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Ishida Y, Shintani T, Nobumoto T, Sakurai S, Hamana T, Yanamoto S, Hayashido Y. Interaction of Integrin αvβ8 With Type I Collagen Promotes Squamous Cell Carcinoma Cell Motility via RAC1 Activation. Anticancer Res 2023; 43:4833-4841. [PMID: 37909974 DOI: 10.21873/anticanres.16680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 11/03/2023]
Abstract
BACKGROUND/AIM The interaction of integrin αvβ8 with type I collagen was shown to promote oral squamous cell carcinoma (SCC) cell proliferation via the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway. However, the role of integrin αvβ8 in SCC progression remains poorly understood. In this study, the role of integrin αvβ8 in oral SCC progression was therefore investigated. MATERIALS AND METHODS Integrin αv and β8 protein expression in oral SCC cells was examined by western blotting. Oral SCC cell motility was investigated using modified Boyden chamber assays. Behavior of oral SCC cells was examined in three-dimensional culture using type I collagen gel. Ras homolog family member A (RHOA), Ras-related C3 botulinum toxin substrate 1 (RAC1), and cell division control protein 42 homolog (CDC42) activity of oral SCC cells was analyzed by pull-down assays. RESULTS SCC cells with high integrin αvβ8 expression levels had a high ability to migrate on type I collagen and exhibited enhanced invasion into type I collagen gel. In SCC cells with high integrin αvβ8 expression level, cultivation on type I collagen induced RAC1 activation. Treatment with RAC1 inhibitor reduced type I collagen-induced motility of SCC cells. Down-regulation of integrin β8 by specific antisense oligonucleotide reduced type I collagen-induced RAC1 activation and suppressed cell motility and invasion into type I collagen gel. CONCLUSION The interaction of integrin αvβ8 with type I collagen facilitates SCC cell motility and invasion via RAC1 activation. Therefore, integrin αvβ8 and RAC1 may represent new targets for inhibiting metastasis and invasion in patients with oral SCC.
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Affiliation(s)
- Yasutaka Ishida
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
| | - Tomoaki Shintani
- Center of Oral Clinical Examination, Hiroshima University Hospital, Hiroshima, Japan
| | - Tadayoshi Nobumoto
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
| | - Shigeru Sakurai
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
| | - Tomoaki Hamana
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
| | - Souichi Yanamoto
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
| | - Yasutaka Hayashido
- Department of Oral Oncology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan
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Fu H, Zhang P, Zhao XD, Zhong XY. Interfering with Rac1-activation during neonatal monocyte-macrophage differentiation influences the inflammatory responses of M1 macrophages. Cell Death Dis 2023; 14:619. [PMID: 37735499 PMCID: PMC10514032 DOI: 10.1038/s41419-023-06150-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 09/04/2023] [Accepted: 09/12/2023] [Indexed: 09/23/2023]
Abstract
Necrotizing enterocolitis (NEC) is a life-threatening, inflammatory disease affecting premature infants with intestinal necrosis, but the mechanism remains unclear. Neonatal macrophages are thought to play an important role in the pathogenesis of NEC through the production of proinflammatory cytokines. Restriction of cytokine expression in macrophages of NEC tissues may be beneficial. In adult macrophages, interfering with Rac1 has been shown to influence the expression of cytokines. Here, we investigated whether interfering with Rac1 in neonatal macrophages affects their inflammatory responses. First, we found that Rac1-activation was upregulated in the macrophages of rats with NEC model induction compared to controls. The M1 macrophages derived from human neonatal monocytes showed greater Rac1-activation than the M2 macrophages derived from the same monocytes. Inhibition of Rac1-activation by NSC23766 potently reduced the production of proinflammatory cytokines in these M1 macrophages. While neonatal monocytes differentiated into M1 macrophages in vitro, NSC23766 significantly altered cell function during the first six days of incubation with GM-CSF rather than during the subsequent stimulation phase. However, the same effect of NSC23766 was not observed in adult macrophages. Using mass spectrometry, Y-box binding protein 1 (YB1) was identified as being downregulated upon inhibition of Rac1-activation in the neonatal macrophages. Moreover, we found that inhibition of Rac1-activation shortens the poly A tail of PABPC1 mRNA, thereby reducing the translation of PABPC1 mRNA. Consequently, the downregulation of PABPC1 resulted in a reduced translation of YB1 mRNA. Furthermore, we found that TLR4 expression was downregulated in neonatal macrophages, while YB1 expression was reduced. Adding resatorvid (TLR4 signaling inhibitor) to the macrophages treated with NSC23766 did not further reduce the cytokine expression. These findings reveal a novel Rac1-mediated pathway to inhibit cytokine expression in neonatal M1 macrophages and suggest potential targets for the prevention or treatment of NEC.
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Affiliation(s)
- Hang Fu
- Department of Pediatrics, Women and Children's Hospital of Chongqing Medical University, 401147, Chongqing, China.
- Department of Pediatrics, Chongqing Health Center for Women and Children, 401147, Chongqing, China.
- Chongqing Research Center for Prevention & Control of Maternal and Child Diseases and Public Health, 401147, Chongqing, China.
| | - Ping Zhang
- Department of Obstetrics and Gynecology, Women and Children's Hospital of Chongqing Medical University, 401147, Chongqing, China
- Department of Obstetrics and Gynecology, Chongqing Health Center for Women and Children, 401147, Chongqing, China
| | - Xiao-Dong Zhao
- Chongqing Key Laboratory of Child Infection and Immunity, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, 400014, Chongqing, China.
- Department of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, 400014, Chongqing, China.
| | - Xiao-Yun Zhong
- Department of Pediatrics, Women and Children's Hospital of Chongqing Medical University, 401147, Chongqing, China.
- Department of Pediatrics, Chongqing Health Center for Women and Children, 401147, Chongqing, China.
- Chongqing Research Center for Prevention & Control of Maternal and Child Diseases and Public Health, 401147, Chongqing, China.
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Dalto JF, Medina JH. Time-dependent inhibition of Rac1 in the VTA enhances long-term aversive memory: implications in active forgetting mechanisms. Sci Rep 2023; 13:13507. [PMID: 37598223 PMCID: PMC10439914 DOI: 10.1038/s41598-023-40434-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/10/2023] [Indexed: 08/21/2023] Open
Abstract
The fate of memories depends mainly on two opposing forces: the mechanisms required for the storage and maintenance of memory and the mechanisms underlying forgetting, being the latter much less understood. Here, we show the effect of inhibiting the small Rho GTPase Rac1 on the fate of inhibitory avoidance memory in male rats. The immediate post-training micro-infusion of the specific Rac1 inhibitor NSC23766 (150 ng/0.5 µl/ side) into the ventral tegmental area (VTA) enhanced long-term memory at 1, 7, and 14 days after a single training. Additionally, an opposed effect occurred when the inhibitor was infused at 12 h after training while no effect was observed immediately after testing animals at 1 day. Control experiments ruled out the possibility that post-training memory enhancement was due to facilitation of memory formation since no effect was found when animals were tested at 1 h after acquisition and no memory enhancement was observed after the formation of a weak memory. Immediate post-training micro-infusion of Rac1 inhibitor into the dorsal hippocampus, or the amygdala did not affect memory. Our findings support the idea of a Rac1-dependent time-specific active forgetting mechanism in the VTA controlling the strength of a long-term aversive memory.
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Affiliation(s)
- Juliana F Dalto
- Instituto de Biología Celular y Neurociencias "Prof. Eduardo de Robertis", Facultad de Medicina, Universidad de Buenos Aires-CONICET, Paraguay 2155, 3rd Floor, C1121ABG, Buenos Aires, Argentina
| | - Jorge H Medina
- Instituto de Biología Celular y Neurociencias "Prof. Eduardo de Robertis", Facultad de Medicina, Universidad de Buenos Aires-CONICET, Paraguay 2155, 3rd Floor, C1121ABG, Buenos Aires, Argentina.
- Instituto Tecnológico de Buenos Aires, Buenos Aires, Argentina.
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Banka S, Bennington A, Baker MJ, Rijckmans E, Clemente GD, Ansor NM, Sito H, Prasad P, Anyane-Yeboa K, Badalato L, Dimitrov B, Fitzpatrick D, Hurst ACE, Jansen AC, Kelly MA, Krantz I, Rieubland C, Ross M, Rudy NL, Sanz J, Stouffs K, Xu ZL, Malliri A, Kazanietz MG, Millard TH. Activating RAC1 variants in the switch II region cause a developmental syndrome and alter neuronal morphology. Brain 2022; 145:4232-4245. [PMID: 35139179 PMCID: PMC9762944 DOI: 10.1093/brain/awac049] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/10/2022] [Accepted: 01/17/2022] [Indexed: 11/14/2022] Open
Abstract
RAC1 is a highly conserved Rho GTPase critical for many cellular and developmental processes. De novo missense RAC1 variants cause a highly variable neurodevelopmental disorder. Some of these variants have previously been shown to have a dominant negative effect. Most previously reported patients with this disorder have either severe microcephaly or severe macrocephaly. Here, we describe eight patients with pathogenic missense RAC1 variants affecting residues between Q61 and R68 within the switch II region of RAC1. These patients display variable combinations of developmental delay, intellectual disability, brain anomalies such as polymicrogyria and cardiovascular defects with normocephaly or relatively milder micro- or macrocephaly. Pulldown assays, NIH3T3 fibroblast spreading assays and staining for activated PAK1/2/3 and WAVE2 suggest that these variants increase RAC1 activity and over-activate downstream signalling targets. Axons of neurons isolated from Drosophila embryos expressing the most common of the activating variants are significantly shorter, with an increased density of filopodial protrusions. In vivo, these embryos exhibit frequent defects in axonal organization. Class IV dendritic arborization neurons expressing this variant exhibit a significant reduction in the total area of the dendritic arbour, increased branching and failure of self-avoidance. RNAi knock down of the WAVE regulatory complex component Cyfip significantly rescues these morphological defects. These results establish that activating substitutions affecting residues Q61-R68 within the switch II region of RAC1 cause a developmental syndrome. Our findings reveal that these variants cause altered downstream signalling, resulting in abnormal neuronal morphology and reveal the WAVE regulatory complex/Arp2/3 pathway as a possible therapeutic target for activating RAC1 variants. These insights also have the potential to inform the mechanism and therapy for other disorders caused by variants in genes encoding other Rho GTPases, their regulators and downstream effectors.
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Affiliation(s)
- Siddharth Banka
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
- Manchester Centre for Genomic Medicine, University of Manchester, St Mary’s Hospital, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
| | - Abigail Bennington
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
| | - Martin J Baker
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Cell Signalling Group, Cancer Research UK Manchester Institute, The University of Manchester, Alderley Park, Macclesfield SK10 4TG, UK
| | - Ellen Rijckmans
- Department of Pediatrics, UZ Brussel, Brussels, Belgium
- Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Giuliana D Clemente
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Nurhuda Mohamad Ansor
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200 Kepala Batas, Penang, Malaysia
| | - Hilary Sito
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
| | - Pritha Prasad
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
| | - Kwame Anyane-Yeboa
- Division of Clinical Genetics, Columbia University Medical Center, New York 10032, USA
| | - Lauren Badalato
- Department of Pediatrics, School of Medicine, Kingston General Hospital, Queen’s University, Kingston, ON, Canada
| | - Boyan Dimitrov
- Centre for Medical Genetics, UZ Brussel, Brussels, Belgium
| | - David Fitzpatrick
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, UK
| | - Anna C E Hurst
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Anna C Jansen
- Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Pediatric Neurology Unit, Department of Pediatrics, UZ Brussel, Brussels, Belgium
| | | | - Ian Krantz
- Roberts Individualized Medical Genetics Center, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Claudine Rieubland
- Department of Human Genetics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Meredith Ross
- Division of Clinical Genetics, Columbia University Medical Center, New York 10032, USA
| | - Natasha L Rudy
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Javier Sanz
- Department of Human Genetics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Katrien Stouffs
- Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Centre for Medical Genetics, UZ Brussel, Brussels, Belgium
| | - Zhuo Luan Xu
- Roberts Individualized Medical Genetics Center, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Angeliki Malliri
- Cell Signalling Group, Cancer Research UK Manchester Institute, The University of Manchester, Alderley Park, Macclesfield SK10 4TG, UK
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tom H Millard
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, University of ManchesterM13 9PL, UK
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Zhang QY, Li X, Zhou XY, Li Y, Zhang J, Zhang XF, Liu YD, Chen YX, Wu XM, Ma LZ, Chen X, Chen SL. Study of differential proteomics in granulosa cells of premature ovarian insufficiency (POI) and the roles and mechanism of RAC1 in granulosa cells. Mol Cell Endocrinol 2022; 555:111719. [PMID: 35850487 DOI: 10.1016/j.mce.2022.111719] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 07/03/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022]
Abstract
In the present study, we focused on characterizing the proteome in granulosa cells in patients with biochemical premature ovarian insufficiency (bPOI) in order to identify differential proteins and investigate the fundamental mechanisms of POI. A total of 2688 proteins were identified based on the data-independent acquisition method, and 70 differentially expressed proteins were significant. Bioinformatic analyses, including gene expression pattern analysis, gene ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and Search Tool for the Retrieval of Interacting Genes/Proteins analysis, revealed discrete modules and the underlying molecular mechanisms in bPOI. Importantly, we observed that Ras-related C3 botulinum toxin substrate 1 (RAC1) was downregulated in the granulosa cells of bPOI. Low expression of RAC1 may affect the development process of POI by affecting the proliferation, apoptosis, and hormone synthesis of granulosa cells. Downregulation of RAC1 expression in the KGN and COV434 cells inhibited cell proliferation, blocked cells in the G1/G0 phase, and promoted apoptosis. Western blot results showed that β-catenin and cyclin D1 in the KGN and COV434 cells transfected with RAC1-siRNA were downregulated, while P21 and Bax were upregulated. Knocking down RAC1 in the KGN cells or adding the RAC1 enzyme inhibitor to the human luteinized granulosa cells (hLGC) inhibited the synthesis of E2, and the expression of aromatase and follicle-stimulating hormone receptor (FSHR) was reduced.
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Affiliation(s)
- Qing-Yan Zhang
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xin Li
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xing-Yu Zhou
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Ying Li
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Jun Zhang
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xiao-Fei Zhang
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yu-Dong Liu
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Ying-Xue Chen
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xiao-Min Wu
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Lin-Zi Ma
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xin Chen
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Shi-Ling Chen
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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Agustina H, Ahyati R, Suryanti S, Hernowo BS. The potential diagnostic value of Rac1 immunohistochemistry in follicular thyroid carcinoma. Malays J Pathol 2022; 44:225-233. [PMID: 36043585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
INTRODUCTION Rac1 and Galectin-3 has been suggested to involve in the invasion and aggressive behaviour of several cancers. The aim of this study is to evaluate the immunoreactivity of Rac1 and Galectin-3 in follicular adenoma (FA) and follicular thyroid carcinoma (FC) in an attempt to investigate its association with the invasion of FC and its immunohistochemical diagnostic value to discriminate FA and FC. MATERIALS AND METHODS This study included 120 selected paraffin embedded tissue blocks from surgically resected follicular thyroid neoplasms, consists of 60 cases of FA and 60 cases of FC. Immunohistochemistry staining for Rac1 and Galectin-3 were performed on all cases. The diagnostic value of these immunohistochemical markers to determine invasion in FC were calculated. RESULTS Positive immunoreactivity of Rac1 were found in 25/60 (41.67%) cases of FA and 56/60 (93.3%) cases of FC (p=0.0001). Positive immunoreactivity of Galectin-3 was found in 8/60 (13.3%) cases of FA and 47/60 (78.3%) cases of FC (p=0.0001). The sensitivity of Rac1 in distinguishing FA from FC were 93.3% with specificity, PPV, NPV, and overall accuracy were 58.3%, 69.1%, 89.7%, and 75.8% consecutively. The sensitivity of combination Rac1 and Galectin-3 were 73.3% with specificity, PPV, NPV, and overall accuracy were 96.7%, 95.7%, 78.4%, and 85% consecutively. CONCLUSIONS Rac1 immunohistochemistry is a sensitive marker in discriminating FA from FC, but its specificity and accuracy are low. Combination of Rac1 and Galectin-3 gives more specific and higher diagnostic accuracy. Combination of Rac1 and Galectin-3 may be useful to determine invasion and diagnose FC.
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Affiliation(s)
- H Agustina
- Universitas Padjadjaran/ Hasan Sadikin General Hospital, Faculty of Medicine, Department of Anatomical Pathology, Bandung, Indonesia.
| | - R Ahyati
- Universitas Padjadjaran/ Hasan Sadikin General Hospital, Faculty of Medicine, Department of Anatomical Pathology, Bandung, Indonesia
| | - S Suryanti
- Universitas Padjadjaran/ Hasan Sadikin General Hospital, Faculty of Medicine, Department of Anatomical Pathology, Bandung, Indonesia
| | - B S Hernowo
- Universitas Padjadjaran/ Hasan Sadikin General Hospital, Faculty of Medicine, Department of Anatomical Pathology, Bandung, Indonesia
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Zhu Y, Xie J, Shi J. Rac1/ROCK-driven membrane dynamics promote natural killer cell cytotoxicity via granzyme-induced necroptosis. BMC Biol 2021; 19:140. [PMID: 34325694 PMCID: PMC8323222 DOI: 10.1186/s12915-021-01068-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/09/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Natural killer (NK) cells play an important role in cancer immunosurveillance and therapy. However, the target selectivity of NK cell activity is still poorly understood. RESULTS Here, we used live-cell reporters to unravel differential epithelial cancer target killing by primary human NK cells. We found highly variable fractions of killing by distinct NK cell cytotoxic modes that were not determined by NK ligand expression. Rather, epithelial plasma membrane dynamics driven by ROCK-mediated blebs and/or Rac1-mediated lamellipodia promoted necrotic mode in preference to the apoptotic mode of killing. Inhibition of granzyme B and key necroptosis regulators RIP1, RIP3, and MLKL significantly attenuated the necrotic killing, revealing a novel NK cell cytotoxic pathway by granzyme-induced necroptosis that conferred target selectivity. CONCLUSIONS Our results not only elucidate a new NK cell effector mechanism but also suggest that tissue microenvironment and oncogenic signaling pathways that promote membrane dynamics, e.g., Rac1 and Rho/ROCK, could be exploited to enhance proinflammatory NK cell killing.
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Affiliation(s)
- Yanting Zhu
- Center for Quantitative Systems Biology, Department of Physics and Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong, China
| | - Jun Xie
- Center for Quantitative Systems Biology, Department of Physics and Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong, China
| | - Jue Shi
- Center for Quantitative Systems Biology, Department of Physics and Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong, China.
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Khan AA, Bano Y. Salmonella enterica subsp. enterica host-pathogen interactions and their implications in gallbladder cancer. Microb Pathog 2021; 157:105011. [PMID: 34062227 DOI: 10.1016/j.micpath.2021.105011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND Several studies have linked chronic typhoid infection with gallbladder carcinoma without completely understood mechanism. This study was performed in order to understand role of Salmonella in gallbladder cancer etiology. METHODS Known Salmonella host-pathogen interactions were screened from database in addition to known gallbladder carcinoma targets. Host-pathogen interaction map of S. enterica was prepared and screened for interactions with gallbladder carcinoma targets. Further functional overrepresentation analysis was performed to understand the role of human targets involved in Salmonella host-pathogen interactions in gallbladder carcinoma. RESULTS Salmonella interact with several human proteins involved in gallbladder carcinoma. MAPK and RAC1 are the most important human proteins based on node degree value among all GBC associated interactors identified in current data search. Functional over-representation analysis reveals that Salmonella can induce adenocarcinoma which constitutes 85% of gallbladder cancer. CONCLUSION Though, the role of MAPK/ERK and PI3K/AKT/mTOR pathway is already suggested for Salmonella mediated gallbladder cancer, but current data based approach indicate several new insight for exploration of the role of Salmonella in gallbladder cancer etiology. The results indicate about several other processes including CREB/SP-1 and BSG(CD147) signaling, that must be given consideration for understanding the role of Salmonella in gallbladder cancer.
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Affiliation(s)
- Abdul Arif Khan
- Indian Council of Medical Research-National AIDS Research Institute, Pune, Maharashtra, 411026, India.
| | - Yasmin Bano
- Department of Molecular and Human Genetics, Jiwaji University, Gwalior, MP, 474001, India
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Guo Y, Chen H, Wang QJ, Qi X, Li Q, Fu W, Huang J, Yao CY, Liu ZY, Wang MZ, An L, Tian JH, Wu ZH. Prolonged melatonin treatment promote testicular recovery by enhancing RAC1-mediated apoptotic cell clearance and cell junction-dependent spermatogensis after heat stress. Theriogenology 2020; 162:22-31. [PMID: 33418161 DOI: 10.1016/j.theriogenology.2020.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 12/08/2020] [Accepted: 12/12/2020] [Indexed: 12/13/2022]
Abstract
INTRODUCTION A decline in semen quality caused by global warming and torrid working conditions is a major cause of human male infertility, and heat stress-induced decreases in male reproductive ability results in economic losses in livestock husbandry. Increasing evidence suggests that melatonin exerts protective effects on stress-induced DNA damage and apoptosis in germ cells. However, few studies have assessed the effects of melatonin on testicular recovery during post-heat stress and the underlying mechanisms. METHODS AND RESULTS In vivo studies using 8-week-old male CD-1 mice revealed that melatonin pretreatment (50 mg/kg for 5 days) did not alleviate heat stress-induced germ cell loss and disrupted testicular histomorphology, however, long-term melatonin administration after heat stress accelerated germ cell apoptosis, spermatogenic cell regeneration, and testicular weight recovery. In vitro studies demonstrated that melatonin enhanced RAC1 activity, resulting in increased phagocytosis of apoptotic germ cells by Sertoli cells. In addition, melatonin restored gap junctions and tight junctions after heat stress, thereby promoting hollow seminiferous tubule filling. DISCUSSION Long-term melatonin administration accelerated testicular recovery after heat stress by enhancing the phagocytotic activity of Sertoli cells and the regeneration of spermatogenic cells. This finding suggests that melatonin is a potential therapeutic for heat stress-induced male infertility.
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Affiliation(s)
- Yao Guo
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Hui Chen
- College of Animal Science and Technology, Hebei Agricultural University, Baoding, 071000, China
| | - Qiang-Jun Wang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Xin Qi
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Qin Li
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Wei Fu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Jie Huang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Chun-Yan Yao
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Zhong-Ying Liu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Mei-Zhi Wang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Lei An
- National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Jian-Hui Tian
- National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China
| | - Zhong-Hong Wu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
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10
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Hall G, Spurney RF. Losing their footing: Rac1 signaling causes podocyte detachment and FSGS. Kidney Int 2019; 92:283-285. [PMID: 28709595 DOI: 10.1016/j.kint.2017.03.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 03/30/2017] [Accepted: 03/30/2017] [Indexed: 12/26/2022]
Abstract
Selective modulation of Rho GTPase activity in podocytes recapitulates characteristic features of human nephrosis. Using a mouse model, Robins et al. found that high levels of Rac1 activation in podocytes caused podocyte detachment and glomerulosclerosis. Podocyte Rac1 activity was enhanced in biopsy specimens from patients with nephrosis, and serum from this patient population activated Rac1 in cultured podocytes. These data provide a causal link between podocyte Rac1 activation and human nephrotic diseases.
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Affiliation(s)
- Gentzon Hall
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Robert F Spurney
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA.
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11
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Skjesol A, Yurchenko M, Bösl K, Gravastrand C, Nilsen KE, Grøvdal LM, Agliano F, Patane F, Lentini G, Kim H, Teti G, Kumar Sharma A, Kandasamy RK, Sporsheim B, Starheim KK, Golenbock DT, Stenmark H, McCaffrey M, Espevik T, Husebye H. The TLR4 adaptor TRAM controls the phagocytosis of Gram-negative bacteria by interacting with the Rab11-family interacting protein 2. PLoS Pathog 2019; 15:e1007684. [PMID: 30883606 PMCID: PMC6438586 DOI: 10.1371/journal.ppat.1007684] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 03/28/2019] [Accepted: 03/07/2019] [Indexed: 02/06/2023] Open
Abstract
Phagocytosis is a complex process that eliminates microbes and is performed by specialised cells such as macrophages. Toll-like receptor 4 (TLR4) is expressed on the surface of macrophages and recognizes Gram-negative bacteria. Moreover, TLR4 has been suggested to play a role in the phagocytosis of Gram-negative bacteria, but the mechanisms remain unclear. Here we have used primary human macrophages and engineered THP-1 monocytes to show that the TLR4 sorting adapter, TRAM, is instrumental for phagocytosis of Escherichia coli as well as Staphylococcus aureus. We find that TRAM forms a complex with Rab11 family interacting protein 2 (FIP2) that is recruited to the phagocytic cups of E. coli. This promotes activation of the actin-regulatory GTPases Rac1 and Cdc42. Our results show that FIP2 guided TRAM recruitment orchestrates actin remodelling and IRF3 activation, two events that are both required for phagocytosis of Gram-negative bacteria. The Gram-negative bacteria E. coli is the most common cause of severe human pathological conditions like sepsis. Sepsis is a clinical syndrome defined by pathological changes due to systemic inflammation, resulting in paralysis of adaptive T-cell immunity with IFN-β as a critical factor. TLR4 is a key sensing receptor of lipopolysaccharide on Gram-negative bacteria. Inflammatory signalling by TLR4 is initiated by the use of alternative pair of TIR-adapters, MAL-MyD88 or TRAM-TRIF. MAL-MyD88 signaling occurs mainly from the plasma membrane giving pro-inflammatory cytokines like TNF, while TRAM-TRIF signaling occurs from vacuoles like endosomes and phagosomes to give type I interferons like IFN-β. It has previously been shown that TLR4 can control phagocytosis and phagosomal maturation through MAL-MyD88 in mice, however, these data have been disputed and published before the role of TRAM was defined in the induction of IFN-β. A role for TRAM or TRIF in phagocytosis has not previously been reported. Here we describe a novel mechanism where TRAM and its binding partner Rab11-FIP2 control phagocytosis of E. coli and regulate IRF3 dependent production of IFN-β. The significance of these results is that we define Rab11-FIP2 as a potential target for modulation of TLR4-dependent signalling in different pathological states.
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Affiliation(s)
- Astrid Skjesol
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mariia Yurchenko
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Korbinian Bösl
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Caroline Gravastrand
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Kaja Elisabeth Nilsen
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Lene Melsæther Grøvdal
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Federica Agliano
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Francesco Patane
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Germana Lentini
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Hera Kim
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Giuseppe Teti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Aditya Kumar Sharma
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Richard K. Kandasamy
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Bjørnar Sporsheim
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Kristian K. Starheim
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Douglas T. Golenbock
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Harald Stenmark
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department for Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo Norway
| | - Mary McCaffrey
- Molecular Cell Biology Laboratory, Biochemistry Department, Biosciences Institute, University College Cork, Cork, Ireland
| | - Terje Espevik
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- The Central Norway Regional Health Authority, St. Olavs Hospital HF, Trondheim, Norway
| | - Harald Husebye
- Centre of Molecular Inflammation Research, Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- The Central Norway Regional Health Authority, St. Olavs Hospital HF, Trondheim, Norway
- * E-mail:
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12
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Lim J, Choi A, Kim HW, Yoon H, Park SM, Tsai CHD, Kaneko M, Kim DS. Constrained Adherable Area of Nanotopographic Surfaces Promotes Cell Migration through the Regulation of Focal Adhesion via Focal Adhesion Kinase/Rac1 Activation. ACS Appl Mater Interfaces 2018; 10:14331-14341. [PMID: 29649358 DOI: 10.1021/acsami.7b18954] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cell migration is crucial in physiological and pathological processes such as embryonic development and wound healing; such migration is strongly guided by the surrounding nanostructured extracellular matrix. Previous studies have extensively studied the cell migration on anisotropic nanotopographic surfaces; however, only a few studies have reported cell migration on isotropic nanotopographic surfaces. We herein, for the first time, propose a novel concept of adherable area on cell migration using isotropic nanopore surfaces with sufficient nanopore depth by adopting a high aspect ratio. As the pore size of the nanopore surface was controlled to 200, 300, and 400 nm in a fixed center-to-center distance of 480 nm, it produced 86, 68, and 36% of adherable area, respectively, on the fabricated surface. A meticulous investigation of the cell migration in response to changes in the constrained adherable area of the nanotopographic surface showed 1.4-, 1.5-, and 1.6-fold increase in migration speeds and a 1.4-, 2-, and 2.5-fold decrease in the number of focal adhesions as the adherable area was decreased to 86, 68, and 36%, respectively. Furthermore, a strong activation of FAK/Rac1 signaling was observed to be involved in the promoted cell migration. These results suggest that the reduced adherable area promotes cell migration through decreasing the FA formation, which in turn upregulates FAK/Rac1 activation. The findings in this study can be utilized to control the cell migration behaviors, which is a powerful tool in the research fields involving cell migration such as promoting wound healing and tissue repair.
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Affiliation(s)
- Jiwon Lim
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
| | - Andrew Choi
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
| | - Hyung Woo Kim
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
| | - Hyungjun Yoon
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
| | - Sang Min Park
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
| | - Chia-Hung Dylan Tsai
- Department of Mechanical Engineering , Osaka University , 1-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Makoto Kaneko
- Department of Mechanical Engineering , Osaka University , 1-1 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Dong Sung Kim
- Department of Mechanical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-gu , Pohang , Gyeongbuk 37673 , Korea
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13
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Sylow L, Jensen TE, Kleinert M, Mouatt JR, Maarbjerg SJ, Jeppesen J, Prats C, Chiu TT, Boguslavsky S, Klip A, Schjerling P, Richter EA. Rac1 is a novel regulator of contraction-stimulated glucose uptake in skeletal muscle. Diabetes 2013; 62:1139-51. [PMID: 23274900 PMCID: PMC3609592 DOI: 10.2337/db12-0491] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In skeletal muscle, the actin cytoskeleton-regulating GTPase, Rac1, is necessary for insulin-dependent GLUT4 translocation. Muscle contraction increases glucose transport and represents an alternative signaling pathway to insulin. Whether Rac1 is activated by muscle contraction and regulates contraction-induced glucose uptake is unknown. Therefore, we studied the effects of in vivo exercise and ex vivo muscle contractions on Rac1 signaling and its regulatory role in glucose uptake in mice and humans. Muscle Rac1-GTP binding was increased after exercise in mice (~60-100%) and humans (~40%), and this activation was AMP-activated protein kinase independent. Rac1 inhibition reduced contraction-stimulated glucose uptake in mouse muscle by 55% in soleus and by 20-58% in extensor digitorum longus (EDL; P < 0.01). In agreement, the contraction-stimulated increment in glucose uptake was decreased by 27% (P = 0.1) and 40% (P < 0.05) in soleus and EDL muscles, respectively, of muscle-specific inducible Rac1 knockout mice. Furthermore, depolymerization of the actin cytoskeleton decreased contraction-stimulated glucose uptake by 100% and 62% (P < 0.01) in soleus and EDL muscles, respectively. These are the first data to show that Rac1 is activated during muscle contraction in murine and human skeletal muscle and suggest that Rac1 and possibly the actin cytoskeleton are novel regulators of contraction-stimulated glucose uptake.
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Affiliation(s)
- Lykke Sylow
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E. Jensen
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Joshua R. Mouatt
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | | | - Jacob Jeppesen
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Clara Prats
- Department of Biomedical Sciences, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Tim T. Chiu
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shlomit Boguslavsky
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Amira Klip
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Peter Schjerling
- Institute of Sports Medicine, Department of Orthopedic Surgery, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Erik A. Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Corresponding author: Erik A. Richter,
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14
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Affiliation(s)
- Leonidas S Lundell
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
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15
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Ali WH, Chen Q, Delgiorno KE, Su W, Hall JC, Hongu T, Tian H, Kanaho Y, Di Paolo G, Crawford HC, Frohman MA. Deficiencies of the lipid-signaling enzymes phospholipase D1 and D2 alter cytoskeletal organization, macrophage phagocytosis, and cytokine-stimulated neutrophil recruitment. PLoS One 2013; 8:e55325. [PMID: 23383154 PMCID: PMC3557251 DOI: 10.1371/journal.pone.0055325] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/21/2012] [Indexed: 01/01/2023] Open
Abstract
Cell migration and phagocytosis ensue from extracellular-initiated signaling cascades that orchestrate dynamic reorganization of the actin cytoskeleton. The reorganization is mediated by effector proteins recruited to the site of activity by locally-generated lipid second messengers. Phosphatidic acid (PA), a membrane phospholipid generated by multiple enzyme families including Phospholipase D (PLD), has been proposed to function in this role. Here, we show that macrophages prepared from mice lacking either of the classical PLD isoforms PLD1 or PLD2, or wild-type macrophages whose PLD activity has been pharmacologically inhibited, display isoform-specific actin cytoskeleton abnormalities that likely underlie decreases observed in phagocytic capacity. Unexpectedly, PA continued to be detected on the phagosome in the absence of either isoform and even when all PLD activity was eliminated. However, a disorganized phagocytic cup was observed as visualized by imaging PA, F-actin, Rac1, an organizer of the F-actin network, and DOCK2, a Rac1 activator, suggesting that PLD-mediated PA production during phagocytosis is specifically critical for the integrity of the process. The abnormal F-actin reorganization additionally impacted neutrophil migration and extravasation from the vasculature into interstitial tissues. Although both PLD1 and PLD2 were important in these processes, we also observed isoform-specific functions. PLD1-driven processes in particular were observed to be critical in transmigration of macrophages exiting the vasculature during immune responses such as those seen in acute pancreatitis or irritant-induced skin vascularization.
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Affiliation(s)
- Wahida H. Ali
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
| | - Qin Chen
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
| | - Kathleen E. Delgiorno
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
| | - Wenjuan Su
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
| | - Jason C. Hall
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
| | - Tsunaki Hongu
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Huasong Tian
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
| | - Yasunori Kanaho
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
| | - Howard C. Crawford
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
| | - Michael A. Frohman
- Department of Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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16
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Ohsawa M, Kobayashi T, Okura H, Igarashi T, Mizuguchi M, Hino O. TSC1 controls distribution of actin fibers through its effect on function of Rho family of small GTPases and regulates cell migration and polarity. PLoS One 2013; 8:e54503. [PMID: 23355874 PMCID: PMC3552859 DOI: 10.1371/journal.pone.0054503] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 12/12/2012] [Indexed: 12/12/2022] Open
Abstract
The tumor-suppressor genes TSC1 and TSC2 are mutated in tuberous sclerosis, an autosomal dominant multisystem disorder. The gene products of TSC1 and TSC2 form a protein complex that inhibits the signaling of the mammalian target of rapamycin complex1 (mTORC1) pathway. mTORC1 is a crucial molecule in the regulation of cell growth, proliferation and survival. When the TSC1/TSC2 complex is not functional, uncontrolled mTORC1 activity accelerates the cell cycle and triggers tumorigenesis. Recent studies have suggested that TSC1 and TSC2 also regulate the activities of Rac1 and Rho, members of the Rho family of small GTPases, and thereby influence the ensuing actin cytoskeletal organization at focal adhesions. However, how TSC1 contributes to the establishment of cell polarity is not well understood. Here, the relationship between TSC1 and the formation of the actin cytoskeleton was analyzed in stable TSC1-expressing cell lines originally established from a Tsc1-deficient mouse renal tumor cell line. Our analyses showed that cell proliferation and migration were suppressed when TSC1 was expressed. Rac1 activity in these cells was also decreased as was formation of lamellipodia and filopodia. Furthermore, the number of basal actin stress fibers was reduced; by contrast, apical actin fibers, originating at the level of the tight junction formed a network in TSC1-expressing cells. Treatment with Rho-kinase (ROCK) inhibitor diminished the number of apical actin fibers, but rapamycin had no effect. Thus, the actin fibers were regulated by the Rho-ROCK pathway independently of mTOR. In addition, apical actin fibers appeared in TSC1-deficient cells after inhibition of Rac1 activity. These results suggest that TSC1 regulates cell polarity-associated formation of actin fibers through the spatial regulation of Rho family of small GTPases.
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Affiliation(s)
- Maki Ohsawa
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Pathology and Oncology, Juntendo University School of Medicine, Tokyo, Japan
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Toshiyuki Kobayashi
- Department of Pathology and Oncology, Juntendo University School of Medicine, Tokyo, Japan
- * E-mail: (OH); (TK)
| | - Hidehiro Okura
- Department of Pathology and Oncology, Juntendo University School of Medicine, Tokyo, Japan
- Department of Neurosurgery, Juntendo University School of Medicine, Tokyo, Japan
| | - Takashi Igarashi
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masashi Mizuguchi
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Okio Hino
- Department of Pathology and Oncology, Juntendo University School of Medicine, Tokyo, Japan
- * E-mail: (OH); (TK)
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17
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Catanuto P, Fornoni A, Pereira-Simon S, Wu F, Burnstein KL, Xia X, Conti F, Lenzi A, Elliot S. In vivo 17β-estradiol treatment contributes to podocyte actin stabilization in female db/db mice. Endocrinology 2012; 153:5888-95. [PMID: 23070549 PMCID: PMC3512061 DOI: 10.1210/en.2012-1637] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We recently showed that 17β-estradiol (E(2)) treatment ameliorated type 2 diabetic glomerulosclerosis in mice in part by protecting podocyte structure and function. Progressive podocyte damage is characterized by foot process effacement, vacuolization, detachment of podocytes from the glomerular basement membrane, and apoptosis. In addition, podocytes are highly dependent on the preservation of their actin cytoskeleton to ensure proper function and survival. Because E(2) administration prevented podocyte damage in our study on diabetic db/db mice and has been shown to regulate both actin cytoskeleton and apoptosis in other cell types and tissues, we investigated whether actin remodeling and apoptosis were prevented in podocytes isolated from E(2)-treated diabetic db/db mice. We performed G-actin/F-actin assays, Western analysis for Hsp25 expression, Ras-related C(3) botulinum toxin substrate 1 (Rac1) activity, and apoptosis assays on previously characterized podocytes isolated from both in vivo-treated placebo and E(2) female db/db mice. We found that in vivo E(2) protects against a phenotype change in the cultured podocytes characterized by a percent increase of F-actin vs. G-actin, suppression of Hsp25 expression and transcriptional activation, increase of Rac1 activity, and decreased apoptotic intermediates. We conclude from these studies that E(2) treatment protects against podocyte damage and may prevent/reduce diabetes-induced kidney disease.
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Affiliation(s)
- Paola Catanuto
- Study Group and Laboratory on Sex and Gender Differences in Health and Disease, University of Miami, Miami, FL 33136, USA.
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18
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Li A, Ma Y, Jin M, Mason S, Mort RL, Blyth K, Larue L, Sansom OJ, Machesky LM. Activated mutant NRas(Q61K) drives aberrant melanocyte signaling, survival, and invasiveness via a Rac1-dependent mechanism. J Invest Dermatol 2012; 132:2610-21. [PMID: 22718121 PMCID: PMC3472562 DOI: 10.1038/jid.2012.186] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/20/2012] [Accepted: 04/20/2012] [Indexed: 12/30/2022]
Abstract
Around a fifth of melanomas exhibit an activating mutation in the oncogene NRas that confers constitutive signaling to proliferation and promotes tumor initiation. NRas signals downstream of the major melanocyte tyrosine kinase receptor c-kit and activated NRas results in increased signaling via the extracellular signal-regulated kinase (ERK)/MAPK/ERK kinase/mitogen-activated protein kinase (MAPK) pathways to enhance proliferation. The Ras oncogene also activates signaling via the related Rho GTPase Rac1, which can mediate growth, survival, and motility signaling. We tested the effects of activated NRas(Q61K) on the proliferation, motility, and invasiveness of melanoblasts and melanocytes in the developing mouse and ex vivo explant culture as well as in a melanoma transplant model. We find an important role for Rac1 downstream of NRas(Q61K) in mediating dermal melanocyte survival in vivo in mouse, but surprisingly NRas(Q61K) does not appear to affect melanoblast motility or proliferation during mouse embryogenesis. We also show that genetic deletion or pharmacological inhibition of Rac1 in NRas(Q61K) induced melanoma suppresses tumor growth, lymph node spread, and tumor cell invasiveness, suggesting a potential value for Rac1 as a therapeutic target for activated NRas-driven tumor growth and invasiveness.
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Affiliation(s)
- Ang Li
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Yafeng Ma
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Meng Jin
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Susan Mason
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Richard L Mort
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, UK
| | - Karen Blyth
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Lionel Larue
- Institut Curie, CNRS UMR3347 INSERM U1021, Institut Curie, Bat 110, Centre Universitaire, Orsay, France
| | - Owen J Sansom
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Laura M Machesky
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
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19
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Schachtner H, Li A, Stevenson D, Calaminus SDJ, Thomas S, Watson SP, Sixt M, Wedlich-Soldner R, Strathdee D, Machesky LM. Tissue inducible Lifeact expression allows visualization of actin dynamics in vivo and ex vivo. Eur J Cell Biol 2012; 91:923-929. [PMID: 22658956 PMCID: PMC3930012 DOI: 10.1016/j.ejcb.2012.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/01/2012] [Accepted: 04/12/2012] [Indexed: 11/21/2022] Open
Abstract
We describe here the development and characterization of a conditionally inducible mouse model expressing Lifeact-GFP, a peptide that reports the dynamics of filamentous actin. We have used this model to study platelets, megakaryocytes and melanoblasts and we provide evidence that Lifeact-GFP is a useful reporter in these cell types ex vivo. In the case of platelets and megakaryocytes, these cells are not transfectable by traditional methods, so conditional activation of Lifeact allows the study of actin dynamics in these cells live. We studied melanoblasts in native skin explants from embryos, allowing the visualization of live actin dynamics during cytokinesis and migration. Our study revealed that melanoblasts lacking the small GTPase Rac1 show a delay in the formation of new pseudopodia following cytokinesis that accounts for the previously reported cytokinesis delay in these cells. Thus, through use of this mouse model, we were able to gain insights into the actin dynamics of cells that could only previously be studied using fixed specimens or following isolation from their native tissue environment.
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Affiliation(s)
- Hannah Schachtner
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
| | - Ang Li
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
| | - David Stevenson
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
| | - Simon D. J. Calaminus
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
| | - Steve Thomas
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT
| | - Steve P. Watson
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT
| | - Michael Sixt
- Institute of Science and Technology, Am Campus 1, A-3400 Klosterneuberg, Austria
| | - Roland Wedlich-Soldner
- Cellular Dynamics and Cell Patterning, Max-Planck Institute of Biochemistry, Am, Klopferspitz 18, 82152 Martinsried, Germany
| | - Douglas Strathdee
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
| | - Laura M. Machesky
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD
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20
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Schwarz J, Proff J, Hävemeier A, Ladwein M, Rottner K, Barlag B, Pich A, Tatge H, Just I, Gerhard R. Serine-71 phosphorylation of Rac1 modulates downstream signaling. PLoS One 2012; 7:e44358. [PMID: 22970203 PMCID: PMC3438190 DOI: 10.1371/journal.pone.0044358] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 08/03/2012] [Indexed: 01/14/2023] Open
Abstract
The Rho GTPases Rac1 and Cdc42 regulate a variety of cellular functions by signaling to different signal pathways. It is believed that the presence of a specific effector at the location of GTPase activation determines the route of downstream signaling. We previously reported about EGF-induced Ser-71 phosphorylation of Rac1/Cdc42. By using the phosphomimetic S71E-mutants of Rac1 and Cdc42 we investigated the impact of Ser-71 phosphorylation on binding to selected effector proteins. Binding of the constitutively active (Q61L) variants of Rac1 and Cdc42 to their specific interaction partners Sra-1 and N-WASP, respectively, as well as to their common effector protein PAK was abrogated when Ser-71 was exchanged to glutamate as phosphomimetic substitution. Interaction with their common effector proteins IQGAP1/2/3 or MRCK alpha was, however, hardly affected. This ambivalent behaviour was obvious in functional assays. In contrast to Rac1 Q61L, phosphomimetic Rac1 Q61L/S71E was not able to induce increased membrane ruffling. Instead, Rac1 Q61L/S71E allowed filopodia formation, which is in accordance with abrogation of the dominant Sra-1/Wave signalling pathway. In addition, in contrast to Rac1 transfected cells Rac1 S71E failed to activate PAK1/2. On the other hand, Rac1 Q61L/S71E was as effective in activation of NF-kappaB as Rac1 Q61L, illustrating positive signal transduction of phosphorylated Rac1. Together, these data suggest that phosphorylation of Rac1 and Cdc42 at serine-71 represents a reversible mechanism to shift specificity of GTPase/effector coupling, and to preferentially address selected downstream pathways.
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Affiliation(s)
- Janett Schwarz
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Julia Proff
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Anika Hävemeier
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Markus Ladwein
- Cytoskeleton Dynamics Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Klemens Rottner
- Cytoskeleton Dynamics Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institut für Genetik, Rheinische Friederich-Wilhelms-Universität, Bonn, Germany
| | - Britta Barlag
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Andreas Pich
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Helma Tatge
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Ingo Just
- Department of Toxicology, Hannover Medical School, Hannover, Germany
| | - Ralf Gerhard
- Department of Toxicology, Hannover Medical School, Hannover, Germany
- * E-mail:
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21
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Hill MM, Daud NH, Aung CS, Loo D, Martin S, Murphy S, Black DM, Barry R, Simpson F, Liu L, Pilch PF, Hancock JF, Parat MO, Parton RG. Co-regulation of cell polarization and migration by caveolar proteins PTRF/Cavin-1 and caveolin-1. PLoS One 2012; 7:e43041. [PMID: 22912783 PMCID: PMC3418245 DOI: 10.1371/journal.pone.0043041] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/16/2012] [Indexed: 11/18/2022] Open
Abstract
Caveolin-1 and caveolae are differentially polarized in migrating cells in various models, and caveolin-1 expression has been shown to quantitatively modulate cell migration. PTRF/cavin-1 is a cytoplasmic protein now established to be also necessary for caveola formation. Here we tested the effect of PTRF expression on cell migration. Using fluorescence imaging, quantitative proteomics, and cell migration assays we show that PTRF/cavin-1 modulates cellular polarization, and the subcellular localization of Rac1 and caveolin-1 in migrating cells as well as PKCα caveola recruitment. PTRF/cavin-1 quantitatively reduced cell migration, and induced mesenchymal epithelial reversion. Similar to caveolin-1, the polarization of PTRF/cavin-1 was dependent on the migration mode. By selectively manipulating PTRF/cavin-1 and caveolin-1 expression (and therefore caveola formation) in multiple cell systems, we unveil caveola-independent functions for both proteins in cell migration.
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Affiliation(s)
- Michelle M. Hill
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Noor Huda Daud
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Cho Sanda Aung
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Dorothy Loo
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Sally Martin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Samantha Murphy
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Debra M. Black
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Rachael Barry
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Fiona Simpson
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Libin Liu
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Paul F. Pilch
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - John F. Hancock
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Marie-Odile Parat
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (RP); (M-OP)
| | - Robert G. Parton
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (RP); (M-OP)
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22
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Abstract
Rac1, a small GTPase, regulates macrophage MMP (matrix metalloproteinase)-9 in an ERK (extracellular-signal-regulated kinase)- and SP (specificity protein)-1-dependent manner. SP-1 contains a PEST (Pro-Glu-Ser-Thr) domain that may modulate protein stability. We hypothesize that Thr578, Ser586 and/or Ser587 in the PEST domain are required for SP-1 stability and MMP-9 expression secondary to activation of ERK, a serine/threonine kinase. We determined the effects of Rac1 and ERK on MMP-9 expression driven by SP-1WT (wild-type) and the SP-1 mutants T578A, S586A and S587A. Expression of WT and mutant SP-1 increased MMP9 promoter activity in alveolar macrophages. However, constitutively active Rac1 suppressed MMP9 promoter activity in cells expressing SP-1WT, SP-1T578A and SP-1S587A, but not SP-1S586A. Furthermore, constitutive ERK activation, which was inhibited by Rac1, significantly increased MMP9 transcription in cells expressing SP-1WT, but not SP-1S586A. As Rac1 activation and ERK inactivation increased degradation of SP-1WT and not SP-1S586A, the results of the present study suggest that SP-1 stability mediated at Ser586 regulates MMP9 transcription. Ex vivo, alveolar macrophages obtained from patients with asbestosis had less MMP-9 expression that was associated with decreased SP-1 expression and ERK activation. These observations demonstrate that Ser586 in the PEST domain of SP-1 is important for MMP9 gene expression in alveolar macrophages and highlight the importance of these proteins in pulmonary fibrosis.
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Affiliation(s)
- Shubha Murthy
- Department of Internal Medicine, Veterans Affairs Medical Center, Iowa City, IA 52242
| | - Alan J. Ryan
- Department of Internal Medicine, Veterans Affairs Medical Center, Iowa City, IA 52242
| | - A. Brent Carter
- Department of Internal Medicine, Veterans Affairs Medical Center, Iowa City, IA 52242
- Department of Free Radical and Radiation Biology, Carver College of Medicine, Veterans Affairs Medical Center, Iowa City, IA 52242
- Department of Human Toxicology, College of Public Health, University of Iowa, Veterans Affairs Medical Center, Iowa City, IA 52242
- Department of Iowa City Veterans Affairs Medical Center, Iowa City, IA 52242
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23
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Park D, Kim Y, Kim H, Kim K, Lee YS, Choe J, Hahn JH, Lee H, Jeon J, Choi C, Kim YM, Jeoung D. Hyaluronic acid promotes angiogenesis by inducing RHAMM-TGFβ receptor interaction via CD44-PKCδ. Mol Cells 2012; 33:563-74. [PMID: 22610405 PMCID: PMC3887750 DOI: 10.1007/s10059-012-2294-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 04/06/2012] [Accepted: 04/23/2012] [Indexed: 12/12/2022] Open
Abstract
Hyaluronic acid (HA) has been shown to promote angiogenesis. However, the mechanism behind this effect remains largely unknown. Therefore, in this study, the mechanism of HA-induced angiogenesis was examined. CD44 and PKCδ were shown to be necessary for induction of the receptor for HA-mediated cell motility (RHAMM), a HA-binding protein. RHAMM was necessary for HA-promoted cellular invasion and endothelial cell tube formation. Cytokine arrays showed that HA induced the expression of plasminogen activator-inhibitor-1 (PAI), a downstream target of TGFβ receptor signaling. The induction of PAI-1 was dependent on CD44 and PKCδ. HA also induced an interaction between RHAMM and TGFβ receptor I, and induction of PAI-1 was dependent on RHAMM and TGFβ receptor I. Histone deacetylase 3 (HDAC3), which is decreased by HA via rac1, reduced induction of plasminogen activator inhibitor-1 (PAI-1) by HA. ERK, which interacts with RHAMM, was necessary for induction of PAI-1 by HA. Snail, a downstream target of TGFβ signaling, was also necessary for induction of PAI-1. The down regulation of PAI-1 prevented HA from enhancing endothelial cell tube formation and from inducing expression of angiogenic factors, such as ICAM-1, VCAM-1 and MMP-2. HDAC3 also exerted reduced expression of MMP-2. In this study, we provide a novel mechanism of HA-promoted angiogenesis, which involved RHAMM-TGFβRI signaling necessary for induction of PAI-1.
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Affiliation(s)
- Deokbum Park
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
| | - Youngmi Kim
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
| | - Hyunah Kim
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
| | - kyungjong Kim
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
| | - Yun-Sil Lee
- College of Pharmacy, Ewha Womans University, Seoul 120-750,
Korea
| | - Jongseon Choe
- School of Medicine, Kangwon National University, Chunchon 200-701,
Korea
| | - Jang-Hee Hahn
- School of Medicine, Kangwon National University, Chunchon 200-701,
Korea
| | - Hansoo Lee
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
| | - Jongwook Jeon
- Cell Signaling and BioImaging Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701,
Korea
| | - Chulhee Choi
- Cell Signaling and BioImaging Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701,
Korea
| | - Young-Myeong Kim
- School of Medicine, Kangwon National University, Chunchon 200-701,
Korea
| | - Dooil Jeoung
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701,
Korea
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24
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Abstract
Glioblastoma multiforme (GBM) is the most common and aggressive primary brain cancer, with a median survival of less than 2 years after diagnosis with current available therapies. The tumor microenvironment serves a critical role in tumor invasion and progression, with microglia as a critical player. Our laboratory has previously demonstrated that propentofylline, an atypical methylxanthine with central nervous system glial modulating and anti-inflammatory actions, significantly decreases tumor growth in a GBM rodent model by preferentially targeting microglia. In the present study, we used the CNS-1 rat glioma model to elucidate the mechanisms of propentofylline. Here we demonstrate that propentofylline targets TROY, a novel signaling molecule up-regulated in infiltrating microglia, and not macrophages, in response to CNS-1 cells. We identify Pyk2, Rac1 and pJNK as the downstream signaling molecules of TROY through western blot analysis and siRNA transfection. We demonstrate that inhibition of TROY expression in microglia by siRNA transfection significantly inhibits microglial migration towards CNS-1 cells similar to 10 µM propentofylline treatment. These results identify TROY as a novel molecule expressed in microglia, involved in their migration and targeted by propentofylline. Furthermore, these results describe a signaling molecule that is differentially expressed between microglia and macrophages in the tumor microenvironment.
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Affiliation(s)
- Valerie L. Jacobs
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- Neuroscience Center at Dartmouth, Lebanon, New Hampshire, United States of America
| | - Yingna Liu
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Joyce A. De Leo
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- Neuroscience Center at Dartmouth, Lebanon, New Hampshire, United States of America
- Emmanuel College, Boston, Massachusetts, United States of America
- * E-mail:
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25
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Cui J, Xiao Y, Shi YH, Wang B, Le GW. Lipoic acid attenuates high-fat-diet-induced oxidative stress and B-cell-related immune depression. Nutrition 2012; 28:275-80. [PMID: 22305006 DOI: 10.1016/j.nut.2011.10.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2009] [Revised: 09/11/2011] [Accepted: 10/24/2011] [Indexed: 11/17/2022]
Abstract
OBJECTIVE This study investigated whether spleen oxidative stress induced by a high-fat diet (HFD) influences the expression of genes involved in B-cell activation, thus leading to B-cell-related immunosuppression. METHODS Male C57BL/6 mice were randomly assigned to one of three groups with eight mice in each group. The control group consumed an ordinary diet (4.9% fat, w/w). The other two groups were fed an HFD (21.2% fat) and an HFD plus 0.1% lipoic acid (LA). After 10 wk, plasma and spleen oxidative stress biomarkers including superoxide dismutase, catalase, glutathione peroxidase, total antioxidant capacity, reduced glutathione/oxidized glutathione ratio, and malondialdehyde were examined. The B-cell-related immune function was evaluated by examining the number of B cells, and the apoptotic percentages of splenic lymphocytes were determined by flow cytometry. Furthermore, the B-cell activation and reactive oxygen species scavenger-related genes differentially expressed between mice fed an HFD and those fed an HFD supplemented with LA were identified through complementary DNA microarray. RESULTS The HFD induced marked decreases in the number of B cells and significantly increased the apoptotic percentages of splenic lymphocytes, accompanied by oxidative stress and increased oxidative damage, in the plasma and spleen. In addition, complementary DNA array analysis results showed that the HFD induced the decreased expression of genes associated with antioxidant defense, such as superoxide dismutase-3 (1.5-fold), metallothionein-1 (3.03-fold), glutathione peroxidase-5 (17.15-fold), and peroxiredoxin-4 (1.5), and B-cell activation, such as immunoglobulin heavy chain 6 (2.46-fold), immunoglobulin κ-chain (1.74-fold), Fc receptor (1.41-fold), and RAS-related C3 botulinum substrate-1 (7.46). The LA supplement prevented the buildup of oxidative stress and upregulated related gene expressions. CONCLUSION These results indicate a role for LA as a possible effective supplement with an HFD to prevent the development of oxidative stress and to attenuate B-cell damnification by increasing the gene expression of the B-cell receptor signaling pathway.
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Affiliation(s)
- Jue Cui
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
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26
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Dhaliwal A, Maldonado M, Lin C, Segura T. Cellular cytoskeleton dynamics modulates non-viral gene delivery through RhoGTPases. PLoS One 2012; 7:e35046. [PMID: 22509380 PMCID: PMC3324413 DOI: 10.1371/journal.pone.0035046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 03/12/2012] [Indexed: 11/18/2022] Open
Abstract
Although it is well accepted that the constituents of the cellular microenvironment modulate a myriad of cellular processes, including cell morphology, cytoskeletal dynamics and uptake pathways, the underlying mechanism of how these pathways influence non-viral gene transfer have not been studied. Transgene expression is increased on fibronectin (Fn) coated surfaces as a consequence of increased proliferation, cell spreading and active engagement of clathrin endocytosis pathway. RhoGTPases mediate the crosstalk between the cell and Fn, and regulate cellular processes involving filamentous actin, in-response to cellular interaction with Fn. Here the role of RhoGTPases specifically Rho, Rac and Cdc42 in modulation of non-viral gene transfer in mouse mesenchymal stem (mMSCs) plated in a fibronectin microenvironment was studied. More than 90% decrease in transgene expression was observed after inactivation of RhoGTPases using difficile toxin B (TcdB) and C3 transferase. Expression of dominant negative RhoA (RhoAT19N), Rac1(Rac1T17N) and Cdc42 (Cdc42T17N) also significantly reduced polyplex uptake and transgene expression. Interactions of cells with Fn lead to activation of RhoGTPases. However, further activation of RhoA, Rac1 and Cdc42 by expression of constitutively active genes (RhoAQ63L, Rac1Q61L and Cdc42Q61L) did not further enhance transgene expression in mMSCs, when plated on Fn. In contrast, activation of RhoA, Rac1 and Cdc42 by expression of constitutively active genes for cells plated on collagen I, which by itself did not increase RhoGTPase activation, resulted in enhanced transgene expression. Our study shows that RhoGTPases regulate internalization and effective intracellular processing of polyplexes that results in efficient gene transfer.
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Affiliation(s)
- Anandika Dhaliwal
- Biomedical Engineering Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Maricela Maldonado
- Chemical and Biomolecular Engineering Department, University of California Los Angeles, Los Angeles, California, United States of America
| | - Clayton Lin
- Chemical and Biomolecular Engineering Department, University of California Los Angeles, Los Angeles, California, United States of America
| | - Tatiana Segura
- Biomedical Engineering Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
- Chemical and Biomolecular Engineering Department, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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27
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Park SJ, Kim YT, Jeon YJ. Antioxidant dieckol downregulates the Rac1/ROS signaling pathway and inhibits Wiskott-Aldrich syndrome protein (WASP)-family verprolin-homologous protein 2 (WAVE2)-mediated invasive migration of B16 mouse melanoma cells. Mol Cells 2012; 33:363-9. [PMID: 22441674 PMCID: PMC3887808 DOI: 10.1007/s10059-012-2285-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/07/2012] [Accepted: 02/17/2012] [Indexed: 12/31/2022] Open
Abstract
Reactive oxygen species (ROS) generation is linked to dynamic actin cytoskeleton reorganization, which is involved in tumor cell motility and metastasis. Thus, inhibition of ROS generation and actin polymerization in tumor cells may represent an effective anticancer strategy. However, the molecular basis of this signaling pathway is currently unknown. Here, we show that the Ecklonia cava-derived antioxidant dieckol downregulates the Rac1/ROS signaling pathway and inhibits Wiskott-Aldrich syndrome protein (WASP)-family verprolin-homologous protein 2 (WAVE2)-mediated invasive migration of B16 mouse melanoma cells. Steady-state intracellular ROS levels were higher in malignant B16F10 cells than in parental, nonmetastatic B16F0 cells. Elevation of ROS by H(2)O(2) treatment increased migration and invasion ability of B16F0 cells to level similar to that of B16F10 cells, suggesting that intracellular ROS signaling mediates the prometastatic properties of B16 mouse melanoma cells. ROS levels and the cell migration and invasion ability of B16 melanoma cells correlated with Rac1 activation and WAVE2 expression. Overexpression of dominant negative Rac1 and depletion of WAVE2 by siRNA suppressed H(2)O(2)-induced cell invasion of B16F0 and B16F10 cells. Similarly, dieckol attenuates the ROS-mediated Rac1 activation and WAVE2 expression, resulting in decreased migration and invasion of B16 melanoma cells. In addition, we found that dieckol decreases association between WAVE2 and NADPH oxidase subunit p47(phox). Therefore, this finding suggests that WAVE2 acts to couple intracellular Rac1/ROS signaling to the invasive migration of B16 melanoma cells, which is inhibited by dieckol.
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Affiliation(s)
- Sun Joo Park
- Department of Chemistry, Pukyong National University, Busan 608-737, Korea.
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28
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Vidaki M, Tivodar S, Doulgeraki K, Tybulewicz V, Kessaris N, Pachnis V, Karagogeos D. Rac1-dependent cell cycle exit of MGE precursors and GABAergic interneuron migration to the cortex. Cereb Cortex 2012; 22:680-92. [PMID: 21690261 PMCID: PMC3589917 DOI: 10.1093/cercor/bhr145] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Cortical γ-aminobutyric acid (GABA)ergic interneurons are characterized by extraordinary neurochemical and functional diversity. Although recent studies have uncovered some of the molecular components underlying interneuron development, including the cellular and molecular mechanisms guiding their migration to the cortex, the intracellular components involved are still unknown. Rac1, a member of the Rac subfamily of Rho-GTPases, has been implicated in various cellular processes such as cell cycle dynamics, axonogenesis, and migration. In this study, we have addressed the specific role of Rac1 in interneuron progenitors originating in the medial ganglionic eminence, via Cre/loxP technology. We show that ablation of Rac1 from Nkx2.1-positive progenitors, results in a migratory impairment. As a consequence, only half of GABAergic interneurons are found in the postnatal cortex. The rest remain aggregated in the ventral telencephalon and show morphological defects in their growing processes in vitro. Ablation of Rac1 from postmitotic progenitors does not result in similar defects, thus underlying a novel cell autonomous and stage-specific requirement for Rac1 activity, within proliferating progenitors of cortical interneurons. Rac1 is necessary for their transition from G1 to S phase, at least in part by regulating cyclin D levels and retinoblastoma protein phosphorylation.
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Affiliation(s)
- Marina Vidaki
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Simona Tivodar
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Katerina Doulgeraki
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
| | - Victor Tybulewicz
- Division of Immune Cell Biology, Medical Research Council, National Institute for Medical Research, NW7-1AA London, UK
| | - Nicoletta Kessaris
- Wolfson Institute for Biomedical Research
- Department of Cell & Developmental Biology, University College London, WC1E-6BT London, UK
| | - Vassilis Pachnis
- Division of Molecular Neurobiology, Medical Research Council, National Institute for Medical Research, NW7-1AA London, UK
| | - Domna Karagogeos
- Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece 71003
- Institute of Molecular Biology & Biotechnology, Foundation of Research & Technology Hellas (IMBB, FORTH), Heraklion, Greece 71110
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29
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Lane SW, De Vita S, Alexander KA, Karaman R, Milsom MD, Dorrance AM, Purdon A, Louis L, Bouxsein ML, Williams DA. Rac signaling in osteoblastic cells is required for normal bone development but is dispensable for hematopoietic development. Blood 2012; 119:736-44. [PMID: 22123845 PMCID: PMC3265198 DOI: 10.1182/blood-2011-07-368753] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 11/02/2011] [Indexed: 12/29/2022] Open
Abstract
Hematopoietic stem cells (HSCs) interact with osteoblastic, stromal, and vascular components of the BM hematopoietic microenvironment (HM) that are required for the maintenance of long-term self-renewal in vivo. Osteoblasts have been reported to be a critical cell type making up the HSC niche in vivo. Rac1 GTPase has been implicated in adhesion, spreading, and differentiation of osteoblast cell lines and is critical for HSC engraftment and retention. Recent data suggest a differential role of GTPases in endosteal/osteoblastic versus perivascular niche function. However, whether Rac signaling pathways are also necessary in the cell-extrinsic control of HSC function within the HM has not been examined. In the present study, genetic and inducible models of Rac deletion were used to demonstrate that Rac depletion causes impaired proliferation and induction of apoptosis in the OP9 cell line and in primary BM stromal cells. Deletion of Rac proteins caused reduced trabecular and cortical long bone growth in vivo. Surprisingly, HSC function and maintenance of hematopoiesis in vivo was preserved despite these substantial cell-extrinsic changes. These data have implications for therapeutic strategies to target Rac signaling in HSC mobilization and in the treatment of leukemia and provide clarification to our evolving concepts of HSC-HM interactions.
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Affiliation(s)
- Steven W Lane
- Division of Hematology/Oncology, Children's Hospital Boston, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
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Zhou H, Zhang F, Chen SH, Zhang D, Wilson B, Hong JS, Gao HM. Rotenone activates phagocyte NADPH oxidase by binding to its membrane subunit gp91phox. Free Radic Biol Med 2012; 52:303-13. [PMID: 22094225 PMCID: PMC3253173 DOI: 10.1016/j.freeradbiomed.2011.10.488] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 10/18/2011] [Accepted: 10/22/2011] [Indexed: 12/21/2022]
Abstract
Rotenone, a widely used pesticide, reproduces parkinsonism in rodents and associates with increased risk for Parkinson disease. We previously reported that rotenone increased superoxide production by stimulating the microglial phagocyte NADPH oxidase (PHOX). This study identified a novel mechanism by which rotenone activates PHOX. Ligand-binding assay revealed that rotenone directly bound to membrane gp91(phox), the catalytic subunit of PHOX; such binding was inhibited by diphenyleneiodonium, a PHOX inhibitor with a binding site on gp91(phox). Functional studies showed that both membrane and cytosolic subunits were required for rotenone-induced superoxide production in cell-free systems, intact phagocytes, and COS7 cells transfected with membrane subunits (gp91(phox)/p22(phox)) and cytosolic subunits (p67(phox) and p47(phox)). Rotenone-elicited extracellular superoxide release in p47(phox)-deficient macrophages suggested that rotenone enabled activation of PHOX through a p47(phox)-independent mechanism. Increased membrane translocation of p67(phox), elevated binding of p67(phox) to rotenone-treated membrane fractions, and coimmunoprecipitation of p67(phox) and gp91(phox) in rotenone-treated wild-type and p47(phox)-deficient macrophages indicated that p67(phox) played a critical role in rotenone-induced PHOX activation via its direct interaction with gp91(phox). Rac1, a Rho-like small GTPase, enhanced p67(phox)-gp91(phox) interaction; Rac1 inhibition decreased rotenone-elicited superoxide release. In conclusion, rotenone directly interacted with gp91(phox); such an interaction triggered membrane translocation of p67(phox), leading to PHOX activation and superoxide production.
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Affiliation(s)
- Hui Zhou
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Feng Zhang
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Shih-heng Chen
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Dan Zhang
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Belinda Wilson
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Jau-shyong Hong
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
| | - Hui-Ming Gao
- Neuropharmacology Section, Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, 27709
- Address correspondence to Hui-Ming Gao, MD F1-01, National Institute of Environmental Health Sciences, 111 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA. Telephone: (919) 541-5162. Fax: (919) 541-0841.
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31
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Sharma M, Urano F, Jaeschke A. Cdc42 and Rac1 are major contributors to the saturated fatty acid-stimulated JNK pathway in hepatocytes. J Hepatol 2012; 56:192-8. [PMID: 21703174 PMCID: PMC3183327 DOI: 10.1016/j.jhep.2011.03.019] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/14/2011] [Accepted: 03/16/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Saturated free fatty acid (SFA)-stimulated c-Jun NH(2)-terminal kinase (JNK) activation is associated with the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the mechanisms responsible for the effects of SFA are incompletely understood. The goal of this study was to determine the molecular mechanisms by which SFA induce JNK activation in hepatocytes. METHODS We used siRNA-mediated knockdown in Hepa1c1c7 and AML12 cell lines, as well as primary mouse hepatocytes for these studies. RESULTS The current model for JNK activation by SFA involves endoplasmic reticulum (ER) stress, which induces JNK activation through an inositol requiring enzyme 1 (IRE1α) Apoptosis Regulating Kinase 1 (ASK1)-dependent mechanism. Here, we find that SFA-induced JNK activation is not inhibited in the absence of IRE1α and ASK1. Instead we show that activation of the small GTP-binding proteins Cdc42 and Rac1 is required for SFA-stimulated MLK3-dependent activation of JNK in hepatocytes. In addition, we demonstrate that SFA-induced cell death in hepatocytes is independent of IRE1α, but dependent on Cdc42, Rac1, and MLK3. CONCLUSIONS Our results demonstrate that Cdc42 and Rac1, rather than ER stress, are important components of a SFA-stimulated signaling pathway that regulates MLK3-dependent activation of JNK in hepatocytes.
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Affiliation(s)
| | - Fumihiko Urano
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts USA
| | - Anja Jaeschke
- Correspondence to: Anja Jaeschke; Department of Pathology; Metabolic Diseases Institute; University of Cincinnati; 2120 E. Galbraith Rd, Cincinnati, Ohio 45237 USA; Tel.: (513) 558-3898; Fax: (513) 558-1312;
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32
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Affiliation(s)
- Samar H. Ibrahim
- Department of Pediatrics, Division of Pediatric Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, 200 First Street SW Rochester, MN 55905, USA
| | - Gregory J. Gores
- Department of Medicine, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, 200 First Street SW Rochester, MN 55905, USA
- Corresponding author. Address: Mayo Clinic College of Medicine, 200 First Street SW Rochester, MN 55905, USA. Tel.: +1 507 284 0686; fax: +1 507 284 0762. (G.J. Gores)
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Abstract
Rac1 influences a multiplicity of vital cellular- and tissue-level control functions, making it an important candidate for targeted therapeutics. The activity of the Rho family member Cdc42 has been shown to be modulated by tyrosine phosphorylation at position 64. We therefore investigated consequences of the point mutations Y64F and Y64D in Rac1. Both mutations altered cell spreading from baseline in the settings of wild type, constitutively active, or dominant negative Rac1 expression, and were accompanied by differences in Rac1 targeting to focal adhesions. Rac1-Y64F displayed increased GTP-binding, increased association with βPIX, and reduced binding with RhoGDI as compared with wild type Rac1. Rac1-Y64D had less binding to PAK than Rac1-WT or Rac1-64F. In vitro assays demonstrated that Y64 in Rac1 is a target for FAK and Src. Taken together, these data suggest a mechanism for the regulation of Rac1 activity by non-receptor tyrosine kinases, with consequences for membrane extension.
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Affiliation(s)
- Fumin Chang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Christopher Lemmon
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Daniel Lietha
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Michael Eck
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Lewis Romer
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Departments of Cell Biology, Biomedical Engineering, Pediatrics, and the Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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34
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Abstract
Directional cell migration is an essential requirement for efficient neutrophil translocation to sites of infection and requires the establishment of a polarized cell characterized by an actin-rich leading edge facing the chemoattractant gradient. The asymmetrical accumulation of phosphatidylinositol(3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)] in the up-gradient leading edge is a hallmark of polarization and regulates the recruitment and localization of various effector proteins at the leading-edge plasma membrane. How shallow gradients of chemoattractants trigger and maintain a much steeper intracellular gradient of PtdIns(3,4,5)P(3) is a critical question in the study of leukocyte chemotaxis. Our data demonstrate that the migration of neutrophils toward the chemoattractant N-formyl-L-methionyl-L-leucyl-L-phenylalanine depends on the generation of reactive oxygen species by the phagocytic NADPH oxidase (NOX2) and subsequent oxidation and inhibition of phosphatase and tensin homolog. Moreover, we show that events downstream of PtdIns(3,4,5)P(3), including phosphorylation of AKT, Rac activation, uncapping of actin filaments, and directional migration, can be attenuated by ROS scavengers or genetic ablation of NOX2. Using Rac mutants that are defective in their ability to activate NOX2, we show that Rac regulates a redox-mediated feedback loop that mediates directional migration of neutrophils.
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Affiliation(s)
- Jan W P Kuiper
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
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35
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Mizukawa B, Wei J, Shrestha M, Wunderlich M, Chou FS, Griesinger A, Harris CE, Kumar AR, Zheng Y, Williams DA, Mulloy JC. Inhibition of Rac GTPase signaling and downstream prosurvival Bcl-2 proteins as combination targeted therapy in MLL-AF9 leukemia. Blood 2011; 118:5235-45. [PMID: 21940819 PMCID: PMC3217406 DOI: 10.1182/blood-2011-04-351817] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 09/04/2011] [Indexed: 12/27/2022] Open
Abstract
The Rac family of small Rho GTPases coordinates diverse cellular functions in hematopoietic cells including adhesion, migration, cytoskeleton rearrangements, gene transcription, proliferation, and survival. The integrity of Rac signaling has also been found to critically regulate cellular functions in the initiation and maintenance of hematopoietic malignancies. Using an in vivo gene targeting approach, we demonstrate that Rac2, but not Rac1, is critical to the initiation of acute myeloid leukemia in a retroviral expression model of MLL-AF9 leukemogenesis. However, loss of either Rac1 or Rac2 is sufficient to impair survival and growth of the transformed MLL-AF9 leukemia. Rac2 is known to positively regulate expression of Bcl-2 family proteins toward a prosurvival balance. We demonstrate that disruption of downstream survival signaling through antiapoptotic Bcl-2 proteins is implicated in mediating the effects of Rac2 deficiency in MLL-AF9 leukemia. Indeed, overexpression of Bcl-xL is able to rescue the effects of Rac2 deficiency and MLL-AF9 cells are exquisitely sensitive to direct inhibition of Bcl-2 family proteins by the BH3-mimetic, ABT-737. Furthermore, concurrent exposure to NSC23766, a small-molecule inhibitor of Rac activation, increases the apoptotic effect of ABT-737, indicating the Rac/Bcl-2 survival pathway may be targeted synergistically.
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MESH Headings
- Aminoquinolines/pharmacology
- Animals
- Biphenyl Compounds/pharmacology
- Cell Line, Tumor
- Gene Expression
- Gene Knockdown Techniques
- Humans
- Leukemia, Biphenotypic, Acute/drug therapy
- Leukemia, Biphenotypic, Acute/genetics
- Leukemia, Biphenotypic, Acute/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Mice, Transgenic
- Neuropeptides/antagonists & inhibitors
- Neuropeptides/deficiency
- Neuropeptides/genetics
- Nitrophenols/pharmacology
- Piperazines/pharmacology
- Proto-Oncogene Proteins c-bcl-2/antagonists & inhibitors
- Pyrimidines/pharmacology
- Signal Transduction
- Sulfonamides/pharmacology
- Transplantation, Heterologous
- bcl-X Protein/genetics
- rac GTP-Binding Proteins/antagonists & inhibitors
- rac GTP-Binding Proteins/deficiency
- rac GTP-Binding Proteins/genetics
- rac1 GTP-Binding Protein
- RAC2 GTP-Binding Protein
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Affiliation(s)
- Benjamin Mizukawa
- Division of Oncology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, OH 45229, USA
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36
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Li A, Ma Y, Yu X, Mort RL, Lindsay CR, Stevenson D, Strathdee D, Insall RH, Chernoff J, Snapper SB, Jackson IJ, Larue L, Sansom OJ, Machesky LM. Rac1 drives melanoblast organization during mouse development by orchestrating pseudopod- driven motility and cell-cycle progression. Dev Cell 2011; 21:722-34. [PMID: 21924960 PMCID: PMC3464460 DOI: 10.1016/j.devcel.2011.07.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 06/03/2011] [Accepted: 07/17/2011] [Indexed: 01/16/2023]
Abstract
During embryogenesis, melanoblasts proliferate and migrate ventrally through the developing dermis and epidermis as single cells. Targeted deletion of Rac1 in melanoblasts during embryogenesis causes defects in migration, cell-cycle progression, and cytokinesis. Rac1 null cells migrate markedly less efficiently, but surprisingly, global steering, crossing the dermal/epidermal junction, and homing to hair follicles occur normally. Melanoblasts navigate in the epidermis using two classes of protrusion: short stubs and long pseudopods. Short stubs are distinct from blebs and are driven by actin assembly but are independent of Rac1, Arp2/3 complex, myosin, or microtubules. Rac1 positively regulates the frequency of initiation of long pseudopods, which promote migration speed and directional plasticity. Scar/WAVE and Arp2/3 complex drive actin assembly for long pseudopod extension, which also depends on microtubule dynamics. Myosin contractility balances the extension of long pseudopods by effecting retraction and allowing force generation for movement through the complex 3D epidermal environment.
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Affiliation(s)
- Ang Li
- The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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37
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Shang X, Cancelas JA, Li L, Guo F, Liu W, Johnson JF, Ficker A, Daria D, Geiger H, Ratner N, Zheng Y. R-Ras and Rac GTPase cross-talk regulates hematopoietic progenitor cell migration, homing, and mobilization. J Biol Chem 2011; 286:24068-78. [PMID: 21572048 PMCID: PMC3129188 DOI: 10.1074/jbc.m111.226951] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 05/12/2011] [Indexed: 11/06/2022] Open
Abstract
Adult hematopoietic progenitor cells (HPCs) are maintained by highly coordinated signals in the bone marrow. The molecular mechanisms linking intracellular signaling network of HPCs with their microenvironment remain poorly defined. The Rho family GTPase Rac1/Rac2 has previously been implicated in cell functions involved in HPC maintenance, including adhesion, migration, homing, and mobilization. In the present studies we have identified R-Ras, a member of the Ras family, as a key signal mediator required for Rac1/Rac2 activation. We found that whereas Rac1 activity is up-regulated upon stem cell factor, integrin, or CXCL12 stimulation, R-Ras activity is inversely up-regulated. Expression of a constitutively active R-Ras mutant resulted in down-regulation of Rac1-activity whereas deletion of R-Ras led to an increase in Rac1/Rac2 activity and signaling. R-Ras(-/-) HPCs displayed a constitutively assembled cortical actin structure and showed increased directional migration. Rac1/Rac2 inhibition reversed the migration phenotype of R-Ras(-/-) HPCs, similar to that by expressing an R-Ras active mutant. Furthermore, R-Ras(-/-) mice showed enhanced responsiveness to G-CSF for HPC mobilization and exhibited decreased bone marrow homing. Transplantation experiments indicate that the R-Ras deficiency-induced HPC mobilization is a HPC intrinsic property. These results indicate that R-Ras is a critical regulator of Rac signaling required for HPC migration, homing, and mobilization.
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Affiliation(s)
- Xun Shang
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Jose A. Cancelas
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Lina Li
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Fukun Guo
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Wei Liu
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - James F. Johnson
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Ashley Ficker
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Deidre Daria
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Hartmut Geiger
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Nancy Ratner
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
| | - Yi Zheng
- From the Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229
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38
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Balasubramanian S, Fan M, Messmer-Blust AF, Yang CH, Trendel JA, Jeyaratnam JA, Pfeffer LM, Vestal DJ. The interferon-gamma-induced GTPase, mGBP-2, inhibits tumor necrosis factor alpha (TNF-alpha) induction of matrix metalloproteinase-9 (MMP-9) by inhibiting NF-kappaB and Rac protein. J Biol Chem 2011; 286:20054-64. [PMID: 21502320 PMCID: PMC3103378 DOI: 10.1074/jbc.m111.249326] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 04/15/2011] [Indexed: 11/06/2022] Open
Abstract
Matrix metalloproteinase-9 (MMP-9) is important in numerous normal and pathological processes, including the angiogenic switch during tumor development and tumor metastasis. Whereas TNF-α and other cytokines up-regulate MMP-9 expression, interferons (IFNs) inhibit MMP-9 expression. We found that IFN-γ treatment or forced expression of the IFN-induced GTPase, mGBP-2, inhibit TNF-α-induced MMP-9 expression in NIH 3T3 fibroblasts, by inhibiting MMP-9 transcription. The NF-κB transcription factor is required for full induction of MMP-9 by TNF-α. Both IFN-γ and mGBP-2 inhibit the transcription of a NF-κB-dependent reporter construct, suggesting that mGBP-2 inhibits MMP-9 induction via inhibition of NF-κB-mediated transcription. Interestingly, mGBP-2 does not inhibit TNF-α-induced degradation of IκBα or p65/RelA translocation into the nucleus. However, mGBP-2 inhibits p65 binding to a κB oligonucleotide probe in gel shift assays and to the MMP-9 promoter in chromatin immunoprecipitation assays. In addition, TNF-α activation of NF-κB in NIH 3T3 cells is dependent on Rac activation, as evidenced by the inhibition of TNF-α induction of NF-κB-mediated transcription by a dominant inhibitory form of Rac1. A role for Rac in the inhibitory action of mGBP-2 on NF-κB is further shown by the findings that mGBP-2 inhibits TNF-α activation of endogenous Rac and constitutively activate Rac can restore NF-κB transcription in the presence of mGBP-2. This is a novel mechanism by which IFNs can inhibit the cytokine induction of MMP-9 expression.
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Affiliation(s)
- Sujata Balasubramanian
- From the Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606 and
| | - Meiyun Fan
- the Department of Pathology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | | | - Chuan H. Yang
- the Department of Pathology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Jill A. Trendel
- From the Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606 and
| | - Jonathan A. Jeyaratnam
- From the Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606 and
| | - Lawrence M. Pfeffer
- the Department of Pathology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Deborah J. Vestal
- From the Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606 and
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39
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Saci A, Cantley LC, Carpenter CL. Rac1 regulates the activity of mTORC1 and mTORC2 and controls cellular size. Mol Cell 2011; 42:50-61. [PMID: 21474067 DOI: 10.1016/j.molcel.2011.03.017] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 12/16/2010] [Accepted: 03/24/2011] [Indexed: 01/22/2023]
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that exists in two separate complexes, mTORC1 and mTORC2, that function to control cell size and growth in response to growth factors, nutrients, and cellular energy levels. Low molecular weight GTP-binding proteins of the Rheb and Rag families are key regulators of the mTORC1 complex, but regulation of mTORC2 is poorly understood. Here, we report that Rac1, a member of the Rho family of GTPases, is a critical regulator of both mTORC1 and mTORC2 in response to growth-factor stimulation. Deletion of Rac1 in primary cells using an inducible-Cre/Lox approach inhibits basal and growth-factor activation of both mTORC1 and mTORC2. Rac1 appears to bind directly to mTOR and to mediate mTORC1 and mTORC2 localization at specific membranes. Binding of Rac1 to mTOR does not depend on the GTP-bound state of Rac1, but on the integrity of its C-terminal domain. This function of Rac1 provides a means to regulate mTORC1 and mTORC2 simultaneously.
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Affiliation(s)
- Abdelhafid Saci
- Department of Medicine, Division of Signal Transduction, Harvard Medical School, Beth Israel Deaconess Medical Center, CLS-417, Boston, MA 02115, USA.
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40
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Abstract
Osteoporosis, which results from excessive bone resorption by osteoclasts, is the major cause of morbidity for elder people. Identification of clinically relevant regulators is needed to develop novel therapeutic strategies. Rho GTPases have essential functions in osteoclasts by regulating actin dynamics. This is of particular importance because actin cytoskeleton is essential to generate the sealing zone, an osteoclast-specific structure ultimately mediating bone resorption. Here we report that the atypical Rac1 exchange factor Dock5 is necessary for osteoclast function both in vitro and in vivo. We discovered that establishment of the sealing zone and consequently osteoclast resorbing activity in vitro require Dock5. Mechanistically, our results suggest that osteoclasts lacking Dock5 have impaired adhesion that can be explained by perturbed Rac1 and p130Cas activities. Consistent with these functional assays, we identified a novel small-molecule inhibitor of Dock5 capable of hindering osteoclast resorbing activity. To investigate the in vivo relevance of these findings, we studied Dock5(-/-) mice and found that they have increased trabecular bone mass with normal osteoclast numbers, confirming that Dock5 is essential for bone resorption but not for osteoclast differentiation. Taken together, our findings characterize Dock5 as a regulator of osteoclast function and as a potential novel target to develop antiosteoporotic treatments.
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Affiliation(s)
- Virginie Vives
- Montpellier Universities 1 and 2, CRBM, Montpellier, France
- CNRS, UMR5237, Montpellier, France
| | - Mélanie Laurin
- Institut de Recherches Cliniques de Montréal, Université de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Gaelle Cres
- Montpellier Universities 1 and 2, CRBM, Montpellier, France
- CNRS, UMR5237, Montpellier, France
| | - Pauline Larrousse
- Montpellier Universities 1 and 2, CRBM, Montpellier, France
- CNRS, UMR5237, Montpellier, France
| | | | | | - Jean-François Côté
- Institut de Recherches Cliniques de Montréal, Université de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Anne Blangy
- Montpellier Universities 1 and 2, CRBM, Montpellier, France
- CNRS, UMR5237, Montpellier, France
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41
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Magalhaes JKRS, Grynpas MD, Willett TL, Glogauer M. Deleting Rac1 improves vertebral bone quality and resistance to fracture in a murine ovariectomy model. Osteoporos Int 2011; 22:1481-92. [PMID: 20683708 DOI: 10.1007/s00198-010-1355-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 07/06/2010] [Indexed: 12/19/2022]
Abstract
SUMMARY The roles of Rac1 and Rac2 in regulating osteoclast-mediated bone quality in postmenopausal osteoporosis were evaluated using an ovariectomized murine model. Animals' bone composition and architecture were evaluated. Our results demonstrate that the deletion of Rac1 increases vertebral bone quality compared to wild-type bones in an ovariectomized model. INTRODUCTION To determine the roles of the Rho family small GTPases Rac1 and Rac2 in regulating osteoclast-mediated bone quality in a model of postmenopausal osteoporosis. METHODS Twelve-month-old female mice from three genotypes-wild type (WT), Rac1 null (LysM.Rac1 KO), and Rac2 null (Rac2KO)--were studied in control and ovariectomized groups (mice previously ovariectomized at 4 months of age). Animals were sacrificed at 12 months of age, and the femora and vertebrae were harvested for mechanical testing, bone densitometry, micro-computed tomography, and histomorphometric analyses to evaluate bone mineralization and architecture. The results were compared between groups using ANOVA and LSD post-hoc tests. RESULTS We observed that LysM.Rac1 KO mice showed higher vertebral bone mineral density compared to WT in both control and ovariectomized groups. Consistent with this finding, LysM.Rac1 KO vertebrae showed increased resistance to fracture and increased trabecular connectivity compared to WT in both groups. Micro-CT analysis revealed that Rac2KO ovariectomized vertebrae have more trabecular bone compared to WT and LysM.Rac1 KO, but this did not translate into increased fracture resistance. CONCLUSION Our results demonstrate that the deletion of Rac1 increases vertebral bone quality compared to WT bones in a postmenopausal osteoporosis model.
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Affiliation(s)
- J K R S Magalhaes
- CIHR Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Fitzgerald Building-150 College Street, Room 221, Toronto, ON, Canada M5S 3E2
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Hunziker L, Aznar Benitah S, Braun KM, Jensen K, McNulty K, Butler C, Potton E, Nye E, Boyd R, Laurent G, Glogauer M, Wright NA, Watt FM, Janes SM. Rac1 deletion causes thymic atrophy. PLoS One 2011; 6:e19292. [PMID: 21559396 PMCID: PMC3084817 DOI: 10.1371/journal.pone.0019292] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 04/01/2011] [Indexed: 12/23/2022] Open
Abstract
The thymic stroma supports T lymphocyte development and consists of an epithelium maintained by thymic epithelial progenitors. The molecular pathways that govern epithelial homeostasis are poorly understood. Here we demonstrate that deletion of Rac1 in Keratin 5/Keratin 14 expressing embryonic and adult thymic epithelial cells leads to loss of the thymic epithelial compartment. Rac1 deletion led to an increase in c-Myc expression and a generalized increase in apoptosis associated with a decrease in thymic epithelial proliferation. Our results suggest Rac1 maintains the epithelial population, and equilibrium between Rac1 and c-Myc may control proliferation, apoptosis and maturation of the thymic epithelial compartment. Understanding thymic epithelial maintenance is a step toward the dual goals of in vitro thymic epithelial cell culture and T cell differentiation, and the clinical repair of thymic damage from graft-versus-host-disease, chemotherapy or irradiation.
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Affiliation(s)
- Lukas Hunziker
- Centre for Respiratory Research, University College London, London, United Kingdom
- Internal Medicine, University Hospital Basel, Basel, Switzerland
| | - Salvador Aznar Benitah
- ICREA Researcher, Centre for Genomic Regulation (CRG) and UPF (Universitat Pompeu Fabra), Barcelona, Spain
| | - Kristin M. Braun
- Centre for Cutaneous Research, Barts and The London, Queen Mary's School of Medicine and Dentistry, London, United Kingdom
| | - Kim Jensen
- Wellcome Trust Centre for Stem Cell Research, Cambridge University, Cambridge, United Kingdom
| | - Katrina McNulty
- Centre for Respiratory Research, University College London, London, United Kingdom
| | - Colin Butler
- Centre for Respiratory Research, University College London, London, United Kingdom
| | - Elspeth Potton
- Centre for Respiratory Research, University College London, London, United Kingdom
| | - Emma Nye
- Department of Experimental Pathology, London Research Institute, Cancer Research UK, London, United Kingdom
| | - Richard Boyd
- Department of Pathology and Immunology, Monash University Medical School, Prahran, Melbourne, Australia
| | - Geoff Laurent
- Centre for Respiratory Research, University College London, London, United Kingdom
| | | | - Nick A. Wright
- Histopathology Unit, London Research Institute, Cancer Research (UK), London, United Kingdom
| | - Fiona M. Watt
- Wellcome Trust Centre for Stem Cell Research, Cambridge University, Cambridge, United Kingdom
- CR UK Cambridge Research Institute, Li Ka Shing Centre, Cambridge, United Kingdom
| | - Sam M. Janes
- Centre for Respiratory Research, University College London, London, United Kingdom
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Chatterjee S, Feinstein SI, Dodia C, Sorokina E, Lien YC, Nguyen S, Debolt K, Speicher D, Fisher AB. Peroxiredoxin 6 phosphorylation and subsequent phospholipase A2 activity are required for agonist-mediated activation of NADPH oxidase in mouse pulmonary microvascular endothelium and alveolar macrophages. J Biol Chem 2011; 286:11696-706. [PMID: 21262967 PMCID: PMC3064221 DOI: 10.1074/jbc.m110.206623] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/14/2011] [Indexed: 11/06/2022] Open
Abstract
Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A2 (PLA(2)) activities, participates in the activation of NADPH oxidase 2 (NOX2) in neutrophils, but the mechanism for this effect is not known. We now demonstrate that Prdx6 is required for agonist-induced NOX2 activation in pulmonary microvascular endothelial cells (PMVEC) and that the effect requires the PLA(2) activity of Prdx6. Generation of reactive oxygen species (ROS) in response to angiotensin II (Ang II) or phorbol 12-myristate 13-acetate was markedly reduced in perfused lungs and isolated PMVEC from Prdx6 null mice. Rac1 and p47(phox), cytosolic components of NOX2, translocated to the endothelial cell membrane after Ang II treatment in wild-type but not Prdx6 null PMVEC. MJ33, an inhibitor of Prdx6 PLA(2) activity, blocked agonist-induced PLA(2) activity and ROS generation in PMVEC by >80%, whereas inhibitors of other PLA(2)s were ineffective. Transfection of Prx6 null cells with wild-type and C47S mutant Prdx6, but not with mutants of the PLA(2) active site (S32A, H26A, and D140A), "rescued" Ang II-induced PLA(2) activity and ROS generation. Ang II treatment of wild-type cells resulted in phosphorylation of Prdx6 and its subsequent translocation from the cytosol to the cell membrane. Phosphorylation as well as PLA(2) activity and ROS generation were markedly reduced by the MAPK inhibitor, U0126. Thus, agonist-induced MAPK activation leads to Prdx6 phosphorylation and translocation to the cell membrane, where its PLA(2) activity facilitates assembly of the NOX2 complex and activation of the oxidase.
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Affiliation(s)
- Shampa Chatterjee
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Sheldon I. Feinstein
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Chandra Dodia
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Elena Sorokina
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Yu-Chin Lien
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Su Nguyen
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - Kris Debolt
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
| | - David Speicher
- the Center for Systems and Computational Biology, The Wistar Institute, Philadelphia, Pennsylvania 19104
| | - Aron B. Fisher
- From the Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6068 and
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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. J Immunol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
Rho GTPases including RhoA, Rac1, and Cdc42 are a class of intracellular signaling proteins critical for the regulation of cytoskeleton organization, adhesion, and migration. Molecular mechanisms of mammalian cell migration were first revealed in fibroblasts where RhoA, Rac1, and Cdc42 facilitate in the multistep process including establishment and maintenance of polarity, formation of actin-rich protrusions, remodeling of adhesive contacts, and generation of force. In hematopoietic stem/progenitor cells, Rho GTPases relay signals from chemokines and cytokines such as SDF-1α and SCF to the actin and microtubule cytoskeleton through effector kinases and/or adaptor molecules that affect adhesion or transcription. Comprehensive use of murine conditional gene knockout technology combined with biochemical approaches in recent studies allows for physiologically relevant investigations of the involvement of Rho GTPases in hematopoietic stem/progenitor cell migration, providing important mechanisms for the stem/progenitor maintenance.
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Affiliation(s)
- Wei Liu
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
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Faroudi M, Hons M, Zachacz A, Dumont C, Lyck R, Stein JV, Tybulewicz VLJ. Critical roles for Rac GTPases in T-cell migration to and within lymph nodes. Blood 2010; 116:5536-47. [PMID: 20870900 PMCID: PMC3368586 DOI: 10.1182/blood-2010-08-299438] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 09/06/2010] [Indexed: 12/28/2022] Open
Abstract
Naive T cells continuously recirculate between secondary lymphoid tissue via the blood and lymphatic systems, a process that maximizes the chances of an encounter between a T cell and its cognate antigen. This recirculation depends on signals from chemokine receptors, integrins, and the sphingosine-1-phosphate receptor. The authors of previous studies in other cell types have shown that Rac GTPases transduce signals leading to cell migration and adhesion; however, their roles in T cells are unknown. By using both 3-dimensional intravital and in vitro approaches, we show that Rac1- and Rac2-deficient T cells have multiple defects in this recirculation process. Rac-deficient T cells home very inefficiently to lymph nodes and the white pulp of the spleen, show reduced interstitial migration within lymph node parenchyma, and are defective in egress from lymph nodes. These mutant T cells show defective chemokine-induced chemotaxis, chemokinesis, and adhesion to integrin ligands. They have reduced lateral motility on endothelial cells and transmigrate in-efficiently. These multiple defects stem from critical roles for Rac1 and Rac2 in transducing chemokine and sphingosine-1-phosphate receptor 1 signals leading to motility and adhesion.
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Affiliation(s)
- Mustapha Faroudi
- Medical Research Council National Institute for Medical Research, London, UK
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Shan L, Li J, Wei M, Ma J, Wan L, Zhu W, Li Y, Zhu H, Arnold JMO, Peng T. Disruption of Rac1 signaling reduces ischemia-reperfusion injury in the diabetic heart by inhibiting calpain. Free Radic Biol Med 2010; 49:1804-14. [PMID: 20883775 DOI: 10.1016/j.freeradbiomed.2010.09.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 09/01/2010] [Accepted: 09/20/2010] [Indexed: 12/13/2022]
Abstract
Diabetes increases myocardial ischemia/reperfusion (I/R) injury. However, the underlying mechanisms remain incompletely understood. This study investigated the role of Rac1 signaling and calpain in exacerbated I/R injury in diabetic hearts. Mice with cardiac-specific deletion of Rac1 (Rac1-ko) and transgenic mice with cardiac-specific superoxide dismutase-2 (SOD2) or calpastatin overexpression were rendered diabetic with streptozotocin. Isolated perfused hearts were subjected to global I/R. After I/R, Rac1 activity was significantly enhanced in diabetic compared with nondiabetic hearts. Diabetic hearts displayed more severe I/R injury than nondiabetic hearts, as evidenced by more lactate dehydrogenase release and apoptosis and decreased cardiac function. These adverse impacts of diabetes were abrogated in Rac1-ko hearts or by perfusion with the Rac1 inhibitor NSC23766. In an in vivo I/R mouse model, infarct size was much smaller in diabetic Rac1-ko compared with wild-type mice. Inhibition of Rac1 signaling prevented NADPH oxidase activation, reactive oxygen species production, and protein carbonyl accumulation, leading to inhibition of calpain activation. Furthermore, SOD2 or calpastatin overexpression significantly reduced I/R injury in diabetic hearts and improved cardiac function after I/R. In summary, Rac1 activation increases I/R injury in diabetic hearts and the role of Rac1 signaling is mediated, at least in part, through calpain activation.
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Affiliation(s)
- Limei Shan
- Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, ON, Canada
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48
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Sosa-García B, Gunduz V, Vázquez-Rivera V, Cress WD, Wright G, Bian H, Hinds PW, Santiago-Cardona PG. A role for the retinoblastoma protein as a regulator of mouse osteoblast cell adhesion: implications for osteogenesis and osteosarcoma formation. PLoS One 2010; 5:e13954. [PMID: 21085651 PMCID: PMC2978706 DOI: 10.1371/journal.pone.0013954] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 10/11/2010] [Indexed: 11/18/2022] Open
Abstract
The retinoblastoma protein (pRb) is a cell cycle regulator inactivated in most human cancers. Loss of pRb function results from mutations in the gene coding for pRb or for any of its upstream regulators. Although pRb is predominantly known as a cell cycle repressor, our data point to additional pRb functions in cell adhesion. Our data show that pRb regulates the expression of a wide repertoire of cell adhesion genes and regulates the assembly of the adherens junctions required for cell adhesion. We conducted our studies in osteoblasts, which depend on both pRb and on cell-to-cell contacts for their differentiation and function. We generated knockout mice in which the RB gene was excised specifically in osteoblasts using the cre-lox P system and found that osteoblasts from pRb knockout mice did not assemble adherens junction at their membranes. pRb depletion in wild type osteoblasts using RNAi also disrupted adherens junctions. Microarrays comparing pRb-expressing and pRb-deficient osteoblasts showed that pRb controls the expression of a number of cell adhesion genes, including cadherins. Furthermore, pRb knockout mice showed bone abnormalities consistent with osteoblast adhesion defects. We also found that pRb controls the function of merlin, a well-known regulator of adherens junction assembly, by repressing Rac1 and its effector Pak1. Using qRT-PCR, immunoblots, co-immunoprecipitation assays, and immunofluorescent labeling, we observed that pRb loss resulted in Rac1 and Pak1 overexpression concomitant with merlin inactivation by Pak1, merlin detachment from the membrane, and adherens junction loss. Our data support a pRb function in cell adhesion while elucidating the mechanism for this function. Our work suggests that in some tumor types pRb inactivation results in both a loss of cell cycle control that promotes initial tumor growth as well as in a loss of cell-to-cell contacts, which contributes to later stages of metastasis.
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Affiliation(s)
| | - Volkan Gunduz
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
| | | | - W. Douglas Cress
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Gabriela Wright
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Haikuo Bian
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Philip W. Hinds
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
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Migeotte I, Omelchenko T, Hall A, Anderson KV. Rac1-dependent collective cell migration is required for specification of the anterior-posterior body axis of the mouse. PLoS Biol 2010; 8:e1000442. [PMID: 20689803 PMCID: PMC2914637 DOI: 10.1371/journal.pbio.1000442] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 06/23/2010] [Indexed: 11/21/2022] Open
Abstract
Live imaging and analysis of conditional mutants show that the embryonic organizer that determines the anterior-posterior axis in the mouse embryo moves by Rac1-dependent collective cell migration. Cell migration and cell rearrangements are critical for establishment of the body plan of vertebrate embryos. The first step in organization of the body plan of the mouse embryo, specification of the anterior-posterior body axis, depends on migration of the anterior visceral endoderm from the distal tip of the embryo to a more proximal region overlying the future head. The anterior visceral endoderm (AVE) is a cluster of extra-embryonic cells that secretes inhibitors of the Wnt and Nodal pathways to inhibit posterior development. Because Rac proteins are crucial regulators of cell migration and mouse Rac1 mutants die early in development, we tested whether Rac1 plays a role in AVE migration. Here we show that Rac1 mutant embryos fail to specify an anterior-posterior axis and, instead, express posterior markers in a ring around the embryonic circumference. Cells that express the molecular markers of the AVE are properly specified in Rac1 mutants but remain at the distal tip of the embryo at the time when migration should take place. Using tissue specific deletions, we show that Rac1 acts autonomously within the visceral endoderm to promote cell migration. High-resolution imaging shows that the leading wild-type AVE cells extend long lamellar protrusions that span several cell diameters and are polarized in the direction of cell movement. These projections are tipped by filopodia-like structures that appear to sample the environment. Wild-type AVE cells display hallmarks of collective cell migration: they retain tight and adherens junctions as they migrate and exchange neighbors within the plane of the visceral endoderm epithelium. Analysis of mutant embryos shows that Rac1 is not required for intercellular signaling, survival, proliferation, or adhesion in the visceral endoderm but is necessary for the ability of visceral endoderm cells to extend projections, change shape, and exchange neighbors. The data show that Rac1-mediated epithelial migration of the AVE is a crucial step in the establishment of the mammalian body plan and suggest that Rac1 is essential for collective migration in mammalian tissues. The specification of the anterior-posterior body axis of the mouse embryo depends on migration of the anterior visceral endoderm (AVE) to a position that overlies the future head. By high-resolution imaging of intact embryos we show that movement of the AVE is a form of collective cell migration, as the migrating cells retain tight and adherens junctions while they migrate and exchange neighbors within the plane of the visceral endoderm epithelium. Using conditional knockouts, we find that the small GTPase Rac1 is absolutely required for specification of the anterior-posterior axis and acts cell-autonomously within the AVE to allow cells to extend long, dynamic lamellar projections that are required for movement. Rac1-mediated epithelial migration of the AVE is a crucial step in the establishment of the mammalian body plan, and Rac1 may be important for collective migration in general in mammalian tissues, including invading tumor cells.
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Affiliation(s)
- Isabelle Migeotte
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | - Tatiana Omelchenko
- Cell Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | - Alan Hall
- Cell Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | - Kathryn V. Anderson
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- * E-mail:
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Li J, Zhu H, Shen E, Wan L, Arnold JMO, Peng T. Deficiency of rac1 blocks NADPH oxidase activation, inhibits endoplasmic reticulum stress, and reduces myocardial remodeling in a mouse model of type 1 diabetes. Diabetes 2010; 59:2033-42. [PMID: 20522592 PMCID: PMC2911061 DOI: 10.2337/db09-1800] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Our recent study demonstrated that Rac1 and NADPH oxidase activation contributes to cardiomyocyte apoptosis in short-term diabetes. This study was undertaken to investigate if disruption of Rac1 and inhibition of NADPH oxidase would prevent myocardial remodeling in chronic diabetes. RESEARCH DESIGN AND METHODS Diabetes was induced by injection of streptozotocin in mice with cardiomyocyte-specific Rac1 knockout and their wild-type littermates. In a separate experiment, wild-type diabetic mice were treated with vehicle or apocynin in drinking water. Myocardial hypertrophy, fibrosis, endoplasmic reticulum (ER) stress, inflammatory response, and myocardial function were investigated after 2 months of diabetes. Isolated adult rat cardiomyocytes were cultured and stimulated with high glucose. RESULTS In diabetic hearts, NADPH oxidase activation, its subunits' expression, and reactive oxygen species production were inhibited by Rac1 knockout or apocynin treatment. Myocardial collagen deposition and cardiomyocyte cross-sectional areas were significantly increased in diabetic mice, which were accompanied by elevated expression of pro-fibrotic genes and hypertrophic genes. Deficiency of Rac1 or apocynin administration reduced myocardial fibrosis and hypertrophy, resulting in improved myocardial function. These effects were associated with a normalization of ER stress markers' expression and inflammatory response in diabetic hearts. In cultured cardiomyocytes, high glucose-induced ER stress was inhibited by blocking Rac1 or NADPH oxidase. CONCLUSIONS Rac1 via NADPH oxidase activation induces myocardial remodeling and dysfunction in diabetic mice. The role of Rac1 signaling may be associated with ER stress and inflammation. Thus, targeting inhibition of Rac1 and NADPH oxidase may be a therapeutic approach for diabetic cardiomyopathy.
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Affiliation(s)
- Jianmin Li
- Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
- Department of Pathology, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Huaqing Zhu
- Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - E Shen
- Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Li Wan
- Department of Pathology, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - J. Malcolm O. Arnold
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Tianqing Peng
- Critical Illness Research, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
- Department of Pathology, University of Western Ontario, London, Ontario, Canada
- Corresponding author: Tianqing Peng,
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