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Chhichholiya Y, Singh HV, Vashistha R, Singh S, Munshi A. Deciphering the role of KRAS gene in oncogenesis: Focus on signaling pathways, genetic alterations in 3'UTR, KRAS specific miRNAs and therapeutic interventions. Crit Rev Oncol Hematol 2024; 194:104250. [PMID: 38143047 DOI: 10.1016/j.critrevonc.2023.104250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/05/2023] [Accepted: 12/20/2023] [Indexed: 12/26/2023] Open
Abstract
Cancer is a significant cause of death after cardiovascular disease. The genomic, epigenetic and environmental factors have been found to be the risk factor for the disease. The most important genes that develop cancer are oncogenes and tumor suppressor genes. Among oncogenes, KRAS has emerged as a significant player in the development of many cancers. Dysregulation of the RAS signaling pathway either on account of mutation in significant genes involved in the pathway or aberrant expression of different miRNAs targeting these genes including KRAS. The focus is also on the alterations in 3'UTR of the KRAS gene sequence as well as the changes in the miRNA encoding genes especially the one targeting the KRAS gene. Efforts are also being put in to target the dysregulated KRAS gene as a therapeutic approach to treat different cancers. However, there are some challenges like resistance to KRAS inhibitors that need to be addressed.
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Affiliation(s)
- Yogita Chhichholiya
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | - Harsh Vikram Singh
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | | | - Sandeep Singh
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | - Anjana Munshi
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India.
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2
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Kim HJ, Lee HN, Jeong MS, Jang SB. Oncogenic KRAS: Signaling and Drug Resistance. Cancers (Basel) 2021; 13:cancers13225599. [PMID: 34830757 PMCID: PMC8616169 DOI: 10.3390/cancers13225599] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/11/2022] Open
Abstract
RAS proteins play a role in many physiological signals transduction processes, including cell growth, division, and survival. The Ras protein has amino acids 188-189 and functions as GTPase. These proteins are switch molecules that cycle between inactive GDP-bound and active GTP-bound by guanine nucleotide exchange factors (GEFs). KRAS is one of the Ras superfamily isoforms (N-RAS, H-RAS, and K-RAS) that frequently mutate in cancer. The mutation of KRAS is essentially performing the transformation in humans. Since most RAS proteins belong to GTPase, mutated and GTP-bound active RAS is found in many cancers. Despite KRAS being an important molecule in mostly human cancer, including pancreatic and breast, numerous efforts in years past have persisted in cancer therapy targeting KRAS mutant. This review summarizes the biological characteristics of these proteins and the recent progress in the exploration of KRAS-targeted anticancer, leading to new insight.
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Affiliation(s)
- Hyeon Jin Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea; (H.J.K.); (H.N.L.)
| | - Han Na Lee
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea; (H.J.K.); (H.N.L.)
| | - Mi Suk Jeong
- Institute for Plastic Information and Energy Materials and Sustainable Utilization of Photovoltaic Energy Research Center, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea
- Correspondence: (M.S.J.); (S.B.J.); Tel.: +82-51-510-2523 (S.B.J.); Fax: +82-51-581-2544 (S.B.J.)
| | - Se Bok Jang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 46241, Korea; (H.J.K.); (H.N.L.)
- Correspondence: (M.S.J.); (S.B.J.); Tel.: +82-51-510-2523 (S.B.J.); Fax: +82-51-581-2544 (S.B.J.)
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3
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Apken LH, Oeckinghaus A. The RAL signaling network: Cancer and beyond. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 361:21-105. [PMID: 34074494 DOI: 10.1016/bs.ircmb.2020.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The RAL proteins RALA and RALB belong to the superfamily of small RAS-like GTPases (guanosine triphosphatases). RAL GTPases function as molecular switches in cells by cycling through GDP- and GTP-bound states, a process which is regulated by several guanine exchange factors (GEFs) and two heterodimeric GTPase activating proteins (GAPs). Since their discovery in the 1980s, RALA and RALB have been established to exert isoform-specific functions in central cellular processes such as exocytosis, endocytosis, actin organization and gene expression. Consequently, it is not surprising that an increasing number of physiological functions are discovered to be controlled by RAL, including neuronal plasticity, immune response, and glucose and lipid homeostasis. The critical importance of RAL GTPases for oncogenic RAS-driven cellular transformation and tumorigenesis still attracts most research interest. Here, RAL proteins are key drivers of cell migration, metastasis, anchorage-independent proliferation, and survival. This chapter provides an overview of normal and pathological functions of RAL GTPases and summarizes the current knowledge on the involvement of RAL in human disease as well as current therapeutic targeting strategies. In particular, molecular mechanisms that specifically control RAL activity and RAL effector usage in different scenarios are outlined, putting a spotlight on the complexity of the RAL GTPase signaling network and the emerging theme of RAS-independent regulation and relevance of RAL.
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Affiliation(s)
- Lisa H Apken
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany
| | - Andrea Oeckinghaus
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany.
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Kubara K, Yamazaki K, Ishihara Y, Naruto T, Lin HT, Nishimura K, Ohtaka M, Nakanishi M, Ito M, Tsukahara K, Morio T, Takagi M, Otsu M. Status of KRAS in iPSCs Impacts upon Self-Renewal and Differentiation Propensity. Stem Cell Reports 2018; 11:380-394. [PMID: 29983389 PMCID: PMC6092694 DOI: 10.1016/j.stemcr.2018.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 12/20/2022] Open
Abstract
Oncogenic KRAS mutations in hematopoietic stem cells cause RAS-associated autoimmune lymphoproliferative syndrome-like disease (RALD). KRAS plays essential roles in stemness maintenance in some types of stem cells. However, its roles in pluripotent stem cells (PSCs) are poorly understood. Here, we investigated the roles of KRAS on stemness in the context of induced PSCs (iPSCs). We used KRAS mutant (G13C/WT) and wild-type isogenic (WT/WT) iPSCs from the same RALD patients, as well as wild-type (WTed/WT) and heterozygous knockout (Δed/WT) iPSCs, both obtained by genome editing from the same G13C/WT clone. Compared with WT iPSCs, G13C/WT iPSCs displayed enforced retention of self-renewal and suppressed capacity for neuronal differentiation, while Δed/WT iPSCs showed normalized cellular characteristics similar to those of isogenic WTed/WT cells. The KRAS-ERK pathway, but not the KRAS-PI3K pathway, was shown to govern these G13C/WT-specific phenotypes, indicating the strong impact of the KRAS-ERK signaling upon self-renewal and differentiation propensity in human iPSCs.
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Affiliation(s)
- Kenji Kubara
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
| | - Kazuto Yamazaki
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
| | - Yasuharu Ishihara
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Takuya Naruto
- Department of Pediatrics and Developmental Biology, Graduate School of Medicine, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Huan-Ting Lin
- Division of Stem Cell Processing/Stem Cell Bank, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Ken Nishimura
- Laboratory of Gene Regulation, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Manami Ohtaka
- TOKIWA-Bio, Inc., 1-1-1 Higashi, Central 5, Tsukuba, Ibaraki 305-8565, Japan
| | - Mahito Nakanishi
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Masashi Ito
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Kappei Tsukahara
- Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
| | - Tomohiro Morio
- Department of Pediatrics and Developmental Biology, Graduate School of Medicine, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Masatoshi Takagi
- Department of Pediatrics and Developmental Biology, Graduate School of Medicine, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Makoto Otsu
- Division of Stem Cell Processing/Stem Cell Bank, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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5
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Umstead M, Xiong J, Qi Q, Du Y, Fu H. Aurora kinase A interacts with H-Ras and potentiates Ras-MAPK signaling. Oncotarget 2018; 8:28359-28372. [PMID: 28177880 PMCID: PMC5438655 DOI: 10.18632/oncotarget.15049] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 01/07/2017] [Indexed: 11/25/2022] Open
Abstract
In cancer, upregulated Ras promotes cellular transformation and proliferation in part through activation of oncogenic Ras-MAPK signaling. While directly inhibiting Ras has proven challenging, new insights into Ras regulation through protein-protein interactions may offer unique opportunities for therapeutic intervention. Here we report the identification and validation of Aurora kinase A (Aurora A) as a novel Ras binding protein. We demonstrate that the kinase domain of Aurora A mediates the interaction with the N-terminal domain of H-Ras. Further more, the interaction of Aurora A and H-Ras exists in a protein complex with Raf-1. We show that binding of H-Ras to Raf-1 and subsequent MAPK signaling is enhanced by Aurora A, and requires active H-Ras. Thus, the functional linkage between Aurora A and the H-Ras/Raf-1 protein complex may provide a mechanism for Aurora A's oncogenic activity through direct activation of the Ras/MAPK pathway.
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Affiliation(s)
- MaKendra Umstead
- Graduate Program in Cancer Biology, Emory University, Atlanta, GA, USA.,Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Jinglin Xiong
- Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA.,Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China
| | - Qi Qi
- Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Yuhong Du
- Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Haian Fu
- Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA.,Winship Cancer Institute, Atlanta, GA, USA
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6
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Yan C, Theodorescu D. RAL GTPases: Biology and Potential as Therapeutic Targets in Cancer. Pharmacol Rev 2017; 70:1-11. [PMID: 29196555 DOI: 10.1124/pr.117.014415] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
More than a hundred proteins comprise the RAS superfamily of small GTPases. This family can be divided into RAS, RHO, RAB, RAN, ARF, and RAD subfamilies, with each shown to play distinct roles in human cells in both health and disease. The RAS subfamily has a well-established role in human cancer with the three genes, HRAS, KRAS, and NRAS being the commonly mutated in tumors. These RAS mutations, most often functionally activating, are especially common in pancreatic, lung, and colorectal cancers. Efforts to inhibit RAS and related GTPases have produced inhibitors targeting the downstream effectors of RAS signaling, including inhibitors of the RAF-mitogen-activated protein kinase/extracellular signal-related kinase (ERK)-ERK kinase pathway and the phosphoinositide-3-kinase-AKT-mTOR kinase pathway. A third effector arm of RAS signaling, mediated by RAL (RAS like) has emerged in recent years as a critical driver of RAS oncogenic signaling and has not been targeted until recently. RAL belongs to the RAS branch of the RAS superfamily and shares a high structural similarity with RAS. In human cells, there are two genes, RALA and RALB, both of which have been shown to play roles in the proliferation, survival, and metastasis of a variety of human cancers, including lung, colon, pancreatic, prostate, skin, and bladder cancers. In this review, we summarize the latest knowledge of RAL in the context of human cancer and the recent advancements in the development of cancer therapeutics targeting RAL small GTPases.
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Affiliation(s)
- Chao Yan
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China (C.Y.); Departments of Surgery (Urology) and Pharmacology, University of Colorado, Aurora, Colorado (D.T.); and University of Colorado Comprehensive Cancer Center, Aurora, Colorado (D.T.)
| | - Dan Theodorescu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China (C.Y.); Departments of Surgery (Urology) and Pharmacology, University of Colorado, Aurora, Colorado (D.T.); and University of Colorado Comprehensive Cancer Center, Aurora, Colorado (D.T.)
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7
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Nussinov R, Tsai CJ, Muratcioglu S, Jang H, Gursoy A, Keskin O. Principles of K-Ras effector organization and the role of oncogenic K-Ras in cancer initiation through G1 cell cycle deregulation. Expert Rev Proteomics 2015; 12:669-82. [DOI: 10.1586/14789450.2015.1100079] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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8
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Gentry LR, Martin TD, Reiner DJ, Der CJ. Ral small GTPase signaling and oncogenesis: More than just 15minutes of fame. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2976-2988. [PMID: 25219551 DOI: 10.1016/j.bbamcr.2014.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 01/26/2023]
Abstract
Since their discovery in 1986, Ral (Ras-like) GTPases have emerged as critical regulators of diverse cellular functions. Ral-selective guanine nucleotide exchange factors (RalGEFs) function as downstream effectors of the Ras oncoprotein, and the RalGEF-Ral signaling network comprises the third best characterized effector of Ras-dependent human oncogenesis. Because of this, Ral GTPases as well as their effectors are being explored as possible therapeutic targets in the treatment of RAS mutant cancer. The two Ral isoforms, RalA and RalB, interact with a variety of downstream effectors and have been found to play key and distinct roles in both normal and neoplastic cell physiology including regulation of vesicular trafficking, migration and invasion, tumor formation, metastasis, and gene expression. In this review we provide an overview of Ral biochemistry and biology, and we highlight recent discoveries.
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Affiliation(s)
- Leanna R Gentry
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA
| | | | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Channing J Der
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA; University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA.
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9
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Osei-Sarfo K, de Castro IP, Pellicer A. p15(INK4b) plays a crucial role in murine lymphoid development and tumorigenesis. Carcinogenesis 2012; 33:708-13. [PMID: 22227036 DOI: 10.1093/carcin/bgs003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To investigate if the cooperation between the Rgr oncogene and the inactivation of INK4b (a CDK inhibitor), as described previously in a sarcoma model, would be operational in a lymphoid system in vivo, we generated a transgenic/knockout murine model. Transgenic mice expressing the Rgr oncogene under a CD4 promoter were crossed into a p15(INK4b)-deficient background. Unexpectedly, mice with a complete ablation of both p15(INK4b) alleles had a lower tumor incidence and higher survival rate when compared with CD4-Rgr progeny with homozygous or heterozygous expression of p15(INK4b). Also, a similar survival pattern was observed in a parallel model in which transgenic mice expressing a constitutively activated N-Ras mutant were crossed into a p15(INK4b)-deficient background. To analyze this paradoxical event, we investigated the hypothesis that the absence of both p15(INK4b) alleles in the presence of the Rgr oncogene could be deleterious for proper thymocyte development. When analyzed, thymocyte development was blocked at the double negative (DN) 3 and DN4 stages in mice missing one or both alleles of p15(INK4b), respectively. We found reduction in overall apoptotic levels in the thymocytes of mice expressing Rgr, compared with their wild-type mice, supporting thymocyte escape from programmed cell death and subsequently facilitating the onset of thymic lymphomas but less for those missing both p15 alleles. These findings provide evidence of the complex interplay between oncogenes and tumor suppressor genes in tumor development and indicate that in the lymphoid tissue the inactivation of both p15 alleles is unlikely to be the first event in tumor development.
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Affiliation(s)
- Kwame Osei-Sarfo
- Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA
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10
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Ahearn IM, Haigis K, Bar-Sagi D, Philips MR. Regulating the regulator: post-translational modification of RAS. Nat Rev Mol Cell Biol 2011; 13:39-51. [PMID: 22189424 PMCID: PMC3879958 DOI: 10.1038/nrm3255] [Citation(s) in RCA: 402] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RAS proteins are monomeric GTPases that act as binary molecular switches to regulate a wide range of cellular processes. The exchange of GTP for GDP on RAS is regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), which regulate the activation state of RAS without covalently modifying it. By contrast, post-translational modifications (PTMs) of RAS proteins direct them to various cellular membranes and, in some cases, modulate GTP-GDP exchange. Important RAS PTMs include the constitutive and irreversible remodelling of its carboxy-terminal CAAX motif by farnesylation, proteolysis and methylation, reversible palmitoylation, and conditional modifications, including phosphorylation, peptidyl-prolyl isomerisation, monoubiquitylation, diubiquitylation, nitrosylation, ADP ribosylation and glucosylation.
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Affiliation(s)
- Ian M Ahearn
- NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
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Castellano E, Downward J. RAS Interaction with PI3K: More Than Just Another Effector Pathway. Genes Cancer 2011; 2:261-74. [PMID: 21779497 DOI: 10.1177/1947601911408079] [Citation(s) in RCA: 519] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RAS PROTEINS ARE SMALL GTPASES KNOWN FOR THEIR INVOLVEMENT IN ONCOGENESIS: around 25% of human tumors present mutations in a member of this family. RAS operates in a complex signaling network with multiple activators and effectors, which allows them to regulate many cellular functions such as cell proliferation, differentiation, apoptosis, and senescence. Phosphatidylinositol 3-kinase (PI3K) is one of the main effector pathways of RAS, regulating cell growth, cell cycle entry, cell survival, cytoskeleton reorganization, and metabolism. However, it is the involvement of this pathway in human tumors that has attracted most attention. PI3K has proven to be necessary for RAS-induced transformation in vitro, and more importantly, mice with mutations in the PI3K catalytic subunit p110α that block its ability to interact with RAS are highly resistant to endogenous oncogenic KRAS-induced lung tumorigenesis and HRAS-induced skin carcinogenesis. These animals also have a delayed development of the lymphatic vasculature. Many PI3K inhibitors have been developed that are now in clinical trials. However, it is a complex pathway with many feedback loops, and interactions with other pathways make the results of its inhibition hard to predict. Combined therapy with another RAS-regulated pathway such as RAF/MEK/ERK may be the most effective way to treat cancer, at least in animal models mimicking the human disease. In this review, we will summarize current knowledge about how RAS regulates one of its best-known effectors, PI3K.
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Affiliation(s)
- Esther Castellano
- Signal Transduction Laboratory, Cancer Research UK London Research Institute, London, UK
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12
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The human Rgr oncogene is overexpressed in T-cell malignancies and induces transformation by acting as a GEF for Ras and Ral. Oncogene 2011; 30:3661-71. [PMID: 21441953 PMCID: PMC3126870 DOI: 10.1038/onc.2011.93] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Ras superfamily of GTPases is involved in the modification of many cellular processes including cellular motility, proliferation and differentiation. Our laboratory has previously identified the RalGDS-related (Rgr) oncogene in a DMBA (7,12-dimethylbenz[α]anthracene)-induced rabbit squamous cell carcinoma and its human orthologue, hRgr. In this study, we analyzed the expression levels of the human hRgr transcript in a panel of human hematopoietic malignancies and found that a truncated form (diseased-truncated (Dtr-hrgr)) was significantly overexpressed in many T-cell-derived neoplasms. Although the Rgr proto-oncogene belongs to the RalGDS family of guanine nucleotide exchange factors (GEFs), we show that upon the introduction of hRgr into fibroblast cell lines, it is able to elicit the activation of both Ral and Ras GTPases. Moreover, in vitro guanine nucleotide exchange assays confirm that hRgr promotes Ral and Ras activation through GDP dissociation, which is a critical characteristic of GEF proteins. hRgr has guanine nucleotide exchange activity for both small GTPases and this activity was reduced when a point mutation within the catalytic domain (CDC25) of the protein, (cd) Dtr-hRgr, was utilized. These observations prompted the analysis of the biological effects of hRgr and (cd) hRgr expression in cultured cells. Here, we show that hRgr increases proliferation in low serum, increases invasion, reduces anchorage dependence and promotes the progression into the S phase of the cell cycle; properties that are abolished or severely reduced in the presence of the catalytic dead mutant. We conclude that the ability of hRgr to activate both Ral and Ras is responsible for its transformation-inducing phenotype and it could be an important contributor in the development of some T-cell malignancies.
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Neel NF, Martin TD, Stratford JK, Zand TP, Reiner DJ, Der CJ. The RalGEF-Ral Effector Signaling Network: The Road Less Traveled for Anti-Ras Drug Discovery. Genes Cancer 2011; 2:275-87. [PMID: 21779498 PMCID: PMC3128631 DOI: 10.1177/1947601911407329] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The high frequency of RAS mutations in human cancers (33%) has stimulated intense interest in the development of anti-Ras inhibitors for cancer therapy. Currently, the major focus of these efforts is centered on inhibitors of components involved in Ras downstream effector signaling. In particular, more than 40 inhibitors of the Raf-MEK-ERK mitogen-activated protein kinase cascade and phosphoinositide 3-kinase-AKT-mTOR effector signaling networks are currently under clinical evaluation. However, these efforts are complicated by the fact that Ras can utilize at least 9 additional functionally distinct effectors, with at least 3 additional effectors with validated roles in Ras-mediated oncogenesis. Of these, the guanine nucleotide exchange factors of the Ras-like (Ral) small GTPases (RalGEFs) have emerged as important effectors of mutant Ras in pancreatic, colon, and other cancers. In this review, we summarize the evidence for the importance of this effector pathway in cancer and discuss possible directions for therapeutic inhibition of aberrant Ral activation and signaling.
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Affiliation(s)
- Nicole F Neel
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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14
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Zipfel PA, Brady DC, Kashatus DF, Ancrile BD, Tyler DS, Counter CM. Ral activation promotes melanomagenesis. Oncogene 2010; 29:4859-64. [PMID: 20562921 PMCID: PMC2928877 DOI: 10.1038/onc.2010.224] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Up to one-third of human melanomas are characterized by an oncogenic mutation in the gene encoding the small guanosine triphosphatase (GTPase) NRAS. Ras proteins activate three primary classes of effectors, namely, Rafs, phosphatidyl-inositol-3-kinases (PI3Ks) and Ral guanine exchange factors (RalGEFs). In melanomas lacking NRAS mutations, the first two effectors can still be activated through an oncogenic BRAF mutation coupled with a loss of the PI3K negative regulator PTEN. This suggests that Ras effectors promote melanoma, regardless of whether they are activated by oncogenic NRas. The only major Ras effector pathway not explored for its role in melanoma is the RalGEF-Ral pathway, in which Ras activation of RalGEFs converts the small GTPases RalA and RalB to an active guanosine triphosphate-bound state. We report that RalA is activated in several human melanoma cancer cell lines harboring an oncogenic NRAS allele, an oncogenic BRAF allele or wild-type NRAS and BRAF alleles. Furthermore, short hairpin RNA (shRNA)-mediated knockdown of RalA, and to a lesser extent of RalB, variably inhibited the tumorigenic growth of melanoma cell lines having these three genotypes. Thus, as is the case for Raf and PI3 K signaling, Rals also contribute to melanoma tumorigenesis.
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Affiliation(s)
- P A Zipfel
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
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15
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Castellano E, Downward J. Role of RAS in the regulation of PI 3-kinase. Curr Top Microbiol Immunol 2010; 346:143-69. [PMID: 20563706 DOI: 10.1007/82_2010_56] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Ras proteins are key regulators of signalling cascades, controlling many processes such as proliferation, differentiation and apoptosis. Mutations in these proteins or in their effectors, activators and regulators are associated with pathological conditions, particularly the development of various forms of human cancer. RAS proteins signal through direct interaction with a number of effector enzymes, one of the best characterized being type I phosphatidylinositol (PI) 3-kinases. Although the ability of RAS to control PI 3-kinase has long been well established in cultured cells, evidence for a role of the interaction of endogenous RAS with PI 3-kinase in normal and malignant cell growth in vivo has only been obtained recently. Mice with mutations in the PI 3-kinase catalytic p110a isoform that block its ability to interact with RAS are highly resistant to endogenous KRAS oncogene induced lung tumourigenesis and HRAS oncogene induced skin carcinogenesis. Cells from these mice show proliferative defects and selective disruption of signalling from certain growth factors to PI 3-kinase, while the mice also display delayed development of the lymphatic vasculature. The interaction of RAS with p110a is thus required in vivo for some normal growth factor signalling and also for RAS-driven tumour formation. RAS family members were among the first oncogenes identified over 40 years ago. In the late 1960s, the rat-derived Harvey and Kirsten murine sarcoma retroviruses were discovered and subsequently shown to promote cancer formation through related oncogenes, termed RAS (from rat sarcoma virus). The central role of RAS proteins in human cancer is highlighted by the large number of tumours in which they are activated by mutation: approximately 20% of human cancers carry a mutation in RAS proteins. Because of the complex signalling network in which RAS operates, with multiple activators and effectors, each with a different pattern of tissue-specific expression and a distinct set of intracellular functions, one of the critical issues concerns the specific role of each effector in RAS-driven oncogenesis. In this chapter, we summarize current knowledge about how RAS regulates one of its best-known effectors, phosphoinositide 3-kinase (PI3K).
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Affiliation(s)
- Esther Castellano
- Signal Transduction Laboratory, Cancer Research UK London Research Institute, London, WC2A 3PX, UK
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16
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Abstract
The Ras superfamily of GTP-binding proteins is involved in many cellular processes, including cell proliferation, movement, and morphology. One such member, Ral GTPase, activates downstream signaling molecules after a conversion to the active state on GTP binding. The RalGDS-related (Rgr) oncogene belongs to the RalGDS family of guanine nucleotide exchange factors (GEFs). RalGEFs activate Ral by stimulating the dissociation of GDP, allowing the binding of GTP and the initiation of downstream signaling events by Ral effectors. Rgr was first identified as a fusion between the rabbit homolog of the Rad 23 gene and the Rgr gene in a rabbit squamous cell carcinoma. The Rgr portion of the fusion was demonstrated to contain the oncogenic activity. The human form of the Rgr oncogene was identified recently, and expression was detected in human T-cell malignancies. This chapter describes the analysis of rabbit and human Rgr function using various methods. These assays may be used for the study of oncogene function in other systems.
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Affiliation(s)
- Laura A Martello
- Department of Pathology, New York Cancer Institute, New York University School of Medicine, New York, New York, USA
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17
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Hansson CM, Buckley PG, Grigelioniene G, Piotrowski A, Hellström AR, Mantripragada K, Jarbo C, Mathiesen T, Dumanski JP. Comprehensive genetic and epigenetic analysis of sporadic meningioma for macro-mutations on 22q and micro-mutations within the NF2 locus. BMC Genomics 2007; 8:16. [PMID: 17222329 PMCID: PMC1781436 DOI: 10.1186/1471-2164-8-16] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Accepted: 01/12/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Meningiomas are the most common intracranial neoplasias, representing a clinically and histopathologically heterogeneous group of tumors. The neurofibromatosis type 2 (NF2) tumor suppressor is the only gene known to be frequently involved in early development of meningiomas. The objective of this study was to identify genetic and/or epigenetic factors contributing to the development of these tumors. A large set of sporadic meningiomas were analyzed for presence of 22q macro-mutations using array-CGH in order to identify tumors carrying gene dosage aberrations not encompassing NF2. The NF2 locus was also comprehensively studied for point mutations within coding and conserved non-coding sequences. Furthermore, CpG methylation within the NF2 promoter region was thoroughly analyzed. RESULTS Monosomy 22 was the predominant finding, detected in 47% of meningiomas. Thirteen percent of the tumors contained interstitial/terminal deletions and gains, present singly or in combinations. We defined at least two minimal overlapping regions outside the NF2 locus that are small enough (approximately 550 kb and approximately 250 kb) to allow analysis of a limited number of candidate genes. Bialleinactivationo the NF2 gne was detected in 36% of meningiomas. Among the monosomy 22 cases, no additional NF2 mutations could be identified in 35% (17 out of 49) of tumors. Furthermore, the majority of tumors (9 out of 12) with interstitial/terminal deletions did not have any detectable NF2 mutations. Methylation within the NF2 promoter region was only identified at a single CpG site in one tumor sample. CONCLUSION We confirmed previous findings of pronounced differences in mutation frequency between different histopathological subtypes. There is a higher frequency of biallelic NF2 inactivation in fibroblastic (52%) compared to meningothelial (18%) tumors. The presence of macro-mutations on 22q also shows marked differences between fibroblastic (86%) and meningothelial (39%) subtypes. Thus, inactivation of NF2, often combined with the presence of macro-mutation on 22q, is likely not as important for the development of the meningothelial subtype, as opposed to the fibroblastic form. Analysis of 40 CpG sites distributed within 750 bp of the promoter region suggests that NF2 promoter methylation does not play a major role in meningioma development.
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Affiliation(s)
- Caisa M Hansson
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Patrick G Buckley
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Giedre Grigelioniene
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Arkadiusz Piotrowski
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | | | - Kiran Mantripragada
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Caroline Jarbo
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - Tiit Mathiesen
- Department of Neurosurgery, Karolinska University Hospital, Solna, SE-171 76 Stockholm, Sweden
| | - Jan P Dumanski
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
- University of Alabama at Birmingham, 1530 3rd. Ave. S., Kaul 420, Birmingham, AL 35294-0024, USA
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18
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Friday BB, Adjei AA. K-ras as a target for cancer therapy. Biochim Biophys Acta Rev Cancer 2005; 1756:127-44. [PMID: 16139957 DOI: 10.1016/j.bbcan.2005.08.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 07/29/2005] [Accepted: 08/01/2005] [Indexed: 11/30/2022]
Abstract
The central role K-, H- and N-Ras play in regulating diverse cellular pathways important for cell growth, differentiation and survival is well established. Dysregulation of Ras proteins by activating mutations, overexpression or upstream activation is common in human tumors. Of the Ras proteins, K-ras is the most frequently mutated and is therefore an attractive target for cancer therapy. The complexity of K-ras signaling presents many opportunities for therapeutic targeting. A number of different approaches aimed at abrogating K-ras activity have been explored in clinical trials. Several of the therapeutic agents tested have demonstrated clinical activity, supporting ongoing development of K-ras targeted therapies. However, many of the agents currently being evaluated have multiple targets and their antitumor effects may not be due to K-Ras inhibition. To date, no selective, specific inhibitor of K-ras is available for routine clinical use. In this review, we will summarize the structure and function of K-ras with attention to its role in tumorigenesis and discuss the successes and failures of the various strategies designed to therapeutically target this important oncogene.
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Affiliation(s)
- Bret B Friday
- Division of Medical Oncology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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19
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González-García A, Pritchard CA, Paterson HF, Mavria G, Stamp G, Marshall CJ. RalGDS is required for tumor formation in a model of skin carcinogenesis. Cancer Cell 2005; 7:219-26. [PMID: 15766660 DOI: 10.1016/j.ccr.2005.01.029] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 12/07/2004] [Accepted: 01/25/2005] [Indexed: 02/04/2023]
Abstract
To investigate the role of signaling by the small GTPase Ral, we have generated mice deficient for RalGDS, a guanine nucleotide exchange factor that activates Ral. We show that RalGDS is dispensable for mouse development but plays a substantial role in Ras-induced oncogenesis. Lack of RalGDS results in reduced tumor incidence, size, and progression to malignancy in multistage skin carcinogenesis, and reduced transformation by Ras in tissue culture. RalGDS does not appear to participate in the regulation of cell proliferation, but instead controls survival of transformed cells. Experiments performed in cells isolated from skin tumors suggest that RalGDS mediates cell survival through the activation of the JNK/SAPK pathway. These studies identify RalGDS as a key component in Ras-dependent carcinogenesis in vivo.
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Affiliation(s)
- Ana González-García
- Cancer Research UK Centre for Cell and Molecular Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, United Kingdom
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20
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Jiménez M, Pérez de Castro I, Benet M, García JF, Inghirami G, Pellicer A. TheRgrOncogene Induces Tumorigenesis in Transgenic Mice. Cancer Res 2004; 64:6041-9. [PMID: 15342385 DOI: 10.1158/0008-5472.can-03-3389] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study the oncogenic potential of Rgr in vivo, we have generated several transgenic Rgr mouse lines, which express the oncogene under the control of different promoters. These studies revealed that Rgr expression leads to the generation of various pathological alterations, including fibrosarcomas, when its transgenic expression is restricted to nonlymphoid tissues. Moreover, the overall incidence and latency of fibrosarcomas were substantially increased and shortened, respectively, in a p15INK4b-defective background. More importantly, we also have demonstrated that Rgr expression in thymocytes of transgenic mice induces severe alterations in the development of the thymocytes, which eventually lead to a high incidence of thymic lymphomas. This study demonstrates that oncogenic Rgr can induce expression of p15INK4b and, more importantly, that both Rgr and p15INK4b cooperate in the malignant phenotype in vivo. These findings provide new insights into the tumorigenic role of Rgr as a potent oncogene and show that p15INK4b can act as a tumor suppressor gene.
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Affiliation(s)
- María Jiménez
- Department of Pathology and New York University Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
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21
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Okuda Y, Nakamura H, Yoshida K, Enomoto H, Uyama H, Hirotani T, Funamoto M, Ito H, Everett AD, Hada T, Kawase I. Hepatoma-derived growth factor induces tumorigenesis in vivo through both direct angiogenic activity and induction of vascular endothelial growth factor. Cancer Sci 2003; 94:1034-41. [PMID: 14662017 PMCID: PMC11160104 DOI: 10.1111/j.1349-7006.2003.tb01397.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Revised: 10/02/2003] [Accepted: 10/10/2003] [Indexed: 11/28/2022] Open
Abstract
Hepatoma-derived growth factor (HDGF) is highly expressed in tumor cells, and stimulates their proliferation. In the present study, we investigated the role of HDGF in tumorigenesis and elucidated the mechanism of action. Stable transfectants of NIH3T3 cells overexpressing HDGF did not show significant anchorage-independent growth in soft agar assay. However, these stable transfectants overexpressing HDGF generated sarcomatous tumors in nude mice. These tumors were red-colored macroscopically, and histologically showed a rich vascularity. Immunohistochemical analysis using CD31 antibody showed new vessel formation. Recombinant HDGF stimulated proliferation of human umbilical vein endothelial cells in a dose-dependent manner, and stimulated tubule formation. Furthermore, vascular endothelial growth factor (VEGF) was detected immunohistochemically in the tumor tissues. Transient expression of HDGF induced both VEGF gene and protein expression as demonstrated by a reporter assay using VEGF gene promoter. The administration of anti-VEGF neutralizing antibody significantly suppressed, but did not block, the tumor growth of HDGF-overexpressing cells in nude mice. Thus, these findings suggested that HDGF-induced tumor formation in vivo involves induction of VEGF as well as direct angiogenic activity.
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Affiliation(s)
- Yorihide Okuda
- Department of Molecular Medicine, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871
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22
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Upadhya SC, Hegde AN. A potential proteasome-interacting motif within the ubiquitin-like domain of parkin and other proteins. Trends Biochem Sci 2003; 28:280-3. [PMID: 12826399 DOI: 10.1016/s0968-0004(03)00092-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Parkin and other unrelated proteins contain a ubiquitin-like domain (UbLD). This article describes a motif that might be important in the interaction of UbLD-containing proteins (UbLPs) with the proteasome. The proteasome-interacting motif, which is conserved in a subset of UbLPs, such as parkin, Rad23 and several transcription factors, is likely to enable the UbLPs to form a complex with the proteasome for proteolysis or the recently discovered non-proteolytic functions of the proteasome.
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Affiliation(s)
- Sudarshan C Upadhya
- Department of Neurobiology and Anatomy, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA
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23
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Quilliam LA, Rebhun JF, Castro AF. A growing family of guanine nucleotide exchange factors is responsible for activation of Ras-family GTPases. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2003; 71:391-444. [PMID: 12102558 DOI: 10.1016/s0079-6603(02)71047-7] [Citation(s) in RCA: 222] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
GTPases of the Ras subfamily regulate a diverse array of cellular-signaling pathways, coupling extracellular signals to the intracellular response machinery. Guanine nucleotide exchange factors (GEFs) are primarily responsible for linking cell-surface receptors to Ras protein activation. They do this by catalyzing the dissociation of GDP from the inactive Ras proteins. GTP can then bind and induce a conformational change that permits interaction with downstream effectors. Over the past 5 years, approximately 20 novel Ras-family GEFs have been identified and characterized. These data indicate that a variety of different signaling mechanisms can be induced to activate Ras, enabling tyrosine kinases, G-protein-coupled receptors, adhesion molecules, second messengers, and various protein-interaction modules to relocate and/or activate GEFs and elevate intracellular Ras-GTP levels. This review discusses the structure and function of the catalytic or CDC25 homology domain common to almost all Ras-family GEFs. It also details our current knowledge about the regulation and function of this rapidly growing family of enzymes that include Sos1 and 2, GRF1 and 2, CalDAG-GEF/GRP1-4, C3G, cAMP-GEF/Epac 1 and 2, PDZ-GEFs, MR-GEF, RalGDS family members, RalGPS, BCAR3, Smg GDS, and phospholipase C(epsilon).
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Affiliation(s)
- Lawrence A Quilliam
- Department of Biochemistry and Molecular, Biology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis 46202, USA
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24
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Abstract
Advances in our understanding of the molecular pathways and genetic mutations that control tumor cell proliferation and metastasis present an opportunity to develop novel, mechanism-based therapeutic strategies. Ras mutations are the most frequently activated oncogenes in human tumors, with over 30% expressing ras mutations. Molecular dissection of the signaling pathway and the mechanisms of ras anchorage, post-translational modification, and downstream effector signaling of ras now under intensive investigation will help us to design additional methods for ras-directed therapy in an effort to reach an optimal treatment for human tumors that will most likely comprise a combination of modalities targeted at the different underlying genetic defects. The successes and limitations of ras-targeted therapies must be viewed in light of the increasing understanding of the complexity of the ras-signaling pathway. Only now are we beginning to discover the many functions of this integrated pathway, such as the differences between the actions of various ras isoforms that may affect our choice of therapeutic approach. Many of these Ras therapeutic targets have shown success in preclinical studies, and some have shown efficacy in clinical trials with minimal toxicities. Compounds that block ras-transforming activity without affecting normal ras function seem more attractive for the future development of ras-targeted therapy. FTIs may partially fulfill such requirements. Based on their specific, novel, and mechanism-based action; minimal toxicity; and encouraging responses in clinical trials, the development of Ras therapeutic targets as single agents or in combination with conventional chemotherapy and radiotherapy should be pursued.
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Affiliation(s)
- Irene M Ghobrial
- Division of Medical Oncology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
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25
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Ehrhardt A, Ehrhardt GRA, Guo X, Schrader JW. Ras and relatives--job sharing and networking keep an old family together. Exp Hematol 2002; 30:1089-106. [PMID: 12384139 DOI: 10.1016/s0301-472x(02)00904-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Many members of the Ras superfamily of GTPases have been implicated in the regulation of hematopoietic cells, with roles in growth, survival, differentiation, cytokine production, chemotaxis, vesicle-trafficking, and phagocytosis. The well-known p21 Ras proteins H-Ras, N-Ras, K-Ras 4A, and K-Ras 4B are also frequently mutated in human cancer and leukemia. Besides the four p21 Ras proteins, the Ras subfamily of the Ras superfamily includes R-Ras, TC21 (R-Ras2), M-Ras (R-Ras3), Rap1A, Rap1B, Rap2A, Rap2B, RalA, and RalB. They exhibit remarkable overall amino acid identities, especially in the regions interacting with the guanine nucleotide exchange factors that catalyze their activation. In addition, there is considerable sharing of various downstream effectors through which they transmit signals and of GTPase activating proteins that downregulate their activity, resulting in overlap in their regulation and effector function. Relatively little is known about the physiological functions of individual Ras family members, although the presence of well-conserved orthologs in Caenorhabditis elegans suggests that their individual roles are both specific and vital. The structural and functional similarities have meant that commonly used research tools fail to discriminate between the different family members, and functions previously attributed to one family member may be shared with other members of the Ras family. Here we discuss similarities and differences in activation, effector usage, and functions of different members of the Ras subfamily. We also review the possibility that the differential localization of Ras proteins in different parts of the cell membrane may govern their responses to activation of cell surface receptors.
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Affiliation(s)
- Annette Ehrhardt
- The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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26
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Hamad NM, Elconin JH, Karnoub AE, Bai W, Rich JN, Abraham RT, Der CJ, Counter CM. Distinct requirements for Ras oncogenesis in human versus mouse cells. Genes Dev 2002; 16:2045-57. [PMID: 12183360 PMCID: PMC186434 DOI: 10.1101/gad.993902] [Citation(s) in RCA: 355] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The spectrum of tumors associated with oncogenic Ras in humans often differs from those in mice either treated with carcinogens or engineered to sporadically express oncogenic Ras, suggesting that the mechanism of Ras transformation may be different in humans. Ras stimulates primarily three main classes of effector proteins, Rafs, PI3-kinase, and RalGEFs, with Raf generally being the most potent at transforming murine cells. Using oncogenic Ras mutants that activate single effectors as well as constitutively active effectors, we find that the RalGEF, and not the Raf or PI3-kinase pathway, is sufficient for Ras transformation in human cells. Thus, oncogenic Ras may transform murine and human cells by distinct mechanisms, and the RalGEF pathway--previously deemed to play a secondary role in Ras transformation--could represent a new target for anti-cancer therapy.
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Affiliation(s)
- Nesrin M Hamad
- Department of Pharmacology, Division of Neurology, Duke University Medical Center, Durham North Carolina 27710, USA
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27
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Leonardi P, Kassin E, Hernandez-Muñoz I, Diaz R, Inghirami G, Pellicer A. Human rgr: transforming activity and alteration in T-cell malignancies. Oncogene 2002; 21:5108-16. [PMID: 12140761 DOI: 10.1038/sj.onc.1205694] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2002] [Revised: 05/15/2002] [Accepted: 05/20/2002] [Indexed: 11/08/2022]
Abstract
We have previously identified the oncogene rgr (ralGDS related) in DNA derived from a rabbit squamous cell carcinoma. Here we describe the identification of the human orthologue of the rabbit rgr gene termed hrgr (human ralGDS related). Four alternatively spliced full-length hrgr transcripts were isolated from normal human testes and liver libraries. Truncation of hrgr confers transforming ability to its cDNA. Using a RT-PCR assay we have been able to detect the expression of an abnormally truncated transcript in several human T-cell lymphoma lines, and in fresh tissue samples of patients with T-cell malignancies. In the DHL cell line, an Anaplastic Large Cell Lymphoma (ALCL) line, a DNA rearrangement was detected within the hrgr gene region. We propose that these T-cell lymphomas, at least in part, owe their malignant phenotypes to genetic alterations of the hrgr gene. These findings also raise the possibility that mutations in the hrgr gene are involved in other malignancies.
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Affiliation(s)
- Peter Leonardi
- Department of Pathology, 550 First Ave., New York University Medical Center, New York, NY 10016, USA
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28
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Linnemann T, Kiel C, Herter P, Herrmann C. The activation of RalGDS can be achieved independently of its Ras binding domain. Implications of an activation mechanism in Ras effector specificity and signal distribution. J Biol Chem 2002; 277:7831-7. [PMID: 11748241 DOI: 10.1074/jbc.m110800200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small GTPases of the Ras family are major players of signal transduction in eukaryotic cells. They receive signals from a number of receptors and transmit them to a variety of effectors. The distribution of signals to different effector molecules allows for the generation of opposing effects like proliferation and differentiation. To understand the specificity of Ras signaling, we investigated the activation of RalGDS, one of the Ras effector proteins with guanine-nucleotide exchange factor activity for Ral. We determined the GTP level on RalA and showed that the highly conserved Ras binding domain (RBD) of RalGDS, which mediates association with Ras, is important but not sufficient to explain the stimulation of the exchange factor. Although a point mutation in the RBD of RalGDS, which abrogates binding to Ras, renders RalGDS independent to activated Ras, an artificially membrane-targeted version of RalGDS lacking its RBD could still be activated by Ras. The switch II region of Ras is involved in the activation, because the mutant Y64W in this region is impaired in the RalGDS activation. Furthermore, it is shown that Rap1, which was originally identified as a Ras antagonist, can block Ras-mediated RalGDS signaling only when RalGDS contains an intact RBD. In addition, kinetic studies of the complex formation between RalGDS-RBD and Ras suggest that the fast association between RalGDS and Ras, which is analogous to the Ras/Raf case, achieves signaling specificity. Conversely, the Ras x RalGDS complex has a short lifetime of 0.1 s and Rap1 forms a long-lived complex with RalGDS, possibly explaining its antagonistic effect on Ras.
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Affiliation(s)
- Thomas Linnemann
- Abteilung Strukturelle Biologie, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, Dortmund 44227, Germany
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29
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Ehrhardt GR, Korherr C, Wieler JS, Knaus M, Schrader JW. A novel potential effector of M-Ras and p21 Ras negatively regulates p21 Ras-mediated gene induction and cell growth. Oncogene 2001; 20:188-97. [PMID: 11313946 DOI: 10.1038/sj.onc.1204053] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2000] [Revised: 10/19/2000] [Accepted: 10/23/2000] [Indexed: 11/09/2022]
Abstract
Here, we report the identification and characterization of a new member of the RalGDS-family, which is widely expressed and interacts strongly and selectively with the GTP-bound forms of M-Ras and p21 Ras. This Ras pathway modulator (RPM), also termed RGL3, exhibited Ras-binding and catalytic domains typical of the RalGDS-family of guanine nucleotide exchange factors, and was most similar to Rlf (RalGDS-like factor), but was distinguished by a unique proline-rich region with multiple candidate SH3-domain binding sites. RPM/RGL3 resembled AF-6 and Nore1 in interacting strongly with constitutively active M-Ras and p21 Ras. In contrast to Rlf, transiently expressed RPM/RGL3 did not activate an Elk-1-inducible reporter gene alone or in combination with activated p21 Ras, but strongly inhibited induction of this reporter gene by co-expression of activated H-Ras or MEKK-1. This inhibitory effect was independent of the Ras binding domain and required a second signal provided by p21 Ras or MEKK-1, but not Raf-1 or M-Ras. Expression of RPM/RGL3 also strongly inhibited cell growth of fibroblasts transformed by an activated Src Y527F. Thus, RPM/RGL3 is a novel potential effector of both p21 Ras and M-Ras with the novel function of negatively regulating Elk-1-dependent gene induction downstream of p21 Ras or MEKK-1.
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Affiliation(s)
- G R Ehrhardt
- The Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver BC, V6T 1Z3 Canada
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30
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de Bruyn KM, de Rooij J, Wolthuis RM, Rehmann H, Wesenbeek J, Cool RH, Wittinghofer AH, Bos JL. RalGEF2, a pleckstrin homology domain containing guanine nucleotide exchange factor for Ral. J Biol Chem 2000; 275:29761-6. [PMID: 10889189 DOI: 10.1074/jbc.m001160200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ral is a ubiquitously expressed Ras-like small GTPase. Several guanine nucleotide exchange factors for Ral have been identified, including members of the RalGDS family, which exhibit a Ras binding domain and are regulated by binding to RasGTP. Here we describe a novel type of RalGEF, RalGEF2. This guanine nucleotide exchange factor has a characteristic Cdc25-like catalytic domain at the N terminus and a pleckstrin homology (PH) domain at the C terminus. RalGEF2 is able to activate Ral both in vivo and in vitro. Deletion of the PH domain results in an increased cytoplasmic localization of the protein and a corresponding reduction in activity in vivo, suggesting that the PH domain functions as a membrane anchor necessary for optimal activity in vivo.
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Affiliation(s)
- K M de Bruyn
- Department of Physiological Chemistry, University Medical Centre Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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Hernandez-Muñoz I, Malumbres M, Leonardi P, Pellicer A. The Rgr oncogene (homologous to RalGDS) induces transformation and gene expression by activating Ras, Ral and Rho mediated pathways. Oncogene 2000; 19:2745-57. [PMID: 10851075 DOI: 10.1038/sj.onc.1203586] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The effects of the 5'-truncated Rgr oncogene, a previously shown specific guanine exchange factor for Ral in vitro, in stimulating proliferation, cell transformation and gene expression were investigated. We have established TetRgr cell lines in which expression of Rgr can be inhibited by the presence of tetracycline in the medium. Using this system, we show that Rgr overexpressing cells are morphologically transformed and grow in a disorganized manner. At the transcriptional level, Rgr enhances the activity of the serum response element and c-Jun. Rgr induces phosphorylation of ERKs, p38 and JNK kinases, and increases the levels of the GTP-bound forms of Ral and Ras. Ras activation could account for the broad spectra of effects displayed by Rgr. The important role of these pathways is confirmed by experiments in which the transcriptional activation events can be blocked by dominant negative versions of Ras, Ral and Rho. Among all the Rgr-induced pathways, the Ras-Raf-MEK-ERK cascade is essential for the transforming properties of Rgr. Additional analysis has shown that the activation of this pathway by Rgr is not due to a feed back mechanism mediated by the Grb2 adaptor protein. Oncogene (2000).
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Affiliation(s)
- I Hernandez-Muñoz
- Department of Pathology and Kaplan Cancer Center, New York University Medical Center, New York, NY 10016, USA
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Malumbres M, Pérez De Castro I, Hernández MI, Jiménez M, Corral T, Pellicer A. Cellular response to oncogenic ras involves induction of the Cdk4 and Cdk6 inhibitor p15(INK4b). Mol Cell Biol 2000; 20:2915-25. [PMID: 10733595 PMCID: PMC85529 DOI: 10.1128/mcb.20.8.2915-2925.2000] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The cell cycle inhibitor p15(INK4b) is frequently inactivated by homozygous deletion together with p16(INK4a) and p19(ARF) in some types of tumors. Although the tumor suppressor capability of p15(INK4b) is still questioned, it has been found to be specifically inactivated by hypermethylation in hematopoietic malignancies in the absence of p16(INK4a) alterations. Here we show that, in vitro, p15(INK4b) is a strong inhibitor of cellular transformation by Ras. Surprisingly, p15(INK4b) is induced in cultured cells by oncogenic Ras to an extent similar to that of p16(INK4a), and their expression is associated with premature G(1) arrest and senescence. Ras-dependent induction of these two INK4 genes is mediated mainly by the Raf-Mek-Erk pathway. Studies with activated and dominant negative forms of Ras effectors indicate that the Raf-Mek-Erk pathway is essential for induction of both the p15(INK4b) and p16(INK4a) promoters, although other Ras effector pathways can collaborate, giving rise to a stronger response. Our results indicate that p15(INK4b), by itself, is able to stop cell transformation by Ras and other oncogenes such as Rgr (a new oncogene member of the Ral-GDS family, whose action is mediated through Ras). In fact, embryonic fibroblasts isolated from p15(INK4b) knockout mice are susceptible to transformation by the Ras or Rgr oncogene whereas wild-type embryonic fibroblasts are not. Similarly, p15(INK4b)-deficient mouse embryo fibroblasts are more sensitive than wild-type cells to transformation by a combination of the Rgr and E1A oncogenes. The cell cycle inhibitor p15(INK4b) is therefore involved, at least in some cell types, in the tumor suppressor activity triggered after inappropriate oncogenic Ras activation in the cell.
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Affiliation(s)
- M Malumbres
- Department of Pathology and Kaplan Comprehensive Cancer Center, New York University Medical Center, New York, New York 10016, USA
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Goi T, Shipitsin M, Lu Z, Foster DA, Klinz SG, Feig LA. An EGF receptor/Ral-GTPase signaling cascade regulates c-Src activity and substrate specificity. EMBO J 2000; 19:623-30. [PMID: 10675331 PMCID: PMC305600 DOI: 10.1093/emboj/19.4.623] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
c-Src is a membrane-associated tyrosine kinase that can be activated by many types of extracellular signals, and can regulate the function of a variety of cellular protein substrates. We demonstrate that epidermal growth factor (EGF) and beta-adrenergic receptors activate c-Src by different mechanisms leading to the phosphorylation of distinct sets of c-Src substrates. In particular, we found that EGF receptors, but not beta(2)-adrenergic receptors, activated c-Src by a Ral-GTPase-dependent mechanism. Also, c-Src activated by EGF treatment or expression of constitutively activated Ral-GTPase led to tyrosine phosphorylation of Stat3 and cortactin, but not Shc or subsequent Erk activation. In contrast, c-Src activated by isoproterenol led to tyrosine phosphorylation of Shc and subsequent Erk activation, but not tyrosine phosphorylation of cortactin or Stat3. These results identify a role for Ral-GTPases in the activation of c-Src by EGF receptors and the coupling of EGF to transcription through Stat3 and the actin cytoskeleton through cortactin. They also show that c-Src kinase activity can be used differently by individual extracellular stimuli, possibly contributing to their ability to generate unique cellular responses.
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Affiliation(s)
- T Goi
- Department of Biochemistry, Tufts University School of Medicine, Boston, MA 02111, USA
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Movilla N, Bustelo XR. Biological and regulatory properties of Vav-3, a new member of the Vav family of oncoproteins. Mol Cell Biol 1999; 19:7870-85. [PMID: 10523675 PMCID: PMC84867 DOI: 10.1128/mcb.19.11.7870] [Citation(s) in RCA: 217] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We report here the identification and characterization of a novel Vav family member, Vav-3. Signaling experiments demonstrate that Vav-3 participates in pathways activated by protein tyrosine kinases. Vav-3 promotes the exchange of nucleotides on RhoA, on RhoG and, to a lesser extent, on Rac-1. During this reaction, Vav-3 binds physically to the nucleotide-free states of those GTPases. These functions are stimulated by tyrosine phosphorylation in wild-type Vav-3 and become constitutively activated upon deletion of the entire calponin-homology region. Expression of truncated versions of Vav-3 leads to drastic actin relocalization and to the induction of stress fibers, lamellipodia, and membrane ruffles. Moreover, expression of Vav-3 alters cytokinesis, resulting in the formation of binucleated cells. All of these responses need only the expression of the central region of Vav-3 encompassing the Dbl homology (DH), pleckstrin homology (PH), and zinc finger (ZF) domains but do not require the presence of the C-terminal SH3-SH2-SH3 regions. Studies conducted with Vav-3 proteins containing loss-of-function mutations in the DH, PH, and ZF regions indicate that only the DH and ZF regions are essential for Vav-3 biological activity. Finally, we show that one of the functions of the Vav-3 ZF region is to work coordinately with the catalytic DH region to promote both the binding to GTP-hydrolases and their GDP-GTP nucleotide exchange. These results highlight the role of Vav-3 in signaling and cytoskeletal pathways and identify a novel functional cross-talk between the DH and ZF domains of Vav proteins that is imperative for the binding to, and activation of, Rho GTP-binding proteins.
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Affiliation(s)
- N Movilla
- Department of Pathology, State University of New York at Stony Brook, University Hospital, Stony Brook, New York 11794-7025, USA
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35
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Cai D, Clayton LK, Smolyar A, Lerner A. AND-34, a Novel p130Cas-Binding Thymic Stromal Cell Protein Regulated by Adhesion and Inflammatory Cytokines. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.4.2104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
We have characterized a novel cDNA whose steady state mRNA levels rise in the thymus 2 to 6 h following the induction of CD4+CD8+ thymocyte apoptosis by in vivo cross-linking of CD3ε. This cDNA, AND-34-1, contains an open reading frame (ORF) encoding a protein with an amino-terminal Src homology 2 (SH2) domain and a carboxyl-terminal domain homologous to GDP-exchange factors (GEFs). Northern analysis demonstrates widespread expression of the AND-34 gene. Anti-CD3ε treatment induces up-regulation of the AND-34 mRNA levels in total thymic RNA but not in RNA from purified thymocytes, suggesting that this transcript is derived from a thymic stromal cell population. IL-1 and TNF increase AND-34 transcript levels in thymic cortical reticular, thymic nurse, and fibroblast cell lines. In the thymic cortical reticular cell line, IL-1 and TNF induce a protein of the predicted 93-kDa size reactive with anti-AND-34 peptide antisera. Fifteen minutes of serum stimulation of vanadate-pretreated AND-34-1-transfected NIH3T3 fibroblasts induces tyrosine phosphorylation of AND-34 as well as coprecipitating 95-, 125-, and 130-kDa proteins. One of these tyrosine phosphorylated proteins is identified as p130Cas (Crk-associated substrate), a signaling molecule previously known to bind to a GDP-exchange factor (C3G) and inducibly associate with the focal adhesion complex. Consistent with such an association, AND-34 tyrosine phosphorylation is induced following adherence of trypsinized fibroblasts to fibronectin or poly-l-lysine-coated surfaces.
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Affiliation(s)
- Dongpo Cai
- *Department of Medicine, Section of Hematology and Oncology, Boston Medical Center, Boston, MA 02118
- †Department of Pathology, Boston University School of Medicine, Boston, MA 02118
| | - Linda K. Clayton
- ‡Laboratory of Immunobiology, Dana Farber Cancer Institute, Boston, MA 02115; and
- §Department of Medicine, Harvard Medical School, Boston, MA 02115
| | - Alex Smolyar
- ‡Laboratory of Immunobiology, Dana Farber Cancer Institute, Boston, MA 02115; and
- §Department of Medicine, Harvard Medical School, Boston, MA 02115
| | - Adam Lerner
- *Department of Medicine, Section of Hematology and Oncology, Boston Medical Center, Boston, MA 02118
- †Department of Pathology, Boston University School of Medicine, Boston, MA 02118
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Aguirre Ghiso JA, Alonso DF, Farías EF, Gomez DE, de Kier Joffè EB. Deregulation of the signaling pathways controlling urokinase production. Its relationship with the invasive phenotype. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 263:295-304. [PMID: 10406935 DOI: 10.1046/j.1432-1327.1999.00507.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We review the evidence in support of the notion that, upon experimental oncogenic transformation or in spontaneous human cancers, mitogenesis and expression of urokinase (uPA) and its receptor (uPAR) are activated through common signaling complexes and pathways. It is well documented that uPA, uPAR or metalloproteinases (MMPs) are overexpressed in tumor cells of mesenchymal or epithelial origin and these molecules are required for tumor invasion and metastasis. Furthermore, oncogenic stimuli, which may render the transformed cells tumorigenic and metastatic in vivo, activate, in a constitutive fashion, the extracellular-regulated kinases (Erk 1 and 2) classical mitogenic pathway and others such as the NH(2)-Jun-kinase (Jnk). Cells from human tumors or oncogene-transformed cells overexpress uPA and uPAR, and also show a sustained activation of the above-mentioned signaling modules. In this paper we show that the classical mitogenic pathway involving Ras-Erk, PKC-Erk or Rac-JNK, among others, is activated by growth factors or endogenously by oncogenes, and constitutively activates uPA and uPAR expression. All the data obtained from human tumors or experimental systems, incorporated into a general model, indicate that oncogenic stimuli lead to the constitutive activation of mitogenesis and uPA and its receptor expression, through the activation of the same classical and nonclassical signaling complexes and pathways that regulate cell proliferation. We also discuss contrasting points of view. For instance, what governs the differential regulation of mitogenesis and the signal that leads to protease overexpression in a way that allows normal cells during physiological events to respond to growth factors, and proliferate without overexpressing extracellular matrix (ECM) proteases? Or how can cells remodel their microenvironment without proliferating? What restrains benign tumors from overexpressing tumor-associated proteases when they certainly have the mitogenic signal fully activated? This may occur by the differential regulation of transcriptional programs and recent reports reviewed in this paper may provide an insight into how this occurs at the signaling and transcriptional levels.
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Affiliation(s)
- J A Aguirre Ghiso
- Division of Medical Oncology, Department of Medicine, Mount Sinai School of Medicine, New York, USA.
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37
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Bauer B, Mirey G, Vetter IR, García-Ranea JA, Valencia A, Wittinghofer A, Camonis JH, Cool RH. Effector recognition by the small GTP-binding proteins Ras and Ral. J Biol Chem 1999; 274:17763-70. [PMID: 10364219 DOI: 10.1074/jbc.274.25.17763] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Ral effector protein RLIP76 (also called RIP/RalBP1) binds to Ral.GTP via a region that shares no sequence homology with the Ras-binding domains of the Ser/Thr kinase c-Raf-1 and the Ral-specific guanine nucleotide exchange factors. Whereas the Ras-binding domains have a similar ubiquitin-like structure, the Ral-binding domain of RLIP was predicted to comprise a coiled-coil region. In order to obtain more information about the specificity and the structural mode of the interaction between Ral and RLIP, we have performed a sequence space and a mutational analysis. The sequence space analysis of a comprehensive nonredundant assembly of Ras-like proteins strongly indicated that positions 36 and 37 in the core of the effector region are tree-determinant positions for all subfamilies of Ras-like proteins and dictate the specificity of the interaction of these GTPases with their effector proteins. Indeed, we could convert the specific interaction with Ras effectors and RLIP by mutating these residues in Ras and Ral. We therefore conclude that positions 36 and 37 are critical for the discrimination between Ras and Ral effectors and that, despite the absence of sequence homology between the Ral-binding and the Ras-binding domains, their mode of interaction is most probably similar.
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Affiliation(s)
- B Bauer
- Max-Planck-Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany
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38
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Nancy V, Wolthuis RM, de Tand MF, Janoueix-Lerosey I, Bos JL, de Gunzburg J. Identification and characterization of potential effector molecules of the Ras-related GTPase Rap2. J Biol Chem 1999; 274:8737-45. [PMID: 10085114 DOI: 10.1074/jbc.274.13.8737] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In search for effectors of the Ras-related GTPase Rap2, we used the yeast two-hybrid method and identified the C-terminal Ras/Rap interaction domain of the Ral exchange factors (RalGEFs) Ral GDP dissociation stimulator (RalGDS), RalGDS-like (RGL), and RalGDS-like factor (Rlf). These proteins, which also interact with activated Ras and Rap1, are effectors of Ras and mediate the activation of Ral in response to the activation of Ras. Here we show that the full-length RalGEFs interact with the GTP-bound form of Rap2 in the two-hybrid system as well as in vitro. When co-transfected in HeLa cells, an activated Rap2 mutant (Rap2Val-12) but not an inactive protein (Rap2Ala-35) co-immunoprecipitates with RalGDS and Rlf; moreover, Rap2-RalGEF complexes can be isolated from the particulate fraction of transfected cells and were localized by confocal microscopy to the resident compartment of Rap2, i.e. the endoplasmic reticulum. However, the overexpression of activated Rap2 neither leads to the activation of the Ral GTPase via RalGEFs nor inhibits Ras-dependent Ral activation in vivo. Several hypotheses that could explain these results, including compartmentalization of proteins involved in signal transduction, are discussed. Our results suggest that in cells, the interaction of Rap2 with RalGEFs might trigger other cellular responses than activation of the Ral GTPase.
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Affiliation(s)
- V Nancy
- INSERM U-248, Institut Curie, Section de Recherche, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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39
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Ferrer N, Garcia-Espana A, Jeffers M, Pellicer A. The unr gene: evolutionary considerations and nucleic acid-binding properties of its long isoform product. DNA Cell Biol 1999; 18:209-18. [PMID: 10098602 DOI: 10.1089/104454999315420] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The unr transcription unit is located just upstream of the N-ras gene in the genome of mammals, in which unr, like N-ras, is ubiquitously expressed. To determine at what point in evolution the unr/N-ras linkage was created, analysis of nucleic acids by Southern and Northern blotting was performed, allowing us to track the presence of the unr gene to the start of vertebrate evolution and the unr/N-ras linkage to the time at which the reptilian and bird lines diverged. We have investigated, with specific anti-unr antibodies, a potential relation between unr protein levels and cellular processes in which N-ras is implicated. A positive correlation in the proliferation of 3T3 cells, but not differentiation of PC12 cells induced by nerve growth factor (NGF), was found. To study the nucleic acid-binding properties of unr, a protein with multiple repeats of a nucleic acid-binding motif, we expressed the long splicing isoform in a eukaryotic cell line and purified it in native form. The results obtained-a high affinity of unr for single-stranded DNA and RNA and lower affinity for double-stranded DNA without regard to nucleic acid sequence, and its intracellular localization in both the nuclear and non-nuclear compartments, together with its ubiquious expression in mammalian tissues-provide molecular information about the function of one of the closest gene tandems in mammalian cells (unr-N-ras).
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Affiliation(s)
- N Ferrer
- Department of Pathology, and Kaplan Cancer Center, New York University Medical Center, New York 10016, USA
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40
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Goi T, Rusanescu G, Urano T, Feig LA. Ral-specific guanine nucleotide exchange factor activity opposes other Ras effectors in PC12 cells by inhibiting neurite outgrowth. Mol Cell Biol 1999; 19:1731-41. [PMID: 10022860 PMCID: PMC83966 DOI: 10.1128/mcb.19.3.1731] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Ras proteins can activate at least three classes of downstream target proteins: Raf kinases, phosphatidylinositol-3 phosphate (PI3) kinase, and Ral-specific guanine nucleotide exchange factors (Ral-GEFs). In NIH 3T3 cells, activated Ral-GEFs contribute to Ras-induced cell proliferation and oncogenic transformation by complementing the activities of Raf and PI3 kinases. In PC12 cells, activated Raf and PI3 kinases mediate Ras-induced cell cycle arrest and differentiation into a neuronal phenotype. Here, we show that in PC12 cells, Ral-GEF activity acts opposite to other Ras effectors. Elevation of Ral-GEF activity induced by transfection of a mutant Ras protein that preferentially activates Ral-GEFs, or by transfection of the catalytic domain of the Ral-GEF Rgr, suppressed cell cycle arrest and neurite outgrowth induced by nerve growth factor (NGF) treatment. In addition, Rgr reduced neurite outgrowth induced by a mutant Ras protein that preferentially activates Raf kinases. Furthermore, inhibition of Ral-GEF activity by expression of a dominant negative Ral mutant accelerated cell cycle arrest and enhanced neurite outgrowth in response to NGF treatment. Ral-GEF activity may function, at least in part, through inhibition of the Rho family GTPases, CDC42 and Rac. In contrast to Ras, which was activated for hours by NGF treatment, Ral was activated for only approximately 20 min. These findings suggest that one function of Ral-GEF signaling induced by NGF is to delay the onset of cell cycle arrest and neurite outgrowth induced by other Ras effectors. They also demonstrate that Ras has the potential to promote both antidifferentiation and prodifferentiation signaling pathways through activation of distinct effector proteins. Thus, in some cell types the ratio of activities among Ras effectors and their temporal regulation may be important determinants for cell fate decisions between proliferation and differentiation.
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Affiliation(s)
- T Goi
- Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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41
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Abstract
The Ral guanine nucleotide exchange factors are direct targets of Ras, providing a mechanism for Ral activation by extracellular signals. In addition, Ral can be activated by a Ras-independent pathway. Ral guanine nucleotide exchange factors contribute to cellular transformation induced by oncogenic Ras through an Erk-independent mechanism which may involve activation of transcription.
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Affiliation(s)
- R M Wolthuis
- Laboratory for Physiological Chemistry, Center for Biomedical Genetics,Stratenum, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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42
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Bos JL. All in the family? New insights and questions regarding interconnectivity of Ras, Rap1 and Ral. EMBO J 1998; 17:6776-82. [PMID: 9843482 PMCID: PMC1171024 DOI: 10.1093/emboj/17.23.6776] [Citation(s) in RCA: 253] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ras, Rap1 and Ral are related small GTPases. While the function of Ras in signal transduction is well established, it has been recognized only recently that Rap1 and Ral also are activated rapidly in response to a large variety of extracellular signals. Between the three GTPase an intriguing interconnectivity exists, in that guanine nucleotide exchange factors for Ral associate with the GTP-bound form of both Ras and Rap1. Furthermore, Rap1 is considered to function as an antagonist of Ras signalling by trapping Ras effectors in an inactive complex. Here, I summarize the recent developments in understanding the functional relationship between these three GTPase and argue that Rap1 functions in a signalling pathway distinct from Ras, while using similar or identical effectors.
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Affiliation(s)
- J L Bos
- Laboratory for Physiological Chemistry and Center for Biomedical Genetics, Utrecht University, Universiteitsweg 100 3584 CG Utrecht, The Netherlands.
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43
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Wolthuis RM, Franke B, van Triest M, Bauer B, Cool RH, Camonis JH, Akkerman JW, Bos JL. Activation of the small GTPase Ral in platelets. Mol Cell Biol 1998; 18:2486-91. [PMID: 9566869 PMCID: PMC110628 DOI: 10.1128/mcb.18.5.2486] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Ral is a ubiquitously expressed Ras-like small GTPase which is abundantly present in human platelets. The biological function of Ral and the signaling pathway in which Ral is involved are largely unknown. Here we describe a novel method to measure Ral activation utilizing the Ral binding domain of the putative Ral effector RLIP76 as an activation-specific probe. With this assay we investigated the signaling pathway that leads to Ral activation in human platelets. We found that Ral is rapidly activated after stimulation with various platelet agonists, including alpha-thrombin. In contrast, the platelet antagonist prostaglandin I2 inhibited alpha-thrombin-induced Ral activation. Activation of Ral by alpha-thrombin could be inhibited by depletion of intracellular Ca2+, whereas the induction of intracellular Ca2+ resulted in the activation of Ral. Our results show that Ral can be activated by extracellular stimuli. Furthermore, we show that increased levels of intracellular Ca2+ are sufficient for Ral activation in platelets. This activation mechanism correlates with the activation mechanism of the small GTPase Rap1, a putative upstream regulator of Ral guanine nucleotide exchange factors.
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Affiliation(s)
- R M Wolthuis
- Laboratory for Physiological Chemistry, Utrecht University, The Netherlands
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44
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Wolthuis RM, de Ruiter ND, Cool RH, Bos JL. Stimulation of gene induction and cell growth by the Ras effector Rlf. EMBO J 1997; 16:6748-61. [PMID: 9362489 PMCID: PMC1170279 DOI: 10.1093/emboj/16.22.6748] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rlf is a ubiquitously expressed distinct relative of RalGDS that interacts with active Ras in vitro. We now demonstrate that Rlf, when co-expressed with Ras mutants, associates in vivo with RasV12 and the effector-domain mutant RasV12G37, but not with RasV12E38 or RasV12C40. Rlf exhibits guanine nucleotide exchange activity towards the small GTPase Ral and, importantly, Rlf-induced Ral activation is stimulated by active Ras. In addition, RasV12 and RasV12G37 synergize with Rlf in the transcriptional activation of the c-fos promoter. Rlf, when targeted to the plasma membrane using the Ras farnesyl attachment site (Rlf-CAAX), is constitutively active, inducing both Ral activation and c-fos promoter activity. Rlf-CAAX-induced gene expression is insensitive to dominant negative Ras and the MEK inhibitor PD98059, and involves activation of the serum response element. Furthermore, expression of Rlf-CAAX is sufficient to induce proliferation of NIH 3T3 cells under low-serum conditions. These data demonstrate that Rlf is an effector of Ras which functions as an exchange factor for Ral. Rlf mediates a distinct Ras-induced signalling pathway to gene induction. Finally, a constitutively active form of Rlf can stimulate transcriptional activation and cell growth.
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Affiliation(s)
- R M Wolthuis
- Laboratory for Physiological Chemistry, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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