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Gossen S, Gerstner S, Borchers A. The RhoGEF Trio is transported by microtubules and affects microtubule stability in migrating neural crest cells. Cells Dev 2024; 177:203899. [PMID: 38160720 DOI: 10.1016/j.cdev.2023.203899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/08/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
Directed cell migration requires a local fine-tuning of Rho GTPase activity to control protrusion formation, cell-cell contraction, and turnover of cellular adhesions. The Rho guanine nucleotide exchange factor (GEF) TRIO is ideally suited to control RhoGTPase activity because it combines two distinct catalytic domains to control Rac1 and RhoA activity in one molecule. However, at the cellular level, this molecular feature also requires a tight spatiotemporal control of TRIO activity. Here, we analyze the dynamic localization of Trio in Xenopus cranial neural crest (NC) cells, where we have recently shown that Trio is required for protrusion formation and migration. Using live cell imaging, we find that the GEF2 domain, but not the GEF1 domain of Trio, dynamically colocalizes with EB3 at microtubule plus-ends. Microtubule-mediated transport of Trio appears to be relevant for its function in NC migration, as a mutant GEF2 construct lacking the SxIP motif responsible for microtubule plus-end localization was significantly impaired in its ability to rescue the Trio loss-of-function phenotype compared to wild-type GEF2. Furthermore, by analyzing microtubule dynamics in migrating NC cells, we observed that loss of Trio function stabilized microtubules at cell-cell contact sites compared to controls, whereas they were destabilized at the leading edge of NC cells. Our data suggest that Trio is transported by microtubules to distinct subcellular locations where it has different functions in controlling microtubule stability, cell morphology, and cell-cell interaction during directed NC migration.
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Affiliation(s)
- Stefanie Gossen
- Department of Biology, Molecular Embryology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Sarah Gerstner
- Department of Biology, Molecular Embryology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Annette Borchers
- Department of Biology, Molecular Embryology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany.
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2
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Bandekar SJ, Chen CL, Ravala SK, Cash JN, Avramova LV, Zhalnina MV, Gutkind JS, Li S, Tesmer JJG. Structural/functional studies of Trio provide insights into its configuration and show that conserved linker elements enhance its activity for Rac1. J Biol Chem 2022; 298:102209. [PMID: 35779635 PMCID: PMC9372627 DOI: 10.1016/j.jbc.2022.102209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 01/20/2023] Open
Abstract
Trio is a large and highly conserved metazoan signaling scaffold that contains two Dbl family guanine nucleotide exchange factor (GEF) modules, TrioN and TrioC, selective for Rac and RhoA GTPases, respectively. The GEF activities of TrioN and TrioC are implicated in several cancers, especially uveal melanoma. However, little is known about how these modules operate in the context of larger fragments of Trio. Here we show via negative stain electron microscopy that the N-terminal region of Trio is extended and could thus serve as a rigid spacer between the N-terminal putative lipid-binding domain and TrioN, whereas the C-terminal half of Trio seems globular. We found that regions C-terminal to TrioN enhance its Rac1 GEF activity and thus could play a regulatory role. We went on to characterize a minimal, well-behaved Trio fragment with enhanced activity, Trio1284-1959, in complex with Rac1 using cryo-electron microscopy and hydrogen-deuterium exchange mass spectrometry and found that the region conferring enhanced activity is disordered. Deletion of two different strongly conserved motifs in this region eliminated this enhancement, suggesting that they form transient intramolecular interactions that promote GEF activity. Because Dbl family RhoGEF modules have been challenging to directly target with small molecules, characterization of accessory Trio domains such as these may provide alternate routes for the development of therapeutics that inhibit Trio activity in human cancer.
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Affiliation(s)
- Sumit J Bandekar
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA; Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Chun-Liang Chen
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Sandeep K Ravala
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Jennifer N Cash
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, California, USA
| | - Larisa V Avramova
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Mariya V Zhalnina
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - J Silvio Gutkind
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, San Diego, California, USA
| | - Sheng Li
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - John J G Tesmer
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA.
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3
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RhoGEF Trio Regulates Radial Migration of Projection Neurons via Its Distinct Domains. Neurosci Bull 2021; 38:249-262. [PMID: 34914033 PMCID: PMC8975900 DOI: 10.1007/s12264-021-00804-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 09/28/2021] [Indexed: 01/20/2023] Open
Abstract
The radial migration of cortical pyramidal neurons (PNs) during corticogenesis is necessary for establishing a multilayered cerebral cortex. Neuronal migration defects are considered a critical etiology of neurodevelopmental disorders, including autism spectrum disorders (ASDs), schizophrenia, epilepsy, and intellectual disability (ID). TRIO is a high-risk candidate gene for ASDs and ID. However, its role in embryonic radial migration and the etiology of ASDs and ID are not fully understood. In this study, we found that the in vivo conditional knockout or in utero knockout of Trio in excitatory precursors in the neocortex caused aberrant polarity and halted the migration of late-born PNs. Further investigation of the underlying mechanism revealed that the interaction of the Trio N-terminal SH3 domain with Myosin X mediated the adherence of migrating neurons to radial glial fibers through regulating the membrane location of neuronal cadherin (N-cadherin). Also, independent or synergistic overexpression of RAC1 and RHOA showed different phenotypic recoveries of the abnormal neuronal migration by affecting the morphological transition and/or the glial fiber-dependent locomotion. Taken together, our findings clarify a novel mechanism of Trio in regulating N-cadherin cell surface expression via the interaction of Myosin X with its N-terminal SH3 domain. These results suggest the vital roles of the guanine nucleotide exchange factor 1 (GEF1) and GEF2 domains in regulating radial migration by activating their Rho GTPase effectors in both distinct and cooperative manners, which might be associated with the abnormal phenotypes in neurodevelopmental disorders.
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4
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The RhoGEF Trio: A Protein with a Wide Range of Functions in the Vascular Endothelium. Int J Mol Sci 2021; 22:ijms221810168. [PMID: 34576329 PMCID: PMC8467920 DOI: 10.3390/ijms221810168] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 12/29/2022] Open
Abstract
Many cellular processes are controlled by small GTPases, which can be activated by guanine nucleotide exchange factors (GEFs). The RhoGEF Trio contains two GEF domains that differentially activate the small GTPases such as Rac1/RhoG and RhoA. These small RhoGTPases are mainly involved in the remodeling of the actin cytoskeleton. In the endothelium, they regulate junctional stabilization and play a crucial role in angiogenesis and endothelial barrier integrity. Multiple extracellular signals originating from different vascular processes can influence the activity of Trio and thereby the regulation of the forementioned small GTPases and actin cytoskeleton. This review elucidates how various signals regulate Trio in a distinct manner, resulting in different functional outcomes that are crucial for endothelial cell function in response to inflammation.
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Schultz-Rogers L, Muthusamy K, Pinto E Vairo F, Klee EW, Lanpher B. Novel loss-of-function variants in TRIO are associated with neurodevelopmental disorder: case report. BMC MEDICAL GENETICS 2020; 21:219. [PMID: 33167890 PMCID: PMC7654171 DOI: 10.1186/s12881-020-01159-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/28/2020] [Indexed: 01/24/2023]
Abstract
Background Damaging variants in TRIO have been associated with moderate to severe neurodevelopmental disorders in humans. While recent work has delineated the positional effect of missense variation on the resulting phenotype, the clinical spectrum associated with loss-of-function variation has yet to be fully defined. Case presentation We report on two probands with novel loss-of-function variants in TRIO. Patient 1 presents with a severe neurodevelopmental disorder and macrocephaly. The TRIO variant is inherited from his affected mother. Patient 2 presents with moderate developmental delays, microcephaly, and cutis aplasia with a frameshift variant of unknown inheritance. Conclusions We describe two patients with neurodevelopmental disorder, macro/microcephaly, and cutis aplasia in one patient. Both patients have loss-of-function variants, helping to further characterize how these types of variants affect the phenotypic spectrum associated with TRIO. We also present the third reported case of autosomal dominant inheritance of a damaging variant in TRIO.
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Affiliation(s)
| | | | - Filippo Pinto E Vairo
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
| | - Brendan Lanpher
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA.
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6
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Affiliation(s)
| | - Helen R. Mott
- Department of Biochemistry University of Cambridge Cambridge UK
| | - Darerca Owen
- Department of Biochemistry University of Cambridge Cambridge UK
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7
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Maldonado MDM, Medina JI, Velazquez L, Dharmawardhane S. Targeting Rac and Cdc42 GEFs in Metastatic Cancer. Front Cell Dev Biol 2020; 8:201. [PMID: 32322580 PMCID: PMC7156542 DOI: 10.3389/fcell.2020.00201] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/09/2020] [Indexed: 12/20/2022] Open
Abstract
The Rho family GTPases Rho, Rac, and Cdc42 have emerged as key players in cancer metastasis, due to their essential roles in regulating cell division and actin cytoskeletal rearrangements; and thus, cell growth, migration/invasion, polarity, and adhesion. This review will focus on the close homologs Rac and Cdc42, which have been established as drivers of metastasis and therapy resistance in multiple cancer types. Rac and Cdc42 are often dysregulated in cancer due to hyperactivation by guanine nucleotide exchange factors (GEFs), belonging to both the diffuse B-cell lymphoma (Dbl) and dedicator of cytokinesis (DOCK) families. Rac/Cdc42 GEFs are activated by a myriad of oncogenic cell surface receptors, such as growth factor receptors, G-protein coupled receptors, cytokine receptors, and integrins; consequently, a number of Rac/Cdc42 GEFs have been implicated in metastatic cancer. Hence, inhibiting GEF-mediated Rac/Cdc42 activation represents a promising strategy for targeted metastatic cancer therapy. Herein, we focus on the role of oncogenic Rac/Cdc42 GEFs and discuss the recent advancements in the development of Rac and Cdc42 GEF-interacting inhibitors as targeted therapy for metastatic cancer, as well as their potential for overcoming cancer therapy resistance.
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Affiliation(s)
- Maria Del Mar Maldonado
- Department of Biochemistry, School of Medicine, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Julia Isabel Medina
- Department of Biochemistry, School of Medicine, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Luis Velazquez
- Department of Biochemistry, School of Medicine, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Suranganie Dharmawardhane
- Department of Biochemistry, School of Medicine, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
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8
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Hypoxia in the Initiation and Progression of Neuroblastoma Tumours. Int J Mol Sci 2019; 21:ijms21010039. [PMID: 31861671 PMCID: PMC6982287 DOI: 10.3390/ijms21010039] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/16/2022] Open
Abstract
Neuroblastoma is the most frequent extracranial solid tumour in children, causing 10% of all paediatric oncology deaths. It arises in the embryonic neural crest due to an uncontrolled behaviour of sympathetic nervous system progenitors, giving rise to heterogeneous tumours. Low local or systemic tissue oxygen concentration has emerged as a cellular stimulus with important consequences for tumour initiation, evolution and progression. In neuroblastoma, several evidences point towards a role of hypoxia in tumour initiation during development, tumour cell differentiation, survival and metastatic spreading. However, the heterogeneous nature of the disease, its developmental origin and the lack of suitable experimental models have complicated a clear understanding of the effect of hypoxia in neuroblastoma tumour progression and the molecular mechanisms implicated. In this review, we have compiled available evidences to try to shed light onto this important field. In particular, we explore the effect of hypoxia in neuroblastoma cell transformation and differentiation. We also discuss the experimental models available and the emerging alternatives to study this problem, and we present hypoxia-related therapeutic avenues being explored in the field.
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9
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Bandekar SJ, Arang N, Tully ES, Tang BA, Barton BL, Li S, Gutkind JS, Tesmer JJG. Structure of the C-terminal guanine nucleotide exchange factor module of Trio in an autoinhibited conformation reveals its oncogenic potential. Sci Signal 2019; 12:12/569/eaav2449. [PMID: 30783010 DOI: 10.1126/scisignal.aav2449] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The C-terminal guanine nucleotide exchange factor (GEF) module of Trio (TrioC) transfers signals from the Gαq/11 subfamily of heterotrimeric G proteins to the small guanosine triphosphatase (GTPase) RhoA, enabling Gαq/11-coupled G protein-coupled receptors (GPCRs) to control downstream events, such as cell motility and gene transcription. This conserved signal transduction axis is crucial for tumor growth in uveal melanoma. Previous studies indicate that the GEF activity of the TrioC module is autoinhibited, with release of autoinhibition upon Gαq/11 binding. Here, we determined the crystal structure of TrioC in its basal state and found that the pleckstrin homology (PH) domain interacts with the Dbl homology (DH) domain in a manner that occludes the Rho GTPase binding site, thereby suggesting the molecular basis of TrioC autoinhibition. Biochemical and biophysical assays revealed that disruption of the autoinhibited conformation destabilized and activated the TrioC module in vitro. Last, mutations in the DH-PH interface found in patients with cancer activated TrioC and, in the context of full-length Trio, led to increased abundance of guanosine triphosphate-bound RhoA (RhoA·GTP) in human cells. These mutations increase mitogenic signaling through the RhoA axis and, therefore, may represent cancer drivers operating in a Gαq/11-independent manner.
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Affiliation(s)
- Sumit J Bandekar
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nadia Arang
- Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, USA.,Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Ena S Tully
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Brittany A Tang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Brenna L Barton
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sheng Li
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - J Silvio Gutkind
- Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, USA.,Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - John J G Tesmer
- Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
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10
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Bustelo XR. RHO GTPases in cancer: known facts, open questions, and therapeutic challenges. Biochem Soc Trans 2018; 46:741-760. [PMID: 29871878 PMCID: PMC7615761 DOI: 10.1042/bst20170531] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/17/2018] [Accepted: 05/03/2018] [Indexed: 02/06/2023]
Abstract
RHO GTPases have been traditionally associated with protumorigenic functions. While this paradigm is still valid in many cases, recent data have unexpectedly revealed that RHO proteins can also play tumor suppressor roles. RHO signaling elements can also promote both pro- and antitumorigenic effects using GTPase-independent mechanisms, thus giving an extra layer of complexity to the role of these proteins in cancer. Consistent with these variegated roles, both gain- and loss-of-function mutations in RHO pathway genes have been found in cancer patients. Collectively, these observations challenge long-held functional archetypes for RHO proteins in both normal and cancer cells. In this review, I will summarize these data and discuss new questions arising from them such as the functional and clinical relevance of the mutations found in patients, the mechanistic orchestration of those antagonistic functions in tumors, and the pros and cons that these results represent for the development of RHO-based anticancer drugs.
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Affiliation(s)
- Xosé R Bustelo
- Centro de Investigación del Cáncer, Instituto de Biología Molecular y Celular del Cáncer, and Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Consejo Superior de Investigaciones Científicas (CSIC)-University of Salamanca, 37007 Salamanca, Spain
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11
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van Unen J, Botman D, Yin T, Wu YI, Hink MA, Gadella TWJ, Postma M, Goedhart J. The C-terminus of the oncoprotein TGAT is necessary for plasma membrane association and efficient RhoA-mediated signaling. BMC Cell Biol 2018; 19:6. [PMID: 29879899 PMCID: PMC5992656 DOI: 10.1186/s12860-018-0155-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 02/28/2018] [Indexed: 02/08/2023] Open
Abstract
Background Rho guanine exchange factors (RhoGEFs) control cellular processes such as migration, adhesion and proliferation. Alternative splicing of the RhoGEF Trio produces TGAT. The RhoGEF TGAT is an oncoprotein with constitutive RhoGEF activity. We investigated whether the subcellular location of TGAT is critical for its RhoGEF activity. Methods Since plasma membrane associated RhoGEFs are particularly effective at activating RhoA, plasma membrane localization of TGAT was examined. To this end, we developed a highly sensitive image analysis method to quantitatively measure plasma membrane association. The method requires a cytoplasmic marker and a plasma membrane marker, which are co-imaged with the tagged protein of interest. Linear unmixing is performed to determine the plasma membrane and cytoplasmic component in the fluorescence signal of protein of interest. Results The analysis revealed that wild-type TGAT is partially co-localized with the plasma membrane. Strikingly, cysteine TGAT-mutants lacking one or more putative palmitoylation sites in the C-tail, still showed membrane association. In contrast, a truncated variant, lacking the last 15 amino acids, TGATΔ15, lost membrane association. We show that membrane localization of TGAT was responsible for high RhoGEF activity by using a RhoA FRET-sensor and by determining F-actin levels. Mutants of TGAT that still maintained membrane association showed similar activity as wild-type TGAT. In contrast, the activity was abrogated for the cytoplasmic TGATΔ15 variant. Synthetic recruitment of TGATΔ15 to membranes confirmed that TGAT effectively activates RhoA at the plasma membrane. Conclusion Together, these results show that membrane association of TGAT is critical for its activity. Electronic supplementary material The online version of this article (10.1186/s12860-018-0155-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- J van Unen
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands
| | - D Botman
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands
| | - T Yin
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, 400 Farmington Avenue, Farmington, CT, 06032-6406, USA
| | - Y I Wu
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, 400 Farmington Avenue, Farmington, CT, 06032-6406, USA
| | - M A Hink
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands
| | - T W J Gadella
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands
| | - M Postma
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands.
| | - J Goedhart
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL, -1090, GE, Amsterdam, The Netherlands.
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12
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Katrancha SM, Wu Y, Zhu M, Eipper BA, Koleske AJ, Mains RE. Neurodevelopmental disease-associated de novo mutations and rare sequence variants affect TRIO GDP/GTP exchange factor activity. Hum Mol Genet 2017; 26:4728-4740. [PMID: 28973398 PMCID: PMC5886096 DOI: 10.1093/hmg/ddx355] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 08/07/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022] Open
Abstract
Bipolar disorder, schizophrenia, autism and intellectual disability are complex neurodevelopmental disorders, debilitating millions of people. Therapeutic progress is limited by poor understanding of underlying molecular pathways. Using a targeted search, we identified an enrichment of de novo mutations in the gene encoding the 330-kDa triple functional domain (TRIO) protein associated with neurodevelopmental disorders. By generating multiple TRIO antibodies, we show that the smaller TRIO9 isoform is the major brain protein product, and its levels decrease after birth. TRIO9 contains two guanine nucleotide exchange factor (GEF) domains with distinct specificities: GEF1 activates both Rac1 and RhoG; GEF2 activates RhoA. To understand the impact of disease-associated de novo mutations and other rare sequence variants on TRIO function, we utilized two FRET-based biosensors: a Rac1 biosensor to study mutations in TRIO (T)GEF1, and a RhoA biosensor to study mutations in TGEF2. We discovered that one autism-associated de novo mutation in TGEF1 (K1431M), at the TGEF1/Rac1 interface, markedly decreased its overall activity toward Rac1. A schizophrenia-associated rare sequence variant in TGEF1 (F1538Intron) was substantially less active, normalized to protein level and expressed poorly. Overall, mutations in TGEF1 decreased GEF1 activity toward Rac1. One bipolar disorder-associated rare variant (M2145T) in TGEF2 impaired inhibition by the TGEF2 pleckstrin-homology domain, resulting in dramatically increased TGEF2 activity. Overall, genetic damage to both TGEF domains altered TRIO catalytic activity, decreasing TGEF1 activity and increasing TGEF2 activity. Importantly, both GEF changes are expected to decrease neurite outgrowth, perhaps consistent with their association with neurodevelopmental disorders.
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Affiliation(s)
- Sara M Katrancha
- Interdepartmental Neuroscience Program
- Department of Neuroscience
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Yi Wu
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT, USA
| | - Minsheng Zhu
- Model Animal Research Center, Nanjing University, Nanjing 210061, China
| | - Betty A Eipper
- Department of Neuroscience
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
| | - Anthony J Koleske
- Interdepartmental Neuroscience Program
- Department of Neuroscience
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
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13
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Huang Z, Nan C, Wang H, Su Q, Xue W, Chen Y, Shan X, Duan J, Chen G, Tao W. Crocetin ester improves myocardial ischemia via Rho/ROCK/NF-κB pathway. Int Immunopharmacol 2016; 38:186-93. [PMID: 27285672 DOI: 10.1016/j.intimp.2016.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 05/27/2016] [Accepted: 05/28/2016] [Indexed: 01/01/2023]
Abstract
Crocetin ester (CE) is the active ingredient of Crocus sativus L. stigmas and Gardenia jasminoides Ellis fruit. The main purpose of the present study was to investigate the protective effect of CE on isoproterenol (ISO)-induced acute myocardial ischemia (AMI) through Rho/ROCK/NF-κB pathway and explore its underlying mechanism. Administration of CE (25 and 50mg/kg) could significantly reduce the serum contents of pro-inflammatory cytokines including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6). In addition, pretreatment with CE attenuated the contents of creatine kinase (CK), malondialdehyde (MDA) and the activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD) in serum. Treatment with CE also improved the histopathological alteration and decreased the ST elevation. Furthermore, CE could ameliorate the cardiac expressions of Cu, Zn-superoxide dismutase (SOD1), MDA5, Rho, ROCK, p-IκB and p-NF-κBp65 in ISO-induced rats. It was assumed that CE might be a new therapeutic candidate for the treatment of AMI possibly through the inhibition of Rho/ROCK/NF-κB pathway.
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Affiliation(s)
- Zhiheng Huang
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Chen Nan
- Medical College of Soochow University, Suzhou 215000, China
| | - Hanqing Wang
- College of Pharmacy, Ningxia Medical University, Ningxia 750004, China
| | - Qiang Su
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Wenda Xue
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Yanyan Chen
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xin Shan
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Jinao Duan
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and National and Local Collaborative Engineering Center of Chinese Medicinal Resources Industrialization and Formulae Innovative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Gang Chen
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Weiwei Tao
- Center for Translational Systems Biology and Neuroscience, School of Basic Biomedical Science, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, and National and Local Collaborative Engineering Center of Chinese Medicinal Resources Industrialization and Formulae Innovative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China.
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14
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Abstract
INTRODUCTION Rho GTPases are master regulators of actomyosin structure and dynamics and play pivotal roles in a variety of cellular processes including cell morphology, gene transcription, cell cycle progression, and cell adhesion. Because aberrant Rho GTPase signaling activities are widely associated with human cancer, key components of Rho GTPase signaling pathways have attracted increasing interest as potential therapeutic targets. Similar to Ras, Rho GTPases themselves were, until recently, deemed "undruggable" because of structure-function considerations. Several approaches to interfere with Rho GTPase signaling have been explored and show promise as new ways for tackling cancer cells. AREAS COVERED This review focuses on the recent progress in targeting the signaling activities of three prototypical Rho GTPases, that is, RhoA, Rac1, and Cdc42. The authors describe the involvement of these Rho GTPases, their key regulators and effectors in cancer. Furthermore, the authors discuss the current approaches for rationally targeting aberrant Rho GTPases along their signaling cascades, upstream and downstream of Rho GTPases, and posttranslational modifications at a molecular level. EXPERT OPINION To date, while no clinically effective drugs targeting Rho GTPase signaling for cancer treatment are available, tool compounds and lead drugs that pharmacologically inhibit Rho GTPase pathways have shown promise. Small-molecule inhibitors targeting Rho GTPase signaling may add new treatment options for future precision cancer therapy, particularly in combination with other anti-cancer agents.
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Affiliation(s)
- Yuan Lin
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229, USA
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229, USA
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15
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Schmidt S, Debant A. Function and regulation of the Rho guanine nucleotide exchange factor Trio. Small GTPases 2014; 5:e29769. [PMID: 24987837 DOI: 10.4161/sgtp.29769] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Rho GTPases oscillate between an inactive GDP-bound state and an active GTP-bound state. They are activated by Rho Guanine nucleotide Exchange Factors (GEF), which accelerate the GDP to GTP exchange. RhoGEFs fall into two different classes: the Dbl family and the DOCK family of proteins. In this review, we focus on the function and regulation of the Dbl family RhoGEF Trio. Trio and its paralog Kalirin are unique within this family in that they display two GEF domains of distinct specificity. Trio is a major regulator of neuronal development, and its function is conserved through evolution. Moreover, Trio plays an important role in cell adhesion and in signaling pathways elicited by Gαq protein-coupled receptors. Combined, these observations suggest that Trio has a major role in cellular physiology. Of note, Trio is an essential gene for mouse development, with a prominent role in the development of the nervous system. Finally, Trio expression is significantly increased in different types of tumors and it has been proposed that it could participate in oncogenesis.
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Affiliation(s)
- Susanne Schmidt
- Centre de Recherche en Biochimie Macromoléculaire; CNRS - UMR 5237; Université de Montpellier; Montpellier, France
| | - Anne Debant
- Centre de Recherche en Biochimie Macromoléculaire; CNRS - UMR 5237; Université de Montpellier; Montpellier, France
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16
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Abstract
Small G proteins of the Rho family and their activators the guanine nucleotide exchange factors (RhoGEFs) regulate essential cellular functions and their deregulation has been associated with an amazing variety of human disorders, including cancer, inflammation, vascular diseases, and mental retardation. Rho GTPases and RhoGEFs therefore represent important targets for inhibition, not only in basic research but also for therapeutic purposes, and strategies to inhibit their function are actively being sought. Our lab has been very active in this field and has used the peptide aptamer technology to develop the first RhoGEF inhibitor, using the RhoGEF Trio as a model. Trio function has been described mainly in cell motility and axon growth in the nervous system via Rac1 GTPase activation, but recent findings suggest it to play also a role in the aggressive phenotype of various cancers, making it an attractive target for drug discovery. The object of this chapter is to demonstrate that targeting a RhoGEF using the peptide aptamer technology represents a valid and efficient approach to inhibit cellular processes in which Rho GTPase activity is upregulated. This is illustrated here by the first description of a peptide inhibitor of the oncogenic RhoGEF Tgat, TRIP(E32G), which is functional in vivo. On a long-term perspective, these peptide inhibitors can also serve as therapeutic tools or as guides for the discovery of small-molecule drugs, using an aptamer displacement screen.
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Affiliation(s)
- Susanne Schmidt
- Centre de Recherche en Biochimie Macromoléculaire, CNRS-UMR 5237, Universités Montpellier I et II, 1919 Route de Mende, Montpellier, France.
| | - Anne Debant
- Centre de Recherche en Biochimie Macromoléculaire, CNRS-UMR 5237, Universités Montpellier I et II, 1919 Route de Mende, Montpellier, France.
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17
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Bouquier N, Fromont S, Debant A, Schmidt S. Random mutagenesis of peptide aptamers as an optimization strategy for inhibitor screening. Methods Mol Biol 2013; 928:97-118. [PMID: 22956136 DOI: 10.1007/978-1-62703-008-3_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Accumulating work over the past decade has shown that peptide aptamer screening represents a valid strategy for inhibitor identification that can be applied to a variety of different targets. Because of the screening method in cells and the highly combinatorial libraries available, this approach yields rapidly highly specific candidate inhibitors. Once a hit peptide has been identified, its interaction strength and affinity towards its target protein can be optimized even more, in order to increase its inhibition efficiency when subsequently applied in vivo. A condition to a successful optimization is that gain of inhibition strength should not result in loss of specificity. Here we present a simple method for peptide aptamer optimization, which can be achieved by PCR-based random mutagenesis combined with a selection screen in yeast using a strong selective drug. The rationale of this approach, which has proven valid and efficient, is that stronger interaction in yeast will also lead to stronger inhibition. Our optimization method is effective, without loss of specificity, which is of a great importance for the discovery of inhibitors that target specific protein-protein interactions.
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Affiliation(s)
- Nathalie Bouquier
- Centre de Recherche de Biochimie Macromoléculaire, CNRS-UMR 5237, Universités Montpellier I et II, Montpellier Cedex, France
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18
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Abstract
Small Rho-GTPases are enzymes that are bound to GDP or GTP, which determines their inactive or active state, respectively. The exchange of GDP for GTP is catalyzed by so-called Rho-guanine nucleotide exchange factors (GEFs). Rho-GEFs are characterized by a Dbl-homology (DH) and adjacent Pleckstrin-homology (PH) domain that serves as enzymatic unit for the GDP/GTP exchange. Rho-GEFs show different GTPase specificities, meaning that a particular GEF can activate either multiple GTPases or only one specific GTPase. We recently reported that the Rho-GEF Trio, known to be able to exchange GTP on Rac1, RhoG and RhoA, regulates lamellipodia formation to mediate cell spreading and migration in a Rac1-dependent manner. In this commentary, we review the current knowledge of Trio in several aspects of cell biology.
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Affiliation(s)
- Jos van Rijssel
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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19
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Mardilovich K, Olson MF, Baugh M. Targeting Rho GTPase signaling for cancer therapy. Future Oncol 2012; 8:165-77. [PMID: 22335581 DOI: 10.2217/fon.11.143] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Accumulating evidence from basic and clinical studies supports the concept that signaling pathways downstream of Rho GTPases play important roles in tumor development and progression. As a result, there has been considerable interest in the possibility that specific proteins in these signal transduction pathways could be potential targets for cancer therapy. A number of inhibitors targeting critical effector proteins, activators or the Rho GTPases themselves, have been developed. We will review the strategies currently being used to develop inhibitors of Rho GTPases and downstream signaling kinases and discuss candidate entities. Although molecularly targeted drugs that inhibit Rho GTPase signaling have not yet been widely adopted for clinical use, their potential value as cancer therapeutics continues to drive considerable pharmaceutical research and development.
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Affiliation(s)
- Katerina Mardilovich
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
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20
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Arsic N, Bendris N, Peter M, Begon-Pescia C, Rebouissou C, Gadéa G, Bouquier N, Bibeau F, Lemmers B, Blanchard JM. A novel function for Cyclin A2: control of cell invasion via RhoA signaling. ACTA ACUST UNITED AC 2012; 196:147-62. [PMID: 22232705 PMCID: PMC3255987 DOI: 10.1083/jcb.201102085] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cyclin A2 plays a key role in cell cycle regulation. It is essential in embryonic cells and in the hematopoietic lineage yet dispensable in fibroblasts. In this paper, we demonstrate that Cyclin A2-depleted cells display a cortical distribution of actin filaments and increased migration. These defects are rescued by restoration of wild-type Cyclin A2, which directly interacts with RhoA, or by a Cyclin A2 mutant unable to associate with Cdk. In vitro, Cyclin A2 potentiates the exchange activity of a RhoA-specific guanine nucleotide exchange factor. Consistent with this, Cyclin A2 depletion enhances migration of fibroblasts and invasiveness of transformed cells via down-regulation of RhoA activity. Moreover, Cyclin A2 expression is lower in metastases relative to primary colon adenocarcinoma in matched human tumors. All together, these data show that Cyclin A2 negatively controls cell motility by promoting RhoA activation, thus demonstrating a novel Cyclin A2 function in cytoskeletal rearrangements and cell migration.
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Affiliation(s)
- Nikola Arsic
- Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier, France
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21
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Portales-Casamar E, Briançon-Marjollet A, Fromont S, Triboulet R, Debant A. Identification of novel neuronal isoforms of the Rho-GEF Trio. Biol Cell 2012; 98:183-93. [PMID: 16033331 DOI: 10.1042/bc20050009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION The large family of GEFs (guanine nucleotide-exchange factors) for Rho GTPases activate the GTPases by accelerating their GDP/GTP exchange. The multidomain protein Trio is the founding member of an intriguing subfamily of Rho-GEFs exhibiting two Rho-GEF and numerous additional domains. The members of the Trio family play an important role in neuronal physiology, and their structural organization is very well conserved through evolution. It has previously been shown that all the members, except mammalian Trio, display several isoforms, the functions of which have been well established. RESULTS In this study, we have identified, by a combination of different approaches, novel Trio isoforms that have been generated by alternative splicing, giving rise to proteins that exhibit one or two Rho-GEF domains (GEFDs). These isoforms are specifically expressed in the nervous system, at a higher level than the full-length Trio, which is ubiquitously expressed. In addition, we show that all the GEFD1-containing isoforms induce neurite outgrowth in neuroblastoma cells. CONCLUSIONS We have identified neuronal specific isoforms of Trio which could be essential for Trio function in neuronal morphology.
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22
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Vigil D, Cherfils J, Rossman KL, Der CJ. Ras superfamily GEFs and GAPs: validated and tractable targets for cancer therapy? Nat Rev Cancer 2010; 10:842-57. [PMID: 21102635 PMCID: PMC3124093 DOI: 10.1038/nrc2960] [Citation(s) in RCA: 572] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
There is now considerable and increasing evidence for a causal role for aberrant activity of the Ras superfamily of small GTPases in human cancers. These GTPases function as GDP-GTP-regulated binary switches that control many fundamental cellular processes. A common mechanism of GTPase deregulation in cancer is the deregulated expression and/or activity of their regulatory proteins, guanine nucleotide exchange factors (GEFs) that promote formation of the active GTP-bound state and GTPase-activating proteins (GAPs) that return the GTPase to its GDP-bound inactive state. In this Review, we assess the association of GEFs and GAPs with cancer and their druggability for cancer therapeutics.
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Affiliation(s)
- Dominico Vigil
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Department of Pharmacology, Chapel Hill, North Carolina 27599, USA
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23
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Guanine nucleotide exchange factors for RhoGTPases: good therapeutic targets for cancer therapy? Cell Signal 2010; 23:969-79. [PMID: 21044680 DOI: 10.1016/j.cellsig.2010.10.022] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 10/23/2010] [Indexed: 12/12/2022]
Abstract
Rho guanosine triphosphatases (GTPases) are a family of small proteins which function as molecular switches in a variety of signaling pathways following stimulation of cell surface receptors. RhoGTPases regulate numerous cellular processes including cytoskeleton organization, gene transcription, cell proliferation, migration, growth and cell survival. Because of their central role in regulating processes that are dysregulated in cancer, it seems reasonable that defects in the RhoGTPase pathway may be involved in the development of cancer. RhoGTPase activity is regulated by a number of protein families: guanine nucleotide exchange factors (GEFs), GTPase activating proteins (GAPs) and guanine nucleotide-dissociation inhibitors (GDIs). This review discusses the participation of RhoGTPases and their regulators, especially GEFs in human cancers. In particular, we focus on the involvement of the RhoGTPase GEF, Vav1, a hematopoietic specific signal transducer which is involved in human neuroblastoma, pancreatic ductal carcinoma and lung cancer. Finally, we summarize recent advances in the design and application of a number of molecules that specifically target individual RhoGTPases or their regulators or effectors, and discuss their potential for cancer therapy.
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24
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Bouquier N, Vignal E, Charrasse S, Weill M, Schmidt S, Léonetti JP, Blangy A, Fort P. A cell active chemical GEF inhibitor selectively targets the Trio/RhoG/Rac1 signaling pathway. ACTA ACUST UNITED AC 2009; 16:657-66. [PMID: 19549603 DOI: 10.1016/j.chembiol.2009.04.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 04/13/2009] [Accepted: 04/29/2009] [Indexed: 11/18/2022]
Abstract
RhoGEFs (guanine nucleotide exchange factors of the Rho GTPase family) are upstream regulators of cell adhesion and migration pathways, thus representing attractive yet relatively unexplored targets for the development of anti-invasive drugs. We screened for chemical inhibitors of TrioN, the N-terminal GEF domain of the multidomain Trio protein, and identified ITX3 as a nontoxic inhibitor. In transfected mammalian cells, ITX3 blocked TrioN-mediated dorsal membrane ruffling and Rac1 activation while having no effect on GEF337-, Tiam1-, or Vav2-mediated RhoA or Rac1 activation. ITX3 specifically inhibited endogenous TrioN activity, as evidenced by its ability to inhibit neurite outgrowth in nerve growth factor (NGF)-stimulated PC12 cells or C2C12 differentiation into myotubes. This study introduces a selective cell active inhibitor of the Trio/RhoG/Rac1 pathway and validates RhoGEFs as druggable targets.
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Affiliation(s)
- Nathalie Bouquier
- Centre de Recherche de Biochimie Macromoléculaire, Universités Montpellier I et II, CNRS, 34293 Montpellier, France
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25
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Aptamer-derived peptides as potent inhibitors of the oncogenic RhoGEF Tgat. ACTA ACUST UNITED AC 2009; 16:391-400. [PMID: 19389625 DOI: 10.1016/j.chembiol.2009.02.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 02/03/2009] [Accepted: 02/09/2009] [Indexed: 12/31/2022]
Abstract
Guanine nucleotide exchange factors (GEFs) activate the Rho GTPases by accelerating their GDP/GTP exchange rate. Some RhoGEFs have been isolated based on their oncogenic potency, and strategies to inhibit their activity are therefore actively being sought. In this study we devise a peptide inhibitor screening strategy to target the GEF activity of Tgat, an oncogenic isoform of the RhoGEF Trio, based on random mutations of the Trio inhibitor TRIP alpha, which we previously isolated using a peptide aptamer screen. This identifies one peptide, TRIP(E32G), which specifically inhibits Tgat GEF activity in vitro and significantly reduces Tgat-induced RhoA activation and foci formation. Furthermore, subcutaneous injection of cells expressing Tgat and TRIP(E32G) into nude mice reduces the formation of Tgat-induced tumors. Our approach thus demonstrates that peptide aptamers are potent inhibitors that can be used to interfere with RhoGEF functions in vivo.
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26
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Mano H. Non-solid oncogenes in solid tumors: EML4-ALK fusion genes in lung cancer. Cancer Sci 2008; 99:2349-55. [PMID: 19032370 PMCID: PMC11158085 DOI: 10.1111/j.1349-7006.2008.00972.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 08/13/2008] [Accepted: 08/14/2008] [Indexed: 11/28/2022] Open
Abstract
It is generally accepted that recurrent chromosome translocations play a major role in the molecular pathogenesis of hematological malignancies but not of solid tumors. However, chromosome translocations involving the e26 transformation-specific sequence transcription factor loci have been demonstrated recently in many prostate cancer cases. Furthermore, through a functional screening with retroviral cDNA expression libraries, we have discovered the fusion-type protein tyrosine kinase echinoderm microtubule-associated protein like-4 (EML4)-anaplastic lymphoma kinase (ALK) in non-small cell lung cancer (NSCLC) specimens. A recurrent chromosome translocation, inv(2)(p21p23), in NSCLC generates fused mRNA encoding the amino-terminal half of EML4 ligated to the intracellular region of the receptor-type protein tyrosine kinase ALK. EML4-ALK oligomerizes constitutively in cells through the coiled coil domain within the EML4 region, and becomes activated to exert a marked oncogenicity both in vitro and in vivo. Break and fusion points within the EML4 locus may diverge in NSCLC cells to generate various isoforms of EML4-ALK, which may constitute approximately 5% of NSCLC cases, at least in the Asian ethnic group. In the present review I summarize how detection of EML4-ALK cDNA may become a sensitive diagnostic means for NSCLC cases that are positive for the fusion gene, and discuss whether suppression of ALK enzymatic activity could be an effective treatment strategy against this intractable disorder.
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Affiliation(s)
- Hiroyuki Mano
- Division of Functional Genomics, Jichi Medical University, 3311-1 Yakushiji, Shimotsukeshi, Tochigi 329-0498, Japan.
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27
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Curwin AJ, McMaster CR. Structure and function of the enigmatic Sec14 domain-containing proteins and the etiology of human disease. ACTA ACUST UNITED AC 2008. [DOI: 10.2217/17460875.3.4.399] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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28
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Identification of noninvasive imaging surrogates for brain tumor gene-expression modules. Proc Natl Acad Sci U S A 2008; 105:5213-8. [PMID: 18362333 DOI: 10.1073/pnas.0801279105] [Citation(s) in RCA: 323] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Glioblastoma multiforme (GBM) is the most common and lethal primary brain tumor in adults. We combined neuroimaging and DNA microarray analysis to create a multidimensional map of gene-expression patterns in GBM that provided clinically relevant insights into tumor biology. Tumor contrast enhancement and mass effect predicted activation of specific hypoxia and proliferation gene-expression programs, respectively. Overexpression of EGFR, a receptor tyrosine kinase and potential therapeutic target, was also directly inferred by neuroimaging and was validated in an independent set of tumors by immunohistochemistry. Furthermore, imaging provided insights into the intratumoral distribution of gene-expression patterns within GBM. Most notably, an "infiltrative" imaging phenotype was identified that predicted patient outcome. Patients with this imaging phenotype had a greater tendency toward having multiple tumor foci and demonstrated significantly shorter survival than their counterparts. Our findings provide an in vivo portrait of genome-wide gene expression in GBM and offer a potential strategy for noninvasively selecting patients who may be candidates for individualized therapies.
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29
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Phillips JM, Goodman JI. Identification of genes that may play critical roles in phenobarbital (PB)-induced liver tumorigenesis due to altered DNA methylation. Toxicol Sci 2008; 104:86-99. [PMID: 18359763 DOI: 10.1093/toxsci/kfn063] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aberrant DNA methylation plays important roles in tumorigenesis, and the nongenotoxic rodent tumor promoter phenobarbital (PB) alters methylation patterns to a greater extent in liver tumor susceptible as compared to resistant mice (Watson and Goodman, 2002). Unique hepatic regions of altered DNA methylation (RAMs) were identified in sensitive B6C3F1, as compared to resistant C57BL/6, mice at 2 or 4 weeks of PB treatment using a novel approach involving methylation-sensitive restriction digestion, arbitrarily primed PCR, and capillary electrophoresis (Bachman et al., 2006b). PCR products representing 90 of 170 (53%) total unique B6C3F1 RAMs at 2 or 4 weeks were cloned and subjected to BLAST-like alignment tool searches that resulted in 51 gene matches; some of these have documented oncogenic or tumor suppressor roles. Importantly, uniquely hypomethylated genes play roles in angiogenesis (e.g., chymase 1, tyrosine kinase nonreceptor 2, and possibly ephrin B2 and triple functional domain, PTPRF interacting) and invasion and metastasis, including those involved in the epithelial-mesenchymal transition (transcription factor 4, transforming growth factor beta receptor II, and ral guanine nucleotide dissociation stimulator). Common cellular targets and regulators of the genes representing unique B6C3F1 RAMs were uncovered, indicating that they might act in concert to more efficiently promote tumorigenesis. Genes not previously associated with mouse liver tumorigenesis exhibited altered methylation at these very early times following PB treatment. We hypothesize that at least some of the unique PB-induced B6C3F1 RAMs represent key events facilitating transformation, which is consistent with a causative role of altered DNA methylation during early stages of tumorigenesis.
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Affiliation(s)
- Jennifer M Phillips
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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30
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Soda M, Choi YL, Enomoto M, Takada S, Yamashita Y, Ishikawa S, Fujiwara SI, Watanabe H, Kurashina K, Hatanaka H, Bando M, Ohno S, Ishikawa Y, Aburatani H, Niki T, Sohara Y, Sugiyama Y, Mano H. Identification of the transforming EML4-ALK fusion gene in non-small-cell lung cancer. Nature 2007; 448:561-6. [PMID: 17625570 DOI: 10.1038/nature05945] [Citation(s) in RCA: 3946] [Impact Index Per Article: 232.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Accepted: 05/17/2007] [Indexed: 02/07/2023]
Abstract
Improvement in the clinical outcome of lung cancer is likely to be achieved by identification of the molecular events that underlie its pathogenesis. Here we show that a small inversion within chromosome 2p results in the formation of a fusion gene comprising portions of the echinoderm microtubule-associated protein-like 4 (EML4) gene and the anaplastic lymphoma kinase (ALK) gene in non-small-cell lung cancer (NSCLC) cells. Mouse 3T3 fibroblasts forced to express this human fusion tyrosine kinase generated transformed foci in culture and subcutaneous tumours in nude mice. The EML4-ALK fusion transcript was detected in 6.7% (5 out of 75) of NSCLC patients examined; these individuals were distinct from those harbouring mutations in the epidermal growth factor receptor gene. Our data demonstrate that a subset of NSCLC patients may express a transforming fusion kinase that is a promising candidate for a therapeutic target as well as for a diagnostic molecular marker in NSCLC.
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MESH Headings
- 3T3 Cells
- Amino Acid Sequence
- Anaplastic Lymphoma Kinase
- Animals
- Carcinoma, Non-Small-Cell Lung/drug therapy
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Non-Small-Cell Lung/pathology
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cell Proliferation/drug effects
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/pathology
- Chromosome Inversion/genetics
- Chromosomes, Human, Pair 2/genetics
- Humans
- Lung Neoplasms/drug therapy
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/pathology
- Mice
- Microtubule-Associated Proteins/genetics
- Microtubule-Associated Proteins/metabolism
- Molecular Sequence Data
- Mutation/genetics
- Oncogene Proteins, Fusion/antagonists & inhibitors
- Oncogene Proteins, Fusion/chemistry
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Receptor Protein-Tyrosine Kinases
- Serine Endopeptidases/genetics
- Serine Endopeptidases/metabolism
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Affiliation(s)
- Manabu Soda
- Division of Functional Genomics, Jichi Medical University, Tochigi 329-0498, Japan
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31
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Yohe ME, Rossman KL, Gardner OS, Karnoub AE, Snyder JT, Gershburg S, Graves LM, Der CJ, Sondek J. Auto-inhibition of the Dbl family protein Tim by an N-terminal helical motif. J Biol Chem 2007; 282:13813-23. [PMID: 17337446 DOI: 10.1074/jbc.m700185200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Dbl-related oncoproteins are guanine nucleotide exchange factors specific for Rho-family GTPases and typically possess tandem Dbl homology (DH) and pleckstrin homology domains that act in concert to catalyze exchange. Because the ability of many Dbl-family proteins to catalyze exchange is constitutively activated by truncations N-terminal to their DH domains, it has been proposed that the activity of Dbl-family proteins is regulated by auto-inhibition. However, the exact mechanisms of regulation of Dbl-family proteins remain poorly understood. Here we show that the Dbl-family protein, Tim, is auto-inhibited by a short, helical motif immediately N-terminal to its DH domain, which directly occludes the catalytic surface of the DH domain to prevent GTPase activation. Similar to the distantly related Vav isozymes, auto-inhibition of Tim is relieved by truncation, mutation, or phosphorylation of the auto-inhibitory helix. A peptide comprising the helical motif inhibits the exchange activity of Tim in vitro. Furthermore, substitutions within the most highly conserved surface of the DH domain designed to disrupt interactions with the auto-inhibitory helix also activate the exchange process.
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Affiliation(s)
- Marielle E Yohe
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA
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32
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Mori T, Moriuchi R, Okazaki E, Yamada K, Katamine S. Tgat oncoprotein functions as a inhibitor of RECK by association of the unique C-terminal region. Biochem Biophys Res Commun 2007; 355:937-43. [PMID: 17328864 DOI: 10.1016/j.bbrc.2007.02.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 02/08/2007] [Indexed: 12/28/2022]
Abstract
We identified RECK, a membrane-anchored glycoprotein negatively regulating the activities of MMPs, as a molecule interacting with Tgat oncoprotein consisting of RhoGEF domain and the unique C-terminal 15 amino acids. The Tgat increased the invasive potential of NIH3T3 cells expressing endogenous mouse RECK and this effect was partially inhibited by the co-expression of human RECK. On the contrary, the expression of exogenous human RECK in HT1080 cell line lacking the endogenous RECK expression reduced its invasive activity, which was recovered by the Tgat co-expression. Moreover, a Tgat mutant lacking the C-terminal region lost the potential to compete the function of RECK in HT1080 cells. These findings indicate that Tgat is the functional inhibitor of RECK, and the activation of MMPs induced by Tgat is likely to enhance invasive activities of cancer cells expressing Tgat.
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Affiliation(s)
- Tsuyoshi Mori
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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Yamada K, Moriuchi R, Mori T, Okazaki E, Kohno T, Nagayasu T, Matsuyama T, Katamine S. Tgat, a Rho-specific guanine nucleotide exchange factor, activates NF-kappaB via physical association with IkappaB kinase complexes. Biochem Biophys Res Commun 2007; 355:269-74. [PMID: 17292329 DOI: 10.1016/j.bbrc.2007.01.147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 01/29/2007] [Indexed: 10/23/2022]
Abstract
Constitutive activity of NF-kappaB is associated with various human cancers including adult T-cell leukemia (ATL). In this study, we have found Tgat that activates NF-kappaB by screening a cDNA expression library derived from ATL cells. We previously identified Tgat as the oncogene, which consists of the Rho-guanine nucleotide exchange factor (Rho-GEF) domain and the unique C-terminal region, as a consequence of alternative splicing of the Trio transcript. Tgat activated the IKK activity by binding with the IkappaB kinase (IKK) complex. The Tgat mutants lacking the C-terminal region failed to associate with the IKK complex suggesting an essential role of the unique sequence. The mutation causing the loss of GEF activity also abolished the NF-kappaB activation. Moreover, co-expressed p100 was efficiently processed into p52 in the Tgat-expressing cells, suggesting the co-involvement of non-canonical pathway.
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Affiliation(s)
- Kenji Yamada
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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Holmquist-Mengelbier L, Fredlund E, Löfstedt T, Noguera R, Navarro S, Nilsson H, Pietras A, Vallon-Christersson J, Borg A, Gradin K, Poellinger L, Påhlman S. Recruitment of HIF-1alpha and HIF-2alpha to common target genes is differentially regulated in neuroblastoma: HIF-2alpha promotes an aggressive phenotype. Cancer Cell 2006; 10:413-23. [PMID: 17097563 DOI: 10.1016/j.ccr.2006.08.026] [Citation(s) in RCA: 549] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 05/30/2006] [Accepted: 08/29/2006] [Indexed: 01/09/2023]
Abstract
In neuroblastoma specimens, HIF-2alpha but not HIF-1alpha is strongly expressed in well-vascularized areas. In vitro, HIF-2alpha protein was stabilized at 5% O2 (resembling end capillary oxygen conditions) and, in contrast to the low HIF-1alpha activity at this oxygen level, actively transcribed genes like VEGF. Under hypoxia (1% O2), HIF-1alpha was transiently stabilized and primarily mediated acute responses, whereas HIF-2alpha protein gradually accumulated and governed prolonged hypoxic gene activation. Knockdown of HIF-2alpha reduced growth of neuroblastoma tumors in athymic mice. Furthermore, high HIF-2alpha protein levels were correlated with advanced clinical stage and high VEGF expression and predicted poor prognosis in a clinical neuroblastoma material. Our results demonstrate the relevance of HIF-2alpha in neuroblastoma progression and have general tumor biological implications.
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Affiliation(s)
- Linda Holmquist-Mengelbier
- Division of Molecular Medicine, Department of Laboratory Medicine, Lund University, University Hospital MAS, SE-205 02 Malmö, Sweden
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Yoshikawa D, Kopacek J, Yamaguchi N, Ishibashi D, Yamanaka H, Yamaguchi Y, Katamine S, Sakaguchi S. Newly established in vitro system with fluorescent proteins shows that abnormal expression of downstream prion protein-like protein in mice is probably due to functional disconnection between splicing and 3' formation of prion protein pre-mRNA. Gene 2006; 386:139-46. [PMID: 17034959 DOI: 10.1016/j.gene.2006.08.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 08/08/2006] [Accepted: 08/25/2006] [Indexed: 11/18/2022]
Abstract
We and others previously showed that, in some lines of prion protein (PrP)-knockout mice, the downstream PrP-like protein (PrPLP/Dpl) was abnormally expressed in brains partly due to impaired cleavage/polyadenylation of the residual PrP promoter-driven pre-mRNA despite the presence of a poly(A) signal. In this study, we newly established an in vitro transient transfection system in which abnormal expression of PrPLP/Dpl can be visualized by expression of the green fluorescence protein, EGFP, in cultured cells. No EGFP was detected in cells transfected by a vector carrying a PrP genomic fragment including the region targeted in the knockout mice intact upstream of the PrPLP/Dpl gene. In contrast, deletion of the targeted region from the vector caused expression of EGFP. By employing this system with other vectors carrying various deletions or point mutations in the targeted region, we identified that disruption of the splicing elements in the PrP terminal intron caused the expression of EGFP. Recent lines of evidence indicate that terminal intron splicing and cleavage/polyadenylation of pre-mRNA are functionally linked to each other. Taken together, our newly established system shows that the abnormal expression of PrPLP/Dpl in PrP-knockout mice caused by the impaired cleavage/polyadenylation of the PrP promoter-driven pre-mRNA is due to the functional dissociation between the pre-mRNA machineries, in particular those of cleavage/polyadenylation and splicing. Our newly established in vitro system, in which the functional dissociation between the pre-mRNA machineries can be visualized by EGFP green fluorescence, may be useful for studies of the functional connection of pre-mRNA machineries.
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Affiliation(s)
- Daisuke Yoshikawa
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto 1-12-4, Nagasaki 852-8523, Japan
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Mesnard JM, Barbeau B, Devaux C. HBZ, a new important player in the mystery of adult T-cell leukemia. Blood 2006; 108:3979-82. [PMID: 16917009 DOI: 10.1182/blood-2006-03-007732] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Adult T-cell leukemia (ATL) was first described in 1977. A link between ATL and human T-cell leukemia virus type 1 (HTLV-1) was clearly established in the early 1980s. Over the years, many aspects of HTLV-1-induced cellular dysfunctions have been clarified. However, the detailed mechanism behind ATL occurrence remains unsolved. Presently, we are still unable to explain the absence of viral Tax protein (thought to play a central role in T-cell transformation) in more than 50% of ATL cells. A novel HTLV-1 HBZ protein, encoded on the negative strand, was characterized by our group and is currently the subject of intensive research efforts to determine its function in viral replication and/or pathophysiology. Recently, 4 studies reported on the existence of different HBZ isoforms and have investigated on their function in both ATL cells or animal models. One report suggests that the HBZ gene might have a bimodal function (at the mRNA and protein levels), which could represent an uncharacterized strategy to regulate viral replication and proliferation of infected T cells.
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MESH Headings
- Animals
- Basic-Leucine Zipper Transcription Factors/genetics
- Basic-Leucine Zipper Transcription Factors/immunology
- Cell Proliferation
- Cell Transformation, Viral/genetics
- Cell Transformation, Viral/immunology
- Disease Models, Animal
- Gene Products, tax/deficiency
- Gene Products, tax/immunology
- Human T-lymphotropic virus 1/genetics
- Human T-lymphotropic virus 1/immunology
- Humans
- Leukemia-Lymphoma, Adult T-Cell/genetics
- Leukemia-Lymphoma, Adult T-Cell/immunology
- Leukemia-Lymphoma, Adult T-Cell/pathology
- Leukemia-Lymphoma, Adult T-Cell/physiopathology
- Protein Isoforms/genetics
- Protein Isoforms/immunology
- RNA, Messenger/genetics
- RNA, Messenger/immunology
- RNA, Viral/genetics
- RNA, Viral/immunology
- Retroviridae Proteins
- T-Lymphocytes/immunology
- T-Lymphocytes/pathology
- T-Lymphocytes/virology
- Viral Proteins/genetics
- Viral Proteins/immunology
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Jean-Michel Mesnard
- Laboratoire Infections Rétrovirales et Signalisation Cellulaire, Centre National de la Recherche Scientifique (CNRS) Unité mixte de recherche (UMR) 5121-UM1, Montpellier, France
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Murata K, Hayashibara T, Sugahara K, Uemura A, Yamaguchi T, Harasawa H, Hasegawa H, Tsuruda K, Okazaki T, Koji T, Miyanishi T, Yamada Y, Kamihira S. A novel alternative splicing isoform of human T-cell leukemia virus type 1 bZIP factor (HBZ-SI) targets distinct subnuclear localization. J Virol 2006; 80:2495-505. [PMID: 16474156 PMCID: PMC1395368 DOI: 10.1128/jvi.80.5.2495-2505.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adult T-cell leukemia (ATL) is associated with prior infection with human T-cell leukemia virus type 1 (HTLV-1); however, the mechanism by which HTLV-1 causes adult T-cell leukemia has not been fully elucidated. Recently, a functional basic leucine zipper (bZIP) protein coded in the minus strand of HTLV-1 genome (HBZ) was identified. We report here a novel isoform of the HTLV-1 bZIP factor (HBZ), HBZ-SI, identified by means of reverse transcription-PCR (RT-PCR) in conjunction with 5' and 3' rapid amplification of cDNA ends (RACE). HBZ-SI is a 206-amino-acid-long protein and is generated by alternative splicing between part of the HBZ gene and a novel exon located in the 3' long terminal repeat of the HTLV-1 genome. Consequently, these isoforms share >95% amino acid sequence identity, and differ only at their N termini, indicating that HBZ-SI is also a functional protein. Duplex RT-PCR and real-time quantitative RT-PCR analyses showed that the mRNAs of these isoforms were expressed at equivalent levels in all ATL cell samples examined. Nonetheless, we found by Western blotting that the HBZ-SI protein was preferentially expressed in some ATL cell lines examined. A key finding was obtained from the subcellular localization analyses of these isoforms. Despite their high sequence similarity, each isoform was targeted to distinguishable subnuclear structures. These data show the presence of a novel isoform of HBZ in ATL cells, and in addition, shed new light on the possibility that each isoform may play a unique role in distinct regions in the cell nucleus.
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Affiliation(s)
- Ken Murata
- Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Japan.
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Shimada T, Moriuchi R, Mori T, Yamada K, Ishimaru T, Katamine S. Identification of NADH dehydrogenase 1 α subcomplex 5 capable to transform murine fibroblasts and overexpressed in human cervical carcinoma cell lines. Biochem Biophys Res Commun 2006; 339:852-7. [PMID: 16329995 DOI: 10.1016/j.bbrc.2005.11.086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 11/16/2005] [Indexed: 01/18/2023]
Abstract
The human papillomavirus (HPV) E6 and E7 proteins play essential roles in HPV-associated cervical carcinogenesis. However, cells transformed by E6 or E7 rarely grow into tumors in nude mice, indicating that the carcinogenesis involves additional molecular events. The highly efficient retroviral cDNA expression system derived from HeLa cells identified two cDNA species coding NADH dehydrogenase 1 alpha subcomplex 5 (NDUFA5) and zinc finger protein 9 (ZNF9), exhibiting the potential to transform murine fibroblast cell line, NIH3T3. The real-time RT-PCR analysis revealed that the expressions of the NDUFA5 mRNA, but not the ZNF9 mRNA level, were significantly up-regulated in all the tested cell lines derived from HPV-positive cervical cancer, HeLa, SW576, and CaSKi. The NDUFA5 expression may contribute to the multi-step carcinogenesis in human cervical cancer.
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Affiliation(s)
- Takako Shimada
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Medical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
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Arf, Sec7 and Brefeldin A: a model towards the therapeutic inhibition of guanine nucleotide-exchange factors. Biochem Soc Trans 2005; 33:1265-8. [PMID: 16246094 DOI: 10.1042/bst0331265] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
GEFs (guanine nucleotide-exchange factors), which stimulate GDP dissociation from small G-proteins, are pivotal regulators of signalling pathways activated by small G-proteins. In the case of Arf proteins, which are major regulators of membrane traffic in the cell and have recently been found to be involved in an increasing number of human diseases, GDP/GTP exchange is stimulated by GEFs that carry a catalytic Sec7 domain. Recent structural results captured snapshots of the exchange reaction, revealing that Sec7 domains secure Arf-GDP to membranes before nucleotide exchange takes place, taking advantage of a built-in structural device in Arf proteins that couples their affinity for membranes to the nature of the bound nucleotide. One of the Arf-Sec7 intermediates was trapped by BFA (Brefeldin A), an uncompetitive inhibitor of Arf activation that has been instrumental in deciphering the molecular principles of membrane traffic at the Golgi. BFA targets a low-affinity Arf-Sec7 intermediate of the exchange reaction. It binds at the Arf-GDP/Sec7 interface, thus freezing the complex in an abortive conformation that cannot proceed to nucleotide dissociation. In the cell, this results in the specific inhibition of Arf1 by a subset of its GEFs, and the efficient and reversible block of membrane traffic at the Golgi. The mechanism of BFA leads to the concept of 'interfacial inhibition', in which a protein-protein interaction of therapeutic interest is stabilized, rather than impaired, by a drug. Up-regulated activity of small G-proteins is involved in various human diseases, making their GEFs attractive candidates to interrupt specifically the corresponding signalling pathway. Interfacial inhibitors are proposed as an alternative to competitive inhibitors that may be explored for their inhibition.
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Kisanuki H, Choi YL, Wada T, Moriuchi R, Fujiwara SI, Kaneda R, Koinuma K, Ishikawa M, Takada S, Yamashita Y, Mano H. Retroviral expression screening of oncogenes in pancreatic ductal carcinoma. Eur J Cancer 2005; 41:2170-5. [PMID: 16125925 DOI: 10.1016/j.ejca.2005.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/03/2005] [Accepted: 05/10/2005] [Indexed: 11/28/2022]
Abstract
Pancreatic ductal carcinoma (PDC) remains one of the most intractable malignancies in humans. In order to clarify the molecular events underlying the carcinogenesis in PDC, we constructed a retroviral cDNA expression library from a PDC cell line, and used it to screen transforming genes in PDC by a focus formation assay with mouse 3T3 fibroblasts. We could obtain a total of 30 transformed cell foci in the screening, and one of the cDNA inserts harvested from such cell clones turned out to encode a wild-type human ARAF1. Unexpectedly, a long terminal repeat-driven overexpression of ARAF1 mRNA was confirmed to induce transformed foci in fibroblasts. The oncogenic potential of ARAF1 was examined by injecting the transformed fibroblasts into athymic nude mice. Importantly, ARAF1 mRNA was highly expressed in pancreatic ductal cell specimens purified from patients with PDC. These results have unveiled the transforming potential of ARAF1 protein, and also suggest that quantity of intracellular ARAF1 may be important in carcinogenesis of various human cancers.
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Affiliation(s)
- Hiroyuki Kisanuki
- Division of Functional Genomics, Jichi Medical School, 3311-1 Yakushiji, Kawachigun, Tochigi 329-0498, Japan
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McPherson CE, Eipper BA, Mains RE. Multiple novel isoforms of Trio are expressed in the developing rat brain. Gene 2005; 347:125-35. [PMID: 15715966 DOI: 10.1016/j.gene.2004.12.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 11/20/2004] [Accepted: 12/15/2004] [Indexed: 11/16/2022]
Abstract
Mammalian Trio is a multifunctional, multidomain Rho guanine nucleotide exchange factor (GEF) closely related to Kalirin. Trio is important for proper axon guidance in Drosophila, and mice lacking Trio exhibit both skeletal muscle and neuronal disorders. Full length mammalian Trio and Kalirin both consist of a Sec14P-like domain, several spectrin-like domains, two Rho GEF domains each containing a Dbl-homology (DH) and a pleckstrin-homology (PH) domain, two src homology 3 domains (SH3), Ig/fibronectin-like domains (Ig/FN), and a kinase domain. We have previously described multiple isoforms of Kalirin derived through alternative splicing and multiple transcription start sites, but multiple isoforms of Trio containing different functional domains have not been described. Using a new antibody directed against the spectrin-like region of rat Trio coupled with reverse transcription PCR and cDNA sequencing, we have identified 4 novel isoforms of Trio expressed in rat cortex and cerebellum. Two isoforms, Trio 9S and Trio 9L, are derived through alternative splicing of Trio exon 48 and are abundantly expressed in rat brain. Trio 8 is expressed in postnatal day 30 and adult cerebellum, but not in cortex or skeletal muscle. Trio/duet is expressed in adult cortex and cerebellum. In the rat brain, each of these Trio isoforms is expressed at a higher level than full length Trio.
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Affiliation(s)
- Clifton E McPherson
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3401, USA
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Matsuoka M. Human T-cell leukemia virus type I (HTLV-I) infection and the onset of adult T-cell leukemia (ATL). Retrovirology 2005; 2:27. [PMID: 15854229 PMCID: PMC1131926 DOI: 10.1186/1742-4690-2-27] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 04/26/2005] [Indexed: 11/13/2022] Open
Abstract
The clinical entity of adult T-cell leukemia (ATL) was established around 1977, and human T-cell leukemia virus type 1 (HTLV-I) was subsequently identified in 1980. In the 25 years since the discovery of HTLV-I, HTLV-I infection and its associated diseases have been extensively studied, and many of their aspects have been clarified. However, the detailed mechanism of leukemogenesis remains unsolved yet, and the prognosis of ATL patients still poor because of its resistance to chemotherapy and immunodeficiency. In this review, I highlight the recent progress and remaining enigmas in HTLV-I infection and its associated diseases, especially ATL.
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Affiliation(s)
- Masao Matsuoka
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
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