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Johansen KH, Golec DP, Okkenhaug K, Schwartzberg PL. Mind the GAP: RASA2 and RASA3 GTPase-activating proteins as gatekeepers of T cell activation and adhesion. Trends Immunol 2023; 44:917-931. [PMID: 37858490 PMCID: PMC10621891 DOI: 10.1016/j.it.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 09/11/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023]
Abstract
Following stimulation, the T cell receptor (TCR) and its coreceptors integrate multiple intracellular signals to initiate T cell proliferation, migration, gene expression, and metabolism. Among these signaling molecules are the small GTPases RAS and RAP1, which induce MAPK pathways and cellular adhesion to activate downstream effector functions. Although many studies have helped to elucidate the signaling intermediates that mediate T cell activation, the molecules and pathways that keep naive T cells in check are less understood. Several recent studies provide evidence that RASA2 and RASA3, which are GAP1-family GTPase-activating proteins (GAPs) that inactivate RAS and RAP1, respectively, are crucial molecules that limit T cell activation and adhesion. In this review we describe recent data on the roles of RASA2 and RASA3 as gatekeepers of T cell activation and migration.
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Affiliation(s)
- Kristoffer H Johansen
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK; Section of Experimental and Translational Immunology, Department of Health Technology, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| | - Dominic P Golec
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Klaus Okkenhaug
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Pamela L Schwartzberg
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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2
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Prohaska CC, Zhang X, Schwantes‐An TL, Stearman RS, Hooker S, Kittles RA, Aldred MA, Lutz KA, Pauciulo MW, Nichols WC, Desai AA, Gordeuk VR, Machado RF. RASA3 is a candidate gene in sickle cell disease-associated pulmonary hypertension and pulmonary arterial hypertension. Pulm Circ 2023; 13:e12227. [PMID: 37101805 PMCID: PMC10124178 DOI: 10.1002/pul2.12227] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/04/2023] [Accepted: 04/06/2023] [Indexed: 04/28/2023] Open
Abstract
Pulmonary hypertension (PH) is associated with significant morbidity and mortality. RASA3 is a GTPase activating protein integral to angiogenesis and endothelial barrier function. In this study, we explore the association of RASA3 genetic variation with PH risk in patients with sickle cell disease (SCD)-associated PH and pulmonary arterial hypertension (PAH). Cis-expression quantitative trait loci (eQTL) were queried for RASA3 using whole genome genotype arrays and gene expression profiles derived from peripheral blood mononuclear cells (PBMC) of three SCD cohorts. Genome-wide single nucleotide polymorphisms (SNPs) near or in the RASA3 gene that may associate with lung RASA3 expression were identified, reduced to 9 tagging SNPs for RASA3 and associated with markers of PH. Associations between the top RASA3 SNP and PAH severity were corroborated using data from the PAH Biobank and analyzed based on European or African ancestry (EA, AA). We found that PBMC RASA3 expression was lower in patients with SCD-associated PH as defined by echocardiography and right heart catheterization and was associated with higher mortality. One eQTL for RASA3 (rs9525228) was identified, with the risk allele correlating with PH risk, higher tricuspid regurgitant jet velocity and higher pulmonary vascular resistance in patients with SCD-associated PH. rs9525228 associated with markers of precapillary PH and decreased survival in individuals of EA but not AA. In conclusion, RASA3 is a novel candidate gene in SCD-associated PH and PAH, with RASA3 expression appearing to be protective. Further studies are ongoing to delineate the role of RASA3 in PH.
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Affiliation(s)
- Clare C. Prohaska
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of MedicineIndiana UniversityIndianapolisIndianaUSA
| | - Xu Zhang
- Division of Hematology and Oncology, Department of MedicineUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | | | | | - Stanley Hooker
- Division of Health Equities, Department of Population SciencesCity of HopeDuarteCaliforniaUSA
| | - Rick A. Kittles
- Department of Community Health and Preventive MedicineMorehouse School of MedicineAtlantaGeorgiaUSA
| | - Micheala A. Aldred
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of MedicineIndiana UniversityIndianapolisIndianaUSA
| | - Katie A. Lutz
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical CenterUniversity of Cincinnati College of MedicineCincinnatiOhioUSA
| | - Michael W. Pauciulo
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical CenterUniversity of Cincinnati College of MedicineCincinnatiOhioUSA
| | - William C. Nichols
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical CenterUniversity of Cincinnati College of MedicineCincinnatiOhioUSA
| | - Ankit A. Desai
- Krannert Institute of Cardiology, Division of Cardiovascular Medicine, Department of MedicineIndiana UniversityIndianapolisIndianaUSA
| | - Victor R. Gordeuk
- Division of Hematology and Oncology, Department of MedicineUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Roberto F. Machado
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of MedicineIndiana UniversityIndianapolisIndianaUSA
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Dangelmaier C, Kunapuli SP. Evidence for a PI3-kinase independent pathway in the regulation of Rap1b activation downstream of the P2Y12 receptor in platelets. Platelets 2022; 33:1301-1306. [PMID: 35514261 PMCID: PMC9547944 DOI: 10.1080/09537104.2022.2071855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/26/2022] [Accepted: 04/14/2022] [Indexed: 10/18/2022]
Abstract
Platelet activation by adenosine diphosphate (ADP) is mediated through two G-protein-coupled receptors, P2Y1 and P2Y12, which signal through Gq and Gi, respectively. P2Y1 stimulation leads to phospholipase C activation and an increase in cytosolic calcium necessary for CalDAG-GEF1 activation. Engagement of P2Y12 inhibits adenylate cyclase, which reduces cAMP, and activation of PI3-kinase, which inhibits RASA3 resulting in sustained activated Rap1b. In this study we activated human platelets with 2-MeSADP in the presence of LY294002, a PI3-kinase inhibitor, AR-C69931MX, a P2Y12 antagonist or MRS2179, a P2Y1 antagonist. We measured the phosphorylation of Akt on Ser473 as an indicator of PI3-kinase activity. As previously shown, LY294002 and ARC69931MX abolished 2MeSADP-induced Akt phosphorylation. MRS2179 reduced ADP-induced Akt phosphorylation but did not abolish it. Rap1b activation, however, was only reduced, but not ablated, using LY294002 and was completely inhibited by ARC69931MX or MRS2179. Furthermore, 2MeSADP-induced Rap1b activation was abolished in either P2Y1 or P2Y12 null platelets. These data suggest that ADP-induced Rap1b activation requires both P2Y1 and P2Y12. In addition, although stimulation of P2Y12 results in PI3-kinase activation leading to Akt phosphorylation and Rap1b activation, Rap1b activation can occur independently of PI3-kinase downstream of P2Y12. Thus, we propose that the P2Y12 receptor can regulate Rap1b, possibly through RASA3, in a pathway independent of PI3-kinase.
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Affiliation(s)
- Carol Dangelmaier
- Sol Sherry Thrombosis Research Center and the Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center and the Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
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Li H, Prever L, Hsu MY, Lo W, Margaria JP, De Santis MC, Zanini C, Forni M, Novelli F, Pece S, Di Fiore PP, Porporato PE, Martini M, Belabed H, Nazare M, Haucke V, Gulluni F, Hirsch E. Phosphoinositide Conversion Inactivates R-RAS and Drives Metastases in Breast Cancer. Adv Sci (Weinh) 2022; 9:e2103249. [PMID: 35098698 PMCID: PMC8948670 DOI: 10.1002/advs.202103249] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/03/2021] [Indexed: 05/05/2023]
Abstract
Breast cancer is the most prevalent cancer and a major cause of death in women worldwide. Although early diagnosis and therapeutic intervention significantly improve patient survival rate, metastasis still accounts for most deaths. Here it is reported that, in a cohort of more than 2000 patients with breast cancer, overexpression of PI3KC2α occurs in 52% of cases and correlates with high tumor grade as well as increased probability of distant metastatic events, irrespective of the subtype. Mechanistically, it is demonstrated that PI3KC2α synthetizes a pool of PI(3,4)P2 at focal adhesions that lowers their stability and directs breast cancer cell migration, invasion, and metastasis. PI(3,4)P2 locally produced by PI3KC2α at focal adhesions recruits the Ras GTPase activating protein 3 (RASA3), which inactivates R-RAS, leading to increased focal adhesion turnover, migration, and invasion both in vitro and in vivo. Proof-of-concept is eventually provided that inhibiting PI3KC2α or lowering RASA3 activity at focal adhesions significantly reduces the metastatic burden in PI3KC2α-overexpressing breast cancer, thereby suggesting a novel strategy for anti-breast cancer therapy.
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Affiliation(s)
- Huayi Li
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Lorenzo Prever
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Myriam Y. Hsu
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Wen‐Ting Lo
- Leibniz‐Forschungsinstitut für Molekulare Pharmakologie (FMP)Berlin13125Germany
| | - Jean Piero Margaria
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Maria Chiara De Santis
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Cristina Zanini
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Marco Forni
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Francesco Novelli
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Salvatore Pece
- IEOEuropean Institute of Oncology IRCCSVia Ripamonti 435Milan20141Italy
- Department of Oncology and Hemato‐OncologyUniversità degli Studi di MilanoMilano20142Italy
| | - Pier Paolo Di Fiore
- IEOEuropean Institute of Oncology IRCCSVia Ripamonti 435Milan20141Italy
- Department of Oncology and Hemato‐OncologyUniversità degli Studi di MilanoMilano20142Italy
| | - Paolo Ettore Porporato
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Miriam Martini
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Hassane Belabed
- Leibniz‐Forschungsinstitut für Molekulare Pharmakologie (FMP)Berlin13125Germany
| | - Marc Nazare
- Leibniz‐Forschungsinstitut für Molekulare Pharmakologie (FMP)Berlin13125Germany
| | - Volker Haucke
- Leibniz‐Forschungsinstitut für Molekulare Pharmakologie (FMP)Berlin13125Germany
- Faculty of Biology, Chemistry and PharmacyFreie Universität BerlinBerlin14195Germany
| | - Federico Gulluni
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
| | - Emilio Hirsch
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurin10126Italy
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Wu B, Zhang S, Guo Z, Wang G, Zhang G, Xie L, Lou J, Chen X, Wu D, Bergmeier W, Zheng J, Wan YY. RAS P21 Protein Activator 3 ( RASA3) Specifically Promotes Pathogenic T Helper 17 Cell Generation by Repressing T-Helper-2-Cell-Biased Programs. Immunity 2018; 49:886-898.e5. [PMID: 30446383 DOI: 10.1016/j.immuni.2018.09.004] [Citation(s) in RCA: 6] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 06/02/2018] [Accepted: 08/31/2018] [Indexed: 12/13/2022]
Abstract
Pathogenic Th17 (pTh17) cells drive inflammation and immune-pathology, but whether pTh17 cells are a Th17 cell subset whose generation is under specific molecular control remains unaddressed. We found that Ras p21 protein activator 3 (RASA3) was highly expressed by pTh17 cells relative to non-pTh17 cells and was required specifically for pTh17 generation in vitro and in vivo. Mice conditionally deficient for Rasa3 in T cells showed less pathology during experimental autoimmune encephalomyelitis. Rasa3-deficient T cells acquired a Th2 cell-biased program that dominantly trans-suppressed pTh17 cell generation via interleukin 4 production. The Th2 cell bias of Rasa3-deficient T cells was due to aberrantly elevated transcription factor IRF4 expression. RASA3 promoted proteasome-mediated IRF4 protein degradation by facilitating interaction of IRF4 with E3-ubiquitin ligase Cbl-b. Therefore, a RASA3-IRF4-Cbl-b pathway specifically directs pTh17 cell generation by balancing reciprocal Th17-Th2 cell programs. These findings indicate that a distinct molecular program directs pTh17 cell generation and reveals targets for treating pTh17 cell-related pathology and diseases.
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Affiliation(s)
- Bing Wu
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Song Zhang
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Zengli Guo
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gang Wang
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu 221002, China
| | - Ge Zhang
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Immunology, Dalian Medical University, Dalian, 116044, China
| | - Ling Xie
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jitong Lou
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Xian Chen
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Di Wu
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Periodontology, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Junnian Zheng
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu 221002, China.
| | - Yisong Y Wan
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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6
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Lin H, Fan X, He L, Zhou D. Methylation patterns of RASA3 associated with clinicopathological factors in hepatocellular carcinoma. J Cancer 2018; 9:2116-2122. [PMID: 29937930 PMCID: PMC6010675 DOI: 10.7150/jca.24567] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 12/26/2017] [Accepted: 03/31/2018] [Indexed: 12/25/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the sixth most common tumor worldwide. The relationship between the gene methylation accumulation and HCC has been widely studied. In our study, we used the Sequenom EpiTYPER assay to investigate the methylation levels of the RASA3 in 164 HCC samples and paired adjacent non-cancerous tissues, and the association between methylation level and clinicopathological features. The methylation level of the RASA3 in HCC samples was found significantly lower than that in the adjacent non-cancerous tissues (P<0.0001). Moreover, the hypomethylation of RASA3 in HCC samples was connected with the presence of tumornecrosis (P=0.029) and alcohol intake (P=0.002). Furthermore, it was found that the expression of RASA3 was significantly decreased in tumor tissues (P=0.0053), which was also correlated with the methylation levels of RASA3 gene. Thus, RASA3 hypomethylation is a common feature in HCC, and may be a potential mechanism for HCC development, and serves as a useful biomarker for the early detection, especially in alcohol-associated HCCs.
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Affiliation(s)
- Hui Lin
- Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoxiao Fan
- Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - LiFeng He
- Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Daizhan Zhou
- Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China.,Present address: Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine; Institute of Medical Genetics, Tongji University, Shanghai, China
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Schurmans S, Polizzi S, Scoumanne A, Sayyed S, Molina-Ortiz P. The Ras/Rap GTPase activating protein RASA3: from gene structure to in vivo functions. Adv Biol Regul 2014; 57:153-61. [PMID: 25294679 DOI: 10.1016/j.jbior.2014.09.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [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: 08/25/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 01/28/2023]
Abstract
RASA3 (or GTPase Activating Protein III, R-Ras GTPase-activating protein, GAP1(IP4BP)) is a GTPase activating protein of the GAP1 subfamily which targets Ras and Rap1. RASA3 was originally purified from pig platelet membranes through its intrinsic ability to bind inositol 1,3,4,5-tetrakisphosphate (I(1,3,4,5)P4) with high affinity, hence its first name GAP1(IP4BP) (for GAP1 subfamily member which binds I(1,3,4,5)P4). RASA3 was thus the first I(1,3,4,5)P4 receptor identified and cloned. The in vitro and in vivo functions of RASA3 remained somewhat elusive for a long time. However, recently, using genetically-modified mice and cells derived from these mice, the function of RASA3 during megakaryopoiesis, megakaryocyte adhesion and migration as well as integrin signaling has been reported. The goal of this review is thus to summarize and comment recent and less recent data in the literature on RASA3, in particular on the in vivo function of this specific GAP1 subfamily member.
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Affiliation(s)
- Stéphane Schurmans
- Laboratoire de Génétique Fonctionnelle, GIGA-Signal Transduction, GIGA B34, Université de Liège, Avenue de l'Hôpital 1, B-4000 Liège, Belgium; Secteur de Biochimie Métabolique, Département des Sciences Fonctionnelles, Faculté de Médecine Vétérinaire, Université de Liège, Boulevard de Colonster 20, 4000 Liège, Belgium; Welbio, Belgium.
| | - Séléna Polizzi
- Institut de Recherches Interdisciplinaires en Biologie Humaine et Moléculaire (IRIBHM), Institut de Biologie et de Médecine Moléculaires (IBMM), Faculté de Médecine, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium.
| | - Ariane Scoumanne
- Laboratoire de Génétique Fonctionnelle, GIGA-Signal Transduction, GIGA B34, Université de Liège, Avenue de l'Hôpital 1, B-4000 Liège, Belgium; Welbio, Belgium
| | - Sufyan Sayyed
- Laboratoire de Génétique Fonctionnelle, GIGA-Signal Transduction, GIGA B34, Université de Liège, Avenue de l'Hôpital 1, B-4000 Liège, Belgium
| | - Patricia Molina-Ortiz
- Laboratoire de Génétique Fonctionnelle, GIGA-Signal Transduction, GIGA B34, Université de Liège, Avenue de l'Hôpital 1, B-4000 Liège, Belgium; Welbio, Belgium
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Peters LL, Paw BH, Blanc L. The scat mouse model highlights RASA3, a GTPase activating protein, as a key regulator of vertebrate erythropoiesis and megakaryopoiesis. Small GTPases 2012; 4:47-50. [PMID: 23221813 DOI: 10.4161/sgtp.23013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [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: 12/27/2022] Open
Abstract
Although significant progress has been made in the past decades in our understanding of bone marrow failure syndromes and anemia, many pathological conditions of unknown origin remain. Mouse models have significantly contributed to our understanding of normal erythropoiesis and the pathogenesis of erythroid disorders. Recently, we identified in the scat (severe combined anemia and thrombocytopenia) mouse model a missense mutation (G125V) in the Rasa3 gene, encoding a Ras GTPase activating protein (GAP). RASA3 is lost during reticulocyte maturation through the exosomal pathway and is therefore absent in mature erythrocytes. In wild-type reticulocytes, RASA3 is bound to the plasma membrane, a prerequisite for its GAP activity, but is mislocalized to the cytosol in scat. This mislocalization leads to RASA3 loss of function and higher levels of Ras-GTP, the active form of Ras, are consistently found in scat mature red cells. Finally, RASA3 function is conserved among vertebrates, since erythropoiesis and thrombopoiesis are impaired in zebrafish in which rasa3 is knocked-down by morpholinos, and RASA3 is expressed in human erythroleukemia cells as well as in primary cells. In this commentary, we highlight the critical, conserved and non-redundant function of RASA3 in the context of vertebrate erythropoiesis and megakaryopoiesis. We notably discuss the mechanism of RASA3 downregulation and speculate on the most intriguing part of the phenotype observed in scat; the transient remission period.
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