC-1 cells promoted by TSLP. TR inhibited MDM2 expression, whereas TR increased the expression of p53, poly ADP-ribose polymerase, and caspase-3 in the TSLP-stimulated HMC-1 cells. TR significantly inhibited Ki67 mRNA expression as well as mRNA expression and production of interleukin (IL)-13 in the TSLP-stimulated HMC-1 cells. Moreover, TR significantly suppressed mRNA expression and production of TNF-α in the TSLP-stimulated HMC-1 cells. Finally, the mRNA expression of IL-7 receptor α chain and TSLP receptor was inhibited by TR in the TSLP-stimulated HMC-1 cells. CONCLUSION Our results suggest that TR determined with new concept has intensive potential for the treatment of mast cell-mediated allergic diseases, such as AD.
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Affiliation(s)
- Na-Ra Han
- Department of Pharmacology, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
| | - Hyung-Min Kim
- Department of Pharmacology, College of Korean Medicine, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea.
| | - Hyun-Ja Jeong
- Department of Food Technology and Inflammatory Disease Research Center, Hoseo University, 20, Hoseo-ro 79 beon-gil, Baebang-eup, Asan, Chungcheongnam-do 336-795, Republic of Korea.
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GPCR activation of Ras and PI3Kc in neutrophils depends on PLCb2/b3 and the RasGEF RasGRP4. EMBO J 2012; 31:3118-29. [PMID: 22728827 PMCID: PMC3400018 DOI: 10.1038/emboj.2012.167] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 05/15/2012] [Indexed: 12/31/2022] Open
Abstract
The molecular mechanisms by which receptors regulate the Ras Binding Domains of the PIP3-generating, class I PI3Ks remain poorly understood, despite their importance in a range of biological settings, including tumorigenesis, activation of neutrophils by pro-inflammatory mediators, chemotaxis of Dictyostelium and cell growth in Drosophila. We provide evidence that G protein-coupled receptors (GPCRs) can stimulate PLCb2/b3 and diacylglycerol- dependent activation of the RasGEF, RasGRP4 in neutrophils. The genetic loss of RasGRP4 phenocopies knock-in of a Ras-insensitive version of PI3Kc in its effects on PI3Kc-dependent PIP3 accumulation, PKB activation, chemokinesis and reactive oxygen species (ROS) formation. These results establish a new mechanism by which GPCRs can stimulate Ras, and the broadly important principle that PLCs can control activation of class I PI3Ks.
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Reedquist KA, Tak PP. Signal transduction pathways in chronic inflammatory autoimmune disease: small GTPases. Open Rheumatol J 2012; 6:259-72. [PMID: 23028410 PMCID: PMC3460313 DOI: 10.2174/1874312901206010259] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/19/2012] [Accepted: 06/21/2012] [Indexed: 01/28/2023] Open
Abstract
Ras superfamily small GTPases represent a wide and diverse class of intracellular signaling proteins that are highly conserved during evolution. These enzymes serve as key checkpoints in coupling antigen receptor, growth factor, cytokine and chemokine stimulation to cellular responses. Once activated, via their ability to regulate multiple downstream signaling pathways, small GTPases amplify and diversify signaling cascades which regulate cellular proliferation, survival, cytokine expression, trafficking and retention. Small GTPases, particularly members of the Ras, Rap, and Rho family, critically coordinate the function and interplay of immune and stromal cells during inflammatory respones, and increasing evidence indicates that alterations in small GTPase signaling contribute to the pathological behavior of these cell populations in human chronic inflammatory diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Here, we review how Ras, Rap, and Rho family GTPases contribute to the biology of cell populations relevant to human chronic inflammatory disease, highlight recent advances in understanding how alterations in these pathways contribute to pathology in RA and SLE, and discuss new therapeutic strategies that may allow specific targeting of small GTPases in the clinic.
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Affiliation(s)
- Kris A Reedquist
- Division of Clinical Immunology and Rheumatology, Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, The Netherlands
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Adachi R, Krilis SA, Nigrovic PA, Hamilton MJ, Chung K, Thakurdas SM, Boyce JA, Anderson P, Stevens RL. Ras guanine nucleotide-releasing protein-4 (RasGRP4) involvement in experimental arthritis and colitis. J Biol Chem 2012; 287:20047-55. [PMID: 22511759 DOI: 10.1074/jbc.m112.360388] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
RasGRP4 (Ras guanine nucleotide-releasing protein-4) is an intracellular, calcium-regulated guanine nucleotide exchange factor and diacylglycerol/phorbol ester receptor expressed in mast cells (MCs) and their progenitors. To study the function of this signaling protein in inflammatory disorders, a homologous recombination approach was used to create a RasGRP4-null C57BL/6 mouse line. The resulting transgenic animals had normal numbers of MCs in their tissues that histochemically and morphologically resembled those in WT C57BL/6 mice. MCs could also be generated from RasGRP4-null mice by culturing their bone marrow cells in IL-3-enriched conditioned medium. Despite these data, the levels of the transcripts that encode the proinflammatory cytokines IL-1β and TNF-α were reduced in phorbol 12-myristate 13-acetate-treated MCs developed from RasGRP4-null mice. Although inflammation was not diminished in a Dermatophagoides farinae-dependent model of allergic airway disease, dextran sodium sulfate-induced colitis was significantly reduced in RasGRP4-null mice relative to similarly treated WT mice. Furthermore, experimental arthritis could not be induced in RasGRP4-null mice that had received K/BxN mouse serum. The latter findings raise the possibility that the pharmacologic inactivation of this intracellular signaling protein might be an effective treatment for arthritis or inflammatory bowel disease.
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Affiliation(s)
- Roberto Adachi
- Department of Pulmonary Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Zhu M, Fuller DM, Zhang W. The role of Ras guanine nucleotide releasing protein 4 in Fc epsilonRI-mediated signaling, mast cell function, and T cell development. J Biol Chem 2012; 287:8135-43. [PMID: 22262848 DOI: 10.1074/jbc.m111.320580] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The RasGRP (Ras guanine nucleotide-releasing protein) family proteins are guanine nucleotide exchange factors that activate Ras GTPases, ultimately leading to MAPK activation and many cellular processes. The RasGRP family has four members. Published studies demonstrate that RasGRP1, RasGRP2, and RasGRP3 play critical roles in T cells, platelets, and B cells, respectively. RasGRP4 is highly expressed in mast cells. Although previous data suggest that it is important in mast cell development and function, the role of RasGRP4 in mast cells and allergic responses has not been clearly demonstrated. In this study, we generated RasGRP4(-/-) mice to examine the function of RasGRP4. Analyses of these mice showed that mast cells were able to develop normally in vivo and in vitro. Despite high levels of RasGRP4 expression in mast cells, RasGRP4 deficiency led to only a modest reduction in FcεRI-mediated degranulation and cytokine production. Interestingly, mast cells deficient in both RasGRP1 and RasGRP4 had a much more severe block in FcεRI-mediated signaling and mast cell function. We also made the unexpected finding that RasGRP4 functions during thymocyte development. Our data suggest that after the engagement of immunoreceptors, immune cells likely employ multiple members of the RasGRP family to transduce critical signals.
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Affiliation(s)
- Minghua Zhu
- Department of Immunology, Duke University, Medical Center, Durham, North Carolina 27710, USA
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Abstract
Ras guanyl nucleotide releasing proteins (RasGRPs) are guanyl nucleotide exchange factors that activate Ras and related GTPases such as Rap. Like Sos proteins, RasGRPs have a catalytic region composed of a Ras exchange motif (REM) and a CDC25 domain. RasGRPs also possess a pair of atypical EF hands that may bind calcium in vivo and a C1 domain resembling the diacylglycerol (DAG)-binding domain of protein kinase C. DAG directly activates RasGRPs by a membrane recruitment mechanism as well as indirectly by PKC-mediated phosphorylation. RasGRPs are prominently expressed in blood cells. RasGRP1 acts downstream of TCR, while RasGRP1 and RasGRP3 both act downstream of BCR. Together, they regulate Ras in adaptive immune cells. RasGRP2, through Rap, plays a role in controlling platelet adhesion, while RasGRP4 controls Ras activation in mast cells. RasGRP malfunction likely contributes to autoimmunity and may contribute to blood malignancies. RasGRPs might prove to be viable drug targets. The intracellular site of RasGRP action and the relationship between RasGRPs and other Ras regulatory mechanisms are subjects of lively debate.
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Affiliation(s)
- James C Stone
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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Hashimoto T, Yasuda S, Koide H, Kataoka H, Horita T, Atsumi T, Koike T. Aberrant splicing of the hRasGRP4 transcript and decreased levels of this signaling protein in the peripheral blood mononuclear cells in a subset of patients with rheumatoid arthritis. Arthritis Res Ther 2011; 13:R154. [PMID: 21933395 PMCID: PMC3308084 DOI: 10.1186/ar3470] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/25/2011] [Accepted: 09/20/2011] [Indexed: 12/26/2022] Open
Abstract
Introduction An unidentified population of peripheral blood mononuclear cells (PBMCs) express Ras guanine nucleotide releasing protein 4 (RasGRP4). The aim of our study was to identify the cells in human blood that express hRasGRP4, and then to determine if hRasGRP4 was altered in any patient with rheumatoid arthritis (RA). Methods Monocytes and T cells were purified from PBMCs of normal individuals, and were evaluated for their expression of RasGRP4 mRNA/protein. The levels of RasGRP4 transcripts were evaluated in the PBMCs from healthy volunteers and RA patients by real-time quantitative PCR. The nucleotide sequences of RasGRP4 cDNAs were also determined. RasGRP4 protein expression in PBMCs/monocytes was evaluated. Recombinant hRasGRP4 was expressed in mammalian cells. Results Circulating CD14+ cells in normal individuals were found to express hRasGRP4. The levels of the hRasGRP4 transcript were significantly higher in the PBMCs of our RA patients relative to healthy individuals. Sequence analysis of hRasGRP4 cDNAs from these PBMCs revealed 10 novel splice variants. Aberrantly spliced hRasGRP4 transcripts were more frequent in the RA patients than in normal individuals. The presence of one of these abnormal splice variants was linked to RA. The levels of hRasGRP4 protein in PBMCs tended to be lower. As expected, the defective transcripts led to altered and/or nonfunctional protein in terms of P44/42 mitogen-activated protein (MAP) kinase activation. Conclusions The identification of defective isoforms of hRasGRP4 transcripts in the PBMCs of RA patients raises the possibility that dysregulated expression of hRasGRP4 in developing monocytes plays a pathogenic role in a subset of RA patients.
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Affiliation(s)
- Toko Hashimoto
- Department of Medicine II, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan
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Naturally occurring free thiols within β2-glycoprotein I in vivo: nitrosylation, redox modification by endothelial cells, and regulation of oxidative stress–induced cell injury. Blood 2010; 116:1961-70. [DOI: 10.1182/blood-2009-04-215335] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Abstractβ2-Glycoprotein I (β2GPI) is an evolutionary conserved, abundant circulating protein. Although its function remains uncertain, accumulated evidence points toward interactions with endothelial cells and components of the coagulation system, suggesting a regulatory role in vascular biology. Our group has shown that thioredoxin 1 (TRX-1) generates free thiols in β2GPI, a process that may have a regulatory role in platelet adhesion. This report extends these studies and shows for the first time evidence of β2GPI with free thiols in vivo in both multiple human and murine serum samples. To explore how the vascular surface may modulate the redox status of β2GPI, unstimulated human endothelial cells and EAhy926 cells are shown to be capable of amplifying the effect of free thiol generation within β2GPI. Multiple oxidoreductase enzymes, such as endoplasmic reticulum protein 46 (ERp 46) and TRX-1 reductase, in addition to protein disulfide isomerase are secreted on the surface of endothelial cells. Furthermore, one or more of these generated free thiols within β2GPI are also shown to be nitrosylated. Finally, the functional significance of these findings is explored, by showing that free thiol–containing β2GPI has a powerful effect in protecting endothelial cells and EAhy926 cells from oxidative stress–induced cell death.
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Nakayama K, Tachikawa T, Majima T. Spatial control of protein binding on lipid bimembrane using photoeliminative linker. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:6425-6428. [PMID: 18507424 DOI: 10.1021/la801028m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Protein adsorption and dissociation on cell membrane surfaces is a topic of important study to reveal biological processes including signal transduction and protein trafficking. We demonstrated here the establishment of a mimic model system for the spatial control of protein adsorption/elimination on a lipid bimembrane using a photochemical technique. The novel photoeliminative linker that we synthesized here consists of three distinct components: a substrate (biotin), a photoeliminative group (4-(4-(1-hydroxyethyl)-2-methoxy-5-nitrophenoxy)butanoic acid), and a lipid bimembrane-adsorbent group (farnesyl). The photoeliminative linker was inserted on the entire surface of the lipid bimembrane and two-dimensionally eliminated by spatial UV irradiation onto the membrane to create a biotin pattern. A target protein, streptavidin was selectively immobilized on the patterned biotin, although it was almost not attached on the nonirradiated region. The streptavidin array was selectively dissociated by UV irradiation onto the entire membrane.
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Affiliation(s)
- Koji Nakayama
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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Many faces of Ras activation. Biochim Biophys Acta Rev Cancer 2008; 1786:178-87. [PMID: 18541156 DOI: 10.1016/j.bbcan.2008.05.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 05/13/2008] [Accepted: 05/13/2008] [Indexed: 11/23/2022]
Abstract
Ras proteins were originally identified as the products of oncogenes capable of inducing cell transformation. Over the last twenty-five years they have been studied in great detail because mutant Ras proteins are associated with many types of human cancer. Wild type Ras proteins play a central role in the regulation of proliferation and differentiation of various cell types. They alternate between an active GTP-bound state and an inactive GDP-bound state. Their activation is catalysed by a specialized group of enzymes known as guanine nucleotide exchange factors (GEFs). To date, four subfamilies of GEF molecules have been identified. Although all of them are able to activate Ras, their structure, tissue expression and regulation are significantly diverse. In this review we will summarize the various mechanisms by which these exchange factors activate Ras.
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