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Chen Y, Chen B, Wang H, Hu W, Wang S, Zhou Z. Combined elevated temperature and soil waterlogging stresses limit fibre biomass accumulation and fibre quality formation by disrupting protein activity during cotton fibre development. FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:715-724. [PMID: 31104693 DOI: 10.1071/fp18192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
Soil waterlogging and high temperature conditions generally occur together, especially in the Yangtze River Valley, China, negatively affecting cotton (Gossypium hirsutum L.) fibre development. Therefore, combined elevated temperature (34.1/29.0°C) and soil waterlogging (6 days) were imposed to study their combined effects on fibre biomass and fibre qualities (length, strength and micronaire). The results showed that in the boll cohort exposed to waterlogging and/or elevated air temperature, combined elevated temperature and soil waterlogging decreased final fibre length (by 8.9-11.3%) and fibre biomass (by 25.8-33.9%) more than either stress individually. A total of 113, 263 and 290 differential abundance proteins were identified related to elevated temperature, waterlogging and the two treatments combined, respectively, in fibres at 15 days after anthesis via the isobaric tags for relative and absolute quantitation technique, which were classified as: carbohydrate and energy metabolism (21.7%), protein metabolism (16.6%), amino acid metabolism (12.8%), intracellular structural components (6.6%), transport (7.9%), oxidation-reduction process (7.9%), signal transduction (5.2%), lipid metabolism (5.2%), stress response (5.2%), nucleic acid metabolism (4.5%), organic acid metabolism (3.4%) and others (2.1%). Both vacuolar ATPase (V-ATPase) and plasma membrane H+-ATPase (PMH+-ATPase) were responsible for fibre length formation, although V-ATPase expression may play a major role in determining fibre cell elongation rather than PM H+-ATPase expression. It was concluded that fibre cell elongation and secondary wall thickening were inhibited mainly by reduced accumulation of osmolytes, blocked synthesis and transport of secondary wall components, and disruption of the cytoskeleton system under combined elevated temperature and soil waterlogging.
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Affiliation(s)
- Yinglong Chen
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China; and College of Agriculture, Yangzhou University, Yangzhou 225009, PR China
| | - Binglin Chen
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China
| | - Haimiao Wang
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China
| | - Wei Hu
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China
| | - Shanshan Wang
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China
| | - Zhiguo Zhou
- College of Agriculture, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, PR China; and Corresponding author.
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Ritchie C, Mack A, Harper L, Alfadhli A, Stork PJS, Nan X, Barklis E. Analysis of K-Ras Interactions by Biotin Ligase Tagging. Cancer Genomics Proteomics 2018. [PMID: 28647697 DOI: 10.21873/cgp.20034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Mutations of the human K-Ras 4B (K-Ras) G protein are associated with a significant proportion of all human cancers. Despite this fact, a comprehensive analysis of K-Ras interactions is lacking. Our investigations focus on characterization of the K-Ras interaction network. MATERIALS AND METHODS We employed a biotin ligase-tagging approach, in which tagged K-Ras proteins biotinylate neighbor proteins in a proximity-dependent fashion, and proteins are identified via mass spectrometry (MS) sequencing. RESULTS In transfected cells, a total of 748 biotinylated proteins were identified from cells expressing biotin ligase-tagged K-Ras variants. Significant differences were observed between membrane-associated variants and a farnesylation-defective mutant. In pancreatic cancer cells, 56 K-Ras interaction partners were identified. Most of these were cytoskeletal or plasma membrane proteins, and many have been identified previously as potential cancer biomarkers. CONCLUSION Biotin ligase tagging offers a rapid and convenient approach to the characterization of K-Ras interaction networks.
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Affiliation(s)
- Christopher Ritchie
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, U.S.A
| | - Andrew Mack
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, U.S.A
| | - Logan Harper
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, U.S.A
| | - Ayna Alfadhli
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, U.S.A
| | - Philip J S Stork
- Department of Vollum Institute, Oregon Health & Science University, Portland, OR, U.S.A
| | - Xiaolin Nan
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, U.S.A
| | - Eric Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, U.S.A.
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Mevalonate Cascade Inhibition by Simvastatin Induces the Intrinsic Apoptosis Pathway via Depletion of Isoprenoids in Tumor Cells. Sci Rep 2017; 7:44841. [PMID: 28344327 PMCID: PMC5366866 DOI: 10.1038/srep44841] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/14/2017] [Indexed: 12/21/2022] Open
Abstract
The mevalonate (MEV) cascade is responsible for cholesterol biosynthesis and the formation of the intermediate metabolites geranylgeranylpyrophosphate (GGPP) and farnesylpyrophosphate (FPP) used in the prenylation of proteins. Here we show that the MEV cascade inhibitor simvastatin induced significant cell death in a wide range of human tumor cell lines, including glioblastoma, astrocytoma, neuroblastoma, lung adenocarcinoma, and breast cancer. Simvastatin induced apoptotic cell death via the intrinsic apoptotic pathway. In all cancer cell types tested, simvastatin-induced cell death was not rescued by cholesterol, but was dependent on GGPP- and FPP-depletion. We confirmed that simvastatin caused the translocation of the small Rho GTPases RhoA, Cdc42, and Rac1/2/3 from cell membranes to the cytosol in U251 (glioblastoma), A549 (lung adenocarcinoma) and MDA-MB-231(breast cancer). Simvastatin-induced Rho-GTP loading significantly increased in U251 cells which were reversed with MEV, FPP, GGPP. In contrast, simvastatin did not change Rho-GTP loading in A549 and MDA-MB-231. Inhibition of geranylgeranyltransferase I by GGTi-298, but not farnesyltransferase by FTi-277, induced significant cell death in U251, A549, and MDA-MB-231. These results indicate that MEV cascade inhibition by simvastatin induced the intrinsic apoptosis pathway via inhibition of Rho family prenylation and depletion of GGPP, in a variety of different human cancer cell lines.
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Goldfinger LE, Michael JV. Regulation of Ras signaling and function by plasma membrane microdomains. Biosci Trends 2017; 11:23-40. [PMID: 28179601 DOI: 10.5582/bst.2016.01220] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Together H-, N- and KRAS mutations are major contributors to ~30% of all human cancers. Thus, Ras inhibition remains an important anti-cancer strategy. The molecular mechanisms of isotypic Ras oncogenesis are still not completely understood. Monopharmacological therapeutics have not been successful in the clinic. These disappointing outcomes have led to attempts to target elements downstream of Ras, mainly targeting either the Phosphatidylinositol 3-Kinase (PI3K) or Mitogen-Activated Protein Kinase (MAPK) pathways. While several such approaches are moderately effective, recent efforts have focused on preclinical evaluation of combination therapies to improve efficacies. This review will detail current understanding of the contributions of plasma membrane microdomain targeting of Ras to mitogenic and tumorigenic signaling and tumor progression. Moreover, this review will outline novel approaches to target Ras in cancers, including targeting schemes for new drug development, as well as putative re-purposing of drugs in current use to take advantage of blunting Ras signaling by interfering with Ras plasma membrane microdomain targeting and retention.
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Affiliation(s)
- Lawrence E Goldfinger
- Department of Anatomy & Cell Biology and The Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine at Temple University, and Cancer Biology Program, Fox Chase Cancer Center
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5
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Caruso ME, Jenna S, Baillie DL, Bossé R, Simpson JC, Chevet E, Taouji S. Systematic functional analysis of the Ras GTPase family unveils a conserved network required for anterograde protein trafficking. Proteomics 2016; 17. [PMID: 27957805 DOI: 10.1002/pmic.201600302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 11/24/2016] [Accepted: 12/07/2016] [Indexed: 11/05/2022]
Abstract
Phylogeny is often used to compare entire families of genes/proteins. We previously showed that classification of Caenorhabditis elegans Rho GTPases on the basis of their enzymatic properties was significantly different from sequence alignments. To further develop this concept, we have developed an integrated approach to classify C. elegans small GTPases based on functional data comprising affinity for GTP, sub-cellular localization, tissue distribution and silencing impact. This analysis led to establish a novel functional classification for small GTPases. To test the relevance of this classification in mammals, we focused our attention on the human orthologs of small GTPases from a specific group comprising arf-1.2, evl-20, arl-1, Y54E10BR.2, unc-108 and rab-7. We then tested their involvement in protein secretion and membrane traffic in mammalian systems. Using this approach we identify a novel network containing 18 GTPases, and 23 functionally interacting proteins, conserved between C. elegans and mammals, which is involved in membrane traffic and protein secretion.
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Affiliation(s)
| | - Sarah Jenna
- Department of Surgery, McGill University, Montreal, QC, Canada
| | - David L Baillie
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | | | - Jeremy C Simpson
- School of Biology & Environmental Science and Conway Institute of Biomolecular & Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - Eric Chevet
- Department of Surgery, McGill University, Montreal, QC, Canada.,INSERM U1242, COSS, Université de Rennes-1, CLCC Eugene Marquis, Rennes, France.,BMYscreen, Bordeaux, France
| | - Saïd Taouji
- BMYscreen, Bordeaux, France.,INSERM U1218, CLCC Institut Bergonié, Bordeaux, France
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Riecken LB, Tawamie H, Dornblut C, Buchert R, Ismayel A, Schulz A, Schumacher J, Sticht H, Pohl KJ, Cui Y, Reis A, Morrison H, Abou Jamra R. Inhibition of RAS Activation Due to a Homozygous Ezrin Variant in Patients with Profound Intellectual Disability. Hum Mutat 2015; 36:270-8. [DOI: 10.1002/humu.22737] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/01/2014] [Indexed: 01/19/2023]
Affiliation(s)
- Lars Björn Riecken
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | - Hasan Tawamie
- Institute of Human Genetics; Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Carsten Dornblut
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | - Rebecca Buchert
- Institute of Human Genetics; Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Amina Ismayel
- Praxis of Pediatrics; Jesser El Sheghour; Idlib Syria
| | - Alexander Schulz
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | | | - Heinrich Sticht
- Bioinformatics; Institute of Biochemistry; Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Katja J. Pohl
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | - Yan Cui
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | - André Reis
- Institute of Human Genetics; Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
| | - Helen Morrison
- Leibniz Institute for Age Research; Fritz Lipmann Institute; Jena Germany
| | - Rami Abou Jamra
- Institute of Human Genetics; Friedrich-Alexander-Universität Erlangen-Nürnberg; Erlangen Germany
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7
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Zhang YF, Wang F, Li FH, Sun YF, Zhang Y, Guo PR, He LL, Zhu YN. Influence of Biejiajian pill on PDGF and Ras signaling pathways in hepatic fibrosis in rats. Shijie Huaren Xiaohua Zazhi 2014; 22:4060-4067. [DOI: 10.11569/wcjd.v22.i27.4060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To explore the anti-fibrotic mechanism of Biejiajian pill, a traditional Chinese medicine for activating blood circulation and eliminating stasis, in rats with hepatic fibrosis.
METHODS: Hepatic fibrosis was induced in rats by subcutaneous injection of CCl4. SD rats were randomly divided into five groups: a control group, a model group, low-, medium- and high-dose Biejiajian pill treatment groups. The three treatment groups were given Biejiajian pill 0.55, 1.10, and 2.20 g/(kg•d), respectively, while the normal control group and model group were treated with equal volume of normal saline by gavage. At the 11th week, hepatic pathological changes were observed. The immunohistochemical technique was applied to analyze the expression of extracellular signal regulated kinase 1 (ERK1) in hepatic tissue. RT-PCR was applied to analyze the expression of platelet derivative growth factor (PDGF) and Ras mRNAs in hepatic tissue.
RESULTS: Compared with the control group, the expression levels of ERK1 protein and PDGF and Ras mRNAs increased significantly in the model group (0.19 ± 0.001 vs 0.71 ± 0.018, 0.12 ± 0.000 vs 0.42 ± 0.006, 0.12 ± 0.000 vs 0.44 ± 0.017, P < 0.05). Compared with the model group, Biejiajian pill significantly improved hepatic pathological changes and decreased the expression of ERK1 protein and PDGF and Ras mRNAs, and the efficacy of high-dose Biejiajian pill was the best.
CONCLUSION: Biejiajian pill can improve hepatic pathological changes in rats with hepatic fibrosis possibly via mechanisms associated with activating the Ras/ERK signaling pathway.
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Silver L, Michael JV, Goldfinger LE, Gallo G. Activation of PI3K and R-Ras signaling promotes the extension of sensory axons on inhibitory chondroitin sulfate proteoglycans. Dev Neurobiol 2014; 74:918-33. [PMID: 24578264 DOI: 10.1002/dneu.22174] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 02/24/2014] [Indexed: 12/22/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are extracellular inhibitors of axon extension and plasticity, and cause growth cones to exhibit dystrophic behaviors. Phosphoinositide 3-kinase (PI3K) is a lipid kinase activated by axon growth promoting signals. In this study, we used embryonic chicken dorsal root ganglion neurons to determine if CSPGs impair signaling through PI3K. We report that CSPGs inhibit PI3K signaling in axons and growth cones, as evidenced by decreased levels of phosphorylated downstream kinases (Akt and S6). Direct activation of PI3K signaling, using a cell permeable phosphopeptide (PI3Kpep), countered the effects of CSPGs on growth cones and axon extension. Both overnight and acute treatment with PI3Kpep promoted axon extension on CSPG-coated substrates. The R-Ras GTPase is an upstream positive regulator of PI3K signaling. Expression of constitutively active R-Ras promoted axon extension and growth cone elaboration on CSPGs and permissive substrata. In contrast, an N-terminus-deleted constitutively active R-Ras, deficient in PI3K activation, promoted axon extension but not growth cone elaboration on CSPGs and permissive substrata. These data indicate that activation of R-Ras-PI3K signaling may be a viable approach for manipulating axon extension on CSPGs.
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Affiliation(s)
- Lee Silver
- Department of Anatomy and Cell Biology, Temple University School of Medicine, 3500 North Broad St., Philadelphia, Pennsylvania, 19140; Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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9
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Borrego-Diaz E, Terai K, Lialyte K, Wise AL, Esfandyari T, Behbod F, Mautner VF, Spyra M, Taylor S, Parada LF, Upadhyaya M, Farassati F. Overactivation of Ras signaling pathway in CD133+ MPNST cells. J Neurooncol 2012; 108:423-34. [DOI: 10.1007/s11060-012-0852-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 03/13/2012] [Indexed: 01/06/2023]
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10
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Rojas AM, Fuentes G, Rausell A, Valencia A. The Ras protein superfamily: evolutionary tree and role of conserved amino acids. ACTA ACUST UNITED AC 2012; 196:189-201. [PMID: 22270915 PMCID: PMC3265948 DOI: 10.1083/jcb.201103008] [Citation(s) in RCA: 280] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Ras superfamily is a fascinating example of functional diversification in the context of a preserved structural framework and a prototypic GTP binding site. Thanks to the availability of complete genome sequences of species representing important evolutionary branch points, we have analyzed the composition and organization of this superfamily at a greater level than was previously possible. Phylogenetic analysis of gene families at the organism and sequence level revealed complex relationships between the evolution of this protein superfamily sequence and the acquisition of distinct cellular functions. Together with advances in computational methods and structural studies, the sequence information has helped to identify features important for the recognition of molecular partners and the functional specialization of different members of the Ras superfamily.
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Affiliation(s)
- Ana Maria Rojas
- Computational Cell Biology Group, Institute for Predictive and Personalized Medicine of Cancer, 08916 Badalona, Barcelona, Spain.
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Tsyganov MA, Kolch W, Kholodenko BN. The topology design principles that determine the spatiotemporal dynamics of G-protein cascades. MOLECULAR BIOSYSTEMS 2012; 8:730-43. [DOI: 10.1039/c2mb05375f] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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12
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de Curtis I, Meldolesi J. Cell surface dynamics – how Rho GTPases orchestrate the interplay between the plasma membrane and the cortical cytoskeleton. J Cell Sci 2012; 125:4435-44. [DOI: 10.1242/jcs.108266] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Small GTPases are known to regulate hundreds of cell functions. In particular, Rho family GTPases are master regulators of the cytoskeleton. By regulating actin nucleation complexes, Rho GTPases control changes in cell shape, including the extension and/or retraction of surface protrusions and invaginations. Protrusion and invagination of the plasma membrane also involves the interaction between the plasma membrane and the cortical cytoskeleton. This interplay between membranes and the cytoskeleton can lead to an increase or decrease in the plasma membrane surface area and its tension as a result of the fusion (exocytosis) or internalization (endocytosis) of membranous compartments, respectively. For a long time, the cytoskeleton and plasma membrane dynamics were investigated separately. However, studies from many laboratories have now revealed that Rho GTPases, their modulation of the cytoskeleton, and membrane traffic are closely connected during the dynamic remodeling of the cell surface. Arf- and Rab-dependent exocytosis of specific vesicles contributes to the targeting of Rho GTPases and their regulatory factors to discrete sites of the plasma membrane. Rho GTPases regulate the tethering of exocytic vesicles and modulate their subsequent fusion. They also have crucial roles in the different forms of endocytosis, where they participate in the sorting of membrane domains as well as the sculpting and sealing of membrane flasks and cups. Here, we discuss how cell surface dynamics depend on the orchestration of the cytoskeleton and the plasma membrane by Rho GTPases.
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Abstract
Inositol phospholipids have been implicated in almost all aspects of cellular physiology including spatiotemporal regulation of cellular signaling, acquisition of cellular polarity, specification of membrane identity, cytoskeletal dynamics, and regulation of cellular adhesion, motility, and cytokinesis. In this review, we examine the critical role phosphoinositides play in these processes to execute the establishment and maintenance of cellular architecture. Epithelial tissues perform essential barrier and transport functions in almost all major organs. Key to their development and function is the establishment of epithelial cell polarity. We place a special emphasis on highlighting recent studies demonstrating phosphoinositide regulation of epithelial cell polarity and how individual cells use phosphoinositides to further organize into epithelial tissues.
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Affiliation(s)
- Annette Shewan
- Department of Anatomy, University of California, San Francisco, San Francisco, California 94143-2140, USA
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Jeon H, Zheng LT, Lee S, Lee WH, Park N, Park JY, Heo WD, Lee MS, Suk K. Comparative analysis of the role of small G proteins in cell migration and cell death: cytoprotective and promigratory effects of RalA. Exp Cell Res 2011; 317:2007-18. [PMID: 21645515 DOI: 10.1016/j.yexcr.2011.05.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 12/30/2022]
Abstract
Small G protein superfamily consists of more than 150 members, and is classified into six families: the Ras, Rho, Rab, Arf, Ran, and RGK families. They regulate a wide variety of cell functions such as cell proliferation/differentiation, cytoskeletal reorganization, vesicle trafficking, nucleocytoplasmic transport and microtubule organization. The small G proteins have also been shown to regulate cell death/survival and cell shape. In this study, we compared the role of representative members of the six families of small G proteins in cell migration and cell death/survival, two cellular phenotypes that are associated with inflammation, tumorigenesis, and metastasis. Our results show that small G proteins of the six families differentially regulate cell death and cell cycle distribution. In particular, our results indicate that Rho family of small G proteins is antiapoptotic. Ras, Rho, and Ran families promoted cell migration. There was no significant correlation between the cell death- and cell migration-regulating activities of the small G proteins. Nevertheless, RalA was not only cytoprotective against multiple chemotherapeutic drugs, but also promigratory inducing stress fiber formation, which was accompanied by the activation of Akt and Erk pathways. Our study provides a framework for further systematic investigation of small G proteins in the perspectives of cell death/survival and motility in inflammation and cancer.
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Affiliation(s)
- Hyejin Jeon
- Department of Pharmacology, Brain Science and Engineering Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
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15
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Valbuena A, Sanz-García M, López-Sánchez I, Vega FM, Lazo PA. Roles of VRK1 as a new player in the control of biological processes required for cell division. Cell Signal 2011; 23:1267-72. [PMID: 21514377 DOI: 10.1016/j.cellsig.2011.04.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 04/04/2011] [Indexed: 11/28/2022]
Abstract
Cell division, in addition to an accurate transmission of genetic information to daughter cells, also requires the temporal and spatial coordination of several biological processes without which cell division would not be feasible. These processes include the temporal coordination of DNA replication and chromosome segregation, regulation of nuclear envelope disassembly and assembly, chromatin condensation and Golgi fragmentation for its redistribution into daughter cells, among others. However, little is known regarding regulatory proteins and signalling pathways that might participate in the coordination of all these different biological functions. Such regulatory players should directly have a role in the processes leading to cell division. VRK1 (Vaccinia-related kinase 1) is an early response gene required for cyclin D1 expression, regulates p53 by a specific Thr18 phosphorylation, controls chromatin condensation by histone phosphorylation, nuclear envelope assembly by phosphorylation of BANF1, and participates in signalling required for Golgi fragmentation late in the G2 phase. We propose that VRK1, a Ser-Thr kinase, might be a candidate to play an important coordinator role in these cell division processes as part of a novel signalling pathway.
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Affiliation(s)
- Alberto Valbuena
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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16
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May D, Pan S, Crispin DA, Lai K, Bronner MP, Hogan J, Hockenbery DM, McIntosh M, Brentnall TA, Chen R. Investigating neoplastic progression of ulcerative colitis with label-free comparative proteomics. J Proteome Res 2010; 10:200-9. [PMID: 20828217 DOI: 10.1021/pr100574p] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Patients with extensive ulcerative colitis (UC) have an increased risk of colorectal cancer. Although UC patients generally undergo lifelong colonoscopic surveillance to detect dysplasia or cancer in the colon, detection of cancer in this manner is expensive and invasive. An objective biomarker of dysplasia would vastly improve the clinical management of cancer risk in UC patients. In the current study, accurate mass and time methods with ion intensity-based label-free proteomics are applied to profile individual rectal and colon samples from UC patients with dysplasia or cancer (UC progressors) compared to rectal samples from patients that are dysplasia/cancer free (UC nonprogressors) to identify a set of proteins in the rectum mucosa that differentiate the two groups. In addition to the identification of proteins in UC dysplastic colon tissue, we for the first time identified differentially expressed proteins in nondysplastic rectal tissue from UC progressors. This provides a candidate pool of biomarkers for dysplasia/cancer that could be detected in a random nondysplastic rectal biopsy. Mitochondrial proteins, cytoskeletal proteins, RAS superfamily, proteins relating to apoptosis and metabolism were important protein clusters differentially expressed in the nondysplastic and dysplastic tissues of UC progressors, suggesting their importance in the early stages of UC neoplastic progression. Among the differentially expressed proteins, immunohistochemistry analysis confirmed that TRAP1 displayed increased IHC staining in UC progressors, in both dysplastic and nondysplastic tissue, and CPS1 showed a statistically significant difference in IHC staining between the nonprogressor and progressor groups. Furthermore, rectal CPS1 staining could be used to predict dysplasia or cancer in the colon with 87% sensitivity and 45% specificity, demonstrating the feasibility of using surrogate biomarkers in rectal biopsies to predict dysplasia and/or cancer in the colon.
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Affiliation(s)
- Damon May
- Fred Hutchinson Cancer Research Center, Molecular Diagnostics Program, Seattle, Washington 98109, USA
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Hollande F, Pannequin J, Joubert D. The long road to colorectal cancer therapy: Searching for the right signals. Drug Resist Updat 2010; 13:44-56. [PMID: 20176501 DOI: 10.1016/j.drup.2009.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Revised: 01/25/2010] [Accepted: 01/26/2010] [Indexed: 02/07/2023]
Affiliation(s)
- Frédéric Hollande
- CNRS, UMR 5203, Institut de Génomique Fonctionnelle, Montpellier F-34094, France.
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Abstract
Rheb belongs to a unique family within the Ras superfamily of G-proteins. Although initially identified in rat brain, this G-protein is highly conserved from yeast to human. While only one Rheb is present in lower eukaryotes, two Rheb proteins exist in mammalian cells. A number of studies establish that one of the functions of Rheb is to activate mTOR leading to growth. In particular, the ability of Rheb to activate mTORC1 in vitro points to direct interaction of Rheb with the mTORC1 complex. Additional functions of Rheb that are independent of mTOR have also been suggested.
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Affiliation(s)
- Nitika Parmar
- Biology Program, California State University Channel Islands, 1 University Drive, Camarillo, California, USA
| | - Fuyuhiko Tamanoi
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California, USA
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Collier FM, Loving A, Baker AJ, McLeod J, Walder K, Kirkland MA. RTKN2 Induces NF-KappaB Dependent Resistance to Intrinsic Apoptosis in HEK Cells and Regulates BCL-2 Genes in Human CD4(+) Lymphocytes. J Cell Death 2009; 2:9-23. [PMID: 26124677 PMCID: PMC4474337 DOI: 10.4137/jcd.s2891] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The gene for Rhotekin 2 (RTKN2) was originally identified in a promyelocytic cell line resistant to oxysterol-induced apoptosis. It is differentially expressed in freshly isolated CD4+ T-cells compared with other hematopoietic cells and is down-regulated following activation of the T-cell receptor. However, very little is known about the function of RTKN2 other than its homology to Rho-GTPase effector, rhotekin, and the possibility that they may have similar roles. Here we show that stable expression of RTKN2 in HEK cells enhanced survival in response to intrinsic apoptotic agents; 25-hydroxy cholesterol and camptothecin, but not the extrinsic agent, TNFα. Inhibitors of NF-KappaB, but not MAPK, reversed the resistance and mitochondrial pro-apoptotic genes, Bax and Bim, were down regulated. In these cells, there was no evidence of RTKN2 binding to the GTPases, RhoA or Rac2. Consistent with the role of RTKN2 in HEK over-expressing cells, suppression of RTKN2 in primary human CD4+ T-cells reduced viability and increased sensitivity to 25-OHC. The expression of the pro-apoptotic genes, Bax and Bim were increased while BCL-2 was decreased. In both cell models RTKN2 played a role in the process of intrinsic apoptosis and this was dependent on either NF-KappaB signaling or expression of downstream BCL-2 genes. As RTKN2 is a highly expressed in CD4+ T-cells it may play a role as a key signaling switch for regulation of genes involved in T-cell survival.
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Affiliation(s)
- Fiona M Collier
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia. ; Metabolic Research Unit, School of Medicine and Institute for Technology Research and Innovation, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Andrea Loving
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia
| | - Adele J Baker
- Department of Malignant Haematology and Stem Cell Transplantation, The Alfred Hospital, Melbourne, Victoria, 3181, Australia
| | - Janet McLeod
- School of Medicine, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Ken Walder
- Metabolic Research Unit, School of Medicine and Institute for Technology Research and Innovation, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Mark A Kirkland
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia
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Abstract
Ras leads an important signaling pathway that is deregulated in neurofibromatosis type 1 and malignant peripheral nerve sheath tumor (MPNST). In this study, we show that overactivation of Ras and many of its downstream effectors occurred in only a fraction of MPNST cell lines. RalA, however, was overactivated in all MPNST cells and tumor samples compared to nontransformed Schwann cells. Silencing Ral or inhibiting it with a dominant-negative Ral (Ral S28N) caused a significant reduction in proliferation, invasiveness, and in vivo tumorigenicity of MPNST cells. Silencing Ral also reduced the expression of epithelial mesenchymal transition markers. Expression of the NF1-GTPase-related domain (NF1-GRD) diminished the levels of Ral activation, implicating a role for neurofibromin in regulating RalA activation. NF1-GRD treatment caused a significant decrease in proliferation, invasiveness, and cell cycle progression, but cell death increased. We propose Ral overactivation as a novel cell signaling abnormality in MPNST that leads to important biological outcomes with translational ramifications.
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Regulator of G-protein signaling 14 (RGS14) is a selective H-Ras effector. PLoS One 2009; 4:e4884. [PMID: 19319189 PMCID: PMC2655719 DOI: 10.1371/journal.pone.0004884] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 02/18/2009] [Indexed: 11/29/2022] Open
Abstract
Background Regulator of G-protein signaling (RGS) proteins have been well-described as accelerators of Gα-mediated GTP hydrolysis (“GTPase-accelerating proteins” or GAPs). However, RGS proteins with complex domain architectures are now known to regulate much more than Gα GTPase activity. RGS14 contains tandem Ras-binding domains that have been reported to bind to Rap- but not Ras GTPases in vitro, leading to the suggestion that RGS14 is a Rap-specific effector. However, more recent data from mammals and Drosophila imply that, in vivo, RGS14 may instead be an effector of Ras. Methodology/Principal Findings Full-length and truncated forms of purified RGS14 protein were found to bind indiscriminately in vitro to both Rap- and Ras-family GTPases, consistent with prior literature reports. In stark contrast, however, we found that in a cellular context RGS14 selectively binds to activated H-Ras and not to Rap isoforms. Co-transfection / co-immunoprecipitation experiments demonstrated the ability of full-length RGS14 to assemble a multiprotein complex with components of the ERK MAPK pathway in a manner dependent on activated H-Ras. Small interfering RNA-mediated knockdown of RGS14 inhibited both nerve growth factor- and basic fibrobast growth factor-mediated neuronal differentiation of PC12 cells, a process which is known to be dependent on Ras-ERK signaling. Conclusions/Significance In cells, RGS14 facilitates the formation of a selective Ras·GTP-Raf-MEK-ERK multiprotein complex to promote sustained ERK activation and regulate H-Ras-dependent neuritogenesis. This cellular function for RGS14 is similar but distinct from that recently described for its closely-related paralogue, RGS12, which shares the tandem Ras-binding domain architecture with RGS14.
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Recacha R, Boulet A, Jollivet F, Monier S, Houdusse A, Goud B, Khan AR. Structural basis for recruitment of Rab6-interacting protein 1 to Golgi via a RUN domain. Structure 2009; 17:21-30. [PMID: 19141279 DOI: 10.1016/j.str.2008.10.014] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Revised: 10/12/2008] [Accepted: 10/15/2008] [Indexed: 12/31/2022]
Abstract
Small GTPase Rab6 regulates vesicle trafficking at the level of Golgi via recruitment of numerous and unrelated effectors. The crystal structure of Rab6a(GTP) in complex with a 378-residue internal fragment of the effector Rab6IP1 was solved at 3.2 angstroms resolution. This Rab6IP1 region encompasses an all alpha-helical RUN domain followed in tandem by a PLAT domain that adopts a beta sandwich fold. The structure reveals that the first and last alpha helices of the RUN domain mediate binding to switch I, switch II, and the interswitch region of Rab6. It represents the largest Rab-effector complex determined to date. Comparisons with the recent structure of Rab6 in complex with an unrelated effector, human golgin GCC185, reveals significant conformational changes in the conserved hydrophobic triad of Rab6. Flexibility in the switch and interswitch regions of Rab6 mediates recognition of compositionally distinct alpha-helical coiled coils, thereby contributing to Rab6 promiscuity in effector recruitment.
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Affiliation(s)
- Rosario Recacha
- School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland
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23
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Schwartz SL, Tessema M, Buranda T, Pylypenko O, Rak A, Simons PC, Surviladze Z, Sklar LA, Wandinger-Ness A. Flow cytometry for real-time measurement of guanine nucleotide binding and exchange by Ras-like GTPases. Anal Biochem 2008; 381:258-66. [PMID: 18638444 DOI: 10.1016/j.ab.2008.06.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Accepted: 06/30/2008] [Indexed: 11/18/2022]
Abstract
Ras-like small GTPases cycle between GTP-bound active and GDP-bound inactive conformational states to regulate diverse cellular processes. Despite their importance, detailed kinetic or comparative studies of family members are rarely undertaken due to the lack of real-time assays measuring nucleotide binding or exchange. Here we report a bead-based flow cytometric assay that quantitatively measures the nucleotide binding properties of glutathione-S-transferase (GST) chimeras for prototypical Ras family members Rab7 and Rho. Measurements are possible in the presence or absence of Mg(2+), with magnesium cations principally increasing affinity and slowing nucleotide dissociation rates 8- to 10-fold. GST-Rab7 exhibited a 3-fold higher affinity for guanosine diphosphate (GDP) relative to guanosine triphosphate (GTP) that is consistent with a 3-fold slower dissociation rate of GDP. Strikingly, GST-Rab7 had a marked preference for GTP with ribose ring-conjugated BODIPY FL. The more commonly used gamma-NH-conjugated BODIPY FL GTP analogue failed to bind to GST-Rab7. In contrast, both BODIPY analogues bound equally well to GST-RhoA and GST-RhoC. Comparisons of the GST-Rab7 and GST-RhoA GTP binding pockets provide a structural basis for the observed binding differences. In sum, the flow cytometric assay can be used to measure nucleotide binding properties of GTPases in real time and to quantitatively assess differences between GTPases.
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Affiliation(s)
- Samantha L Schwartz
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131, USA
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