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Xiu Y, Zhang H, Wang S, Gan T, Wei M, Zhou S, Chen S. cDNA cloning, characterization, and expression analysis of the Rac1 and Rac2 genes from Cynoglossus semilaevis. FISH & SHELLFISH IMMUNOLOGY 2019; 84:998-1006. [PMID: 30399403 DOI: 10.1016/j.fsi.2018.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/26/2018] [Accepted: 11/01/2018] [Indexed: 06/08/2023]
Abstract
Rac1 and Rac2, belonging to the small Rho GTPase family, play an important role during the immune responses. In this study, a Rac1 homolog (CsRac1) and a Rac2 homolog (CsRac2) were cloned from the Cynoglossus semilaevis. The full-length of CsRac1 and CsRac2 cDNA was 1219 bp and 1047 bp, respectively. Both CsRac1 and CsRac2 contain a 579 bp open reading frame (ORF) which encoding a 192 amino acids putative protein. The predicted molecular weight of CsRac1 and CsRac2 was 21.41 kDa and 21.35 kDa, and their theoretical pI was 8.50 and 7.91, respectively. Sequence analysis showed that the conserved RHO domain was detected both from amino acid of CsRac1 and CsRac2. Homologous analysis showed that CsRac1 and CsRac2 share high conservation with other counterparts from different species. The CsRac1 and CsRac2 transcript showed wide tissue distribution, in which CsRac1 and CsRac2 exhibit the highest expression level in liver and gill, respectively. The expression level of CsRac1 and CsRac2 fluctuated in the liver and gill tissues at different time points after challenged by Vibrio harveyi. Specifically, CsRac1 and CsRac2 were significantly up-regulated at 48 h and 96 h post injection. Moreover, the knocking down of CsRac1 and CsRac2 in cell line (TSHKC) reduced the expression of CsPAK1, CsIL1-β and CsTNF-α. The present data suggests that CsRac1 and CsRac2 might play important roles in the innate immunity of half-smooth tongue sole.
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Affiliation(s)
- Yunji Xiu
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China
| | - Hongxiang Zhang
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Shuangyan Wang
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Tian Gan
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Min Wei
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China
| | - Shun Zhou
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China
| | - Songlin Chen
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology Yellow Sea Fisheries Research Institute, CAFS, Qingdao, 266071, China; Key Lab of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Qingdao, 266071, China.
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2
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Pantarelli C, Welch HCE. Rac-GTPases and Rac-GEFs in neutrophil adhesion, migration and recruitment. Eur J Clin Invest 2018; 48 Suppl 2:e12939. [PMID: 29682742 PMCID: PMC6321979 DOI: 10.1111/eci.12939] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/17/2018] [Indexed: 12/15/2022]
Abstract
Rac-GTPases and their Rac-GEF activators play important roles in the recruitment and host defence functions of neutrophils. These proteins control the activation of adhesion molecules and the cytoskeletal dynamics that enable the adhesion, migration and tissue recruitment of neutrophils. They also regulate the effector functions that allow neutrophils to kill bacterial and fungal pathogens, and to clear debris. This review focuses on the roles of Rac-GTPases and Rac-GEFs in neutrophil adhesion, migration and recruitment.
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3
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Mylvaganam SM, Grinstein S, Freeman SA. Picket-fences in the plasma membrane: functions in immune cells and phagocytosis. Semin Immunopathol 2018; 40:605-615. [DOI: 10.1007/s00281-018-0705-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 12/20/2022]
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4
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Li Z, Liu X, Liu J, Zhang K, Yu H, He Y, Wang X, Qi J, Wang Z, Zhang Q. Transcriptome profiling based on protein-protein interaction networks provides a core set of genes for understanding blood immune response mechanisms against Edwardsiella tarda infection in Japanese flounder (Paralichthys olivaceus). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 78:100-113. [PMID: 28923591 DOI: 10.1016/j.dci.2017.09.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 08/30/2017] [Accepted: 09/14/2017] [Indexed: 06/07/2023]
Abstract
Marine organisms are commonly under threat from various pathogens. Edwardsiella tarda is one of the fish pathogens that can infect both cultured and wild fish species. E. tarda can also infect other vertebrates, including amphibians, reptiles, and mammals. Bacteremia caused by E. tarda can be a fatal disease in humans. Blood acts as a pipeline for the fish immune system. Generating blood transcriptomic resources from fish challenged by E. tarda is crucial for understanding molecular mechanisms underlying blood immune response process. In this study, we performed transcriptome-wide gene expression profiling of Japanese flounder (Paralichthys olivaceus) challenged by 8 and 48 h E. tarda stress. An average of 37 million clean reads per library was obtained, and approximately 85.6% of these reads were successfully mapped to the reference genome. In addition, 808 and 1265 differential expression genes (DEGs) were found at 8 and 48 h post-injection, respectively. Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to search immune-related DEGs. A protein-protein interaction network was constructed to obtain the interaction relationship of immune genes during pathogens stress. Based on KEGG and protein association networks analysis, 30 hub genes were discovered and validated by quantitative RT-PCR. This study represents the first transcriptome analysis based on protein-protein interaction networks in fish and provides us with valuable gene resources for the research of fish blood immunity, which can significantly assist us to further understand the molecular mechanisms of humans and other vertebrates against E. tarda.
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Affiliation(s)
- Zan Li
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China
| | - Xiumei Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China
| | - Jinxiang Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China
| | - Kai Zhang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China
| | - Haiyang Yu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China
| | - Yan He
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China
| | - Xubo Wang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China
| | - Jie Qi
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China
| | - Zhigang Wang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China
| | - Quanqi Zhang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao 266003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, PR China.
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Sintsova A, Guo CX, Sarantis H, Mak TW, Glogauer M, Gray-Owen SD. Bcl10 synergistically links CEACAM3 and TLR-dependent inflammatory signalling. Cell Microbiol 2018; 20:e12788. [PMID: 28886618 DOI: 10.1111/cmi.12788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 01/27/2023]
Abstract
The neutrophil-specific innate immune receptor CEACAM3 functions as a decoy to capture Gram-negative pathogens, such as Neisseria gonorrhoeae, that exploit CEACAM family members to adhere to the epithelium. Bacterial binding to CEACAM3 results in their efficient engulfment and triggers activation of an nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-dependent inflammatory response by human neutrophils. Herein, we report that CEACAM3 cross-linking is not sufficient for induction of cytokine production and show that the inflammatory response induced by Neisseria gonorrhoeae infection is elicited by an integration of signals from CEACAM3 and toll-like receptors. Using neutrophils from a human CEACAM-expressing mouse line (CEABAC), we use a genetic approach to reveal a molecular bifurcation of the CEACAM3-mediated antimicrobial and inflammatory responses. Ex vivo experiments with CEABAC-Rac2-/- , CEABAC-Bcl10-/- , and CEABAC-Malt1-/- neutrophils indicate that these effectors are not necessary for gonococcal engulfment, yet all 3 effectors contribute to CEACAM3-mediated cytokine production. Interestingly, although Bcl10 and Malt1 are often inextricably linked, Bcl10 enabled synergy between toll-like receptor 4 and CEACAM3, whereas Malt1 did not. Together, these findings reveal an integration of the specific innate immune receptor CEACAM3 into the network of more conventional pattern recognition receptors, providing a mechanism by which the innate immune system can unleash its response to a relentless pathogen.
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Affiliation(s)
- Anna Sintsova
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Cynthia X Guo
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Helen Sarantis
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Tak W Mak
- The Campbell Family Institute for Breast Cancer Research, University Health Network, Toronto, Ontario, Canada
| | - Michael Glogauer
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Scott D Gray-Owen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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6
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Dayam RM, Sun CX, Choy CH, Mancuso G, Glogauer M, Botelho RJ. The Lipid Kinase PIKfyve Coordinates the Neutrophil Immune Response through the Activation of the Rac GTPase. THE JOURNAL OF IMMUNOLOGY 2017; 199:2096-2105. [DOI: 10.4049/jimmunol.1601466] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 07/11/2017] [Indexed: 11/19/2022]
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7
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Levin R, Grinstein S, Canton J. The life cycle of phagosomes: formation, maturation, and resolution. Immunol Rev 2017; 273:156-79. [PMID: 27558334 DOI: 10.1111/imr.12439] [Citation(s) in RCA: 194] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phagocytosis, the regulated uptake of large particles (>0.5 μm in diameter), is essential for tissue homeostasis and is also an early, critical component of the innate immune response. Phagocytosis can be conceptually divided into three stages: phagosome, formation, maturation, and resolution. Each of these involves multiple reactions that require exquisite spatial and temporal orchestration. The molecular events underlying these stages are being unraveled and the current state of knowledge is briefly summarized in this article.
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Affiliation(s)
- Roni Levin
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Johnathan Canton
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada
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Abstract
During an innate immune response, myeloid cells undergo complex morphological adaptations in response to inflammatory cues, which allow them to exit the vasculature, enter the tissues, and destroy invading pathogens. The actin and microtubule cytoskeletons are central to many of the most essential cellular functions including cell division, cell morphology, migration, intracellular trafficking, and signaling. Cytoskeletal structure and regulation are crucial for many myeloid cell functions, which require rapid and dynamic responses to extracellular signals. In this chapter, we review the roles of the actin and microtubule cytoskeletons in myeloid cells, focusing primarily on their roles in chemotaxis and phagocytosis. The role of myeloid cell cytoskeletal defects in hematological disorders is highlighted throughout.
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9
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Abstract
Phagocytosis refers to the active process that allows cells to take up large particulate material upon binding to surface receptors. The discovery of phagocytosis in 1883 by Elie Metchnikoff, leading to the concept that specialized cells are implicated in the defense against microbes, was one of the starting points of the field of immunology. After more than a century of research, phagocytosis is now appreciated to be a widely used process that enables the cellular uptake of a remarkable variety of particles, including bacteria, fungi, parasites, viruses, dead cells, and assorted debris and solid materials. Uptake of foreign particles is performed almost exclusively by specialized myeloid cells, commonly termed "professional phagocytes": neutrophils, monocytes, macrophages, and dendritic cells. Phagocytosis of microbes not only stops or at least restricts the spread of infection but also plays an important role in regulating the innate and adaptive immune responses. Activation of the myeloid cells upon phagocytosis leads to the secretion of cytokines and chemokines that convey signals to a variety of immune cells. Moreover, foreign antigens generated by the degradation of microbes following phagocytosis are loaded onto the major histocompatibility complex for presentation to specific T lymphocytes. However, phagocytosis is not restricted to professional myeloid phagocytes; an expanding diversity of cell types appear capable of engulfing apoptotic bodies and debris, playing a critical role in tissue remodeling and in the clearance of billions of effete cells every day.
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10
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Tanaka K, Kim SE, Yano H, Matsumoto G, Ohuchida R, Ishikura Y, Araki M, Araki K, Park S, Komatsu T, Hayashi H, Ikematsu K, Tanaka K, Hirano A, Martin P, Shimokawa I, Mori R. MiR-142 Is Required for Staphylococcus aureus Clearance at Skin Wound Sites via Small GTPase-Mediated Regulation of the Neutrophil Actin Cytoskeleton. J Invest Dermatol 2017; 137:931-940. [DOI: 10.1016/j.jid.2016.11.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 11/14/2016] [Accepted: 11/16/2016] [Indexed: 11/26/2022]
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11
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Cao M, Shikama Y, Kimura H, Noji H, Ikeda K, Ono T, Ogawa K, Takeishi Y, Kimura J. Mechanisms of Impaired Neutrophil Migration by MicroRNAs in Myelodysplastic Syndromes. THE JOURNAL OF IMMUNOLOGY 2017; 198:1887-1899. [PMID: 28130497 DOI: 10.4049/jimmunol.1600622] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 12/30/2016] [Indexed: 12/14/2022]
Abstract
In myelodysplastic syndromes (MDS), functional defects of neutrophils result in high mortality because of infections; however, the molecular basis remains unclear. We recently found that miR-34a and miR-155 were significantly increased in MDS neutrophils. To clarify the effects of the aberrant microRNA expression on neutrophil functions, we introduced miR-34a, miR-155, or control microRNA into neutrophil-like differentiated HL60 cells. Ectopically introduced miR-34a and miR-155 significantly attenuated migration toward chemoattractants fMLF and IL-8, but enhanced degranulation. To clarify the mechanisms for inhibition of migration, we studied the effects of miR-34a and miR-155 on the migration-regulating Rho family members, Cdc42 and Rac1. The introduced miR-34a and miR-155 decreased the fMLF-induced active form of Cdc42 to 29.0 ± 15.9 and 39.7 ± 4.8% of that in the control cells, respectively, although Cdc42 protein levels were not altered. miR-34a decreased a Cdc42-specific guanine nucleotide exchange factor (GEF), dedicator of cytokinesis (DOCK) 8, whereas miR-155 reduced another Cdc42-specific GEF, FYVE, RhoGEF, and PH domain-containing (FGD) 4. The knockdown of DOCK8 and FGD4 by small interfering RNA suppressed Cdc42 activation and fMLF/IL-8-induced migration. miR-155, but not miR-34a, decreased Rac1 protein, and introduction of Rac1 small interfering RNA attenuated Rac1 activation and migration. Neutrophils from patients showed significant attenuation in migration compared with healthy cells, and protein levels of DOCK8, FGD4, and Rac1 were well correlated with migration toward fMLF (r = 0.642, 0.686, and 0.436, respectively) and IL-8 (r = 0.778, 0.659, and 0.606, respectively). Our results indicated that reduction of DOCK8, FGD4, and Rac1 contributes to impaired neutrophil migration in MDS.
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Affiliation(s)
- Meiwan Cao
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Yayoi Shikama
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan; .,Center for Medical Education and Career Development, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Hideo Kimura
- Department of Hematology, Kita-Fukushima Medical Center, Date 960-0502, Japan
| | - Hideyoshi Noji
- Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan.,Department of Medical Oncology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan; and
| | - Kazuhiko Ikeda
- Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan.,Department of Blood Transfusion and Transplantation Immunology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Tomoyuki Ono
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Kazuei Ogawa
- Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Yasuchika Takeishi
- Department of Cardiology and Hematology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Junko Kimura
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
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12
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Rosowski EE, Deng Q, Keller NP, Huttenlocher A. Rac2 Functions in Both Neutrophils and Macrophages To Mediate Motility and Host Defense in Larval Zebrafish. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 197:4780-4790. [PMID: 27837107 PMCID: PMC5367389 DOI: 10.4049/jimmunol.1600928] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/09/2016] [Indexed: 11/19/2022]
Abstract
Leukocyte motility is required for host defense responses. Rac-family Rho GTPases are implicated in leukocyte function; however, the distinct roles of different Rac isoforms in host defense in vivo have remained unclear. In this study, we generated Rac2-deficient zebrafish using transcription activator-like effector nucleases to directly compare the role of Rac2 in vivo in neutrophils and macrophages in motility and the response to infection. This zebrafish larval model is highly amenable to live imaging of leukocyte behavior, and we report that in rac2-/- larvae both neutrophils and macrophages are defective in basic motility, leading to impaired responses to localized wounds or infections. rac2-/- larvae are highly susceptible to infection with Pseudomonas aeruginosa, which can be almost fully rescued by ectopic expression of either Rac2 or Rac1 specifically in neutrophils, indicating that these isoforms have partially overlapping functions in vivo. Rescue of Rac2 expression specifically in macrophages also confers resistance to Pseudomonas infection, highlighting an important role for Rac2 in this leukocyte population as well. Surprisingly, in contrast to neutrophils expressing a Rac2 dominant inhibitory human disease mutation, rac2-/- neutrophils do not have altered polarity or mobilization from hematopoietic tissue, suggesting that a different Rac isoform, such as Rac1, also contributes to these phenotypes in vivo.
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Affiliation(s)
- Emily E Rosowski
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706
| | - Qing Deng
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706; and
| | - Anna Huttenlocher
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706;
- Department of Pediatrics, University of Wisconsin, Madison, WI 53706
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13
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Small GTPases and their guanine-nucleotide exchange factors and GTPase-activating proteins in neutrophil recruitment. Curr Opin Hematol 2016; 23:44-54. [PMID: 26619317 DOI: 10.1097/moh.0000000000000199] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW The review describes the roles of Rho- and Rap-guanosine triphosphatases (GTPases) and of their activators, guanine-nucleotide exchange factors (GEFs), and inhibitors, GTPase activating proteins (GAPs), in neutrophil recruitment from the blood stream into inflamed tissues, with a focus on recently identified roles in neutrophils, endothelial cells, and platelets. RECENT FINDINGS Recent studies have identified important roles of Rho- and Rap-GTPases, and of their GEFs and GAPs, in the neutrophil recruitment cascade. These proteins control the upregulation and/or activation of adhesion molecules on the surface of neutrophils, endothelial cells, and platelets, and they alter cell/cell adhesion in the vascular endothelium. This enables the capture of neutrophils from the blood stream, their migration along and through the vessel wall, and their passage into the inflamed tissue. In particular, it has recently become clear that P-Rex and Vav family Rac-GEFs in platelets are crucial for neutrophil recruitment. SUMMARY These recent findings have contributed greatly to our understanding of the signalling pathways that control neutrophil recruitment to sites of inflammation and have opened up new avenues of research in this field.
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Hendricks L, Aziz M, Yang WL, Nicastro J, Coppa GF, Symons M, Wang P. Milk fat globule-epidermal growth factor-factor VIII-derived peptide MSP68 is a cytoskeletal immunomodulator of neutrophils that inhibits Rac1. J Surg Res 2016; 208:10-19. [PMID: 27993196 DOI: 10.1016/j.jss.2016.08.098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/17/2016] [Accepted: 08/31/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Prolonged neutrophil infiltration leads to exaggerated inflammation and tissue damage during sepsis. Neutrophil migration requires rearrangement of their cytoskeleton. Milk fat globule-epidermal growth factor-factor VIII-derived short peptide 68 (MSP68) has recently been shown to be beneficial in sepsis-induced tissue injury and mortality. We hypothesize that MSP68 inhibits neutrophil migration by modulating small GTPase Rac1-dependent cytoskeletal rearrangements. METHODS Bone marrow-derived neutrophils (BMDNs) or whole lung digest isolated neutrophils were isolated from 8 to 10 wk old C57BL/6 mice by Percoll density gradient centrifugation. The purity of BMDN was verified by flow cytometry with CD11b/Gr-1 staining. Neutrophils were stimulated with N-formylmethionine-leucine-phenylalanine (f-MLP) (10 nM) in the presence or absence of MSP68 at 10 nM or cecal ligation and puncture (CLP) was used to induce sepsis, and MSP68 was administered at 1 mg/kg intravenously. Cytoskeletal organization was assessed by phalloidin staining, followed by analysis using fluorescence microscopy. Activity of the Rac1 GTPase in f-MLP or CLP-activated BMDN in the presence or absence of MSP68 was assessed by GTPase enzyme-linked immunosorbent assay. Mitogen-activated protein (MAP) kinase activity was determined by western blot densitometry. RESULTS BMDN treatment with f-MLP increased cytoskeletal remodeling as revealed by the localization of filamentous actin to the periphery of the neutrophil. By contrast, cells pretreated with MSP68 had considerably reduced filamentous actin polymerization. Cytoskeletal spreading is associated with the activation of the small GTPase Rac1. We found BMDN-treated with f-MLP or that were exposed to sepsis by CLP had increased Rac1 signaling, whereas the cells pretreated with MSP68 had significantly reduced Rac1 activation (P < 0.05). MAP kinases related to cell migration including pp38 and pERK were upregulated by treatment with f-MLP. Upregulation of these MAP kinases was also significantly reduced after pretreatment with MSP68 (P < 0.05). CONCLUSIONS MSP68 downregulates actin cytoskeleton-dependent, Rac1-MAP kinase-mediated neutrophil motility. Thus, MSP68 is a novel therapeutic candidate for regulating inflammation and tissue damage caused by excessive neutrophil migration in sepsis.
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Affiliation(s)
- Louie Hendricks
- Department of Surgery, Hofstra Northwell School of Medicine, Manhasset, New York; Center for Immunology and Inflammation, The Feinstein Institute for Medical Research, Manhasset, New York
| | - Monowar Aziz
- Center for Immunology and Inflammation, The Feinstein Institute for Medical Research, Manhasset, New York
| | - Weng-Lang Yang
- Department of Surgery, Hofstra Northwell School of Medicine, Manhasset, New York; Center for Immunology and Inflammation, The Feinstein Institute for Medical Research, Manhasset, New York
| | - Jeffrey Nicastro
- Department of Surgery, Hofstra Northwell School of Medicine, Manhasset, New York
| | - Gene F Coppa
- Department of Surgery, Hofstra Northwell School of Medicine, Manhasset, New York
| | - Marc Symons
- Karches Center for Oncology Research, The Feinstein Institute for Medical Research, Manhasset, New York
| | - Ping Wang
- Department of Surgery, Hofstra Northwell School of Medicine, Manhasset, New York; Center for Immunology and Inflammation, The Feinstein Institute for Medical Research, Manhasset, New York.
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15
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P-Rex and Vav Rac-GEFs in platelets control leukocyte recruitment to sites of inflammation. Blood 2014; 125:1146-58. [PMID: 25538043 DOI: 10.1182/blood-2014-07-591040] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The small GTPase Rac is required for neutrophil recruitment during inflammation, but its guanine-nucleotide exchange factor (GEF) activators seem dispensable for this process, which led us to investigate the possibility of cooperation between Rac-GEF families. Thioglycollate-induced neutrophil recruitment into the peritoneum was more severely impaired in P-Rex1(-/-) Vav1(-/-) (P1V1) or P-Rex1(-/-) Vav3(-/-) (P1V3) mice than in P-Rex null or Vav null mice, suggesting cooperation between P-Rex and Vav Rac-GEFs in this process. Neutrophil transmigration and airway infiltration were all but lost in P1V1 and P1V3 mice during lipopolysaccharide (LPS)-induced pulmonary inflammation, with altered intercellular adhesion molecule 1-dependent slow neutrophil rolling and strongly reduced L- and E-selectin-dependent adhesion in airway postcapillary venules. Analysis of adhesion molecule expression, neutrophil adhesion, spreading, and migration suggested that these defects were only partially neutrophil-intrinsic and were not obviously involving vascular endothelial cells. Instead, P1V1 and P1V3 platelets recapitulated the impairment of LPS-induced intravascular neutrophil adhesion and recruitment, showing P-Rex and Vav expression in platelets to be crucial. Similarly, during ovalbumin-induced allergic inflammation, pulmonary recruitment of P1V1 and P1V3 eosinophils, monocytes, and lymphocytes was compromised in a platelet-dependent manner, and airway inflammation was essentially abolished, resulting in improved airway responsiveness. Therefore, platelet P-Rex and Vav family Rac-GEFs play important proinflammatory roles in leukocyte recruitment.
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Levin R, Grinstein S, Schlam D. Phosphoinositides in phagocytosis and macropinocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:805-23. [PMID: 25238964 DOI: 10.1016/j.bbalip.2014.09.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/23/2014] [Accepted: 09/08/2014] [Indexed: 01/08/2023]
Abstract
Professional phagocytes provide immunoprotection and aid in the maintenance of tissue homeostasis. They perform these tasks by recognizing, engulfing and eliminating pathogens and endogenous cell debris. Here, we examine the paramount role played by phosphoinositides in phagocytosis and macropinocytosis, two major endocytic routes that mediate the uptake of particulate and fluid matter, respectively. We analyze accumulating literature describing the molecular mechanisms whereby phosphoinositides translate environmental cues into the complex, sophisticated responses that underlie the phagocytic and macropinocytic responses. In addition, we exemplify virulence strategies involving modulation of host cell phosphoinositide signaling that are employed by bacteria to undermine immunity. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Roni Levin
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada; Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria St., Toronto M5C1N8, Canada.
| | - Daniel Schlam
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
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17
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Flannagan RS, Canton J, Furuya W, Glogauer M, Grinstein S. The phosphatidylserine receptor TIM4 utilizes integrins as coreceptors to effect phagocytosis. Mol Biol Cell 2014; 25:1511-22. [PMID: 24623723 PMCID: PMC4004599 DOI: 10.1091/mbc.e13-04-0212] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
TIM4 is a receptor for phosphatidylserine that mediates engulfment of apoptotic cells. Remarkably, it does not require its cytosolic or transmembrane domains to mediate phagocytosis. TIM4 associates with integrins that serve as signal-transducing coreceptors. T-cell immunoglobulin mucin protein 4 (TIM4), a phosphatidylserine (PtdSer)-binding receptor, mediates the phagocytosis of apoptotic cells. How TIM4 exerts its function is unclear, and conflicting data have emerged. To define the mode of action of TIM4, we used two distinct but complementary approaches: 1) we compared bone marrow–derived macrophages from wild-type and TIM4−/− mice, and 2) we heterologously expressed TIM4 in epithelioid AD293 cells, which rendered them competent for engulfment of PtdSer-bearing targets. Using these systems, we demonstrate that rather than serving merely as a tether, as proposed earlier by others, TIM4 is an active participant in the phagocytic process. Furthermore, we find that TIM4 operates independently of lactadherin, which had been proposed to act as a bridging molecule. Of interest, TIM4-driven phagocytosis depends on the activation of integrins and involves stimulation of Src-family kinases and focal adhesion kinase, as well as the localized accumulation of phosphatidylinositol 3,4,5-trisphosphate. These mediators promote recruitment of the nucleotide-exchange factor Vav3, which in turn activates small Rho-family GTPases. Gene silencing or ablation experiments demonstrated that RhoA, Rac1, and Rac2 act synergistically to drive the remodeling of actin that underlies phagocytosis. Single-particle detection experiments demonstrated that TIM4 and β1 integrins associate upon receptor clustering. These findings support a model in which TIM4 engages integrins as coreceptors to evoke the signal transduction needed to internalize PtdSer-bearing targets such as apoptotic cells.
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Affiliation(s)
- Ronald S Flannagan
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON M5C 1N8, Canada
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18
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Barteneva NS, Maltsev N, Vorobjev IA. Microvesicles and intercellular communication in the context of parasitism. Front Cell Infect Microbiol 2013; 3:49. [PMID: 24032108 PMCID: PMC3764926 DOI: 10.3389/fcimb.2013.00049] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/20/2013] [Indexed: 01/18/2023] Open
Abstract
There is a rapidly growing body of evidence that production of microvesicles (MVs) is a universal feature of cellular life. MVs can incorporate microRNA (miRNA), mRNA, mtDNA, DNA and retrotransposons, camouflage viruses/viral components from immune surveillance, and transfer cargo between cells. These properties make MVs an essential player in intercellular communication. Increasing evidence supports the notion that MVs can also act as long-distance vehicles for RNA molecules and participate in metabolic synchronization and reprogramming eukaryotic cells including stem and germinal cells. MV ability to carry on DNA and their general distribution makes them attractive candidates for horizontal gene transfer, particularly between multi-cellular organisms and their parasites; this suggests important implications for the co-evolution of parasites and their hosts. In this review, we provide current understanding of the roles played by MVs in intracellular pathogens and parasitic infections. We also discuss the possible role of MVs in co-infection and host shifting.
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Affiliation(s)
- Natasha S Barteneva
- Program in Cellular and Molecular Medicine, Children's Hospital Boston and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA. Natasha.Barteneva@ childrens.harvard.edu
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19
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20
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Fattouh R, Guo CH, Lam GY, Gareau MG, Ngan BY, Glogauer M, Muise AM, Brumell JH. Rac2-deficiency leads to exacerbated and protracted colitis in response to Citrobacter rodentium infection. PLoS One 2013; 8:e61629. [PMID: 23613889 PMCID: PMC3628927 DOI: 10.1371/journal.pone.0061629] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/12/2013] [Indexed: 02/04/2023] Open
Abstract
Recent genetic-based studies have implicated a number of immune-related genes in the pathogenesis of inflammatory bowel disease (IBD). Our recent genetic studies showed that RAC2 is associated with human IBD; however, its role in disease pathogenesis is unclear. Given Rac2's importance in various fundamental immune cell processes, we investigated whether a defect in Rac2 may impair host immune responses in the intestine and promote disease in the context of an infection-based (Citrobacter rodentium) model of colitis. In response to infection, Rac2(-/-) mice showed i) worsened clinical symptoms (days 13-18), ii) increased crypt hyperplasia at days 11 and 22 (a time when crypt hyperplasia was largely resolved in wild-type mice; WT), and iii) marked mononuclear cell infiltration characterized by higher numbers of T (CD3(+)) cells (day 22), compared to WT-infected mice. Moreover, splenocytes harvested from infected Rac2(-/-) mice and stimulated in vitro with C. rodentium lysate produced considerably higher levels of interferon-γ and interleukin-17A. The augmented responses observed in Rac2(-/-) mice did not appear to stem from Rac2's role in NADPH oxidase-driven reactive oxygen species production as no differences in crypt hyperplasia, nor inflammation, were observed in infected NOX2(-/-) mice compared to WT. Collectively, our findings demonstrate that Rac2(-/-) mice develop more severe disease when subjected to a C. rodentium-induced model of infectious colitis, and suggest that impaired Rac2 function may promote the development of IBD in humans.
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Affiliation(s)
- Ramzi Fattouh
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Cong-Hui Guo
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Grace Y. Lam
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melanie G. Gareau
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bo-Yee Ngan
- Department of Pathology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael Glogauer
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Aleixo M. Muise
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Sickkids IBD Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - John H. Brumell
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Sickkids IBD Centre, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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21
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Tell RM, Kimura K, Palić D. Rac2 expression and its role in neutrophil functions of zebrafish (Danio rerio). FISH & SHELLFISH IMMUNOLOGY 2012; 33:1086-94. [PMID: 22992407 DOI: 10.1016/j.fsi.2012.07.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/26/2012] [Accepted: 07/29/2012] [Indexed: 06/01/2023]
Abstract
The neutrophil contributes significantly to the immune response. In particular, their phagocytosis and pathogen-killing functions are vital for defense from invading pathogens. Rac2, a Rho small GTPase, is involved in many key neutrophil functions. Loss of Rac2 activity results in severe bacterial infections and neutrophil function deficits in humans and mice. While the genes rac1, 2, and 3 have been identified in the zebrafish genome, their expression has not been well-characterized. We describe rac1, 2, and 3 expression over the first three days of development, as well as the presence and localization of Rac2 protein in adult zebrafish neutrophils. The mRNA for each Rac isoform was detected in zebrafish embryos as early as 12 h post fertilization. Immunocytochemistry and confocal microscopy of adult zebrafish neutrophils confirmed diffuse Rac2 protein within the cytoplasm. Only rac2 was found in sorted neutrophil samples. Armed with knowledge of its presence and exclusive expression, the role of Rac2 in key antimicrobial zebrafish neutrophil responses was examined by small molecule inhibition of Rac during respiratory burst, NET release, and phagocytosis assays. Inhibition of Rac2 during these assays produced a dose-dependent decrease in each function, as was expected due to previous work in mammals. The expression pattern and role of Rac2 in zebrafish neutrophil function allows for comparative studies of innate immune responses in this animal model.
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Affiliation(s)
- Rachel M Tell
- Immunobiology Graduate Program, 1068 Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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22
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De Filippis B, Fabbri A, Simone D, Canese R, Ricceri L, Malchiodi-Albedi F, Laviola G, Fiorentini C. Modulation of RhoGTPases improves the behavioral phenotype and reverses astrocytic deficits in a mouse model of Rett syndrome. Neuropsychopharmacology 2012; 37:1152-63. [PMID: 22157810 PMCID: PMC3306877 DOI: 10.1038/npp.2011.301] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 10/28/2011] [Accepted: 10/28/2011] [Indexed: 11/09/2022]
Abstract
RhoGTPases are crucial molecules in neuronal plasticity and cognition, as confirmed by their role in non-syndromic mental retardation. Activation of brain RhoGTPases by the bacterial cytotoxic necrotizing factor 1 (CNF1) reshapes the actin cytoskeleton and enhances neurotransmission and synaptic plasticity in mouse brains. We evaluated the effects of a single CNF1 intracerebroventricular inoculation in a mouse model of Rett syndrome (RTT), a rare neurodevelopmental disorder and a genetic cause of mental retardation, for which no effective therapy is available. Fully symptomatic MeCP2-308 male mice were evaluated in a battery of tests specifically tailored to detect RTT-related impairments. At the end of behavioral testing, brain sections were immunohistochemically characterized. Magnetic resonance imaging and spectroscopy (MRS) were also applied to assess morphological and metabolic brain changes. The CNF1 administration markedly improved the behavioral phenotype of MeCP2-308 mice. CNF1 also dramatically reversed the evident signs of atrophy in astrocytes of mutant mice and restored wt-like levels of this cell population. A partial rescue of the overexpression of IL-6 cytokine was also observed in RTT brains. CNF1-induced brain metabolic changes detected by MRS analysis involved markers of glial integrity and bioenergetics, and point to improved mitochondria functionality in CNF1-treated mice. These results clearly indicate that modulation of brain RhoGTPases by CNF1 may constitute a totally innovative therapeutic approach for RTT and, possibly, for other disorders associated with mental retardation.
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Affiliation(s)
- Bianca De Filippis
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Alessia Fabbri
- Department Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Roma, Italy
| | - Daiana Simone
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Rossella Canese
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Laura Ricceri
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | | | - Giovanni Laviola
- Department Cell Biology and Neuroscience, Istituto Superiore di Sanità, Roma, Italy
| | - Carla Fiorentini
- Department Therapeutic Research and Medicines Evaluation, Istituto Superiore di Sanità, Roma, Italy
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23
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Tzircotis G, Braga VMM, Caron E. RhoG is required for both FcγR- and CR3-mediated phagocytosis. J Cell Sci 2012; 124:2897-902. [PMID: 21878497 DOI: 10.1242/jcs.084269] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis is a highly ordered process orchestrated by signalling through Rho GTPases to locally organise the actin cytoskeleton and drive particle uptake. Specific Rho family members that regulate phagocytosis are not known, as the majority of studies have relied on the use of dominant-negative mutants and/or toxins, which can inactivate multiple Rho GTPases. To identify the relevant GTPases for phagocytosis through the Fcγ receptor (FcγR) and complement receptor 3 (CR3), we depleted 20 Rho proteins individually in an RNA interference (RNAi) screen. We find that distinct GTPase subsets are required for actin polymerisation and uptake by macrophages: FcγR-dependent engulfment requires Cdc42 and Rac2 (but not Rac1), whereas CR3 requires RhoA. Surprisingly, RhoG is required for particle uptake through both FcγR and CR3. RhoG has been previously linked to Rac and Cdc42 signalling in different model systems, but not to RhoA. Interestingly, we find that RhoG is also recruited and activated at phagocytic cups downstream of FcγR and CR3, irrespective of their distinct actin structures and mechanisms of internalisation. Thus, the functional links between RhoG and RhoA downstream of CR3-dependent phagocytosis are new and unexpected. Our data suggest a broad role for RhoG in consolidating signals from multiple receptors during phagocytosis.
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Affiliation(s)
- George Tzircotis
- Centre for Molecular Microbiology and Infection, Faculty of Medicine, Imperial College, London SW72AZ, UK.
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24
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Flannagan RS, Jaumouillé V, Grinstein S. The Cell Biology of Phagocytosis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2012; 7:61-98. [PMID: 21910624 DOI: 10.1146/annurev-pathol-011811-132445] [Citation(s) in RCA: 652] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ronald S. Flannagan
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada;
| | - Valentin Jaumouillé
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada;
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada;
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25
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Karavitis J, Murdoch EL, Deburghgraeve C, Ramirez L, Kovacs EJ. Ethanol suppresses phagosomal adhesion maturation, Rac activation, and subsequent actin polymerization during FcγR-mediated phagocytosis. Cell Immunol 2012; 274:61-71. [PMID: 22381996 PMCID: PMC3334404 DOI: 10.1016/j.cellimm.2012.02.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 12/16/2022]
Abstract
Clinical and laboratory investigations have provided evidence that ethanol suppresses normal lung immunity. Our initial studies revealed that acute ethanol exposure results in transient suppression of phagocytosis of Pseudomonas aeruginosa by macrophages as early as 3 h after initial exposure. Focusing on mechanisms by which ethanol decreases macrophage Fcγ-receptor (FcγR) phagocytosis we targeted the study on the focal adhesion and cytoskeletal elements that are necessary for phagosome progression. Ethanol inhibited macrophage phagocytosis of IgG-coated bead recruitment of actin to the site of the phagosome, dampened the phosphorylation of vinculin, but had no effect on paxillin phosphorylation suggesting a loss in "phagosomal adhesion" maturation. Moreover, our observations revealed that FcγR-phagocytosis induced Rac activation, which was increased by only 50% in ethanol exposed cells, compared to 175% in the absence of ethanol. This work is the first to show evidence of the cellular mechanisms involved in the ethanol-induced suppression of FcγR-mediated phagocytosis.
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Affiliation(s)
- John Karavitis
- Program of Cell Biology, Neurobiology and Anatomy, Loyola University Medical Center, Maywood, IL, United States
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26
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Balenga NAB, Aflaki E, Kargl J, Platzer W, Schröder R, Blättermann S, Kostenis E, Brown AJ, Heinemann A, Waldhoer M. GPR55 regulates cannabinoid 2 receptor-mediated responses in human neutrophils. Cell Res 2011; 21:1452-69. [PMID: 21467997 PMCID: PMC3132458 DOI: 10.1038/cr.2011.60] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/20/2010] [Accepted: 01/12/2011] [Indexed: 12/16/2022] Open
Abstract
The directional migration of neutrophils towards inflammatory mediators, such as chemokines and cannabinoids, occurs via the activation of seven transmembrane G protein coupled receptors (7TM/GPCRs) and is a highly organized process. A crucial role for controlling neutrophil migration has been ascribed to the cannabinoid CB(2) receptor (CB(2)R), but additional modulatory sites distinct from CB(2)R have recently been suggested to impact CB(2)R-mediated effector functions in neutrophils. Here, we provide evidence that the recently de-orphanized 7TM/GPCR GPR55 potently modulates CB(2)R-mediated responses. We show that GPR55 is expressed in human blood neutrophils and its activation augments the migratory response towards the CB(2)R agonist 2-arachidonoylglycerol (2-AG), while inhibiting neutrophil degranulation and reactive oxygen species (ROS) production. Using HEK293 and HL60 cell lines, along with primary neutrophils, we show that GPR55 and CB(2)R interfere with each other's signaling pathways at the level of small GTPases, such as Rac2 and Cdc42. This ultimately leads to cellular polarization and efficient migration as well as abrogation of degranulation and ROS formation in neutrophils. Therefore, GPR55 limits the tissue-injuring inflammatory responses mediated by CB(2)R, while it synergizes with CB(2)R in recruiting neutrophils to sites of inflammation.
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MESH Headings
- Arachidonic Acids/pharmacology
- Cannabinoid Receptor Modulators/pharmacology
- Cell Degranulation/drug effects
- Cell Degranulation/physiology
- Cell Movement/drug effects
- Cell Movement/physiology
- Endocannabinoids
- Glycerides/pharmacology
- HEK293 Cells
- HL-60 Cells
- Humans
- Inflammation/genetics
- Inflammation/metabolism
- Neutrophil Activation/drug effects
- Neutrophil Activation/physiology
- Neutrophils/metabolism
- Reactive Oxygen Species/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/metabolism
- Receptors, Cannabinoid
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- cdc42 GTP-Binding Protein/genetics
- cdc42 GTP-Binding Protein/metabolism
- rac GTP-Binding Proteins/genetics
- rac GTP-Binding Proteins/metabolism
- RAC2 GTP-Binding Protein
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Affiliation(s)
- Nariman A B Balenga
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, Graz A-8010, Austria
| | - Elma Aflaki
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Julia Kargl
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, Graz A-8010, Austria
| | - Wolfgang Platzer
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, Graz A-8010, Austria
| | - Ralf Schröder
- Section Molecular, Cellular and Pharmacobiology, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Stefanie Blättermann
- Section Molecular, Cellular and Pharmacobiology, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- Section Molecular, Cellular and Pharmacobiology, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Andrew J Brown
- Department of Screening and Compound Profiling, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire, UK
| | - Akos Heinemann
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, Graz A-8010, Austria
| | - Maria Waldhoer
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, Graz A-8010, Austria
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27
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Muise AM, Walters T, Xu W, Shen-Tu G, Guo CH, Fattouh R, Lam GY, Wolters VM, Bennitz J, Van Limbergen J, Renbaum P, Kasirer Y, Ngan BY, Turner D, Denson LA, Sherman PM, Duerr RH, Cho J, Lees CW, Satsangi J, Wilson DC, Paterson AD, Griffiths AM, Glogauer M, Silverberg MS, Brumell JH. Single nucleotide polymorphisms that increase expression of the guanosine triphosphatase RAC1 are associated with ulcerative colitis. Gastroenterology 2011; 141:633-41. [PMID: 21684284 PMCID: PMC3152589 DOI: 10.1053/j.gastro.2011.04.057] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 04/16/2011] [Accepted: 04/26/2011] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS RAC1 is a guanosine triphosphatase that has an evolutionarily conserved role in coordinating immune defenses, from plants to mammals. Chronic inflammatory bowel diseases are associated with dysregulation of immune defenses. We studied the role of RAC1 in inflammatory bowel diseases using human genetic and functional studies and animal models of colitis. METHODS We used a candidate gene approach to HapMap-Tag single nucleotide polymorphisms in a discovery cohort; findings were confirmed in 2 additional cohorts. RAC1 messenger RNA expression was examined from peripheral blood cells of patients. Colitis was induced in mice with conditional disruption of Rac1 in phagocytes by administration of dextran sulfate sodium. RESULTS We observed a genetic association between RAC1 with ulcerative colitis in a discovery cohort, 2 independent replication cohorts, and in combined analysis for the single nucleotide polymorphisms rs10951982 (P(combined UC) = 3.3 × 10(-8), odds ratio = 1.43 [95% confidence interval: 1.26-1.63]) and rs4720672 (P(combined UC) = 4.7 × 10(-6), odds ratio = 1.36 [95% confidence interval: 1.19-1.58]). Patients with inflammatory bowel disease who had the rs10951982 risk allele had increased expression of RAC1 compared to those without this allele. Conditional disruption of Rac1 in macrophage and neutrophils of mice protected against dextran sulfate sodium-induced colitis. CONCLUSIONS Human studies and knockout mice demonstrated a role for the guanosine triphosphatase RAC1 in the development of ulcerative colitis; increased expression of RAC1 was associated with susceptibility to colitis.
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Affiliation(s)
- Aleixo M Muise
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada.
| | - Thomas Walters
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Wei Xu
- Public Health Sciences, University of Toronto, 5-507, Princess Margaret Hospital 610 University Ave, Toronto, Ontario, M5G 2M9
| | - Grace Shen-Tu
- Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Cong-Hui Guo
- Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Ramzi Fattouh
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8,Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Grace Y Lam
- Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8,Institute of Medical Science, University of Toronto
| | - Victorien M Wolters
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Joshua Bennitz
- Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Johan Van Limbergen
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Paul Renbaum
- Genetic Institute, Shaare Zedek Medical Center, The Hebrew University of Jerusalem, Israel, P.O.B 3235, Jerusalem 91031
| | - Yair Kasirer
- Pediatric Gastroenterology Unit, Shaare Zedek Medical Center, The Hebrew University of Jerusalem, Israel, P.O.B 3235, Jerusalem 91031
| | - Bo-Yee Ngan
- Department of Pathology, the Hospital for Sick Children and University of Toronto
| | - Dan Turner
- Pediatric Gastroenterology Unit, Shaare Zedek Medical Center, The Hebrew University of Jerusalem, Israel, P.O.B 3235, Jerusalem 91031
| | - Lee A Denson
- Division of Gastroenterology, Hepatology, and Nutrition Fellowship Cincinnati Children's Hospital Medical Center MLC 2010 3333 Burnet Avenue Cincinnati, OH 45229-3039
| | - Philip M Sherman
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8,Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8
| | - Richard H Duerr
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, School of Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, UPMC Presbyterian, Mezzanine Level, C-Wing, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Judy Cho
- Diseases, Departments of Medicine and Genetics, Yale University
| | - Charlie W Lees
- Department of Gastroenterology, Western General Hospital, University of Edinburgh, Edinburgh
| | - Jack Satsangi
- Department of Gastroenterology, Western General Hospital, University of Edinburgh, Edinburgh
| | - David C Wilson
- Child Life and Health, Department of Pediatrics, University of Edinburgh, Edinburgh
| | | | - Anne M Griffiths
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, 555 University Ave, Toronto, Ontario M5G 1X8
| | | | - Mark S Silverberg
- Mount Sinai Hospital Inflammatory Bowel Disease Disease Group, University of Toronto Group, Dr. Zane Cohen Digestive Diseases Clinical Research Centre, 600 University Ave, Toronto, Ontario M5G 1X5
| | - John H Brumell
- Program in Cell Biology, the Hospital for Sick Children and University of Toronto, 555 University Ave, Toronto, Ontario M5G 1X8,Institute of Medical Science, University of Toronto,Department of Molecular Genetics, University of Toronto
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28
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Abstract
Abstract
In phagocytes, GTPases of the Rac family control crucial antimicrobial functions. The RacGAP ArhGAP15 negatively modulates Rac activity in leukocytes, but its in vivo role in innate immunity remains largely unknown. Here we show that neutrophils and macrophages derived from mice lacking ArhGAP15 presented higher Rac activity but distinct phenotypes. In macrophages, the loss of ArhGAP15 induced increased cellular elongation and membrane protrusions but did not modify chemotactic responses. Conversely, the lack of ArhGAP15 in neutrophils affected critical Rac-dependent antimicrobial functions, specifically causing enhanced chemotactic responses, straighter directional migration, amplified reactive oxygen species production, increased phagocytosis, and improved bacterial killing. In vivo, in a model of severe abdominal sepsis, these effects contributed to increase neutrophil recruitment to the site of infection, thereby limiting bacterial growth, controlling infection spread, reducing systemic inflammation, and ultimately improving survival in ArhGAP15-null mice. Altogether, these results demonstrate the relevance of ArhGAP15 in the selective regulation of multiple neutrophil functions, suggesting that ArhGAP15 targeting might be beneficial in specific pathologic settings like severe sepsis.
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Wei H, Lin Z, Feng J, Peng H, Guo R, Han G, Geng S, Lang X, Sun Y, Shen B, Li Y. Identification of conformational core epitope Lys68 in C5a based on the 3-D modeling complex C5a and its functional antibody F20. Mol Immunol 2011; 48:1377-83. [DOI: 10.1016/j.molimm.2011.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/10/2011] [Accepted: 03/14/2011] [Indexed: 11/24/2022]
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30
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Lawson CD, Donald S, Anderson KE, Patton DT, Welch HCE. P-Rex1 and Vav1 cooperate in the regulation of formyl-methionyl-leucyl-phenylalanine-dependent neutrophil responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 186:1467-76. [PMID: 21178006 DOI: 10.4049/jimmunol.1002738] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
G protein-coupled receptor (GPCR) activation elicits neutrophil responses such as chemotaxis and reactive oxygen species (ROS) formation, which depend on the small G protein Rac and are essential for host defense. P-Rex and Vav are two families of guanine-nucleotide exchange factors (GEFs) for Rac, which are activated through distinct mechanisms but can both control GPCR-dependent neutrophil responses. It is currently unknown whether they play specific roles or whether they can compensate for each other in controlling these responses. In this study, we have assessed the function of neutrophils from mice deficient in P-Rex and/or Vav family GEFs. We found that both the P-Rex and the Vav family are important for LPS priming of ROS formation, whereas particle-induced ROS responses and cell spreading are controlled by the Vav family alone. Surprisingly, fMLF-stimulated ROS formation, adhesion, and chemotaxis were synergistically controlled by P-Rex1 and Vav1. These responses were more severely impaired in neutrophils lacking both P-Rex1 and Vav1 than those lacking the entire P-Rex family, the entire Vav family, or both P-Rex1 and Vav3. P-Rex1/Vav1 (P1V1) double-deficient cells also showed the strongest reduction in fMLF-stimulated activation of Rac1 and Rac2. This reduction in Rac activity may be sufficient to cause the defects observed in fMLF-stimulated P1V1 neutrophil responses. Additionally, Mac-1 surface expression was reduced in P1V1 cells, which might contribute further to defects in responses involving integrins, such as GPCR-stimulated adhesion and chemotaxis. We conclude that P-Rex1 and Vav1 together are the major fMLFR-dependent Dbl family Rac-GEFs in neutrophils and cooperate in the control of fMLF-stimulated neutrophil responses.
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Affiliation(s)
- Campbell D Lawson
- Inositide Laboratory, Babraham Research Campus, Babraham Institute, Cambridge CB22 3AT, United Kingdom
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31
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Han F, Wang X, Yang Q, Cai M, Wang ZY. Characterization of a RacGTPase up-regulated in the large yellow croaker Pseudosciaena crocea immunity. FISH & SHELLFISH IMMUNOLOGY 2011; 30:501-508. [PMID: 21130170 DOI: 10.1016/j.fsi.2010.11.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 11/26/2010] [Accepted: 11/26/2010] [Indexed: 05/30/2023]
Abstract
The Rac proteins are members of the Rho family of small G proteins and are implicated in the regulation of several pathways, including those leading to cytoskeleton reorganization, gene expression, cell proliferation, cell adhesion and cell migration and survival. In this investigation, a Rac gene (named as LycRac gene) was obtained from the large yellow croaker and it was expressed in Escherichia coli and purified. Subsequently the specific antibody was raised using the purified fusion protein (GST-LycRac). Moreover, the GTP-binding assay showed that the LycRac protein had GTP-binding activity. The LycRac gene was ubiquitously transcribed and expressed in 9 tissues. Quantitative real-time RT-PCR and Western blot analysis revealed the highest expression in gill and the weakest expression in spleen. Time-course analysis revealed that LycRac expression was obviously up-regulated in blood, spleen and liver after immunization with polyinosinic polycytidynic acid (poly I:C), formalin-inactive Gram-negative bacterium Vibrio parahemolyticus and bacterial lipopolysaccharides (LPS). These results suggested that LycRac protein might play an important role in the immune response against microorganisms in large yellow croaker.
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Affiliation(s)
- Fang Han
- Key Laboratory of Science and Technology for Aquaculture and Food Safety, Fisheries College, Jimei University, Xiamen 361021, China
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32
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Songsungthong W, Higgins MC, Rolán HG, Murphy JL, Mecsas J. ROS-inhibitory activity of YopE is required for full virulence of Yersinia in mice. Cell Microbiol 2010; 12:988-1001. [PMID: 20148901 DOI: 10.1111/j.1462-5822.2010.01448.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
YopE, a type III secreted effector of Yersinia, is a GTPase Activating Protein for Rac1 and RhoA whose catalytic activity is critical for virulence. We found that YopE also inhibited reactive oxygen species (ROS) production and inactivated Rac2. How YopE distinguishes among its targets and which specific targets are critical for Yersinia survival in different tissues are unknown. A screen identifying YopE mutants in Yersinia pseudotuberculosis that interact with different Rho GTPases showed that YopE residues at positions 102, 106, 109 and 156 discern among switch I and II regions of Rac1, Rac2 and RhoA. Two mutants, which expressed YopE alleles with different antiphagocytic, ROS-inhibitory and cell-rounding activities, YptbL109A and YptbESptP, were studied in animal infections. Inhibition of both phagocytosis and ROS production were required for splenic colonization, whereas fewer YopE activities were required for Peyer's patch colonization. This study shows that Y. pseudotuberculosis encounters multiple host defences in different tissues and uses distinct YopE activities to disable them.
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Nakamura S, Kobayashi M, Sugino T, Kajimoto O, Matoba R, Matsubara K. Effect of exercise on gene expression profile in unfractionated peripheral blood leukocytes. Biochem Biophys Res Commun 2009; 391:846-51. [PMID: 19945435 DOI: 10.1016/j.bbrc.2009.11.150] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 11/21/2009] [Indexed: 12/20/2022]
Abstract
A 4-h bout of exercise induces immunomodulatory effects. Peripheral blood was withdrawn before, and at 4, 8 and 24h after the start of exercise. RNA from the unfractionated white blood cells was analyzed using Agilent human 44K microarray. The expression profiles were sorted into seven clusters based on their unique time-dependent kinetics. In a separate experiment, cell-specific markers were collected and compared among the members in each cluster. Two clusters were assigned as representing neutrophils, one as NK cells, and another mostly as T cells. Three clusters seemed to be mixtures of several cell types. Extension of this approach to other systems is discussed.
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Affiliation(s)
- Seiji Nakamura
- DNA Chip Research Inc, Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan.
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34
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Abstract
Rho family GTPases are intracellular signaling proteins regulating multiple pathways involved in cell actomyosin organization, adhesion, and proliferation. Our knowledge of their cellular functions comes mostly from previous biochemical studies that used mutant overexpression approaches in various clonal cell lines. Recent progress in understanding Rho GTPase functions in blood cell development and regulation by gene targeting of individual Rho GTPases in mice has allowed a genetic understanding of their physiologic roles in hematopoietic progenitors and mature lineages. In particular, mouse gene-targeting studies have provided convincing evidence that individual members of the Rho GTPase family are essential regulators of cell type-specific functions and stimuli-specific pathways in regulating hematopoietic stem cell interaction with bone marrow niche, erythropoiesis, and red blood cell actin dynamics, phagocyte migration and killing, and T- and B-cell maturation. In addition, deregulation of Rho GTPase family members has been associated with multiple human hematologic diseases such as neutrophil dysfunction, leukemia, and Fanconi anemia, raising the possibility that Rho GTPases and downstream signaling pathways are of therapeutic value. In this review we discuss recent genetic studies of Rho GTPases in hematopoiesis and several blood lineages and the implications of Rho GTPase signaling in hematologic malignancies, immune pathology. and anemia.
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35
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Bcr and Abr cooperate in negatively regulating acute inflammatory responses. Mol Cell Biol 2009; 29:5742-50. [PMID: 19703997 DOI: 10.1128/mcb.00357-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bcr and Abr are GTPase-activating proteins for the small GTPase Rac. Both proteins are expressed in cells of the innate immune system, including neutrophils and macrophages. The function of Bcr has been linked to the negative regulation of neutrophil reactive oxygen species (ROS) production, but the function of Abr in the innate immune system was unknown. Here, we report that mice lacking both proteins are severely affected in two models of experimental endotoxemia, including exposure to Escherichia coli lipopolysaccharide and polymicrobial sepsis, with extensive microvascular leakage, resulting in severe pulmonary edema and hemorrhage. Additionally, in vivo-activated neutrophils of abr and bcr null mutant mice produced excessive tissue-damaging myeloperoxidase (MPO), elastase, and ROS. Moreover, the secretion of the tissue metalloproteinase MMP9 by monocytes and ROS by elicited macrophages was abnormally high. In comparison, ROS production from bone marrow monocytes was not significantly different from that of controls, and the exocytosis of neutrophil secondary and tertiary granule products, including lactoferrin, was normal. These data show that Abr and Bcr normally curb very specific functions of mature tissue innate immune cells, and that each protein has distinct as well as partly overlapping functions in the downregulation of inflammatory processes.
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36
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Zhang H, Sun C, Glogauer M, Bokoch GM. Human neutrophils coordinate chemotaxis by differential activation of Rac1 and Rac2. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 183:2718-28. [PMID: 19625648 PMCID: PMC3056163 DOI: 10.4049/jimmunol.0900849] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Rac1 and Rac2, members of the small Rho GTPase family, play essential roles in coordinating directional migration and superoxide production during neutrophil responses to chemoattractants. Although earlier studies in Rac1 and Rac2 knockout mice have demonstrated unique roles for each Rac isoform in chemotaxis and NADPH oxidase activation, it is still unclear how human neutrophils use Rac1 and Rac2 to achieve their immunological responses to foreign agent stimulation. In the current study, we used TAT dominant-negative Rac1-T17N and Rac2-T17N fusion proteins to acutely alter the activity of Rac1 and Rac2 individually in human neutrophils. We demonstrate distinct activation kinetics and different roles for Rac1 and Rac2 in response to low vs high concentrations of fMLP. These observations were verified using neutrophils from mice in which Rac1 or Rac2 was genetically absent. Based on these results, we propose a model to explain how human neutrophils kill invading microbes while limiting oxidative damage to the adjacent surrounding healthy tissue through the differential activation of Rac1 and Rac2 in response to different concentrations of chemoattractant.
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Affiliation(s)
- Hui Zhang
- Department of Immunology and Microbial Science, Scripps Research Institute, La Jolla, CA 92037-1092, USA
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37
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Heasman SJ, Ridley AJ. Mammalian Rho GTPases: new insights into their functions from in vivo studies. Nat Rev Mol Cell Biol 2008; 9:690-701. [PMID: 18719708 DOI: 10.1038/nrm2476] [Citation(s) in RCA: 1434] [Impact Index Per Article: 89.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rho GTPases are key regulators of cytoskeletal dynamics and affect many cellular processes, including cell polarity, migration, vesicle trafficking and cytokinesis. These proteins are conserved from plants and yeast to mammals, and function by interacting with and stimulating various downstream targets, including actin nucleators, protein kinases and phospholipases. The roles of Rho GTPases have been extensively studied in different mammalian cell types using mainly dominant negative and constitutively active mutants. The recent availability of knockout mice for several members of the Rho family reveals new information about their roles in signalling to the cytoskeleton and in development.
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Affiliation(s)
- Sarah J Heasman
- Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK.
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Avet-Rochex A, Perrin J, Bergeret E, Fauvarque MO. Rac2 is a major actor of Drosophila resistance to Pseudomonas aeruginosa acting in phagocytic cells. Genes Cells 2007; 12:1193-204. [PMID: 17903178 DOI: 10.1111/j.1365-2443.2007.01121.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Pathogen recognition and engulfment by phagocytic cells of the blood cell lineage constitute the first line of defense against invading pathogens. This cellular immune response is conserved throughout evolution and depends strictly on cytoskeletal changes regulated by the RhoGTPases family. Many pathogens have developed toxins modifying RhoGTPases activity to their own benefit. In particular, the Exoenzyme S (ExoS) toxin of the Gram-negative bacteria Pseudomonas aeruginosa is directly injected into the host cell cytoplasm and contains a GAP domain (ExoSGAP) targeting RhoGTPases. Searching for the contribution of each RhoGTPases, Rho1, Rac1, Rac2, Mtl (Mig2-like) and Cdc42 to fly resistance to P. aeruginosa infections, we found that Rac2 is required to resist to P. aeruginosa and to other Gram-negative or Gram-positive bacteria. The Rac2 immune-deficient phenotype is attributable to defective engulfment of pathogens since Rac2-mutant macrophages exhibited strong reduction in the phagocytosis level of both Gram-negative and Gram-positive bacterial particles whereas systemic immune signaling pathways, including Toll, Immune deficiency and Jun kinases, were not affected. Co-expression of Rac2 and ExoSGAP rescued the increased sensitivity to P. aeruginosa observed in ExoSGAP-expressing flies suggesting that Rac2 is the main host factor whose function is inhibited by the GAP domain of the ExoS toxin.
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Affiliation(s)
- Amélie Avet-Rochex
- Commissariat à l'Energie Atomique, DSV, iRTSV, 17 rue des Martyrs, Grenoble F-38054, France
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Koh A, da Silva APB, Bansal AK, Bansal M, Sun C, Lee H, Glogauer M, Sodek J, Zohar R. Role of osteopontin in neutrophil function. Immunology 2007; 122:466-75. [PMID: 17680800 PMCID: PMC2266047 DOI: 10.1111/j.1365-2567.2007.02682.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Osteopontin (OPN) is important for the function of fibroblasts, macrophages and lymphocytes during inflammation and wound healing. In recent studies of experimental colitis we demonstrated exacerbated tissue destruction in OPN-null mice, associated with reduced tumour necrosis factor-alpha expression and increased myeloperoxidase activity. The objective of this investigation therefore was to determine the importance of OPN expression in neutrophil function. Although, in contrast to macrophages, neutrophils expressed low levels of OPN with little or no association with the CD44 receptor, intraperitoneal recruitment of neutrophils in OPN-null mice was impaired in response to sodium periodate. The importance of exogenous OPN for neutrophil recruitment was demonstrated by a robust increase in peritoneal infiltration of PMNs in response to injections of native or recombinant OPN. In vitro, OPN(-/-) neutrophils exhibited reduced chemokinesis and chemotaxis towards N-formyl methionyl leucyl phenylalanine (fMLP), reflecting a reduction in migration speed and polarization. Exogenous OPN, which was chemotactic for the neutrophils, rescued the defects in polarization and migration speed of the OPN(-/-) neutrophils. In contrast, the defensive and cytocidal activities of OPN(-/-) neutrophils, measured by assays for phagocytosis, generation of reactive oxygen species, cytokine production and matrix metalloproteinase-9, were not impaired. These studies demonstrate that, while exogenous OPN may be important for the recruitment and migration of neutrophils, expression of OPN by neutrophils is not required for their destructive capabilities.
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Affiliation(s)
- Adeline Koh
- CIHR Group in Matrix Dynamics, Faculty of Dentistry, Department of Biochemistry, University of Toronto, Toronto, ONT, Canada
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Lerm M, Brodin VP, Ruishalme I, Stendahl O, Särndahl E. Inactivation of Cdc42 Is Necessary for Depolymerization of Phagosomal F-Actin and Subsequent Phagosomal Maturation. THE JOURNAL OF IMMUNOLOGY 2007; 178:7357-65. [PMID: 17513786 DOI: 10.4049/jimmunol.178.11.7357] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Phagocytosis is a complex process involving the activation of various signaling pathways, such as the Rho GTPases, and the subsequent reorganization of the actin cytoskeleton. In neutrophils, Rac and Cdc42 are activated during phagocytosis but less is known about the involvement of these GTPases during the different stages of the phagocytic process. The aim of this study was to elucidate the role of Cdc42 in phagocytosis and the subsequent phagosomal maturation. Using a TAT-based protein transduction technique, we introduced dominant negative and constitutively active forms of Cdc42 into neutrophil-like HL60 (human leukemia) cells that were allowed to phagocytose IgG-opsonized yeast particles. Staining of cellular F-actin in cells transduced with constitutively active Cdc42 revealed that the activation of Cdc42 induced sustained accumulation of periphagosomal actin. Moreover, the fusion of azurophilic granules with the phagosomal membrane was prevented by the accumulated F-actin. In contrast, introducing dominant negative Cdc42 impaired the translocation per se of azurophilic granules to the periphagosomal area. These results show that efficient phagosomal maturation and the subsequent eradication of ingested microbes in human neutrophils is dependent on a strictly regulated Cdc42. To induce granule translocation, Cdc42 must be in its active state but has to be inactivated to allow depolymerization of the F-actin cage around the phagosome, a process essential for phagolysosome formation.
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Affiliation(s)
- Maria Lerm
- Division of Medical Microbiology, Institute for Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
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41
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Ruse M, Knaus UG. New players in TLR-mediated innate immunity: PI3K and small Rho GTPases. Immunol Res 2006; 34:33-48. [PMID: 16720897 DOI: 10.1385/ir:34:1:33] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLRs) play a crucial role in the innate immune system as a first line of defense against pathogens. TLR activation in phagocytes produces pro-inflammatory cytokines and chemokines that contribute directly to elimination of infectious agents and activation of adaptive immune responses. However, a sustained inflammatory response can result in tissue damage and generalized sepsis. This review summarizes the complex and sometimes conflicting links of TLR signaling with two important regulators of immune cells functions: phosphoinositide 3-kinases (PI3Ks) and small GTPases of the Rho family. A unified model of hierarchical organization of these signaling participants is still premature, given that the tools for delineating how control of TLRmediated pathways is achieved are just emerging. Critical progress in our understanding of spatial-temporal propagation of TLR signaling will certainly be provided in the near future by pharmacological targeting of PI3Ks using recently characterized, second-generation PI3K inhibitors in combination with gene-targeting strategies for PI3K subunits and Rho GTPases targeted to the murine myeloid compartment.
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Affiliation(s)
- Monica Ruse
- Department of Immunology, The Scripps Research Institute La Jolla, California.
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