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Gao X, Lin X, Lin M, Lan Y, Wang Y, Wu R, Li J, Huang C, Zhong D. Silencing Rac1 and Prex1 Inhibit Epithelial-Mesenchymal Transition in Human Gastric Cancer Cells Induced by Transforming Growth Factor-β1. Turk J Gastroenterol 2023; 34:975-981. [PMID: 37434402 PMCID: PMC10543419 DOI: 10.5152/tjg.2023.23108] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 05/26/2023] [Indexed: 07/13/2023]
Abstract
BACKGROUND/AIMS Transforming growth factor-beta can influence tumor cells, causing epithelial-mesenchymal transition and enhancing their invasion and metastasis ability. Rac1 protein could be used as an independent tumor diagnostic marker and survival predictor. Prex1 is closely related to cell metastasis. In this study, the impact of silencing Rac1 and Prex1 on transforming growth factor-beta 1-induced epithelial-mesenchymal transition and apoptosis of human gastric cancer cells MGC-803 and MKN45 was investigated. MATERIALS AND METHODS MGC-803 and MKN45 cells received recombinant transforming growth factor-beta 1 (rTGF-β1) treatments at various concentrations. Cell Counting Kit-8 kit was used to determine cell viability. Rac1 and Prex1 interference vectors were transfected into the rTGF-β1-treated MGC-803 and MKN45 cells. Cell apoptosis and migration were detected by flow cytometry and scratch test, respectively. Western blot was used to detect the epithelial-mesenchymal transition-related markers E-cadherin, N-cadherin, vimentin, and PDLIM2 expression levels. RESULTS The rTGF-β1 (10 ng/mL) could promote MGC-803 and MKN45 cell viability. Silencing Rac1 and Prex1 could increase E-cadherin and PDLIM2 expression, decrease N-cadherin and vimentin expression, inhibit cell viability and migration, and promote apoptosis in rTGF-β1-treated MGC-803 and MKN45 cells. CONCLUSIONS Silencing Rac1 and Prex1 could inhibit epithelial-mesenchymal transition, reduce cell viability and migration, and promote apoptosis in human gastric cancer cells.
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Affiliation(s)
- Xinyan Gao
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Xiaoyan Lin
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Mengxin Lin
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Yanqin Lan
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Yao Wang
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Riping Wu
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Junde Li
- Department of Medical Oncology, Zhangzhou Municipal Hospital, Zhangzhou, Fujian Province, China
| | - Chuanyong Huang
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Dongta Zhong
- Department of Medical Oncology, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
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Abstract
Neuropathic pain is a debilitating form of pain arising from injury or disease of the nervous system that affects millions of people worldwide. Despite its prevalence, the underlying mechanisms of neuropathic pain are still not fully understood. Dendritic spines are small protrusions on the surface of neurons that play an important role in synaptic transmission. Recent studies have shown that dendritic spines reorganize in the superficial and deeper laminae of the spinal cord dorsal horn with the development of neuropathic pain in multiple models of disease or injury. Given the importance of dendritic spines in synaptic transmission, it is possible that studying dendritic spines could lead to new therapeutic approaches for managing intractable pain. In this review article, we highlight the emergent role of dendritic spines in neuropathic pain, as well as discuss the potential for studying dendritic spines for the development of new therapeutics.
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Affiliation(s)
- Curtis A Benson
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Jared F King
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Marike L Reimer
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Sierra D Kauer
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Andrew M Tan
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
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Tran V, Goyette MA, Martínez-García M, Jiménez de Domingo A, Fernández-Mayoralas DM, Fernández-Perrone AL, Tirado P, Calleja-Pérez B, Álvarez S, Côté JF, Fernández-Jaén A. Biallelic ELMO3 mutations and loss of function for DOCK-mediated RAC1 activation result in intellectual disability. Small GTPases 2022; 13:48-55. [PMID: 33660564 PMCID: PMC9707537 DOI: 10.1080/21541248.2021.1888557] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The engulfment and cell motility 3 (ELMO3) protein belongs to the ELMO-family of proteins. ELMO proteins form a tight complex with the DOCK1-5 guanine nucleotide exchange factors that regulate RAC1 spatiotemporal activation and signalling. DOCK proteins and RAC1 are known to have fundamental roles in central nervous system development. Here, we searched for homozygous or compound heterozygous mutations in the ELMO3 gene in 390 whole exomes sequenced in trio in individuals with neurodevelopmental disorders compatible with a genetic origin. We found a compound heterozygous mutation in ELMO3 (c.1153A>T, p.Ser385Cys and c.1009 G > A, p.Val337Ile) in a 5 year old male child with autism spectrum disorder (ASD) and developmental delay. These mutations did not interfere with the formation of an ELMO3/DOCK1 complex, but markedly impaired the ability of the complex to promote RAC1-GTP-loading. Consequently, cells expressing DOCK1 and either of the ELMO3 mutants displayed impaired migration and invasion. Collectively, our results suggest that biallelic loss-of-function mutations in ELMO3 may cause a developmental delay and provide new insight into the role of ELMO3 in neurodevelopmental as well as the pathological consequences of ELMO3 mutations.
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Affiliation(s)
- Viviane Tran
- Laboratory of Cytoskeletal Organization and Cell Migration, Montreal Clinical Research Institute (IRCM), Montréal, QC, Canada,Department of Biochemistry and Molecular Medicine, Université De Montréal, Montréal, QC, Canada
| | - Marie-Anne Goyette
- Laboratory of Cytoskeletal Organization and Cell Migration, Montreal Clinical Research Institute (IRCM), Montréal, QC, Canada,Molecular Biology Programs, Université De Montréal, Montréal, QC, Canada
| | | | | | | | | | - Pilar Tirado
- Department of Pediatric Neurology. Hospital Universitario La Paz. Madrid. Spain
| | | | - Sara Álvarez
- Department of Genomics and Medicine, NIMGenetics, Madrid, Spain
| | - Jean-François Côté
- Laboratory of Cytoskeletal Organization and Cell Migration, Montreal Clinical Research Institute (IRCM), Montréal, QC, Canada,Department of Biochemistry and Molecular Medicine, Université De Montréal, Montréal, QC, Canada,Molecular Biology Programs, Université De Montréal, Montréal, QC, Canada,Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
| | - Alberto Fernández-Jaén
- Department of Pediatric Neurology. ónsalud. Madrid. Spain,Department of Pediatric Neurology, Medicine School. Universidad Europea De, Madrid, Spain,CONTACT Alberto Fernández-Jaén Cytoskeletal Organization and Cell Migration Laboratory Montreal Clinical Research Institute (IRCM)110 Avenue Des, Pins, Ouest, Canada
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Jiang ZB, Ma BQ, Feng Z, Liu SG, Gao P, Yan HT. miR-365 inhibits the progression of gallbladder carcinoma and predicts the prognosis of Gallbladder carcinoma patients. Cell Cycle 2021; 20:308-319. [PMID: 33459111 DOI: 10.1080/15384101.2021.1874694] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Gallbladder carcinoma (GBC) is one of the most common fatal biliary tract tumors in the world. Its 3-year survival rate is 30% and the recurrence rate remains very high. miR-365 was downregulated in numerous tumors and worked as tumor suppressor gene. However, the role of miR-365 in GBC was unclear. In this study, our results found that the expression of miR-365 in GBC tissues was reduced rather than that in non-cancerous tissues. miR-365 overexpression inhibited the proliferation, metastasis and expansion of GBC CSCs. Mechanically, bioinformatic and luciferase reporter analysis identified Ras-related C3 botulinum toxin substrate 1 (RAC1) as a direct target of miR-365. Overexpression of miR-365 in GBC cells reduced the RAC1 mRNA and protein expression. The special RAC1 inhibitor EHop-106 abolished the discrepancy of growth, metastasis and self-renewal ability between miR-365-overexpression GBC cells and their control cells, which further demonstrated that RAC1 was involved in miR-365-disrupted GBC cells growth, metastasis and self-renewal. More importantly, reduced expression of miR-365 was a predictor of poor prognosis of GBC patients. In conclusion, miR-365 inhibited GBC cell growth, metastasis and self-renewal capacity by directly targeting RAC1, and may therefore prove to be a novel prognosis biomarker for GBC patients.
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Affiliation(s)
- Ze-Bin Jiang
- Department of General Surgery, Gansu Provincial Hospital , Gansu, China
| | - Bing-Qiang Ma
- Department of General Surgery, Gansu Provincial Hospital , Gansu, China
| | - Zongfeng Feng
- Department of General Surgery, Cao County People's Hospital , Heze, Shandong Province, China
| | - Shao-Guang Liu
- Department of Emergency Surgery, Gansu Provincial Hospital , Gansu, China
| | - Peng Gao
- Department of General Surgery, Gansu Provincial Hospital , Gansu, China
| | - Hui-Ting Yan
- Department of Nursing Department, Gansu Provincial Hospital , Gansu, China
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Liu Y, Lu Y, Li A, Celiku O, Han S, Qian M, Yang C. mTORC2/ Rac1 Pathway Predisposes Cancer Aggressiveness in IDH1-Mutated Glioma. Cancers (Basel) 2020; 12:E787. [PMID: 32224866 DOI: 10.3390/cancers12040787] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/18/2020] [Accepted: 03/20/2020] [Indexed: 12/21/2022] Open
Abstract
Isocitrate dehydrogenase (IDH) mutations are common genetic abnormalities in lower grade gliomas. The neomorphic enzyme activity of IDH mutants leads to tumor formation through epigenetic alteration, dysfunction of dioxygenases, and metabolic reprogramming. However, it remains elusive as to how IDH mutants regulate the pathways associated with oncogenic transformation and aggressiveness. In the present study, by using unbiased transcriptomic profiling, we showed that IDH1 mutations result in substantial changes in the gene sets that govern cellular motility, chemotaxis, and invasion. Mechanistically, rapamycin-insensitive companion of mammalian target of rapamycin (Rictor)/Ras-related C3 botulinum toxin substrate 1 (Rac1) signaling plays an essential role in the motility and proliferation of IDH1-mutated cells by prompting cytoskeleton reorganization, lamellipodia formation, and enhanced endocytosis. Targeting the Rictor/Rac1 pathway suppresses IDH1-mutated cells by limiting endocytosis and cell proliferation. Overall, our findings indicate a novel metabolic reprogramming mechanism of IDH1-mutated cells by exploiting metabolites from the extracellular milieu. Targeting the Rictor/Rac1 pathway could be an alternative therapeutic strategy for IDH1-mutated malignancies.
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Feddersen CR, Schillo JL, Varzavand A, Vaughn HR, Wadsworth LS, Voigt AP, Zhu EY, Jennings BM, Mullen SA, Bobera J, Riordan JD, Stipp CS, Dupuy AJ. Src-Dependent DBL Family Members Drive Resistance to Vemurafenib in Human Melanoma. Cancer Res 2019; 79:5074-5087. [PMID: 31416844 PMCID: PMC6774858 DOI: 10.1158/0008-5472.can-19-0244] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [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: 01/24/2019] [Revised: 06/05/2019] [Accepted: 08/06/2019] [Indexed: 12/25/2022]
Abstract
The use of selective BRAF inhibitors (BRAFi) has produced remarkable outcomes for patients with advanced cutaneous melanoma harboring a BRAFV600E mutation. Unfortunately, the majority of patients eventually develop drug-resistant disease. We employed a genetic screening approach to identify gain-of-function mechanisms of BRAFi resistance in two independent melanoma cell lines. Our screens identified both known and unappreciated drivers of BRAFi resistance, including multiple members of the DBL family. Mechanistic studies identified a DBL/RAC1/PAK signaling axis capable of driving resistance to both current and next-generation BRAFis. However, we show that the SRC inhibitor, saracatinib, can block the DBL-driven resistance. Our work highlights the utility of our straightforward genetic screening method in identifying new drug combinations to combat acquired BRAFi resistance. SIGNIFICANCE: A simple, rapid, and flexible genetic screening approach identifies genes that drive resistance to MAPK inhibitors when overexpressed in human melanoma cells.
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Affiliation(s)
- Charlotte R Feddersen
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Jacob L Schillo
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Afshin Varzavand
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa
| | - Hayley R Vaughn
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Lexy S Wadsworth
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Andrew P Voigt
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Eliot Y Zhu
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Brooke M Jennings
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa
| | - Sarah A Mullen
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa
| | - Jeremy Bobera
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa
| | - Jesse D Riordan
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Christopher S Stipp
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa.
- Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa
| | - Adam J Dupuy
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa.
- Holden Comprehensive Cancer Center, University of Iowa, Iowa City, Iowa
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Shen T, Han B, Leng Y, Yan S, Shi J, Yue S, Cheng SY. Sonic Hedgehog stimulates migration of MCF-7 breast cancer cells through Rac1. J Biomed Res 2019. [PMCID: PMC6813532 DOI: 10.7555/jbr.32.20180100] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
As one of the most common tumors in women, breast cancer has drawn considerable interest from investigators and clinicians in recent years. Despite early diagnosis and best therapeutic regimens available, the prognosis of malignant or metastatic breast cancer patients is still not optimistic. Hedgehog signaling, a classical pathway indispensable to embryonic development, participates in the growth of a variety of tumors. In the present study, the effect of Sonic Hedgehog (Shh) on breast cancer cells was investigated. We identified that Shh signal stimulated the migration of MCF-7 breast cancer cells. Smo and Gli1 were involved in Shh-stimulated migration of MCF-7 cells. Activating Smo and Gli1 induced cell migration, which was blocked by their specific antagonists. The effect of Shh signaling on MCF-7 cells was independent of Wnt5a, Dvl2 and Rab35, but directly dependent on Rac1. In conclusion, our study suggested that Shh promotes breast cancer cell migration via Rac1 independently of the non-canonical Wnt signaling pathway, which may represent a rational molecular target for combination medication in breast cancer.
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Affiliation(s)
- Tian Shen
- Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics,Department of Pathology and Pathophysiology
| | - Bo'ang Han
- Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yan Leng
- Department of Pathology, Jiangsu Province Hospital, Nanjing, Jiangsu 210029, China
| | - Sen Yan
- Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics
| | - Junfeng Shi
- Department of Oncology, Nanjing First Hospital Affiliated to Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Shen Yue
- Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Steven Y Cheng
- Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics,Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu 211166, China,Steven Y Cheng and Shen Yue, Jiangsu Key Laboratory of Xenotransplanation, Department of Medical Genetics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, Jiangsu 211166, China. Tel: + 86-25-86869463, E-mails:
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8
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Abstract
Over eighty million people in the United States have cardiovascular disease that can affect the heart causing myocardial infarction; the carotid arteries causing stroke; and the lower extremities leading to amputation. The treatment for end-stage cardiovascular disease is surgical—either endovascular therapy with balloons and stents—or open reconstruction to reestablish blood flow. All interventions damage or destroy the protective inner lining of the blood vessel—the endothelium. An intact endothelium is essential to provide a protective; antithrombotic lining of a blood vessel. Currently; there are no agents used in the clinical setting that promote reendothelialization. This process requires migration of endothelial cells to the denuded vessel; proliferation of endothelial cells on the denuded vessel surface; and the reconstitution of the tight adherence junctions responsible for the formation of an impermeable surface. These processes are all regulated in part and are dependent on small GTPases. As important as the small GTPases are for reendothelialization, dysregulation of these molecules can result in various vascular pathologies including aneurysm formation, atherosclerosis, diabetes, angiogenesis, and hypertension. A better understanding of the role of small GTPases in endothelial cell migration is essential to the development for novel agents to treat vascular disease.
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Affiliation(s)
- Alison Flentje
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
| | - Richa Kalsi
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
| | - Thomas S Monahan
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
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Dai J, Ma J, Yu B, Zhu Z, Hu Y. [ARTICLE WITHDRAWN] Long Noncoding RNA TUNAR Represses Growth, Migration, and Invasion of Human Glioma Cells Through Regulating miR-200a and Rac1. Oncol Res 2018; 27:107-115. [PMID: 29540255 PMCID: PMC7848266 DOI: 10.3727/096504018x15205622257163] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
THIS ARTICLE WAS WITHDRAWN BY THE PUBLISHERS IN NOVEMBER 2020.
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Affiliation(s)
- Jinhua Dai
- *Department of Clinical Laboratory, Ningbo No. 2 Hospital, Ningbo, P.R. China
| | - Jianbo Ma
- *Department of Clinical Laboratory, Ningbo No. 2 Hospital, Ningbo, P.R. China
| | - Bixia Yu
- †Department of Clinical Laboratory, Zhenhai Longsai Hospital, Ningbo, P.R. China
| | - Zhankun Zhu
- *Department of Clinical Laboratory, Ningbo No. 2 Hospital, Ningbo, P.R. China
| | - Yanqin Hu
- †Department of Clinical Laboratory, Zhenhai Longsai Hospital, Ningbo, P.R. China
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Razaghi B, Steele SL, Prykhozhij SV, Stoyek MR, Hill JA, Cooper MD, McDonald L, Lin W, Daugaard M, Crapoulet N, Chacko S, Lewis SM, Scott IC, Sorensen PHB, Berman JN. hace1 Influences zebrafish cardiac development via ROS-dependent mechanisms. Dev Dyn 2017; 247:289-303. [PMID: 29024245 DOI: 10.1002/dvdy.24600] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 08/23/2017] [Accepted: 09/15/2017] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND In this study, we reveal a previously undescribed role of the HACE1 (HECT domain and Ankyrin repeat Containing E3 ubiquitin-protein ligase 1) tumor suppressor protein in normal vertebrate heart development using the zebrafish (Danio rerio) model. We examined the link between the cardiac phenotypes associated with hace1 loss of function to the expression of the Rho small family GTPase, rac1, which is a known target of HACE1 and promotes ROS production via its interaction with NADPH oxidase holoenzymes. RESULTS We demonstrate that loss of hace1 in zebrafish via morpholino knockdown results in cardiac deformities, specifically a looping defect, where the heart is either tubular or "inverted". Whole-mount in situ hybridization of cardiac markers shows distinct abnormalities in ventricular morphology and atrioventricular valve formation in the hearts of these morphants, as well as increased expression of rac1. Importantly, this phenotype appears to be directly related to Nox enzyme-dependent ROS production, as both genetic inhibition by nox1 and nox2 morpholinos or pharmacologic rescue using ROS scavenging agents restores normal cardiac structure. CONCLUSIONS Our study demonstrates that HACE1 is critical in the normal development and proper function of the vertebrate heart via a ROS-dependent mechanism. Developmental Dynamics 247:289-303, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Babak Razaghi
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Shelby L Steele
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sergey V Prykhozhij
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Matthew R Stoyek
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jessica A Hill
- Department of Marine Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Matthew D Cooper
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Lindsay McDonald
- Department of Emergency Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - William Lin
- Undergraduate Program, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Mads Daugaard
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada.,Vancouver Prostate Centre, Vancouver, British Columbia, Canada
| | | | - Simi Chacko
- Atlantic Cancer Research Institute, Moncton, New Brunswick, Canada
| | - Stephen M Lewis
- Atlantic Cancer Research Institute, Moncton, New Brunswick, Canada
| | - Ian C Scott
- Department of Molecular Genetics, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Poul H B Sorensen
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada.,Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jason N Berman
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.,IWK Health Centre, Halifax, Nova Scotia, Canada
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朱 俊, 涂 维, 曾 超, 毛 珩, 杜 庆, 蔡 红. [Mechanism of Platycarya strobilacea Sieb. et Zucc extract-induced methuosis in human nasopharyngeal carcinoma CNE1 and CNE2 cells]. Nan Fang Yi Ke Da Xue Xue Bao 2017; 37:827-832. [PMID: 28669961 PMCID: PMC6744143 DOI: 10.3969/j.issn.1673-4254.2017.06.20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Indexed: 06/07/2023]
Abstract
OBJECTIVE To study the effect of Platycarya strobilacea Sieb. et Zucc (PSZ) extract on methuosis of human nasopharyngeal carcinoma CNE1 and CNE2 cells and explore the underlying mechanism. METHODS CNE1 and CNE2 cells were treated with 1 mg/mL PSZ extract and the expressions of Rac1 mRNA and Rac1 protein were detected using RT-qPCR and Western blotting, respectively. Results CNE1 and CNE2 cells showed obvious morphological changes typical of methuosis following treatment with PSZ extract characterized by cell merging, accumulation of large cytoplasmic vacuoles, and membrane rupture without obvious changes in the nuclei. PSZ treatment resulted in up-regulated Rac1 mRNA and Rac1 protein expressions in the cells. Application of EHT 1864 obviously blocked the effect of PSZ extract in inducing methuosis in CNE1 and CNE2 cells. CONCLUSION PSZ extract can induce methuosis in CNE1 and CNE2 cells by inducing the overexpression of Rac1.
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Affiliation(s)
- 俊谕 朱
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
- 南方医科大学珠江医院,广东 广州 510282Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - 维 涂
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
- 南方医科大学中西结合医院,广东 广州 510315Traditional Chinese Medicine-Integrated Cancer Center of Southern Medical University, Guangzhou 510315, China
| | - 超 曾
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
- 南方医科大学中西结合医院,广东 广州 510315Traditional Chinese Medicine-Integrated Cancer Center of Southern Medical University, Guangzhou 510315, China
| | - 珩旭 毛
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
- 南方医科大学珠江医院,广东 广州 510282Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - 庆锋 杜
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
| | - 红兵 蔡
- 南方医科大学,广东 广州 510515Southern Medical University, Guangzhou 510515, China
- 南方医科大学中西结合医院,广东 广州 510315Traditional Chinese Medicine-Integrated Cancer Center of Southern Medical University, Guangzhou 510315, China
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Rolo A, Savery D, Escuin S, de Castro SC, Armer HEJ, Munro PMG, Molè MA, Greene NDE, Copp AJ. Regulation of cell protrusions by small GTPases during fusion of the neural folds. eLife 2016; 5:e13273. [PMID: 27114066 PMCID: PMC4846376 DOI: 10.7554/elife.13273] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/18/2016] [Indexed: 11/26/2022] Open
Abstract
Epithelial fusion is a crucial process in embryonic development, and its failure underlies several clinically important birth defects. For example, failure of neural fold fusion during neurulation leads to open neural tube defects including spina bifida. Using mouse embryos, we show that cell protrusions emanating from the apposed neural fold tips, at the interface between the neuroepithelium and the surface ectoderm, are required for completion of neural tube closure. By genetically ablating the cytoskeletal regulators Rac1 or Cdc42 in the dorsal neuroepithelium, or in the surface ectoderm, we show that these protrusions originate from surface ectodermal cells and that Rac1 is necessary for the formation of membrane ruffles which typify late closure stages, whereas Cdc42 is required for the predominance of filopodia in early neurulation. This study provides evidence for the essential role and molecular regulation of membrane protrusions prior to fusion of a key organ primordium in mammalian development. DOI:http://dx.doi.org/10.7554/eLife.13273.001 The neural tube is an embryonic structure that gives rise to the brain and spinal cord. It originates from a flat sheet of cells – the neural plate – that rolls up and fuses to form a tube during development. If this closure fails, it leads to birth defects such as spina bifida, a condition that causes severe disability because babies are born with an exposed and damaged spinal cord. As the edges of the neural plate meet, they need to fuse together to produce a closed tube. It was known that cells at these edges extend protrusions. However, it was unclear how these protrusions are regulated, whether they arise from neural or non-neural cells and whether or not they are required for the neural tube to close fully. By studying mutant mouse embryos, Rolo et al. found that cellular protrusions are indeed required for the neural tube to close completely. These protrusions proved to be regulated by proteins called Rac1 and Cdc42, which control the filaments inside the cell that are responsible for cell shape and movement. Rolo et al. also found that the cells that give rise to the protrusions are not part of the neural plate itself. Instead, these cells are neighboring cells from the layer that later forms the epidermis of the skin (the surface ectoderm). Future studies will need to investigate which signals instruct those precise cells to make protrusions and to discover what happens to the protrusions after contact is made with cells on the opposite side. It will also be important to determine whether spina bifida may arise in humans if the protrusions are defective or absent. DOI:http://dx.doi.org/10.7554/eLife.13273.002
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Affiliation(s)
- Ana Rolo
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Dawn Savery
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Sarah Escuin
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Sandra C de Castro
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Hannah E J Armer
- Imaging Unit, Institute of Ophthalmology, University College London, London, United Kingdom
| | - Peter M G Munro
- Imaging Unit, Institute of Ophthalmology, University College London, London, United Kingdom
| | - Matteo A Molè
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Nicholas D E Greene
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
| | - Andrew J Copp
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London, United Kingdom
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13
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Li J, Mi X, Chen L, Jiang G, Wang N, Zhang Y, Deng W, Wang Z, Chen G, Wang X. Dock3 Participate in Epileptogenesis Through rac1 Pathway in Animal Models. Mol Neurobiol 2016; 53:2715-25. [PMID: 26319681 DOI: 10.1007/s12035-015-9406-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 08/20/2015] [Indexed: 10/23/2022]
Abstract
Epilepsy is one of the most common and severe neurologic diseases. The mechanisms of epilepsy are still not fully understood. Dock3 (dedicator of cytokinesis 3) is one of the new kinds of guanine-nucleotide exchange factors (GEF) and plays an important role in neuronal synaptic plasticity and cytoskeleton rearrangement; the same mechanisms were also found in epilepsy. However, little is known regarding the expression of Dock3 in the epileptic brain and whether Dock3 interventions affect the epileptic process. In this study, we showed that the expression of Dock3 significantly increased in IE patients and a lithium-pilocarpine epilepsy model compared with the controls. Inhibition of Dock3 by Dock3 shRNA impaired the severity of status epilepticus in the acute stage and decreased the spontaneous recurrent seizures times in the chronic stage of lithium-pilocarpine model and decreased the expression of rac1-GTP. Consistent with decreased expression of Dock3, the latent period in a pentylenetetrazole kindling model also increased. Our results demonstrated that the increased expression of Dock3 in the brain is associated with epileptogenesis and specific inhibition of Dock3 may be a potential target in preventing the development of epilepsy in patients.
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Mitkovski M, Dahm L, Heinrich R, Monnheimer M, Gerhart S, Stegmüller J, Hanisch UK, Nave KA, Ehrenreich H. Erythropoietin dampens injury-induced microglial motility. J Cereb Blood Flow Metab 2015; 35:1233-6. [PMID: 25966953 PMCID: PMC4527993 DOI: 10.1038/jcbfm.2015.100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 04/19/2015] [Accepted: 04/21/2015] [Indexed: 11/22/2022]
Abstract
Traumatic brain injury causes progressive brain atrophy and cognitive decline. Surprisingly, an early treatment with erythropoietin (EPO) prevents these consequences of secondary neurodegeneration, but the mechanisms have remained obscure. Here we show by advanced imaging and innovative analytical tools that recombinant human EPO, a clinically established and neuroprotective growth factor, dampens microglial activity, as visualized also in vivo by a strongly attenuated injury-induced cellular motility.
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Affiliation(s)
- Miso Mitkovski
- Light Microscopy Facility, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Liane Dahm
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Ralf Heinrich
- Department of Cellular Neurobiology, Institute of Zoology, Georg-August-University, Göttingen, Germany
| | - Mathieu Monnheimer
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Simone Gerhart
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Judith Stegmüller
- 1] Cellular and Molecular Neurobiology Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany [2] Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | | | - Klaus-Armin Nave
- 1] Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany [2] Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Hannelore Ehrenreich
- 1] Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany [2] Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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Natsvlishvili N, Goguadze N, Zhuravliova E, Mikeladze D. Sigma-1 receptor directly interacts with Rac1-GTPase in the brain mitochondria. BMC Biochem 2015; 16:11. [PMID: 25924612 PMCID: PMC4430930 DOI: 10.1186/s12858-015-0040-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/22/2015] [Indexed: 11/25/2022]
Abstract
BACKGROUND Small Rho-GTPases are critical mediators of neuronal plasticity and are involved in the pathogenesis of several psychiatric and neurological disorders. Rac-GTPase forms a multiprotein complex with upstream and downstream regulators that are essential for the spatiotemporal transmission of Rac signaling. The sigma-1 receptor (Sig1R) is a ligand-regulated membrane protein chaperone, and multiprotein complex assembly is essential to sigma-receptor function. RESULTS Using immunoprecipitation techniques, we have shown that in mitochondrial membranes Sig1R could directly interact with Rac1. Besides Rac1, the Sig1R forms complexes with inositol 1,4,5-trisphosphate receptor and Bcl2, suggesting that mitochondrial associated membranes (MAM) are involved in this macromolecular complex formation. Assembly of this complex is ligand-specific and depends on the presence of sigma agonist/antagonist, as well as on the presence of GTP/GDP. Treatment of mitochondrial membranes with (+)-pentazocine leads to the (+)-pentazocine-sensitive phosphorylation of Bad and the pentazocine-sensitive NADPH-dependent production of ROS. CONCLUSION We suggest that Sig1R through Rac1 signaling induces mild oxidative stress that possibly is involved in the regulation of neuroplasticity, as well as in the prevention of apoptosis and autophagy.
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Affiliation(s)
- Nino Natsvlishvili
- Institute of Chemical Biology, Ilia State University, 3/5 Cholokashvili av, Tbilisi, 0162, Georgia.
- Department of Biochemistry, I.Beritashvili Center of Experimental Biomedicine, 14 Gotua st, Tbilisi, 0160, Georgia.
| | - Nino Goguadze
- Institute of Chemical Biology, Ilia State University, 3/5 Cholokashvili av, Tbilisi, 0162, Georgia.
| | - Elene Zhuravliova
- Institute of Chemical Biology, Ilia State University, 3/5 Cholokashvili av, Tbilisi, 0162, Georgia.
- Department of Biochemistry, I.Beritashvili Center of Experimental Biomedicine, 14 Gotua st, Tbilisi, 0160, Georgia.
| | - David Mikeladze
- Institute of Chemical Biology, Ilia State University, 3/5 Cholokashvili av, Tbilisi, 0162, Georgia.
- Department of Biochemistry, I.Beritashvili Center of Experimental Biomedicine, 14 Gotua st, Tbilisi, 0160, Georgia.
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Yoon S, Han E, Choi YC, Kee H, Jeong Y, Yoon J, Baek K. Inhibition of cell proliferation and migration by miR-509-3p that targets CDK2, Rac1, and PIK3C2A. Mol Cells 2014; 37:314-21. [PMID: 24802056 PMCID: PMC4012080 DOI: 10.14348/molcells.2014.2360] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/07/2014] [Accepted: 03/11/2014] [Indexed: 11/27/2022] Open
Abstract
CDK2 is a key regulator of cell cycle progression. In this study, we screened for miRNAs targeting CDK2 using a luciferase-3'-untranslated region reporter assay. Among 11 hit miRNAs, miR-509-3p reduced CDK2 protein levels and significantly inhibited cancer cell growth. Microarray, Western blotting, and luciferase reporter analyses revealed additional targets of miR-509-3p, including Rac1 and PIK3C2A. Overexpression of miR-509-3p induced G1 cell-cycle arrest and inhibited colony formation and migration. RNAi experiments indicated that the growth-inhibitory effects of miR-509-3p may occur through down-regulation of CDK2, Rac1, and PIK3C2A. Targeting of multiple growth regulatory genes by miR-509-3p may contribute to effective anti-cancer therapy.
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Affiliation(s)
- Sena Yoon
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Eunji Han
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Young-Chul Choi
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Honghwan Kee
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Yongsu Jeong
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Jaeseung Yoon
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
| | - Kwanghee Baek
- Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701,
Korea
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Chang JH, Lee KJ, Kim SK, Yoo DH, Kang TY. Validity of SW982 synovial cell line for studying the drugs against rheumatoid arthritis in fluvastatin-induced apoptosis signaling model. Indian J Med Res 2014; 139:117-24. [PMID: 24604047 PMCID: PMC3994728] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND & OBJECTIVES To study effects of drugs against rheumatoid arthritis (RA) synoviocytes or fibroblast like synoviocytes (FLS) are used. To overcome the drawbacks of using FLS, this study was conducted to show the validity of SW982 synovial cell line in RA study. METHODS 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Annexin V propidium iodide (PI) staining, mitochondrial membrane potential assay, Triton X-114 Phase partitioning, and immunolot for apoptosis signaling in SW982 human synovial cell line were performed. RESULTS Fluvastatin induced apoptosis in a dose- and time-dependent manner in TNFα -stimulated SW982 human synovial cells. A geranylgeranylpyrophosphate (GGPP) inhibitor, but not a farnesylpyrophosphate (FPP) inhibitor, induced apoptosis, and fluvastatin-induced apoptosis was associated with the translocation of isoprenylated RhoA and Rac1 proteins from the cell membrane to the cytosol. Fluvastatin-induced downstream apoptotic signals were associated with inhibition of the phosphoinositide 3-kinase (PI3K)/Akt pathway. Accordingly, 89 kDa apoptotic cleavage fragment of poly (ADP-ribose) polymerase (PARP) was detected. INTERPRETATION & CONCLUSIONS Collectively, our data indicate that fluvastatin induces apoptotic cell death in TNFα-stimulated SW982 human synovial cells through the inactivation of the geranylgerenylated membrane fraction of RhoA and Rac1 proteins and the subsequent inhibition of the PI3K/Akt signaling pathway. This finding shows the validity of SW982 cell line for RA study.
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Affiliation(s)
- Jae-Ho Chang
- Institute of Biomaterials, Yonsei University, Wonju, Korea
| | - Kyu-Jae Lee
- Department of Environmental Medical Biology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Soo-Ki Kim
- Institute of Biomaterials, Yonsei University, Wonju, Korea,Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea,Reprint requests: Dr Soo-Ki Kim, Department of Microbiology, Wonju College of Medicine Yonsei University 162 Ilsan-dong, Wonju, Gangwon province 220-701, Republic of Korea e-mail: and
Dr Tae-Young Kang, Department of Rheumatology, Yonsei University Wonju College of Medicine Wonju, Gangwon province 220-701, Republic of Korea e-mail:
| | - Dae-Hyun Yoo
- The Hospital for Rheumatic Diseases, Hanyang University Medical Center, Seoul, Korea
| | - Tae-Young Kang
- Department of Rheumatology, Yonsei University Wonju College of Medicine, Wonju, Korea,Reprint requests: Dr Soo-Ki Kim, Department of Microbiology, Wonju College of Medicine Yonsei University 162 Ilsan-dong, Wonju, Gangwon province 220-701, Republic of Korea e-mail: and
Dr Tae-Young Kang, Department of Rheumatology, Yonsei University Wonju College of Medicine Wonju, Gangwon province 220-701, Republic of Korea e-mail:
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Salgado APC, Soares-Martins JAP, Andrade LG, Albarnaz JD, Ferreira PCP, Kroon EG, Bonjardim CA. Study of vaccinia and cowpox viruses' replication in Rac1-N17 dominant-negative cells. Mem Inst Oswaldo Cruz 2013; 108. [PMID: 23903969 PMCID: PMC3970603 DOI: 10.1590/0074-0276108052013004] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Interfering with cellular signal transduction pathways is a common strategy used by many viruses to create a propitious intracellular environment for an efficient replication. Our group has been studying cellular signalling pathways activated by the orthopoxviruses Vaccinia (VACV) and Cowpox (CPXV) and their significance to viral replication. In the present study our aim was to investigate whether the GTPase Rac1 was an upstream signal that led to the activation of MEK/ERK1/2, JNK1/2 or Akt pathways upon VACV or CPXV' infections. Therefore, we generated stable murine fibroblasts exhibiting negative dominance to Rac1-N17 to evaluate viral growth and the phosphorylation status of ERK1/2, JNK1/2 and Akt. Our results demonstrated that VACV replication, but not CPXV, was affected in dominant-negative (DN) Rac1-N17 cell lines in which viral yield was reduced in about 10-fold. Viral late gene expression, but not early, was also reduced. Furthermore, our data showed that Akt phosphorylation was diminished upon VACV infection in DN Rac1-N17 cells, suggesting that Rac1 participates in the phosphoinositide-3 kinase pathway leading to the activation of Akt. In conclusion, our results indicate that while Rac1 indeed plays a role in VACV biology, perhaps another GTPase may be involved in CPXV replication.
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Affiliation(s)
- Ana Paula Carneiro Salgado
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Jamária Adriana Pinheiro Soares-Martins
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil , Department of Microbiology and Molecular Genetics, Medical College
of Wisconsin, Milwaukee, WI, USA
| | - Luciana Garcia Andrade
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Jonas Dutra Albarnaz
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Paulo César Peregrino Ferreira
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Erna Geessien Kroon
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil
| | - Cláudio Antônio Bonjardim
- Grupo de Transdução de Sinal/Orthopoxvirus e Flavivírus - LABVÍRUS , Laboratório de Vírus, Departamento de Microbiologia, Instituto de
Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG,
Brasil , Corresponding author:
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Li J, Guo B, Wang J, Cheng X, Xu Y, Sang J. Ovarian cancer G protein coupled receptor 1 suppresses cell migration of MCF7 breast cancer cells via a Gα12/13-Rho- Rac1 pathway. J Mol Signal 2013; 8:6. [PMID: 23663350 PMCID: PMC3665705 DOI: 10.1186/1750-2187-8-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 05/01/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ovarian cancer G protein coupled receptor 1 (OGR1) mediates inhibitory effects on cell migration in human prostate and ovarian cancer cells. However, the mechanisms and signaling pathways that mediate these inhibitory effects are essentially unknown. METHODS MCF7 cell line was chosen as a model system to study the mechanisms by which OGR1 regulates cell migration, since it expresses very low levels of endogenous OGR1. Cell migratory activities were assessed using both wound healing and transwell migration assays. The signaling pathways involved were studied using pharmacological inhibitors and genetic forms of the relevant genes, as well as small G protein pull-down activity assays. The expression levels of various signaling molecules were analyzed by Western blot and quantitative PCR analysis. RESULTS Over-expression of OGR1 in MCF7 cells substantially enhanced activation of Rho and inhibition of Rac1, resulting in inhibition of cell migration. In addition, expression of the Gα12/13 specific regulator of G protein signaling (RGS) domain of p115RhoGEF, but not treatment with pertussis toxin (PTX, a Gαi specific inhibitor), could abrogate OGR1-dependent Rho activation, Rac1 inactivation, and inhibition of migration in MCF7 cells. The bioactive lipids tested had no effect on OGR1 function in cell migration. CONCLUSION Our data suggest, for the first time, that OGR1 inhibits cell migration through a Gα12/13 -Rho-Rac1 signaling pathway in MCF7 cells. This pathway was not significantly affected by bioactive lipids and all the assays were conducted at constant pH, suggesting a constitutive activity of OGR1. This is the first clear delineation of an OGR1-mediated cell signaling pathway involved in migration.
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Affiliation(s)
- Jing Li
- Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Institute of Cell Biology, College of Life Science, Beijing Normal University, Beijing, 100875, PR of China
| | - Bin Guo
- Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Institute of Cell Biology, College of Life Science, Beijing Normal University, Beijing, 100875, PR of China
| | - Jing Wang
- Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Institute of Cell Biology, College of Life Science, Beijing Normal University, Beijing, 100875, PR of China
| | - Xiaoyan Cheng
- Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Institute of Cell Biology, College of Life Science, Beijing Normal University, Beijing, 100875, PR of China
| | - Yan Xu
- Department of Obstetrics and Gynecology, Indiana University, 975 W. Walnut St. IB355A, Indianapolis, IN 46202, USA
| | - Jianli Sang
- Key Laboratory for Cell Proliferation and Regulation Biology of Ministry of Education, Institute of Cell Biology, College of Life Science, Beijing Normal University, Beijing, 100875, PR of China
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Asahara S, Shibutani Y, Teruyama K, Inoue HY, Kawada Y, Etoh H, Matsuda T, Kimura-Koyanagi M, Hashimoto N, Sakahara M, Fujimoto W, Takahashi H, Ueda S, Hosooka T, Satoh T, Inoue H, Matsumoto M, Aiba A, Kasuga M, Kido Y. Ras-related C3 botulinum toxin substrate 1 ( RAC1) regulates glucose-stimulated insulin secretion via modulation of F-actin. Diabetologia 2013; 56:1088-97. [PMID: 23412604 PMCID: PMC3622740 DOI: 10.1007/s00125-013-2849-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 01/17/2013] [Indexed: 11/03/2022]
Abstract
AIMS/HYPOTHESIS The small G-protein ras-related C3 botulinum toxin substrate 1 (RAC1) plays various roles in mammalian cells, such as in the regulation of cytoskeletal organisation, cell adhesion, migration and morphological changes. The present study examines the effects of RAC1 ablation on pancreatic beta cell function. METHODS Isolated islets from pancreatic beta cell-specific Rac1-knockout (betaRac1(-/-)) mice and RAC1 knockdown INS-1 insulinoma cells treated with small interfering RNA were used to investigate insulin secretion and cytoskeletal organisation in pancreatic beta cells. RESULTS BetaRac1(-/-) mice showed decreased glucose-stimulated insulin secretion, while there were no apparent differences in islet morphology. Isolated islets from the mice had blunted insulin secretion in response to high glucose levels. In RAC1 knockdown INS-1 cells, insulin secretion was also decreased in response to high glucose levels, consistent with the phenotype of betaRac1(-/-) mice. Even under high glucose levels, RAC1 knockdown INS-1 cells remained intact with F-actin, which inhibits the recruitment of the insulin granules, resulting in an inhibition of insulin secretion. CONCLUSIONS/INTERPRETATION In RAC1-deficient pancreatic beta cells, F-actin acts as a barrier for insulin granules and reduces glucose-stimulated insulin secretion.
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Affiliation(s)
- S. Asahara
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Y. Shibutani
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - K. Teruyama
- Division of Medical Chemistry, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
| | - H. Y. Inoue
- Division of Medical Chemistry, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
| | - Y. Kawada
- Division of Medical Chemistry, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
| | - H. Etoh
- Division of Medical Chemistry, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
| | - T. Matsuda
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - M. Kimura-Koyanagi
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - N. Hashimoto
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - M. Sakahara
- Cancer Institute, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - W. Fujimoto
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - H. Takahashi
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - S. Ueda
- Kobe University Graduate School of Agricultural Science, Kobe, Japan
| | - T. Hosooka
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - T. Satoh
- Division of Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - H. Inoue
- Department of Physiology and Metabolism, Brain/Liver Interface Medicine Research Center, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - M. Matsumoto
- Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - A. Aiba
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan
| | - M. Kasuga
- Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Y. Kido
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan
- Division of Medical Chemistry, Kobe University Graduate School of Health Sciences, Kobe, 654-0142 Japan
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Abstract
Our major theme is that the layered structure of the endothelial barrier requires continuous activation of signalling pathways regulated by sphingosine-1-phosphate (S1P) and intracellular cAMP. These pathways modulate the adherens junction, continuity of tight junction strands, and the balance of synthesis and degradation of glycocalyx components. We evaluate recent evidence that baseline permeability is maintained by constant activity of mechanisms involving the small GTPases Rap1 and Rac1. In the basal state, the barrier is compromised when activities of the small GTPases are reduced by low S1P supply or delivery. With inflammatory stimulus, increased permeability can be understood in part as the action of signalling to reduce Rap1 and Rac1 activation. With the hypothesis that microvessel permeability and selectivity under both normal and inflammatory conditions are regulated by mechanisms that are continuously active, it follows that when S1P or intracellular cAMP are elevated at the time of inflammatory stimulus, they can buffer changes induced by inflammatory agents and maintain normal barrier stability. When endothelium is exposed to inflammatory conditions and subsequently exposed to elevated S1P or intracellular cAMP, the same processes restore the functional barrier by first re-establishing the adherens junction, then modulating tight junctions and glycocalyx. In more extreme inflammatory conditions, loss of the inhibitory actions of Rac1-dependent mechanisms may promote expression of more inflammatory endothelial phenotypes by contributing to the up-regulation of RhoA-dependent contractile mechanisms and the sustained loss of surface glycocalyx allowing access of inflammatory cells to the endothelium.
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Affiliation(s)
- F-R E Curry
- Department of Physiology & Membrane Biology, School of Medicine, University of California at Davis, Davis, CA 95616, USA.
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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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Huh JY, Son DJ, Lee Y, Lee J, Kim B, Lee HM, Jo H, Choi S, Ha H, Chung MH. 8-Hydroxy-2-deoxyguanosine prevents plaque formation and inhibits vascular smooth muscle cell activation through Rac1 inactivation. Free Radic Biol Med 2012; 53:109-21. [PMID: 22580124 PMCID: PMC5489255 DOI: 10.1016/j.freeradbiomed.2012.03.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [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: 10/31/2011] [Revised: 02/16/2012] [Accepted: 03/12/2012] [Indexed: 12/23/2022]
Abstract
8-Hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative stress, has been recently rediscovered to inhibit Rac1 in neutrophils and macrophages, thereby inhibiting Rac1-linked functions of these cells, including reactive oxygen species production through NADPH oxidase activation, phagocytosis, chemotaxis, and cytokine release. In vascular smooth muscle cells (VSMCs), reactive oxygen species also induce abnormal proliferation and migration leading to progression of atherosclerosis. Based upon the involvement of reactive oxygen species in phagocytic cells and VSMCs during the atherosclerotic process, we hypothesized that 8-OHdG could have antiatherosclerotic action and tested this hypothesis in an experimentally induced atherosclerosis in mice. Partially ligated ApoE knockout mice, a more physiologically relevant model of low and oscillatory flow, developed an advanced lesion in 2 weeks, and orally administered 8-OHdG significantly reduced plaque formation along with reduced superoxide formation, monocyte/macrophage infiltration, and extracellular matrix (ECM) accumulation. The effects of 8-OHdG observed in primary VSMCs were consistent with the in vivo effects of 8-OHdG and were inhibitory to angiotensin II or platelet-derived growth factor-induced production of reactive oxygen species, proliferation, migration, and ECM production. Also, angiotensin II-induced Rac1 activity in VSMCs was significantly inhibited by 8-OHdG, and transfection of constitutively active Rac1 reversed the inhibitory effect of 8-OHdG on VSMC activation. Molecular docking study showed that 8-OHdG stabilizes Rac1-GEF complex, indicating the physical contact of 8-OHdG with Rac1. These findings highly suggest that the antiatherosclerotic effect of 8-OHdG is mediated by inhibition of Rac1 activity. In conclusion, our results show a novel action of orally active 8-OHdG in suppressing atherosclerotic plaque formation in vivo and VSMC activation in vitro through inhibition of Rac1, which emphasizes a new therapeutic avenue to benefit atherosclerosis.
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MESH Headings
- 8-Hydroxy-2'-Deoxyguanosine
- Angiotensin II/pharmacology
- Animals
- Apolipoproteins E/physiology
- Blotting, Western
- Cell Movement/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Chemotaxis/drug effects
- Deoxyguanosine/analogs & derivatives
- Deoxyguanosine/pharmacology
- Immunoenzyme Techniques
- Male
- Mice
- Mice, Knockout
- Models, Molecular
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Oxidative Stress/drug effects
- Plaque, Atherosclerotic/metabolism
- Plaque, Atherosclerotic/prevention & control
- Reactive Oxygen Species/metabolism
- Superoxides/metabolism
- Vasoconstrictor Agents/pharmacology
- rac1 GTP-Binding Protein/antagonists & inhibitors
- rac1 GTP-Binding Protein/metabolism
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Affiliation(s)
- Joo Young Huh
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
| | - Dong Ju Son
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Yoonji Lee
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
| | - Junghyun Lee
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
| | - Boyeon Kim
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
| | - Hwan Myung Lee
- Department of Cosmetic Science, College of Natural Sciences, Hoseo University, Asan, Korea
| | - Hanjoong Jo
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Sun Choi
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
- Corresponding author. (S. Choi), (H. Ha)
| | - Hunjoo Ha
- Division of Life & Pharmaceutical Sciences and Center for Cell Signaling & Drug Discovery Research, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
- Corresponding author. Fax: +82 2 3277 2851
| | - Myung-Hee Chung
- Samsung Advanced Institute for Health Sciences & Technology, Sung Kyun Kwan University, Seoul, Korea
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24
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Osborn-Heaford HL, Ryan AJ, Murthy S, Racila AM, He C, Sieren JC, Spitz DR, Carter AB. Mitochondrial Rac1 GTPase import and electron transfer from cytochrome c are required for pulmonary fibrosis. J Biol Chem 2012; 287:3301-12. [PMID: 22157762 PMCID: PMC3270985 DOI: 10.1074/jbc.m111.308387] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [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: 09/27/2011] [Revised: 11/21/2011] [Indexed: 12/22/2022] Open
Abstract
The generation of reactive oxygen species, particularly H(2)O(2), from alveolar macrophages is causally related to the development of pulmonary fibrosis. Rac1, a small GTPase, is known to increase mitochondrial H(2)O(2) generation in macrophages; however, the mechanism by which this occurs is not known. This study shows that Rac1 is localized in the mitochondria of alveolar macrophages from asbestosis patients, and mitochondrial import requires the C-terminal cysteine of Rac1 (Cys-189), which is post-translationally modified by geranylgeranylation. Furthermore, H(2)O(2) generation mediated by mitochondrial Rac1 requires electron transfer from cytochrome c to a cysteine residue on Rac1 (Cys-178). Asbestos-exposed mice harboring a conditional deletion of Rac1 in macrophages demonstrated decreased oxidative stress and were significantly protected from developing pulmonary fibrosis. These observations demonstrate that mitochondrial import and direct electron transfer from cytochrome c to Rac1 modulates mitochondrial H(2)O(2) production in alveolar macrophages pulmonary fibrosis.
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Affiliation(s)
| | | | | | | | - Chao He
- Radiation Oncology, Free Radical and Radiation Biology Program, and
| | - Jessica C. Sieren
- Department of Radiology, University of Iowa Carver College of Medicine, and
| | - Douglas R. Spitz
- Radiation Oncology, Free Radical and Radiation Biology Program, and
| | - A. Brent Carter
- From the Departments of Internal Medicine and
- Radiation Oncology, Free Radical and Radiation Biology Program, and
- Human Toxicology Program, University of Iowa College of Public Health, Iowa City, Iowa 52242
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25
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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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26
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Miller T, Yang F, Wise CE, Meng F, Priester S, Munshi MK, Guerrier, Dostal DE, Glaser SS. Simvastatin stimulates apoptosis in cholangiocarcinoma by inhibition of Rac1 activity. Dig Liver Dis 2011; 43:395-403. [PMID: 21334995 PMCID: PMC3071437 DOI: 10.1016/j.dld.2011.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/03/2011] [Accepted: 01/10/2011] [Indexed: 12/11/2022]
Abstract
BACKGROUND Simvastatin is a cholesterol-lowering drug that is widely used to prevent and treat atherosclerotic cardiovascular disease. Simvastatin exhibits numerous pleiotropic effects including anti-cancer activity. However, the effect of simvastatin on cholangiocarcinoma has not been evaluated. AIM The aim of our study was to determine the effect of simvastatin on cholangiocarcinoma proliferation. METHODS The effect of simvastatin was evaluated in five human cholangiocarcinoma cell lines (Mz-ChA-1, HuH-28, TFK-1, SG231, and HuCCT1) and normal cholangiocyte cell line (HiBEpiC). RESULTS We found that simvastatin stimulates a reduction in cell viability and apoptosis of cholangiocarcinoma cell lines, whilst in normal human cholangiocytes, HiBEpiC, simvastatin inhibits proliferation with no effect on apoptosis. Simvastatin-induced reduction of cell viability was partially blocked by pre-treatment with metabolites of the mevalonate pathway. In Mz-ChA-1 cells, pre-treatment with cholesterol alone stimulated an increase in the number of viable cells and fully restored cell viability following simvastatin treatment. Treatment with simvastatin triggered the loss of lipid raft localised Rac1 and reduction of Rac1 activity in Mz-ChA-1 cells. This effect was prevented by pre-treatment with cholesterol. CONCLUSION Collectively, our results demonstrate that simvastatin induces cholangiocarcinoma cancer cell death by disrupting Rac1/lipid raft colocalisation and depression of Rac1 activity.
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Affiliation(s)
- Timothy Miller
- Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Fuquan Yang
- Shengjing Hospital, China Medical University, Shenyang City, Liaoning Province, China, 100004
| | - Candace E. Wise
- Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Fanyin Meng
- Scott & White Digestive Disease Research Center, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504,Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Sally Priester
- Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Md Kamruzzaman Munshi
- Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Guerrier
- Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - David E. Dostal
- Molecular Cardiology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
| | - Shannon S. Glaser
- Scott & White Digestive Disease Research Center, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504,Department of Medicine, Division of Gastroenterology, Scott & White and Texas A&M Health Science Center, College of Medicine, 702 Southwest HK Dodgen Loop, Temple, Texas USA 76504
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27
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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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28
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Yi C, Troutman S, Fera D, Stemmer-Rachamimov A, Avila JL, Christian N, Persson NL, Shimono A, Speicher DW, Marmorstein R, Holmgren L, Kissil JL. A tight junction-associated Merlin-angiomotin complex mediates Merlin's regulation of mitogenic signaling and tumor suppressive functions. Cancer Cell 2011; 19:527-40. [PMID: 21481793 PMCID: PMC3075552 DOI: 10.1016/j.ccr.2011.02.017] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 10/20/2010] [Accepted: 02/22/2011] [Indexed: 01/12/2023]
Abstract
The Merlin/NF2 tumor suppressor restrains cell growth and tumorigenesis by controlling contact-dependent inhibition of proliferation. We have identified a tight-junction-associated protein complex comprising Merlin, Angiomotin, Patj, and Pals1. We demonstrate that Angiomotin functions downstream of Merlin and upstream of Rich1, a small GTPase Activating Protein, as a positive regulator of Rac1. Merlin, through competitive binding to Angiomotin, releases Rich1 from the Angiomotin-inhibitory complex, allowing Rich1 to inactivate Rac1, ultimately leading to attenuation of Rac1 and Ras-MAPK pathways. Patient-derived Merlin mutants show diminished binding capacities to Angiomotin and are unable to dissociate Rich1 from Angiomotin or inhibit MAPK signaling. Depletion of Angiomotin in Nf2(-/-) Schwann cells attenuates the Ras-MAPK signaling pathway, impedes cellular proliferation in vitro and tumorigenesis in vivo.
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Affiliation(s)
- Chunling Yi
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Scott Troutman
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Daniela Fera
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | - Jacqueline L. Avila
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Neepa Christian
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Nathalie Luna Persson
- Department of Oncology-Pathology, Cancer Center Karolinska Institutet, SE-17176 Stockholm, Sweden
| | - Akihiko Shimono
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117456
| | - David W. Speicher
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Ronen Marmorstein
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lars Holmgren
- Department of Oncology-Pathology, Cancer Center Karolinska Institutet, SE-17176 Stockholm, Sweden
| | - Joseph L. Kissil
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
- Corresponding author. ; Phone: 1-215-898-3874
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29
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Jayaram B, Syed I, Singh A, Subasinghe W, Kyathanahalli CN, Kowluru A. Isoprenylcysteine carboxyl methyltransferase facilitates glucose-induced Rac1 activation, ROS generation and insulin secretion in INS 832/13 β-cells. Islets 2011; 3:48-57. [PMID: 21346419 PMCID: PMC3092562 DOI: 10.4161/isl.3.2.15016] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Isoprenylcysteine carboxyl methyltransferase (ICMT) catalyzes the post-translational methylation of C-terminal cysteines of isoprenylated proteins, including small G-proteins and the γ-subunits of heterotrimeric G-proteins. It is widely felt that carboxymethylation promotes efficient membrane association of the methylated proteins and specific protein-protein interactions. In the current study, we tested the hypothesis that ICMT-mediated carboxymethylation of specific proteins (e.g., Rac1) plays a regulatory role in glucose-stimulated insulin secretion (GSIS). Western blot analysis indicated that lCMT is expressed and predominantly membrane associated in INS 832/13 β-cells. siRNA-mediated knockdown of endogenous expression of ICMT markedly attenuated glucose, but not KCl-induced insulin secretion. These findings were further supported by pharmacological observations, which suggested a marked reduction in glucose-, but not KCl-stimulated insulin secretion by acetyl farnesyl cysteine (AFC), a selective inhibitor of ICMT. In addition, glucose-induced Rac1 activation, a hallmark signaling step involved in glucose-stimulated insulin secretion, was markedly inhibited following pharmacological (AFC) or molecular biological (siRNA-ICMT) inhibition of ICMT. Lastly, we also noticed a marked reduction in glucose-induced acute increase in the generation of reactive oxygen species in INS 832/13 cells pre-treated with AFC or transfected with siRNA-ICMT. Together, these data suggest that ICMT regulates glucose-induced Rac1 activation, generation of reactive oxygen species and insulin secretion in pancreatic β-cells.
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Affiliation(s)
- Bhavaani Jayaram
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Science, Wayne State University, Detroit, MI, USA
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30
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Dai Y, Dudek NL, Li Q, Muma NA. Phospholipase C, Ca2+, and calmodulin signaling are required for 5-HT2A receptor-mediated transamidation of Rac1 by transglutaminase. Psychopharmacology (Berl) 2011; 213:403-12. [PMID: 20717650 DOI: 10.1007/s00213-010-1984-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 07/28/2010] [Indexed: 01/12/2023]
Abstract
RATIONALE Serotonin and especially serotonin 2A (5-HT(2A)) receptor signaling are important in the etiology and treatment of schizophrenia and affective disorders. We previously reported a novel 5-HT(2A) receptor effector, increased transglutaminase (TGase)-catalyzed transamidation, and activation of the small G protein Rac1 in A1A1v cells, a rat embryonic cortical cell line. OBJECTIVES In this study, we explore the signaling pathway involved in 5-HT(2A) receptor-mediated Rac1 transamidation. METHODS A1A1v cells were pretreated with pharmacological inhibitors of phospholipase C (PLC) or calmodulin (CaM), and then stimulated by the 5-HT(2A) receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI). Intracellular Ca(2+) concentration and TGase-modified Rac1 transamidation were monitored. The effect of manipulation of intracellular Ca(2+) by a Ca(2+) ionophore or a chelating agent on Rac1 transamidation was also evaluated. RESULTS In cells pretreated with a PLC inhibitor U73122, DOI-stimulated increases in the intracellular Ca(2+) concentration and TGase-modified Rac1 were significantly attenuated as compared to those pretreated with U73343, an inactive analog. The membrane-permeant Ca(2+) chelator, BAPTA-AM strongly reduced TGase-catalyzed Rac1 transamidation upon DOI stimulation. Conversely, the Ca(2+) ionophore ionomycin, at a concentration that induced an elevation of cytosolic Ca(2+) to a level comparable to cells treated with DOI, produced an increase in TGase-modified Rac1 without 5-HT(2A) receptor activation. Moreover, the CaM inhibitor W-7, significantly decreased Rac1 transamidation in a dose-dependent manner in DOI-treated cells. CONCLUSIONS These results indicate that 5-HT(2A) receptor-coupled PLC activation and subsequent Ca(2+) and CaM signaling are necessary for TGase-catalyzed Rac1 transamidation, and an increase in intracellular Ca(2+) is sufficient to induce Rac1 transamidation.
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31
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Theveneau E, Mayor R. Integrating chemotaxis and contact-inhibition during collective cell migration: Small GTPases at work. Small GTPases 2010; 1:113-117. [PMID: 21686264 PMCID: PMC3116595 DOI: 10.4161/sgtp.1.2.13673] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 09/15/2010] [Accepted: 09/20/2010] [Indexed: 01/22/2023] Open
Abstract
For directional cell migration to occur cells must interpret guiding cues present in their environment. Chemotaxis based on negative or positive signals has been long thought as the main driving force of guided cell migration. However during collective cell migration cells do receive information from external signals but also upon interactions with their direct neighbours. These multiple inputs must be translated into intracellular reorganisation in order to promote efficient directional migration. Small GTPases, being involved in establishing cell polarity and regulating protrusive activity, are likely to play a central role in signal integration. Indeed, recent findings from our laboratory indicate that Contact-Inhibition of Locomotion controlled by N-Cadherin and chemotaxis dependent on Sdf1/Cxcr4 signaling converge towards regulation of the localized activity of RhoA and Rac1. All together they establish cell polarity and select well-oriented cell protrusions to ensure directional cell migration.
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Affiliation(s)
- Eric Theveneau
- Department of Cell and Developmental Biology; University College London; London UK
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Mohamadnejad M, Sohail MA, Watanabe A, Krause DS, Swenson ES, Mehal WZ. Adenosine inhibits chemotaxis and induces hepatocyte-specific genes in bone marrow mesenchymal stem cells. Hepatology 2010; 51:963-73. [PMID: 20044808 PMCID: PMC2840188 DOI: 10.1002/hep.23389] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Bone marrow-derived mesenchymal stem cells (MSCs) have therapeutic potential in liver injury, but the signals responsible for MSC localization to sites of injury and initiation of differentiation are not known. Adenosine concentration is increased at sites of cellular injury and inflammation, and adenosine is known to signal a variety of cellular changes. We hypothesized that local elevations in the concentration of adenosine at sites of tissue injury regulate MSC homing and differentiation. Here we demonstrate that adenosine does not induce MSC chemotaxis but dramatically inhibits MSC chemotaxis in response to the chemoattractant hepatocyte growth factor (HGF). Inhibition of HGF-induced chemotaxis by adenosine requires the A2a receptor and is mediated via up-regulation of the cyclic adenosine monophosphate (AMP)/protein kinase A pathway. This results in inhibition of cytosolic calcium signaling and down-regulation of HGF-induced Rac1. Because of the important role of Rac1 in the formation of actin stress fibers, we examined the effect of adenosine on stress fiber formation and found that adenosine inhibits HGF-induced stress fiber formation. In addition, we found that adenosine induces the expression of some key endodermal and hepatocyte-specific genes in mouse and human MSCs in vitro. CONCLUSION We propose that the inhibition of MSC chemotaxis at sites of high adenosine concentration results in localization of MSCs to areas of cellular injury and death in the liver. We speculate that adenosine might initiate the process of differentiation of MSCs into hepatocyte-like cells.
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Affiliation(s)
- Mehdi Mohamadnejad
- Yale University, School of Medicine, Department of Internal Medicine, Section of Digestive Diseases, New Haven, CT, USA, Digestive Disease Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Muhammad A Sohail
- Yale University, School of Medicine, Department of Internal Medicine, Section of Digestive Diseases, New Haven, CT, USA
| | - Azuma Watanabe
- Yale University, School of Medicine, Department of Internal Medicine, Section of Digestive Diseases, New Haven, CT, USA
| | - Diane S Krause
- Yale University, School of Medicine, Department of Laboratory Medicine, New Haven, CT, USA
| | - E Scott Swenson
- Yale University, School of Medicine, Department of Internal Medicine, Section of Digestive Diseases, New Haven, CT, USA
| | - Wajahat Z Mehal
- Yale University, School of Medicine, Department of Internal Medicine, Section of Digestive Diseases, New Haven, CT, USA
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Yoshida S, Hoppe AD, Araki N, Swanson JA. Sequential signaling in plasma-membrane domains during macropinosome formation in macrophages. J Cell Sci 2009; 122:3250-61. [PMID: 19690049 PMCID: PMC2736863 DOI: 10.1242/jcs.053207] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [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] [Accepted: 06/21/2009] [Indexed: 12/17/2022] Open
Abstract
Macropinosomes are large endocytic vesicles that form in ruffling regions of plasma membrane. To analyze signal organization relative to ruffle closure into circular ruffles and cup closure into macropinosomes, this study used quantitative microscopy to measure 3' phosphoinositides and small-GTPase activities in a representative subset of forming macropinosomes. Macropinocytosis was stimulated by the addition of macrophage colony-stimulating factor (M-CSF) to macrophages expressing fluorescent reporter proteins. Ratiometric and fluorescence resonance energy transfer (FRET) microscopy determined that Rac1 activity and phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)] levels increased transiently, peaking 26-30 seconds after ruffle closure. Three-dimensional reconstruction of cells labeled with the fluorescent dye FM4-64 showed that PtdIns(3,4,5)P(3) was restricted to open, circular cups in the plasma membrane. Quantitative fluorescence microscopic methods determined the timing of cup closure, which followed 40-100 seconds after Rac1 and PtdIns(3,4,5)P(3) deactivation and coincided with accumulation of phosphatidylinositol 3-phosphate and Rab5a. Thus, ruffle closure creates a circular domain of plasma membrane that localizes the activation and deactivation of Rac1 and phosphoinositide 3-kinase (PI3K), followed by recruitment of Rab5a and the contractile activities of cup closure.
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Affiliation(s)
- Sei Yoshida
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Abstract
Osteosarcoma is the most frequent type of primary bone cancer in children and adolescents. These malignant osteoid forming tumors are characterized by their uncontrolled hyperproliferation. Here, we investigate the role of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in the growth of human osteosarcoma. We show that alpha-CaMKII is expressed in human osteosarcoma cell lines and in primary osteosarcoma tissue derived from patients. The pharmacologic inhibition of CaMKII in MG-63 and 143B human osteosarcoma cells by KN-93 resulted in an 80 and 70% decrease in proliferation, respectively, and induced cell cycle arrest in the G(0)/G(1) phase. The in vivo administration of KN-93 to mice xenografted with human osteosarcoma cells significantly decreased intratibial and subcutaneous tumor growth. Mechanistically, KN-93 and alpha-CaMKII siRNA increased p21((CIP/KIP)) gene expression, protein levels, and decreased the phosphorylation of retinoblastoma protein and E2F transactivation. Furthermore, the inhibition of CaMKII decreased membrane-bound Tiam1 and GTP-bound Rac1, which are known to be involved in p21 expression and tumor growth in a variety of solid malignant neoplasms. Our results suggest that CaMKII plays a critical role in the growth of osteosarcoma, and its inhibition could be an attractive therapeutic target to combat conventional high-grade osteosarcoma in children.
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Affiliation(s)
- Kaiyu Yuan
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Oh J, Diaz T, Wei B, Chang H, Noda M, Stetler-Stevenson WG. TIMP-2 upregulates RECK expression via dephosphorylation of paxillin tyrosine residues 31 and 118. Oncogene 2006; 25:4230-4. [PMID: 16491114 PMCID: PMC1502148 DOI: 10.1038/sj.onc.1209444] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [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: 11/17/2005] [Revised: 01/10/2006] [Accepted: 01/10/2006] [Indexed: 02/07/2023]
Abstract
We previously demonstrated that TIMP-2 increases the association of Crk with C3G and via subsequent activation of Rap1 enhances the expression of RECK, a membrane-anchored MMP inhibitor. In the present study, we investigate the mechanism of how the TIMP-2 signal is transduced from the alpha3beta1 integrin receptor to the Crk-C3G-Rap1 molecular complex. TIMP-2 treatment of human microvascular endothelial cells (hMVECs) increased the phosphorylation levels of Src at Tyr-527, the negative regulatory site, through enhanced association of Src with Csk. This results in the reduction of Src kinase activity and dephosphorylation of paxillin at Tyr-31/118, the target sites for Src kinase phosphorylation and also the binding sites for the downstream effector Crk. Such TIMP-2 effects accompany the disassembly of paxillin-Crk-DOCK180 molecular complex and, in turn, Rac1 inactivation. On the contrary, levels of paxillin-Crk-C3G complex formation are not reduced, rather slightly increased, which is consistent with our previous finding. Therefore, TIMP-2-mediated inhibition of Src kinase activity leads to the signaling switch from Rac1 to Rap1, thereby leading to enhanced RECK expression.
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Affiliation(s)
- J Oh
- Laboratory of Cellular Oncology, Korea University Graduate School of Medicine, Ansan, Gyeonggi do, Korea.
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ten Klooster J, Evers E, Janssen L, Machesky L, Michiels F, Hordijk P, Collard J. Interaction between Tiam1 and the Arp2/3 complex links activation of Rac to actin polymerization. Biochem J 2006; 397:39-45. [PMID: 16599904 PMCID: PMC1479755 DOI: 10.1042/bj20051957] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 03/27/2006] [Accepted: 04/07/2006] [Indexed: 12/22/2022]
Abstract
The Rac-specific GEF (guanine-nucleotide exchange factor) Tiam1 (T-lymphoma invasion and metastasis 1) regulates migration, cell-matrix and cell-cell adhesion by modulating the actin cytoskeleton through the GTPase, Rac1. Using yeast two-hybrid screening and biochemical assays, we found that Tiam1 interacts with the p21-Arc [Arp (actin-related protein) complex] subunit of the Arp2/3 complex. Association occurred through the N-terminal pleckstrin homology domain and the adjacent coiled-coil region of Tiam1. As a result, Tiam1 co-localizes with the Arp2/3 complex at sites of actin polymerization, such as epithelial cell-cell contacts and membrane ruffles. Deletion of the p21-Arc-binding domain in Tiam1 impairs its subcellular localization and capacity to activate Rac1, suggesting that binding to the Arp2/3 complex is important for the function of Tiam1. Indeed, blocking Arp2/3 activation with a WASP (Wiskott-Aldrich syndrome protein) inhibitor leads to subcellular relocalization of Tiam1 and decreased Rac activation. Conversely, functionally active Tiam1, but not a GEF-deficient mutant, promotes activation of the Arp2/3 complex and its association with cytoskeletal components, indicating that Tiam1 and Arp2/3 are mutually dependent for their correct localization and signalling. Our data suggests a model in which the Arp2/3 complex acts as a scaffold to localize Tiam1, and thereby Rac activity, which are both required for activation of the Arp2/3 complex and further Arp2/3 recruitment. This 'self-amplifying' signalling module involving Tiam1, Rac and the Arp2/3 complex could thus drive actin polymerization at specific sites in cells that are required for dynamic morphological changes.
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Key Words
- actin
- arp2/3 complex
- wiskott–aldrich syndrome protein (wasp)
- p21-arc
- rac1
- t-lymphoma invasion and metastasis 1 (tiam1)
- 3at, 3-aminotriazole
- arc, arp complex
- arp, actin-related protein
- cc, coiled-coil
- cdc42, cell division cycle 42
- crib, cdc42/rac interacting binding
- dh, dbl homology
- ex, extended
- fl, full-length
- gef, guanine-nucleotide exchange factor
- gst, glutathione s-transferase
- ha, haemagglutinin
- irsp53, insulin receptor substrate p53
- jip, c-jun n-terminal kinase-interacting protein
- mdck, madin–darby canine kidney cells
- pak, p21-activated kinase
- ph, pleckstrin homology
- phn, n-terminal ph domain
- pir121, p53-inducible mrna with an mr of 140000
- tiam1, t-lymphoma invasion and metastasis
- wasp, wiskott–aldrich syndrome protein
- wave, wasp-family verprolin homologous protein
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Affiliation(s)
- Jean Paul ten Klooster
- *The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Eva E. Evers
- *The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Lennert Janssen
- *The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Laura M. Machesky
- †Division of Molecular Cell Biology, School of Biosciences, University of Birmingham, Birmingham B15 2TT, U.K
| | - Frits Michiels
- *The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Peter Hordijk
- ‡Sanquin Research and Landsteiner Laboratorium, Academic Medical Center, University of Amsterdam, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
| | - John G. Collard
- *The Netherlands Cancer Institute, Division of Cell Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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Bouguet-Bonnet S, Buck M. 1H, 15N, 13C assignments for the activated form of the small Rho-GTPase Rac1. J Biomol NMR 2006; 36 Suppl 1:51. [PMID: 16858624 PMCID: PMC2782406 DOI: 10.1007/s10858-006-9029-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Accepted: 05/11/2006] [Indexed: 05/10/2023]
Abstract
In cell signaling events, small GTPases are classical on/off switches depending on the nucleotide, GTP or GDP, that is bound; Rac1 and Cdc42 are two of the best studied examples of the Rho-family of proteins which are known to regulate the actin cytoskeleton and are involved with cell motility. While Rac1.GDP assignments are published (Thapar et al., 2003), no NMR assignments have been reported for the active form of Rac1. Rac1, uniformly labeled with 13C and 15N, was loaded with a GTP analogue by nucleotide exchange in presence of excess GMPPNP and alkaline phosphatase. Following gel filtration, heteronuclear NMR experiments were carried out on this active protein at 0.8 mM and 25°C. A mutant C178S, K184Stop was used in physiological buffer (Kremer et al., 2001), with 4 mM DTT and 4 mM MgCl2, at pH 6.8 to improve the quality of spectra. Partially deuterated protein was used in some experiments. Cross peaks for 150 out of 168 possible resonances are observed in 1H–15N HSQC spectra. Backbone assignment was completed for 141 resonances; side-chain carbon assignments for the corresponding residues are nearly complete, e.g. >95% for Cβ. We observe excellent agreement of the secondary structure predicted from the NMR data (based on CSI) with that found in the crystal structure of Rac1.GMPPNP (pdb 1 MH1). Additional materials are given in the online supplements. BMRB deposit number 6970.
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Affiliation(s)
- Sabine Bouguet-Bonnet
- Department of Physiology and Biophysics, Case Western Reserve University, Medical School, E642, 2109 Adelbert Road, Cleveland, Ohio 44106, USA.
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Kholmanskikh SS, Dobrin JS, Wynshaw-Boris A, Letourneau PC, Ross ME. Disregulated RhoGTPases and actin cytoskeleton contribute to the migration defect in Lis1-deficient neurons. J Neurosci 2003; 23:8673-81. [PMID: 14507966 PMCID: PMC6740411] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Lissencephaly is a severe brain malformation caused by impaired neuronal migration. Lis1, a causative gene, functions in an evolutionarily conserved nuclear translocation pathway regulating dynein motor and microtubule dynamics. Whereas microtubule contributions to neuronal motility are incompletely understood, the actin cytoskeleton is essential for crawling cell movement of all cell types investigated. Lis1 haploinsufficiency is shown here to also result in reduced filamentous actin at the leading edge of migrating neurons, associated with upregulation of RhoA and downregulation of Rac1 and Cdc42 activity. Disruption of RhoA function through pharmacological inhibition of its effector kinase, p160ROCK, restores normal Rac1 and Cdc42 activity and rescues the motility defect in Lis1+/- neurons. These data indicate a previously unrecognized role for Lis1 protein in neuronal motility by promoting actin polymerization through the regulation of Rho GTPase activity. This effect of Lis1 on GTPases does not appear to occur through direct Lis1 binding of Rho, but could involve Lis1 effects on Rho modulatory proteins or on microtubule dynamics.
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Abstract
Efficient entry of the bacterium Yersinia pseudotuberculosis into mammalian cells requires the binding of the bacterial invasin protein to beta1 integrin receptors and the activation of the small GTPase Rac1. We report here that this Rac1-dependent pathway involves recruitment of phosphoinositol-4-phosphate-5-kinase (PIP5K) to form phosphoinositol-4,5-bisphosphate (PIP2) at the phagocytic cup. Reducing the concentration of PIP2 in the target cell by using a membrane-targeted PIP2-specific phosphatase lowered bacterial uptake proportionately. PIP2 formation is regulated by Arf6. An Arf6 derivative defective for nucleotide binding (Arf6N122I) interfered with uptake and decreased the level of PIP2 around extracellular bacteria bound to host cells. This reduction in PIP2 occurred in spite of fact that PIP5K appeared to be recruited efficiently to the site of bacterial binding, indicating a role for Arf6 in activation of the kinase. The elimination of the Rac1-GTP-bound form from the cell by the introduction of the Y. pseudotuberculosis YopE RhoGAP protein could be bypassed by the overproduction of either PIP5K or Arf6, although the degree of bypass was greater for Arf6 transfectants. These results indicate that both Arf6 and PIP5K are involved in integrin-dependent uptake, and that Arf6 participates in both activation of PIP5K as well as in other events associated with bacterial uptake.
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Affiliation(s)
- Ka-Wing Wong
- Howard Hughes Medical Institute, Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA.
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40
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Kubo T, Yamashita T, Yamaguchi A, Sumimoto H, Hosokawa K, Tohyama M. A novel FERM domain including guanine nucleotide exchange factor is involved in Rac signaling and regulates neurite remodeling. J Neurosci 2002; 22:8504-13. [PMID: 12351724 PMCID: PMC6757789] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
The Rho family of small GTPases, key regulators of the actin cytoskeleton in eukaryotic cells from yeast to human, is implicated in the control of neuronal morphology. Guanine nucleotide exchange factors (GEFs) are upstream positive regulators of Rho GTPases and integrate extracellular signaling for appropriate activation of Rho GTPases at specific subcellular regions. Here we describe the identification of a novel Dbl family GEF for Rho GTPases in Homo sapiens and Mus musculus. It contains a tandem Dbl homology-pleckstrin homology domain and FERM domain, characteristic of the plasma membrane proteins linker. This gene, termed FERM domain including RhoGEF (FIR), was abundantly expressed in brain, lung, and testis, as well as embryonic hippocampal and cortical neurons. FIR was found to activate the biochemical pathway specific for Rac1 but not for RhoA or Cdc42. Ectopic expression of FIR in the cortical neurons resulted in significantly shortened neurites and excessive growth cones, presumably mediated by Rac1. These results suggest that FIR may regulate neurite remodeling by mediating the signaling pathways from membrane proteins to Rac.
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Affiliation(s)
- Tateki Kubo
- Department of Anatomy and Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
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Reynolds LF, Smyth LA, Norton T, Freshney N, Downward J, Kioussis D, Tybulewicz VLJ. Vav1 transduces T cell receptor signals to the activation of phospholipase C-gamma1 via phosphoinositide 3-kinase-dependent and -independent pathways. J Exp Med 2002; 195:1103-14. [PMID: 11994416 PMCID: PMC2193701 DOI: 10.1084/jem.20011663] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Vav1 is a signal transducing protein required for T cell receptor (TCR) signals that drive positive and negative selection in the thymus. Furthermore, Vav1-deficient thymocytes show greatly reduced TCR-induced intracellular calcium flux. Using a novel genetic system which allows the study of signaling in highly enriched populations of CD4(+)CD8(+) double positive thymocytes, we have studied the mechanism by which Vav1 regulates TCR-induced calcium flux. We show that in Vav1-deficient double positive thymocytes, phosphorylation, and activation of phospholipase C-gamma1 (PLCgamma1) is defective. Furthermore, we demonstrate that Vav1 regulates PLCgamma1 phosphorylation by at least two distinct pathways. First, in the absence of Vav1 the Tec-family kinases Itk and Tec are no longer activated, most likely as a result of a defect in phosphoinositide 3-kinase (PI3K) activation. Second, Vav1-deficient thymocytes show defective assembly of a signaling complex containing PLCgamma1 and the adaptor molecule Src homology 2 domain-containing leukocyte phosphoprotein 76. We show that this latter function is independent of PI3K.
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Penzes P, Johnson RC, Kambampati V, Mains RE, Eipper BA. Distinct roles for the two Rho GDP/GTP exchange factor domains of kalirin in regulation of neurite growth and neuronal morphology. J Neurosci 2001; 21:8426-34. [PMID: 11606631 PMCID: PMC6762781] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
The actin cytoskeleton, essential for neuronal development, is regulated in part by small GTP binding proteins of the Rho subfamily. Kalirin-9, with two Rho subfamily-specific GDP/GTP exchange factor (GEF) domains, localizes to neurites and growth cones of primary cortical neurons. Kalirin-9 overexpression in cultured cortical neurons induces longer neurites and altered neuronal morphology. Expression of the first GEF domain alone results in drastically shortened axons and excessive growth cones, mediated by Rac1. Expression of the second GEF domain alone induces axonal over-elongation and abundant filopodial neurites, mediated by RhoA. Coordination of the actions of the individual GEF domains through their presence in Kalirin-9, with its Sec14p, spectrin, and Src homology domain 3 motifs, is essential for regulating neurite extension and neuronal morphology.
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Affiliation(s)
- P Penzes
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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43
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Berrier AL, Mastrangelo AM, Downward J, Ginsberg M, LaFlamme SE. Activated R-ras, Rac1, PI 3-kinase and PKCepsilon can each restore cell spreading inhibited by isolated integrin beta1 cytoplasmic domains. J Cell Biol 2000; 151:1549-60. [PMID: 11134082 PMCID: PMC2150687 DOI: 10.1083/jcb.151.7.1549] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [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] [Indexed: 11/30/2022] Open
Abstract
Attachment of many cell types to extracellular matrix proteins triggers cell spreading, a process that strengthens cell adhesion and is a prerequisite for many adhesion-dependent processes including cell migration, survival, and proliferation. Cell spreading requires integrins with intact beta cytoplasmic domains, presumably to connect integrins with the actin cytoskeleton and to activate signaling pathways that promote cell spreading. Several signaling proteins are known to regulate cell spreading, including R-Ras, PI 3-kinase, PKCepsilon and Rac1; however, it is not known whether they do so through a mechanism involving integrin beta cytoplasmic domains. To study the mechanisms whereby cell spreading is regulated by integrin beta cytoplasmic domains, we inhibited cell spreading on collagen I or fibrinogen by expressing tac-beta1, a dominant-negative inhibitor of integrin function, and examined whether cell spreading could be restored by the coexpression of either V38R-Ras, p110alpha-CAAX, myr-PKCepsilon, or L61Rac1. Each of these activated signaling proteins was able to restore cell spreading as assayed by an increase in the area of cells expressing tac-beta1. R-Ras and Rac1 rescued cell spreading in a GTP-dependent manner, whereas PKCstraightepsilon required an intact kinase domain. Importantly, each of these signaling proteins required intact beta cytoplasmic domains on the integrins mediating adhesion in order to restore cell spreading. In addition, the rescue of cell spreading by V38R-Ras was inhibited by LY294002, suggesting that PI 3-kinase activity is required for V38R-Ras to restore cell spreading. In contrast, L61Rac1 and myr-PKCstraightepsilon each increased cell spreading independent of PI 3-kinase activity. Additionally, the dominant-negative mutant of Rac1, N17Rac1, abrogated cell spreading and inhibited the ability of p110alpha-CAAX and myr-PKCstraightepsilon to increase cell spreading. These studies suggest that R-Ras, PI 3-kinase, Rac1 and PKCepsilon require the function of integrin beta cytoplasmic domains to regulate cell spreading and that Rac1 is downstream of PI 3-kinase and PKCepsilon in a pathway involving integrin beta cytoplasmic domain function in cell spreading.
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Affiliation(s)
- Allison L. Berrier
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York 12208
| | - Anthony M. Mastrangelo
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York 12208
| | - Julian Downward
- Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
| | - Mark Ginsberg
- Department of Vascular Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Susan E. LaFlamme
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York 12208
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Abstract
We have used the chemotactic ability of Dictyostelium cells to examine the roles of Rho family members, known regulators of the assembly of F-actin, in cell movement. Wild-type cells polarize with a leading edge enriched in F-actin toward a chemoattractant. Overexpression of constitutively active Dictyostelium Rac1B(61L) or disruption of DdRacGAP1, which encodes a Dictyostelium Rac1 GAP, induces membrane ruffles enriched with actin filaments around the perimeter of the cell and increased levels of F-actin in resting cells. Whereas wild-type cells move linearly toward the cAMP source, Rac1B(61L) and Ddracgap1 null cells make many wrong turns and chemotaxis is inefficient, which presumably results from the unregulated activation of F-actin assembly and pseudopod extension. Cells expressing dominant-negative DdRac1B(17N) do not have a well-defined F-actin-rich leading edge and do not protrude pseudopodia, resulting in very poor cell motility. From these studies and assays examining chemoattractant-mediated F-actin assembly, we suggest DdRac1 regulates the basal levels of F-actin assembly, its dynamic reorganization in response to chemoattractants, and cellular polarity during chemotaxis.
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Affiliation(s)
- C Y Chung
- Section of Cell and Developmental Biology, Division of Biology, Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0634, USA
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45
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Abstract
Both cell adhesion protein CD44 and its main ligand hyaluronic acid (HA) are thought to be involved in several processes ultimately requiring cytoskeleton rearrangements. Here, we show that the small guanine nucleotide (GTP)-binding protein, Rac1, can be activated upon HA binding to CD44. When applied locally to a passive cell edge, HA promoted the formation of lamellipodial protrusions in the direction of the stimulus. This process was inhibited by the prior injection of cells with dominant-negative N17Rac recombinant protein or by pretreatment of cells with monoclonal anti-CD44 antibodies, interfering with HA binding, implying the direct involvement of CD44 in signaling to Rac1.
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Affiliation(s)
| | - Irina Kaverina
- Institute of Molecular Biology, Austrian Academy of Sciences, A-5020 Salzburg, Austria
| | - J. Victor Small
- Institute of Molecular Biology, Austrian Academy of Sciences, A-5020 Salzburg, Austria
| | - Lukas A. Huber
- Research Institute of Molecular Pathology (IMP), A-1030 Vienna, Austria
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Ruchhoeft ML, Ohnuma S, McNeill L, Holt CE, Harris WA. The neuronal architecture of Xenopus retinal ganglion cells is sculpted by rho-family GTPases in vivo. J Neurosci 1999; 19:8454-63. [PMID: 10493746 PMCID: PMC6783015] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Dendritogenesis, axonogenesis, pathfinding, and target recognition are all affected in distinct ways when Xenopus retinal ganglion cells (RGCs) are transfected with constitutively active (ca), wild-type (wt), and dominant negative (dn) Rho-family GTPases in vivo. Dendritogenesis required Rac1 and Cdc42 activity. Moreover, ca-Rac1 caused dendrite hyperproliferation. Axonogenesis, in contrast, was inhibited by ca-Rac1. This phenotype was partially rescued by the coexpression of dn cyclin-dependent kinase (Cdk5), a proposed effector of Rac1, suggesting that Rac1 activity must be regulated tightly for normal axonogenesis. Growth cone morphology was particularly sensitive to dn-RhoA and wt-Cdc42 constructs. These also caused targeting errors, such as tectal bypass, suggesting that cytoskeletal rearrangements are involved in target recognition and are transduced by these pathways.
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Affiliation(s)
- M L Ruchhoeft
- Biology Department, University of California at San Diego, La Jolla, California 92093-0357, USA
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Kuhn TB, Brown MD, Wilcox CL, Raper JA, Bamburg JR. Myelin and collapsin-1 induce motor neuron growth cone collapse through different pathways: inhibition of collapse by opposing mutants of rac1. J Neurosci 1999; 19:1965-75. [PMID: 10066250 PMCID: PMC6782563] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Precise growth cone guidance is the consequence of a continuous reorganization of actin filament structures within filopodia and lamellipodia in response to inhibitory and promoting cues. The small GTPases rac1, cdc42, and rhoA are critical for regulating distinct actin structures in non-neuronal cells and presumably in growth cones. Collapse, a retraction of filopodia and lamellipodia, is a typical growth cone behavior on contact with inhibitory cues and is associated with depolymerization and redistribution of actin filaments. We examined whether small GTPases mediate the inhibitory properties of CNS myelin or collapsin-1, a soluble semaphorin, in chick embryonic motor neuron cultures. As demonstrated for collapsin-1, CNS myelin-evoked growth cone collapse was accompanied by a reduction of rhodamine-phalloidin staining most prominent in the growth cone periphery, suggesting actin filament disassembly. Specific mutants of small GTPases were capable of desensitizing growth cones to CNS myelin or collapsin-1. Adenoviral-mediated expression of constitutively active rac1 or rhoA abolished CNS myelin-induced collapse and allowed remarkable neurite extension on a CNS myelin substrate. In contrast, expression of dominant negative rac1 or cdc42 negated collapsin-1-induced growth cone collapse and promoted neurite outgrowth on a collapsin-1 substrate. These findings suggest that small GTPases can modulate the signaling pathways of inhibitory stimuli and, consequently, allow the manipulation of growth cone behavior. However, the fact that opposite mutants of rac1 were effective against different inhibitory stimuli speaks against a universal signaling pathway underlying growth cone collapse.
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Affiliation(s)
- T B Kuhn
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
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Hashimoto A, Okada H, Jiang A, Kurosaki M, Greenberg S, Clark EA, Kurosaki T. Involvement of guanosine triphosphatases and phospholipase C-gamma2 in extracellular signal-regulated kinase, c-Jun NH2-terminal kinase, and p38 mitogen-activated protein kinase activation by the B cell antigen receptor. J Exp Med 1998; 188:1287-95. [PMID: 9763608 PMCID: PMC2212492 DOI: 10.1084/jem.188.7.1287] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.5] [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: 04/30/1998] [Revised: 07/29/1998] [Indexed: 01/07/2023] Open
Abstract
Mitogen-activated protein (MAP) kinase family members, including extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase ( JNK), and p38 MAP kinase, have been implicated in coupling the B cell antigen receptor (BCR) to transcriptional responses. However, the mechanisms that lead to the activation of these MAP kinase family members have been poorly elucidated. Here we demonstrate that the BCR-induced ERK activation is reduced by loss of Grb2 or expression of a dominant-negative form of Ras, RasN17, whereas this response is not affected by loss of Shc. The inhibition of the ERK response was also observed in phospholipase C (PLC)-gamma2-deficient DT40 B cells, and expression of RasN17 in the PLC-gamma2-deficient cells completely abrogated the ERK activation. The PLC-gamma2 dependency of ERK activation was most likely due to protein kinase C (PKC) activation rather than calcium mobilization, since loss of inositol 1,4,5-trisphosphate receptors did not affect ERK activation. Similar to cooperation of Ras with PKC activation in ERK response, both PLC-gamma2-dependent signal and GTPase are required for BCR-induced JNK and p38 responses. JNK response is dependent on Rac1 and calcium mobilization, whereas p38 response requires Rac1 and PKC activation.
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Affiliation(s)
- A Hashimoto
- Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570-8506, Japan
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Billadeau DD, Brumbaugh KM, Dick CJ, Schoon RA, Bustelo XR, Leibson PJ. The Vav- Rac1 pathway in cytotoxic lymphocytes regulates the generation of cell-mediated killing. J Exp Med 1998; 188:549-59. [PMID: 9687532 PMCID: PMC2212464 DOI: 10.1084/jem.188.3.549] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [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: 03/24/1998] [Revised: 05/19/1998] [Indexed: 11/04/2022] Open
Abstract
The Rac1 guanine nucleotide exchange factor, Vav, is activated in hematopoietic cells in response to a large variety of stimuli. The downstream signaling events derived from Vav have been primarily characterized as leading to transcription or transformation. However, we report here that Vav and Rac1 in natural killer (NK) cells regulate the development of cell-mediated killing. There is a rapid increase in Vav tyrosine phosphorylation during the development of antibody-dependent cellular cytotoxicity and natural killing. In addition, overexpression of Vav, but not of a mutant lacking exchange factor activity, enhances both forms of killing by NK cells. Furthermore, dominant-negative Rac1 inhibits the development of NK cell-mediated cytotoxicity by two mechanisms: (a) conjugate formation between NK cells and target cells is decreased; and (b) those NK cells that do form conjugates have decreased ability to polarize their granules toward the target cell. Therefore, our results suggest that in addition to participating in the regulation of transcription, Vav and Rac1 are pivotal regulators of adhesion, granule exocytosis, and cellular cytotoxicity.
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Affiliation(s)
- D D Billadeau
- Department of Immunology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Jin Z, Strittmatter SM. Rac1 mediates collapsin-1-induced growth cone collapse. J Neurosci 1997; 17:6256-63. [PMID: 9236236 PMCID: PMC6568359] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Collapsin-1 or semaphorin III(D) inhibits axonal outgrowth by collapsing the lamellipodial and filopodial structures of the neuronal growth cones. Because growth cone collapse is associated with actin depolymerization, we considered whether small GTP-binding proteins of the rho subfamily might participate in collapsin-1 signal transduction. Recombinant rho, rac1, and cdc42 proteins were triturated into embryonic chick (DRG) neurons. Constitutively active rac1 increases the proportion of collapsed growth cones, and dominant negative rac1 inhibits collapsin-1-induced collapse of growth cones and collapsin-1 inhibition of neurite outgrowth. DRG neurons treated with dominant negative rac1 remain sensitive to myelin-induced growth cone collapse. Similar mutants of cdc42 do not alter growth cone structure, neurite elongation, or collapsin-1 sensitivity. Whereas the addition of activated rho has no effect, the inhibition of rho with Clostridium botulinum C3 transferase stimulates the outgrowth of DRG neurites. C3 transferase-treated growth cones exhibit little or no lamellipodial spreading and are minimally responsive to collapsin-1 and myelin. These data demonstrate a prominent role for rho and rac1 in modulating growth cone motility and indicate that rac1 may mediate collapsin-1 action.
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Affiliation(s)
- Z Jin
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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