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Kuschman HP, Palczewski MB, Hoffman B, Menhart M, Wang X, Glynn S, Islam ABMMK, Benevolenskaya EV, Thomas DD. Nitric oxide inhibits FTO demethylase activity to regulate N 6-methyladenosine mRNA methylation. Redox Biol 2023; 67:102928. [PMID: 37866163 PMCID: PMC10623363 DOI: 10.1016/j.redox.2023.102928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/27/2023] [Accepted: 10/07/2023] [Indexed: 10/24/2023] Open
Abstract
N6-methyladenosine (m6A) is the most abundant internal modification on eukaryotic mRNAs. Demethylation of m6A on mRNA is catalyzed by the enzyme fat mass and obesity-associated protein (FTO), a member of the nonheme Fe(II) and 2-oxoglutarate (2-OG)-dependent family of dioxygenases. FTO activity and m6A-mRNA are dysregulated in multiple diseases including cancers, yet endogenous signaling molecules that modulate FTO activity have not been identified. Here we show that nitric oxide (NO) is a potent inhibitor of FTO demethylase activity by directly binding to the catalytic iron center, which causes global m6A hypermethylation of mRNA in cells and results in gene-specific enrichment of m6A on mRNA of NO-regulated transcripts. Both cell culture and tumor xenograft models demonstrated that endogenous NO synthesis can regulate m6A-mRNA levels and transcriptional changes of m6A-associated genes. These results build a direct link between NO and m6A-mRNA regulation and reveal a novel signaling mechanism of NO as an endogenous regulator of the epitranscriptome.
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Affiliation(s)
| | - Marianne B Palczewski
- University of Illinois Chicago, College of Pharmacy, Department of Pharmaceutical Sciences, USA
| | - Brian Hoffman
- Weinberg College of Arts and Sciences, Northwestern University, Department of Chemistry, USA
| | - Mary Menhart
- College of Medicine, Departments of Pharmacology and Bioengineering, USA
| | - Xiaowei Wang
- College of Medicine, Departments of Pharmacology and Bioengineering, USA
| | - Sharon Glynn
- University of Galway, College of Medicine, Nursing and Health Sciences, School of Medicine, D. of Pathology, USA
| | | | | | - Douglas D Thomas
- University of Illinois Chicago, College of Pharmacy, Department of Pharmaceutical Sciences, USA.
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2
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Abramova MY, Ponomarenko IV, Churnosov MI. The Polymorphic Locus rs167479 of the RGL3 Gene Is Associated with the Risk of Severe Preeclampsia. RUSS J GENET+ 2022. [DOI: 10.1134/s102279542212002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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3
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Endo T. M-Ras is Muscle-Ras, Moderate-Ras, Mineral-Ras, Migration-Ras, and Many More-Ras. Exp Cell Res 2020; 397:112342. [PMID: 33130177 DOI: 10.1016/j.yexcr.2020.112342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 10/23/2020] [Indexed: 11/19/2022]
Abstract
The Ras family of small GTPases comprises about 36 members in humans. M-Ras is related to classical Ras with regard to its regulators and effectors, but solely constitutes a subfamily among the Ras family members. Although classical Ras strongly binds Raf and highly activates the ERK pathway, M-Ras less strongly binds Raf and moderately but sustainedly activates the ERK pathway to induce neuronal differentiation. M-Ras also possesses specific effectors, including RapGEFs and the PP1 complex Shoc2-PP1c, which dephosphorylates Raf to activate the ERK pathway. M-Ras is highly expressed in the brain and plays essential roles in dendrite formation during neurogenesis, in contrast to the axon formation by R-Ras. M-Ras is also highly expressed in the bone and induces osteoblastic differentiation and transdifferentiation accompanied by calcification. Moreover, M-Ras elicits epithelial-mesenchymal transition-mediated collective and single cell migration through the PP1 complex-mediated ERK pathway activation. Activating missense mutations in the MRAS gene have been detected in Noonan syndrome, one of the RASopathies, and MRAS gene amplification occurs in several cancers. Furthermore, several SNPs in the MRAS gene are associated with coronary artery disease, obesity, and dyslipidemia. Therefore, M-Ras carries out a variety of cellular, physiological, and pathological functions. Further investigations may reveal more functions of M-Ras.
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Affiliation(s)
- Takeshi Endo
- Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoicho, Inageku, Chiba, Chiba 263-8522, Japan.
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4
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Nakagawa N, Kikuchi K, Yagyu S, Miyachi M, Iehara T, Tajiri T, Sakai T, Hosoi H. Mutations in the RAS pathway as potential precision medicine targets in treatment of rhabdomyosarcoma. Biochem Biophys Res Commun 2019; 512:524-530. [PMID: 30904164 DOI: 10.1016/j.bbrc.2019.03.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 03/07/2019] [Indexed: 01/14/2023]
Abstract
Precision medicine strategies for treating rhabdomyosarcoma (RMS), a childhood malignancy, have not been developed. We examined the effect of CH5126766, a potent selective dual RAF/MEK inhibitor, on RMS cell lines. Among the eleven cell lines studied, one NRAS and two HRAS mutated cell lines were detected. CH5126766 inhibited the proliferation and growth in all of the RAS-mutated RMS cell lines, while it induced G1 cell cycle arrest in two of them. G1 cell cycle arrest was accompanied by p21 up-regulation and RB dephosphorylation. CH5126766 also suppressed the in vivo growth of RAS-mutated RMS tumor, and the mice showed improved survival. Thus, our results demonstrate that CH5126766 is an effective RAF/MEK inhibitor in RAS-mutated RMS. This study not only shows that in RMS, mutations in the RAS pathway can be a target for precision medicine, but also demonstrates that the evaluation of the gene mutation status is important in childhood malignancies.
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Affiliation(s)
- Norio Nakagawa
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Ken Kikuchi
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan; Department of Pediatrics, Uji Takeda Hospital, Kyoto, Japan
| | - Shigeki Yagyu
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Mitsuru Miyachi
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Tomoko Iehara
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
| | - Tatsuro Tajiri
- Department of Pediatric Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Toshiyuki Sakai
- Department of Molecular-Targeting Cancer Prevention, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hajime Hosoi
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
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5
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Young LC, Rodriguez-Viciana P. MRAS: A Close but Understudied Member of the RAS Family. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a033621. [PMID: 29311130 DOI: 10.1101/cshperspect.a033621] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
MRAS is the closest relative to the classical RAS oncoproteins and shares most regulatory and effector interactions. However, it also has unique functions, including its ability to function as a phosphatase regulatory subunit when in complex with SHOC2 and protein phosphatase 1 (PP1). This phosphatase complex regulates a crucial step in the activation cycle of RAF kinases and provides a key coordinate input required for efficient ERK pathway activation and transformation by RAS. MRAS mutations rarely occur in cancer but deregulated expression may play a role in tumorigenesis in some settings. Activating mutations in MRAS (as well as SHOC2 and PP1) do occur in the RASopathy Noonan syndrome, underscoring a key role for MRAS within the RAS-ERK pathway. MRAS also has unique roles in cell migration and differentiation and has properties consistent with a key role in the regulation of cell polarity. Further investigations should shed light on what remains a relatively understudied RAS family member.
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Affiliation(s)
- Lucy C Young
- UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, California 94158
| | - Pablo Rodriguez-Viciana
- UCL Cancer Institute, Paul O'Gorman Building, University College London, London WC1E 6BT, United Kingdom
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Nakhaei-Rad S, Haghighi F, Nouri P, Rezaei Adariani S, Lissy J, Kazemein Jasemi NS, Dvorsky R, Ahmadian MR. Structural fingerprints, interactions, and signaling networks of RAS family proteins beyond RAS isoforms. Crit Rev Biochem Mol Biol 2018; 53:130-156. [PMID: 29457927 DOI: 10.1080/10409238.2018.1431605] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Saeideh Nakhaei-Rad
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Fereshteh Haghighi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Parivash Nouri
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Soheila Rezaei Adariani
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Jana Lissy
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Neda S Kazemein Jasemi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Radovan Dvorsky
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Mohammad Reza Ahmadian
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
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7
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Exome sequencing in pooled DNA samples to identify maternal pre-eclampsia risk variants. Sci Rep 2016; 6:29085. [PMID: 27384325 PMCID: PMC4935848 DOI: 10.1038/srep29085] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/14/2016] [Indexed: 02/04/2023] Open
Abstract
Pre-eclampsia is a common pregnancy disorder that is a major cause for maternal and perinatal mortality and morbidity. Variants predisposing to pre-eclampsia might be under negative evolutionary selection that is likely to keep their population frequencies low. We exome sequenced samples from a hundred Finnish pre-eclamptic women in pools of ten to screen for low-frequency, large-effect risk variants for pre-eclampsia. After filtering and additional genotyping steps, we selected 28 low-frequency missense, nonsense and splice site variants that were enriched in the pre-eclampsia pools compared to reference data, and genotyped the variants in 1353 pre-eclamptic and 699 non-pre-eclamptic women to test the association of them with pre-eclampsia and quantitative traits relevant for the disease. Genotypes from the SISu project (n = 6118 exome sequenced Finnish samples) were included in the binary trait association analysis as a population reference to increase statistical power. In these analyses, none of the variants tested reached genome-wide significance. In conclusion, the genetic risk for pre-eclampsia is likely complex even in a population isolate like Finland, and larger sample sizes will be necessary to detect risk variants.
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8
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Liu Y, Bezverbnaya K, Zhao T, Parsons MJ, Shi M, Treanor B, Ehrhardt GRA. Involvement of the HCK and FGR src-family kinases in FCRL4-mediated immune regulation. THE JOURNAL OF IMMUNOLOGY 2015; 194:5851-60. [PMID: 25972488 DOI: 10.4049/jimmunol.1401533] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 04/18/2015] [Indexed: 12/26/2022]
Abstract
FCRL4 is an immunoregulatory receptor expressed by a subpopulation of memory B cells. These tissue-based cells express increased levels of the src-family kinases HCK and FGR. In this study, we investigate the roles of these src-family kinases in FCRL4-mediated immunoregulation of B cells in the context of previously unrecognized palmitoylation of the receptor. We observed enhanced phosphorylation of FCRL4 on tyrosine residues in the presence of the HCK p59 or FGR. This phosphorylation was markedly reduced in assays using a palmitoylation-defective mutant of FCRL4. In reporter gene studies, we observe that FCRL4 expression enhances CpG-mediated activation of NF-κB signaling. Surprisingly, using a reporter gene linked to activation of the MAPK substrate Elk-1 in response to Ag receptor ligation, we find that FCRL4 has inhibitory activity in cells coexpressing FGR but an activating function in cells coexpressing HCK p59. We provide evidence that in primary memory B cells, expression of FCRL4 leads to increased expression of IL-10 in the presence of FGR or HCK p59 in response to CpG, but increased levels of IFN-γ only in the context of coexpression of FGR. Our study supports the specific requirement of HCK p59 and FGR src-family kinases for FCRL4-mediated immunomodulatory activity and indicates that palmitoylation serves as an additional level of regulatory control of FCRL4.
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Affiliation(s)
- Yanling Liu
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
| | - Ksenia Bezverbnaya
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
| | - Tiantian Zhao
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
| | - Marion J Parsons
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
| | - Mengyao Shi
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
| | - Bebhinn Treanor
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Götz R A Ehrhardt
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; and
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9
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Castro AF, Campos T, Babcock JT, Armijo ME, Martínez-Conde A, Pincheira R, Quilliam LA. M-Ras induces Ral and JNK activation to regulate MEK/ERK-independent gene expression in MCF-7 breast cancer cells. J Cell Biochem 2012; 113:1253-64. [PMID: 22121046 DOI: 10.1002/jcb.23458] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Constitutive activation of M-Ras has previously been reported to cause morphologic and growth transformation of murine cells, suggesting that M-Ras plays a role in tumorigenesis. Cell transformation by M-Ras correlated with weak activation of the Raf/MEK/ERK pathway, although contributions from other downstream effectors were suggested. Recent studies indicate that signaling events distinct from the Raf/MEK/ERK cascade are critical for human tumorigenesis. However, it is unknown what signaling events M-Ras triggers in human cells. Using constitutively active M-Ras (Q71L) containing additional mutations within its effector-binding loop, we found that M-Ras induces MEK/ERK-dependent and -independent Elk1 activation as well as phosphatidylinositol 3 kinase (PI3K)/Akt and JNK/cJun activation in human MCF-7 breast cancer cells. Among several human cell lines examined, M-Ras-induced MEK/ERK-independent Elk1 activation was only detected in MCF-7 cells, and correlated with Rlf/M-Ras interaction and Ral/JNK activation. Supporting a role for M-Ras signaling in breast cancer, EGF activated M-Ras and promoted its interaction with endogenous Rlf. In addition, constitutive activation of M-Ras induced estrogen-independent growth of MCF-7 cells that was dependent on PI3K/Akt, MEK/ERK, and JNK activation. Thus, our studies demonstrate that M-Ras signaling activity differs between human cells, highlighting the importance of defining Ras protein signaling within each cell type, especially when designing treatments for Ras-induced cancer. These findings also demonstrate that M-Ras activity may be important for progression of EGFR-dependent tumors.
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Affiliation(s)
- Ariel F Castro
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
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10
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Vigil D, Martin TD, Williams F, Yeh JJ, Campbell SL, Der CJ. Aberrant overexpression of the Rgl2 Ral small GTPase-specific guanine nucleotide exchange factor promotes pancreatic cancer growth through Ral-dependent and Ral-independent mechanisms. J Biol Chem 2010; 285:34729-40. [PMID: 20801877 DOI: 10.1074/jbc.m110.116756] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Our recent studies established essential and distinct roles for RalA and RalB small GTPase activation in K-Ras mutant pancreatic ductal adenocarcinoma (PDAC) cell line tumorigencity, invasion, and metastasis. However, the mechanism of Ral GTPase activation in PDAC has not been determined. There are four highly related mammalian RalGEFs (RalGDS, Rgl1, Rgl2, and Rgl3) that can serve as Ras effectors. Whether or not they share distinct or overlapping functions in K-Ras-mediated growth transformation has not been explored. We found that plasma membrane targeting to mimic persistent Ras activation enhanced the growth-transforming activities of RalGEFs. Unexpectedly, transforming activity did not correlate directly with total cell steady-state levels of Ral activation. Next, we observed elevated Rgl2 expression in PDAC tumor tissue and cell lines. Expression of dominant negative Ral, which blocks RalGEF function, as well as interfering RNA suppression of Rgl2, reduced PDAC cell line steady-state Ral activity, growth in soft agar, and Matrigel invasion. Surprisingly, the effect of Rgl2 on anchorage-independent growth could not be rescued by constitutively activated RalA, suggesting a novel Ral-independent function for Rgl2 in transformation. Finally, we determined that Rgl2 and RalB both localized to the leading edge, and this localization of RalB was dependent on endogenous Rgl2 expression. In summary, our observations support nonredundant roles for RalGEFs in Ras-mediated oncogenesis and a key role for Rgl2 in Ral activation and Ral-independent PDAC growth.
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11
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Ferro E, Trabalzini L. RalGDS family members couple Ras to Ral signalling and that's not all. Cell Signal 2010; 22:1804-10. [PMID: 20478380 DOI: 10.1016/j.cellsig.2010.05.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 05/07/2010] [Indexed: 11/26/2022]
Abstract
Ras proteins function as molecular switches that are activated in response to signalling pathways initiated by various extracellular stimuli and subsequently bind to numerous effector proteins leading to the activation of several signalling cascades within the cell. Ras and Ras-related proteins belong to a large superfamily of small GTPases characterized by significant sequence and function similarities. Several evidence indicate the existence of complex signalling networks that link Ras with its relatives in the family. A key role in this cross-talk is played by guanine nucleotide exchange factors (GEFs) that serve both as regulators and as effectors of Ras family proteins. The members of the RalGDS family, RalGDS, RGL, RGL2/Rlf and RGL3, can interact with activated Ras through their Ras Binding Domain (RBD), but may function as effectors for other Ras family members. They possess a REM-CDC25 homology region like RasGEFs, but specifically activate only RalA and RalB and not Ras or other Ras-related small GTPases. In this review we provide an update on this recently discovered family of GEFs, highlighting their crucial role in coupling activated Ras to activation of Ral, thus regulating several fundamental cell processes, and also discussing some evidence supporting Ras-independent additional functions of RalGDS proteins.
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Affiliation(s)
- Elisa Ferro
- Dipartimento di Biologia Molecolare, Università degli Studi di Siena, Via Fiorentina, 1, 53100 Siena, Italy
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12
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M-Ras evolved independently of R-Ras and its neural function is conserved between mammalian and ascidian, which lacks classical Ras. Gene 2008; 429:49-58. [PMID: 18977283 DOI: 10.1016/j.gene.2008.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/26/2008] [Accepted: 10/01/2008] [Indexed: 10/21/2022]
Abstract
The Ras family small GTPases play a variety of essential roles in eukaryotes. Among them, classical Ras (H-Ras, K-Ras, and N-Ras) and its orthologues are conserved from yeast to human. In ascidians, which phylogenetically exist between invertebrates and vertebrates, the fibroblast growth factor (FGF)-Ras-MAP kinase signaling is required for the induction of neural system, notochord, and mesenchyme. Analyses of DNA databases revealed that no gene encoding classical Ras is present in the ascidians, Ciona intestinalis and Halocynthia roretzi, despite the presence of classical Ras-orthologous genes in nematode, fly, amphioxus, and fish. By contrast, both the ascidians contain single genes orthologous to Mras, Rras, Ral, Rap1, and Rap2. A single Mras orthologue exists from nematode to mammalian. Thus, Mras evolved in metazoans independently of other Ras family genes such as Rras. Whole-mount in situ hybridization showed that C. intestinalis Mras orthologue (Ci-Mras) was expressed in the neural complex of the ascidian juveniles after metamorphosis. Knockdown of Ci-Mras with morpholino antisense oligonucleotides in the embryos and larvae resulted in undeveloped tails and neuronal pigment cells, abrogation of the notochord marker brachyury expression, and perturbation of the neural marker Otx expression, as has been shown in the experiments of the FGF-Ras-MAP kinase signaling inhibition. Mammalian Ras and M-Ras mediate nerve growth factor-induced neuronal differentiation in rat PC12 cells by activating the ERK/MAP kinase pathway transiently and sustainedly, respectively. Activated Ci-M-Ras bound to target proteins of mammalian M-Ras and Ras. Exogenous expression of an activated Ci-M-Ras in PC12 cells caused ERK activation and induced neuritogenesis via the ERK pathway as do mammalian M-Ras and Ras. These results suggest that the ascidian M-Ras orthologue compensates for lacked classical Ras and plays essential roles in neurogenesis in the ascidian.
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Yoshikawa Y, Satoh T, Tamura T, Wei P, Bilasy SE, Edamatsu H, Aiba A, Katagiri K, Kinashi T, Nakao K, Kataoka T. The M-Ras-RA-GEF-2-Rap1 pathway mediates tumor necrosis factor-alpha dependent regulation of integrin activation in splenocytes. Mol Biol Cell 2007; 18:2949-59. [PMID: 17538012 PMCID: PMC1949361 DOI: 10.1091/mbc.e07-03-0250] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The Rap1 small GTPase has been implicated in regulation of integrin-mediated leukocyte adhesion downstream of various chemokines and cytokines in many aspects of inflammatory and immune responses. However, the mechanism for Rap1 regulation in the adhesion signaling remains unclear. RA-GEF-2 is a member of the multiple-member family of guanine nucleotide exchange factors (GEFs) for Rap1 and characterized by the possession of a Ras/Rap1-associating domain, interacting with M-Ras-GTP as an effector, in addition to the GEF catalytic domain. Here, we show that RA-GEF-2 is specifically responsible for the activation of Rap1 that mediates tumor necrosis factor-alpha (TNF-alpha)-triggered integrin activation. In BAF3 hematopoietic cells, activated M-Ras potently induced lymphocyte function-associated antigen 1 (LFA-1)-mediated cell aggregation. This activation was totally abrogated by knockdown of RA-GEF-2 or Rap1. TNF-alpha treatment activated LFA-1 in a manner dependent on M-Ras, RA-GEF-2, and Rap1 and induced activation of M-Ras and Rap1 in the plasma membrane, which was accompanied by recruitment of RA-GEF-2. Finally, we demonstrated that M-Ras and RA-GEF-2 were indeed involved in TNF-alpha-stimulated and Rap1-mediated LFA-1 activation in splenocytes by using mice deficient in RA-GEF-2. These findings proved a crucial role of the cross-talk between two Ras-family GTPases M-Ras and Rap1, mediated by RA-GEF-2, in adhesion signaling.
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Affiliation(s)
- Yoko Yoshikawa
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Takaya Satoh
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Takashi Tamura
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Ping Wei
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Shymaa E. Bilasy
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Hironori Edamatsu
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
| | - Atsu Aiba
- Division of Molecular Genetics, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Koko Katagiri
- Department of Molecular Genetics, Institute of Biomedical Science, Kansai Medical University, Osaka 570-8506, Japan; and
| | - Tatsuo Kinashi
- Department of Molecular Genetics, Institute of Biomedical Science, Kansai Medical University, Osaka 570-8506, Japan; and
| | - Kazuki Nakao
- Laboratory of Animal Resources and Genetic Engineering, Riken Center for Developmental Biology, Kobe 650-0047, Japan
| | - Tohru Kataoka
- *Division of Molecular Biology, Department of Biochemistry and Molecular Biology, and
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Ikeda M, Hirabayashi S, Fujiwara N, Mori H, Kawata A, Iida J, Bao Y, Sato Y, Iida T, Sugimura H, Hata Y. Ras-association domain family protein 6 induces apoptosis via both caspase-dependent and caspase-independent pathways. Exp Cell Res 2007; 313:1484-95. [PMID: 17367779 DOI: 10.1016/j.yexcr.2007.02.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 02/06/2007] [Accepted: 02/06/2007] [Indexed: 01/09/2023]
Abstract
The Ras-association domain family (RASSF) comprises six members (RASSF1-6) that each harbors a RalGDS/AF-6 (RA) and Sav/RASSF/Hippo (SARAH) domain. The RASSF proteins are known as putative tumor suppressors but RASSF6 has not yet been studied. We have here characterized human RASSF6. Although RASSF6 has RA domain, it does not bind Ki-Ras, Ha-Ras, N-Ras, M-Ras, or TC21 under the condition that Nore1 (RASSF5) binds these Ras proteins. The message of RASSF6 is detected by RT-PCR in several cell lines including HeLa, MCF-7, U373, A549, and HepG2 cells, but the protein expression is low. The enhanced expression of RASSF6 causes apoptosis in HeLa cells. RASSF6 activates Bax and induces cytochrome C release. Caspase-3 activation is also induced, but the caspase inhibitor, Z-VAD-FMK, does not block RASSF6-mediated apoptosis. Apoptosis-inducing factor and endonuclease G are released from the mitochondria upon expression of RASSF6 and their releases are not blocked by Z-VAD-FMK. The knock down of RASSF6 partially blocks tumor necrosis factor-alpha-induced cell death in HeLa cells. These findings indicate that RASSF6 is implicated in apoptosis in HeLa cells and that it triggers both caspase-dependent and caspase-independent pathways.
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Affiliation(s)
- Mitsunobu Ikeda
- Department of Medical Biochemistry, Graduate School of Medicine, Rm D602, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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15
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Xu J, Shi S, Matsumoto N, Noda M, Kitayama H. Identification of Rgl3 as a potential binding partner for Rap-family small G-proteins and profilin II. Cell Signal 2007; 19:1575-82. [PMID: 17382517 DOI: 10.1016/j.cellsig.2007.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2007] [Revised: 02/07/2007] [Accepted: 02/07/2007] [Indexed: 11/20/2022]
Abstract
A cDNA encoding a RalGDS-related protein, Rgl3, was isolated by yeast two-hybrid screening using a small G-protein, Rap1, as a bait. Rgl3 mRNA is commonly detectable in several visceral organs (e.g. kidney, heart, liver, and lung) in the mouse and human. The Rgl3 protein mainly localizes in the cytoplasm when expressed in fibroblasts. Yeast two-hybrid assay indicated that Rgl3 could interact with Rap1, Rap2, H-Ras, N-Ras, and R-Ras but failed to interact efficiently with Ral and Rho. Interestingly, Rgl3 was found to affect cell morphology in two assay systems in culture. First, Rgl3 suppressed cell-spreading induced by Rap1, R-Ras, or C3G-CAAX (a membrane-targeted Rap/R-Ras activator) in HEK-293 cells. Second, Rgl3 enhanced the focus-formation induced by oncogenic H-Ras and N-Ras mutants in NIH3T3 cells. Moreover, we identified profilin II as a potential binding partner for Rgl3 by yeast two-hybrid screening. This interaction requires the characteristic proline cluster in the Rgl3 amino-terminal domain. Profilin II and Rgl3 co-operated in enhancing the N-Ras-induced focus-formation. These findings raise the possibility that Rgl3 mediates interaction between Ras/Rap-family proteins and profilin II, an important activator of actin polymerization.
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Affiliation(s)
- Jiegou Xu
- Department of Molecular Oncology, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501 Japan
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16
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Nuñez Rodriguez N, Lee INL, Banno A, Qiao HF, Qiao RF, Yao Z, Hoang T, Kimmelman AC, Chan AML. Characterization of R-ras3/m-ras null mice reveals a potential role in trophic factor signaling. Mol Cell Biol 2006; 26:7145-54. [PMID: 16980617 PMCID: PMC1592885 DOI: 10.1128/mcb.00476-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
R-Ras3/M-Ras is a member of the RAS superfamily of small-molecular-weight GTP-binding proteins. Previous studies have demonstrated high levels of expression in several regions of the central nervous system, and a constitutively active form of M-Ras promotes cytoskeletal reorganization, cellular transformation, survival, and differentiation. However, the physiological functions of M-Ras during embryogenesis and postnatal development have not been elucidated. By using a specific M-Ras antibody, we demonstrated a high level of M-Ras expression in astrocytes, in addition to neurons. Endogenous M-Ras was activated by several trophic factors in astrocytes, including epidermal growth factor (EGF), basic fibroblast growth factor, and hepatocyte growth factor. Interestingly, M-Ras activation by EGF was more sustained compared to prototypic Ras. A mouse strain deficient in M-Ras was generated to investigate its role in development. M-Ras null mice appeared phenotypically normal, and there was a lack of detectable morphological and neurological defects. In addition, primary astrocytes derived from Mras(-/-) mice did not appear to display substantial alterations in the activation of both the mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways in response to trophic factors.
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Affiliation(s)
- Nelson Nuñez Rodriguez
- Department of Oncological Sciences, The Mount Sinai School of Medicine, New York, New York 10029, USA
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17
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Hoshino M, Yoshimori T, Nakamura S. Small GTPase proteins Rin and Rit Bind to PAR6 GTP-dependently and regulate cell transformation. J Biol Chem 2005; 280:22868-74. [PMID: 15831491 DOI: 10.1074/jbc.m411592200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The novel small GTPases Rin and Rit are close relatives of Ras, and recent studies show that they play a role in mediating neuronal differentiation. However, the direct effectors of Rin and Rit have yet to be fully characterized. Here we showed that Rin and Rit directly bind to the PDZ domain of PAR6, a cell polarity-regulating protein, in a GTP-dependent manner both in vivo and in vitro. Moreover, Rin and Rit can form a ternary complex consisting of PAR6 and Rac/Cdc42, members of the Rho family of small GTPases modulating cell growth and polarity. This ternary complex synergistically potentiates cell transformation in NIH3T3 cells, and the interaction between Rin/Rit and the PDZ domain of PAR6 is important for this effect. These results suggest that the Rin/Rit-PAR6-Rac/Cdc42 ternary complex may work physiologically in the cells, such as in tumorigenesis.
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Affiliation(s)
- Mitsunobu Hoshino
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.
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18
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Guo X, Schrader KA, Xu Y, Schrader JW. Expression of a constitutively active mutant of M-Ras in normal bone marrow is sufficient for induction of a malignant mastocytosis/mast cell leukemia, distinct from the histiocytosis/monocytic leukemia induced by expression of activated H-Ras. Oncogene 2005; 24:2330-42. [PMID: 15735740 DOI: 10.1038/sj.onc.1208441] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Expression of constitutively activated M-Ras in normal murine bone-marrow cells was sufficient to induce the factor-independent, in vitro growth and differentiation of colonies of macrophages and neutrophils, and the generation of immortal lines of factor-independent mast cells, and, upon in vivo injection of the transduced cells, a fatal mastocytosis/mast-cell leukemia. In contrast, expression of constitutively activated H-Ras in bone-marrow cells resulted in the in vitro growth, in the absence of exogenous factors, of colonies that contained only macrophages and of lines of cells resembling dendritic cells, and, upon in vivo injection of the transduced cells, a fatal histiocytosis/monocytic leukemia. Macrophages generated by bone-marrow cells expressing activated M-Ras or activated H-Ras differed morphologically, the latter appearing more activated, a difference abrogated by an inhibitor of Erk activation. Inhibition of either Erk or PI3 kinase blocked the capacity of both activated M-Ras and activated H-Ras to support proliferation and viability. However, inhibition of p38 MAPK activity suppressed proliferation of bone-marrow cells expressing activated H-Ras, but enhanced that of bone-marrow cells expressing activated M-Ras. Thus, expression of either activated M-Ras or H-Ras in normal hematopoietic cells was sufficient for transformation but each resulted in the generation of distinct lineages of cells.
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Affiliation(s)
- Xuecui Guo
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada V6T1Z3
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19
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Vasilescu J, Guo X, Kast J. Identification of protein-protein interactions usingin vivo cross-linking and mass spectrometry. Proteomics 2004; 4:3845-54. [PMID: 15540166 DOI: 10.1002/pmic.200400856] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The purification of protein complexes can be accomplished by different types of affinity chromatography. In a typical immunoaffinity experiment, protein complexes are captured from a cell lysate by an immobilized antibody that recognizes an epitope on one of the known components of the complex. After extensive washing to remove unspecifically bound proteins, the complexes are eluted and analyzed by mass spectrometry (MS). Transient complexes, which are characterized by high dissociation constants, are typically lost by this approach. In the present study, we describe a novel method for identifying transient protein-protein interactions using in vivo cross-linking and MS-based protein identification. Live cells are treated with formaldehyde, which rapidly permeates the cell membrane and generates protein-protein cross-links. Proteins cross-linked to a Myc-tagged protein of interest are copurified by immunoaffinity chromatography and subjected to a procedure which dissociates the cross-linked complexes. After separation by SDS-PAGE, proteins are identified by tandem mass spectrometry. Application of this method enabled the identification of numerous proteins that copurified with a constitutively active form of M-Ras (M-Ras(Q71L)). Among these, we identified the RasGAP-related protein IQGAP1 to be a novel interaction partner of M-Ras(Q71L). This method is applicable to many proteins and will aid in the study of protein-protein interactions.
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Affiliation(s)
- Julian Vasilescu
- The Biomedical Research Centre, University of British Columbia, Vancouver, Canada
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20
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Abstract
The tumor oncoproteins HRAS, KRAS, and NRAS are the founding members of a larger family of at least 35 related human proteins. Using a somewhat broader definition of sequence similarity reveals a more extended superfamily of more than 170 RAS-related proteins. The RAS superfamily of GTP (guanosine triphosphate) hydrolysis-coupled signal transduction relay proteins can be subclassified into RAS, RHO, RAB, and ARF families, as well as the closely related Galpha family. The members of each family can, in turn, be arranged into evolutionarily conserved branches. These groupings reflect structural, biochemical, and functional conservation. Recent findings have provided insights into the signaling characteristics of representative members of most RAS superfamily branches. The analysis presented here may serve as a guide for predicting the function of numerous uncharacterized superfamily members. Also described are guanosine triphosphatases (GTPases) distinct from members of the RAS superfamily. These related proteins employ GTP binding and GTPase domains in diverse structural contexts, expanding the scope of their function in humans.
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21
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Ehrhardt A, David MD, Ehrhardt GRA, Schrader JW. Distinct mechanisms determine the patterns of differential activation of H-Ras, N-Ras, K-Ras 4B, and M-Ras by receptors for growth factors or antigen. Mol Cell Biol 2004; 24:6311-23. [PMID: 15226433 PMCID: PMC434254 DOI: 10.1128/mcb.24.14.6311-6323.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Although GTPases of the Ras family have been implicated in many aspects of the regulation of cells, little is known about the roles of individual family members. Here, we analyzed the mechanisms of activation of H-Ras, N-Ras, K-Ras 4B, and M-Ras by two types of external stimuli, growth factors and ligation of the antigen receptors of B or T lymphocytes (BCRs and TCRs). The growth factors interleukin-3, colony-stimulating factor 1, and epidermal growth factor all preferentially activated M-Ras and K-Ras 4B over H-Ras or N-Ras. Preferential activation of M-Ras and K-Ras 4B depended on the presence of their polybasic carboxy termini, which directed them into high-buoyant-density membrane domains where the activated receptors, adapters, and mSos were also present. In contrast, ligation of the BCR or TCR resulted in activation of H-Ras, N-Ras, and K-Ras 4B, but not M-Ras. This pattern of activation was not influenced by localization of the Ras proteins to membrane domains. Activation of H-Ras, N-Ras, and K-Ras 4B instead depended on the presence of phospholipase C-gamma and RasGRP. Thus, the molecular mechanisms leading to activation of Ras proteins vary with the stimulus and can be influenced by either colocalization with activated receptors or differential sensitivity to the exchange factors activated by a stimulus.
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Affiliation(s)
- Annette Ehrhardt
- The Biomedical Research Centre, University of British Columbia, Vancouver, Canada
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22
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Rodriguez-Viciana P, Sabatier C, McCormick F. Signaling specificity by Ras family GTPases is determined by the full spectrum of effectors they regulate. Mol Cell Biol 2004; 24:4943-54. [PMID: 15143186 PMCID: PMC416418 DOI: 10.1128/mcb.24.11.4943-4954.2004] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ras family GTPases (RFGs) regulate signaling pathways that control multiple biological processes. How signaling specificity among the closely related family members is achieved is poorly understood. We have taken a proteomics approach to signaling by RFGs, and we have analyzed interactions of a panel of RFGs with a comprehensive group of known and potential effectors. We have found remarkable differences in the ability of RFGs to regulate the various isoforms of known effector families. We have also identified several proteins as novel effectors of RFGs with differential binding specificities to the various RFGs. We propose that specificity among RFGs is achieved by the differential regulation of combinations of effector families as well as by the selective regulation of different isoforms within an effector family. An understanding of this new level of complexity in the signaling pathways regulated by RFGs is necessary to understand how they carry out their many cellular functions. It will also likely have critical implications in the treatment of human diseases such as cancer.
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Affiliation(s)
- Pablo Rodriguez-Viciana
- Cancer Research Institute and Comprehensive Cancer Center, University of California, San Francisco, 2340 Sutter St., San Francisco, CA 94143, USA
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23
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Zhang KX, Ward KR, Schrader JW. Multiple Aspects of the Phenotype of Mammary Epithelial Cells Transformed by Expression of Activated M-Ras Depend on an Autocrine Mechanism Mediated by Hepatocyte Growth Factor/Scatter Factor. Mol Cancer Res 2004. [DOI: 10.1158/1541-7786.242.2.4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Multiple aspects of the transformed phenotype induced in a murine mammary epithelial cell line scp-2 by expression of activated G22V M-Ras, including maintainance of cell number at low density, anchorage-independent growth, invasion of Matrigel, and secretion of matrix metalloproteinases (MMP) 2 and 9, were dependent on an autocrine mechanism. Conditioned medium from dense cultures of scp-2 cells expressing G22V M-Ras, but not from parental cells, induced activation of Erk and Akt in cells expressing G22V M-Ras, maintained the cell number and promoted anchorage-independent growth of cells expressing G22V M-Ras (although not the parental cells), and induced scattering of MDCK cells. The latter activities were blocked by neutralizing antibodies to hepatocyte growth factor/scatter factor (HGF/SF) and could be mimicked by HGF/SF. Anti-HGF/SF antibodies also inhibited invasion of Matrigel, and the production of MMP-2 and MMP-9, together with urokinase-type plasminogen activator, was secreted by G22V M-Ras scp-2 cells but not by parental cells. Invasion of Matrigel was blocked by an inhibitor of MMPs, BB94, and by the mitogen-activated protein kinase kinase 1/2 kinase inhibitor PD98059 but was only marginally affected by the phosphatidylinositol 3-kinase inhibitor LY294002. Autocrine HGF/SF was thus critical for expression of key features of the phenotype of mammary epithelial cells transformed by expression of activated M-Ras.
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Affiliation(s)
- Kai-Xin Zhang
- The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Katherine R. Ward
- The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - John W. Schrader
- The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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24
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Ward KR, Zhang KX, Zhang KX, Somasiri AM, Roskelley CD, Schrader JW. Expression of activated M-Ras in a murine mammary epithelial cell line induces epithelial-mesenchymal transition and tumorigenesis. Oncogene 2004; 23:1187-96. [PMID: 14961075 DOI: 10.1038/sj.onc.1207226] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The expression of activated mutants of M-Ras (G22V or Q71L), but not wild-type M-Ras, in a murine mammary epithelial cell line, scp2, resulted in epithelial-mesenchymal transition (EMT) and oncogenic transformation. Cells expressing constitutively active M-Ras continued to grow in the absence of serum and exhibited a loss of the epithelial markers cytokeratin, E-cadherin and beta-catenin, together with a gain of the mesenchymal marker vimentin, a loss of contact inhibition in monolayer growth and a gain of the capacity for anchorage-independent growth. Moreover, unlike the parental cells, they failed to form differentiated mammospheres on Matrigel and instead formed branched networks of cells that grew and invaded the Matrigel. The expression of activated p21 Ras (G12V H-Ras or Q61K N-Ras) also resulted in EMT and tumorigenesis, although there was evidence that expression of higher levels was toxic. Tumors derived from scp2 cells expressing activated M-Ras exhibited activation of Akt and of ERK. The levels of expression of Q71L M-Ras and G12V H-Ras required for tumorigenesis were comparable, although higher levels of the weaker G22V M-Ras mutant were selected for in vivo. These data indicate that the expression of activated mutants of M-Ras was sufficient for oncogenic transformation of a murine mammary epithelial cell line.
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Affiliation(s)
- Katherine R Ward
- The Biomedical Research Centre, 2222, Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
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25
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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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26
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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: 140] [Impact Index Per Article: 6.4] [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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27
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Schrader JW, Schallhorn A, Grill B, Guo X. Activation of small GTPases of the Ras and Rho family by growth factors active on mast cells. Mol Immunol 2002; 38:1181-6. [PMID: 12217381 DOI: 10.1016/s0161-5890(02)00060-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The small GTPases of the Ras and Rho families are activated by the key growth factors for mast cell development and survival, SLF and IL-3. While there are many clues that activation of Ras and Rho proteins play critical roles in growth, survival and differentiation, as well as in functions, such as migration and degranulation, limitations in the specificity of experimental tools still obscure their precise functions. There is increasing evidence that differences in subcellular localization of closely related GTPases determines important differences in their function. However, other data also point to differences in sensitivity to activation by GEF and in the effectors they engage.
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Affiliation(s)
- John W Schrader
- The Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, BC, V6T 1Z3, Vancouver, Canada.
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28
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Hoshino M, Nakamura S. The Ras-like small GTP-binding protein Rin is activated by growth factor stimulation. Biochem Biophys Res Commun 2002; 295:651-6. [PMID: 12099688 DOI: 10.1016/s0006-291x(02)00731-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A novel 25 K Ras-like protein, Rin, binds calmodulin in a Ca2+-dependent manner and is considered to participate in a calcium/calmodulin-mediated signaling pathway. However, little is known about Rin signaling mechanism. Here we examined the signal transduction pathway through Rin protein using pull down assay system. When we stimulated Rin-expressed Cos-7 cells with ionomycin, phorbol 12-myristate 13-acetate or epidermal growth factor (EGF), Rin protein was rapidly activated. Moreover, cells cotransfected with Rin and mSos showed a similar Rin activation profile, and Rin protein was coimmunoprecipitated with mSos protein in vivo. When cells were cotransfected with Rin and Ras-GTPase-activating proteins, basal Rin activity was decreased. Association with Rin and calmodulin was potentiated after stimulation and Rin activation was regulated by both calcium ion and calmodulin. These studies suggest that Rin may be involved in EGF receptor and mSos-mediated signaling pathway and may participate in calcium/calmodulin-mediated cellular processes.
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Affiliation(s)
- Mitsunobu Hoshino
- Division of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1, Ogawahigashi, Kodaira, Tokyo 187-8502, Japan.
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29
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Dumont JE, Dremier S, Pirson I, Maenhaut C. Cross signaling, cell specificity, and physiology. Am J Physiol Cell Physiol 2002; 283:C2-28. [PMID: 12055068 DOI: 10.1152/ajpcell.00581.2001] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The literature on intracellular signal transduction presents a confusing picture: every regulatory factor appears to be regulated by all signal transduction cascades and to regulate all cell processes. This contrasts with the known exquisite specificity of action of extracellular signals in different cell types in vivo. The confusion of the in vitro literature is shown to arise from several causes: the inevitable artifacts inherent in reductionism, the arguments used to establish causal effect relationships, the use of less than adequate models (cell lines, transfections, acellular systems, etc.), and the implicit assumption that networks of regulations are universal whereas they are in fact cell and stage specific. Cell specificity results from the existence in any cell type of a unique set of proteins and their isoforms at each level of signal transduction cascades, from the space structure of their components, from their combinatorial logic at each level, from the presence of modulators of signal transduction proteins and of modulators of modulators, from the time structure of extracellular signals and of their transduction, and from quantitative differences of expression of similar sets of factors.
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Affiliation(s)
- J E Dumont
- Institute of Interdisciplinary Research, Free University of Brussels, Campus Erasme, B-1070 Brussels, Belgium.
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30
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Post GR, Swiderski C, Waldrop BA, Salty L, Glembotski CC, Wolthuis RMF, Mochizuki N. Guanine nucleotide exchange factor-like factor (Rlf) induces gene expression and potentiates alpha 1-adrenergic receptor-induced transcriptional responses in neonatal rat ventricular myocytes. J Biol Chem 2002; 277:15286-92. [PMID: 11847222 DOI: 10.1074/jbc.m111844200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of constitutively active Ras (V12Ras) in cultured neonatal rat ventricular myocytes or targeted cardiac expression of V12Ras in transgenic mice induces myocardial cell growth and expression of genes that are markers of cardiac hypertrophy including atrial natriuretic factor (ANF) and myosin light chain-2. However, the signaling pathways that modulate the effects of Ras on acquisition of the various features of cardiac hypertrophy are not known. We identified the Ral guanine nucleotide exchange factor-like factor (Rlf) in a yeast two-hybrid screen of human heart cDNA library using Ras as bait, suggesting that Ras signaling in the heart may involve Rlf. We demonstrate here that Rlf is expressed in human heart. Expression of wild type Rlf or Rlf-CAAX, a membrane-targeted mutant of Rlf, transactivated ANF and myosin light chain-2 promoters but did not activate canonical cAMP responsive elements or phorbol ester responsive elements, suggesting that Rlf expression does not lead to a generalized increase in transcription. Transfection of mutant ANF promoter-reporter gene constructs demonstrated that the proximal serum response element is both necessary and sufficient for Rlf-inducible ANF expression. Rlf-induced ANF promoter activation required Ral and Cdc42 but not RhoA, Rac1, ERK, or p38 kinase activation. In addition, Rlf potentiated alpha(1)-adrenergic receptor (alpha(1)-AR)-induced ANF expression. Prolonged activation of the alpha(1)-AR increases RalGTP levels in neonatal rat ventricular myocytes, further emphasizing a role for Ral guanine nucleotide exchange factors in alpha(1)-AR signaling. Overall, this study supports the concept that Rlf and Ral are important previously unrecognized signaling components that regulate transcriptional responses in myocardial cells.
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Affiliation(s)
- Ginell R Post
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky 40536, USA.
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31
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Ortiz-Vega S, Khokhlatchev A, Nedwidek M, Zhang XF, Dammann R, Pfeifer GP, Avruch J. The putative tumor suppressor RASSF1A homodimerizes and heterodimerizes with the Ras-GTP binding protein Nore1. Oncogene 2002; 21:1381-90. [PMID: 11857081 DOI: 10.1038/sj.onc.1205192] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2001] [Revised: 11/26/2001] [Accepted: 11/26/2001] [Indexed: 12/14/2022]
Abstract
Nore and RASSF1A are noncatalytic proteins that share 50% identity over their carboxyterminal 300 AA, a segment that encompasses a putative Ras-Rap association (RA) domain. RASSF1 is expressed as several splice variants, each of which contain an RA domain, however the 340 AA RASSF1A, but not the shorter RASSF1C variant, is a putative tumor suppressor. Nore binds to Ras and several Ras-like GTPases in a GTP dependent fashion however neither RASSF1 (A or C) or the C. elegans Nore/RASSF1 homolog, T24F1.3 exhibit any interaction with Ras or six other Ras-like GTPases in a yeast two-hybrid expression assay. A low recovery of RASSF1A (but not RASSF1C) in association with RasG12V is observed however on transient expression in COS cells. Nore and RASSF1A can each efficiently homodimerize and heterodimerize with each other through their nonhomologous aminoterminal segments. Recombinant RASSF1C exhibits a much weaker ability to homodimerize or heterodimerize; thus the binding of RASSF1C to Nore is very much less than the binding of RASSF1A to Nore. The association of RASSF1A with RasG12V in COS cells appears to reflect the heterodimerization of RASSF1A with Nore, inasmuch the recovery of RASSF1A with RasG12V is increased by concurrent expression of full length Nore, and abolished by expression of Nore deleted of its RA domain. The preferential ability of RASSF1A to heterodimerize with Nore and thereby associate with Ras-like GTPases may be relevant to its putative tumor suppressor function.
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Affiliation(s)
- Sara Ortiz-Vega
- Diabetes Unit and Medical Services, Massachusetts General Hospital, Boston, Massachusetts, MA 02114, USA
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Wang FS, Wang CJ, Huang HJ, Chung H, Chen RF, Yang KD. Physical shock wave mediates membrane hyperpolarization and Ras activation for osteogenesis in human bone marrow stromal cells. Biochem Biophys Res Commun 2001; 287:648-55. [PMID: 11563844 DOI: 10.1006/bbrc.2001.5654] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physical shock wave (SW) has shown effectiveness on promotion of bone growth. We have recently demonstrated that SW could promote bone marrow stromal cell differentiation toward osteoprogenitor associated with induction of TGF-beta1. We have further demonstrated that SW-induced membrane hyperpolarization and Ras activation acted an early signal for the osteogenesis in human bone marrow stromal cells. An optimal dose of SW treatment at 0.16 mJ/mm(2) for 500 impulses induced a rapid membrane hyperpolarization in 5 min, activation of Ras in 30 min, and cell proliferation in 2 days. The SW-promoted cell growth was related to osteogenesis as demonstrated by increase of bone alkaline phosphatase activity in 6 days and osteocalcin mRNA expression in 12 days. In support that SW-induced Ras activation mediated osteogenesis of human bone marrow stromal cells, we further demonstrated that transfection of bone marrow stromal cells with a dominant negative Ras mutant (Asn-17 ras(H)) abrogated the SW enhancement of osteogenic transcription factor (CBFA1) activation, osteocalcin mRNA expression, and bone nodule formations. These results suggest that physical SW promotes bone marrow stromal cell differentiation toward osteogenic lineage via membrane hyperpolarization, followed by Ras activation and specific osteogenic transcription factor CBFA1 expression. A link between physical SW and biomembrane perturbation-mediated Ras activation may highlight how noninvasive physical agents could be used to promote fracture healing and to rescue patients with osteoporosis and osteopenic disorders in the future.
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Affiliation(s)
- F S Wang
- Department of Medical Research, Chang Gung University, Kaohsiung, Taiwan, Republic of China
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