1
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Cook DR, Kang M, Martin TD, Galanko JA, Loeza GH, Trembath DG, Justilien V, Pickering KA, Vincent DF, Jarosch A, Jurmeister P, Waters AM, Hibshman PS, Campbell AD, Ford CA, Keku TO, Yeh JJ, Lee MS, Cox AD, Fields AP, Sandler RS, Sansom OJ, Sers C, Schaefer A, Der CJ. Aberrant Expression and Subcellular Localization of ECT2 Drives Colorectal Cancer Progression and Growth. Cancer Res 2022; 82:90-104. [PMID: 34737214 PMCID: PMC9056178 DOI: 10.1158/0008-5472.can-20-4218] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 09/20/2021] [Accepted: 10/29/2021] [Indexed: 11/16/2022]
Abstract
ECT2 is an activator of RHO GTPases that is essential for cytokinesis. In addition, ECT2 was identified as an oncoprotein when expressed ectopically in NIH/3T3 fibroblasts. However, oncogenic activation of ECT2 resulted from N-terminal truncation, and such truncated ECT2 proteins have not been found in patients with cancer. In this study, we observed elevated expression of full-length ECT2 protein in preneoplastic colon adenomas, driven by increased ECT2 mRNA abundance and associated with APC tumor-suppressor loss. Elevated ECT2 levels were detected in the cytoplasm and nucleus of colorectal cancer tissue, suggesting cytoplasmic mislocalization as one mechanism of early oncogenic ECT2 activation. Importantly, elevated nuclear ECT2 correlated with poorly differentiated tumors, and a low cytoplasmic:nuclear ratio of ECT2 protein correlated with poor patient survival, suggesting that nuclear and cytoplasmic ECT2 play distinct roles in colorectal cancer. Depletion of ECT2 reduced anchorage-independent cancer cell growth and invasion independent of its function in cytokinesis, and loss of Ect2 extended survival in a Kras G12D Apc-null colon cancer mouse model. Expression of ECT2 variants with impaired nuclear localization or guanine nucleotide exchange catalytic activity failed to restore cancer cell growth or invasion, indicating that active, nuclear ECT2 is required to support tumor progression. Nuclear ECT2 promoted ribosomal DNA transcription and ribosome biogenesis in colorectal cancer. These results support a driver role for both cytoplasmic and nuclear ECT2 overexpression in colorectal cancer and emphasize the critical role of precise subcellular localization in dictating ECT2 function in neoplastic cells. SIGNIFICANCE: ECT2 overexpression and mislocalization support its role as a driver in colon cancer that is independent from its function in normal cell cytokinesis.
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Affiliation(s)
- Danielle R Cook
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Melissa Kang
- Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Timothy D Martin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Joseph A Galanko
- Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gabriela H Loeza
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Dimitri G Trembath
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Verline Justilien
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, Florida
| | | | - David F Vincent
- Cancer Research UK Beatson Institute, Glasgow, United Kingdom
| | - Armin Jarosch
- Charité Universitätsmedizin Berlin, Institute of Pathology, Laboratory of Molecular Tumor Pathology and Systems Biology, Berlin, Germany
| | - Philipp Jurmeister
- Charité Universitätsmedizin Berlin, Institute of Pathology, Laboratory of Molecular Tumor Pathology and Systems Biology, Berlin, Germany
| | - Andrew M Waters
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Priya S Hibshman
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | | | - Catriona A Ford
- Cancer Research UK Beatson Institute, Glasgow, United Kingdom
| | - Temitope O Keku
- Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jen Jen Yeh
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michael S Lee
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Adrienne D Cox
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alan P Fields
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, Florida
| | - Robert S Sandler
- Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Owen J Sansom
- Cancer Research UK Beatson Institute, Glasgow, United Kingdom
- Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christine Sers
- Charité Universitätsmedizin Berlin, Institute of Pathology, Laboratory of Molecular Tumor Pathology and Systems Biology, Berlin, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Antje Schaefer
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Channing J Der
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Charité Universitätsmedizin Berlin, Institute of Pathology, Laboratory of Molecular Tumor Pathology and Systems Biology, Berlin, Germany
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2
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Abstract
Control of protein activity in living cells can reveal the role of spatiotemporal dynamics in signaling circuits. Protein analogs with engineered allosteric responses can be particularly effective in the interrogation of protein signaling, as they can replace endogenous proteins with minimal perturbation of native interactions. However, it has been a challenge to identify allosteric sites in target proteins where insertion of responsive domains produces an allosteric response comparable to the activity of native proteins. Here, we describe a detailed protocol to generate genetically encoded analogs of proteins that can be allosterically controlled by either rapamycin or blue light, as well as experimental procedures to produce and test these analogs in vitro and in mammalian cell lines. We describe computational methods, based on crystal structures or homology models, to identify effective sites for insertion of either an engineered rapamycin-responsive (uniRapR) domain or the light-responsive light-oxygen-voltage 2 (LOV2) domain. The inserted domains allosterically regulate the active site, responding to rapamycin with irreversible activation, or to light with reversible inactivation at higher spatial and temporal resolution. These strategies have been successfully applied to catalytic domains of protein kinases, Rho family GTPases, and guanine exchange factors (GEFs), as well as the binding domain of a GEF Vav2. Computational tasks can be completed within a few hours, followed by 1-2 weeks of experimental validation. We provide protocols for computational design, cloning, and experimental testing of the engineered proteins, using Src tyrosine kinase, GEF Vav2, and Rho GTPase Rac1 as examples.
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Affiliation(s)
- Onur Dagliyan
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Nikolay V Dokholyan
- Departments of Pharmacology and of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, USA
| | - Klaus M Hahn
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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3
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Sun Q, Luo T, Ren Y, Florey O, Shirasawa S, Sasazuki T, Robinson DN, Overholtzer M. Competition between human cells by entosis. Cell Res 2014; 24:1299-310. [PMID: 25342560 PMCID: PMC4220161 DOI: 10.1038/cr.2014.138] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/07/2014] [Accepted: 07/30/2014] [Indexed: 11/09/2022] Open
Abstract
Human carcinomas are comprised of complex mixtures of tumor cells that are known to compete indirectly for nutrients and growth factors. Whether tumor cells could also compete directly, for example by elimination of rivals, is not known. Here we show that human cells can directly compete by a mechanism of engulfment called entosis. By entosis, cells are engulfed, or cannibalized while alive, and subsequently undergo cell death. We find that the identity of engulfing ("winner") and engulfed ("loser") cells is dictated by mechanical deformability controlled by RhoA and actomyosin, where tumor cells with high deformability preferentially engulf and outcompete neighboring cells with low deformability in heterogeneous populations. We further find that activated Kras and Rac signaling impart winner status to cells by downregulating contractile myosin, allowing for the internalization of neighboring cells that eventually undergo cell death. Finally, we compute the energy landscape of cell-in-cell formation, demonstrating that a mechanical differential between winner and loser cells is required for entosis to proceed. These data define a mechanism of competition in mammalian cells that occurs in human tumors.
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Affiliation(s)
- Qiang Sun
- Laboratory of Cell Engineering, Institute of Biotechnology, Beijing 100071, China
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Tianzhi Luo
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yixin Ren
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Oliver Florey
- Signalling Programme, The Babraham Institute, Cambridge, CB22 3AT, UK
| | - Senji Shirasawa
- Department of Cell Biology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan
| | - Takehiko Sasazuki
- Department of Pathology, Research Institute, International Medical Center of Japan, Tokyo 163-8655, Japan
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael Overholtzer
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
- BCMB Allied Program, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
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4
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Jafari M, Seese RR, Babayan AH, Gall CM, Lauterborn JC. Glucocorticoid receptors are localized to dendritic spines and influence local actin signaling. Mol Neurobiol 2012; 46:304-15. [PMID: 22717988 PMCID: PMC3973133 DOI: 10.1007/s12035-012-8288-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 06/05/2012] [Indexed: 11/29/2022]
Abstract
Glucocorticoids affect learning and memory but the cellular mechanisms involved are poorly understood. The present studies tested if the stress-responsive glucocorticoid receptor (GR) is present and regulated within dendritic spines, and influences local signaling to the actin cytoskeleton. In hippocampal field CA1, 13 % of synapses contained GR-immunoreactivity. Three-dimensional reconstructions of CA1 dendrites showed that GR aggregates are present in both spine heads and necks. Consonant with evidence that GRα mRNA associates with the translation regulator Fragile X Mental Retardation Protein (FMRP), spine GR levels were rapidly increased by group 1 mGluR activation and reduced in mice lacking FMRP. Treatment of cultured hippocampal slices with the GR agonist dexamethasone rapidly (15-30 min) increased total levels of phosphorylated (p) Cofilin and extracellular signal-regulated kinase (ERK) 1/2, proteins that regulate actin polymerization and stability. Dexamethasone treatment of adult hippocampal slices also increased numbers of PSD95+ spines containing pERK1/2, but reduced numbers of pCofilin-immunoreactive spines. Dexamethasone-induced increases in synaptic pERK1/2 were blocked by the GR antagonist RU-486. These results demonstrate that GRs are present in hippocampal spines where they mediate acute glucocorticoid effects on local spine signaling. Through effects on these actin regulatory pathways, GRs are positioned to exert acute effects on synaptic plasticity.
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Affiliation(s)
- Matiar Jafari
- Department of Anatomy and Neurobiology, 3226 Gillespie Neuroscience Research Facility, University of California at Irvine, Irvine, CA 92697-1275, USA
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5
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Abstract
Here, we provide procedures for imaging the Rho GTPase biosensors in both single and multiplex acquisition modes. The multiplex approach enables the direct visualization of two biosensor readouts from a single living cell. Here, we take as an example a combination of the RhoA biosensor based on a CFP/YFP FRET modality and the Cdc42 biosensor based on organic dyes that change fluorescence as a function of the local solvent polarity. We list the required optical components as well as cellular manipulation techniques necessary to successfully image these two ratiometric biosensors in a single living cell.
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Affiliation(s)
- Désirée Spiering
- Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, USA
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6
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Abstract
Trace conditioning is valued as a simple experimental model to assess how the brain associates events that are discrete in time. Here, we adapted an olfactory trace conditioning procedure in Drosophila melanogaster by training fruit flies to avoid an odor that is followed by foot shock many seconds later. The molecular underpinnings of the learning are distinct from the well-characterized simultaneous conditioning, where odor and punishment temporally overlap. First, Rutabaga adenylyl cyclase (Rut-AC), a putative molecular coincidence detector vital for simultaneous conditioning, is dispensable in trace conditioning. Second, dominant-negative Rac expression, thought to sustain early labile memory, significantly enhances learning of trace conditioning, but leaves simultaneous conditioning unaffected. We further show that targeting Rac inhibition to the mushroom body (MB) but not the antennal lobe (AL) suffices to achieve the enhancement effect. Moreover, the absence of trace conditioning learning in D1 dopamine receptor mutants is rescued by restoration of expression specifically in the adult MB. These results suggest the MB as a crucial neuroanatomical locus for trace conditioning, which may harbor a Rac activity-sensitive olfactory "sensory buffer" that later converges with the punishment signal carried by dopamine signaling. The distinct molecular signature of trace conditioning revealed here shall contribute to the understanding of how the brain overcomes a temporal gap in potentially related events.
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Affiliation(s)
- Yichun Shuai
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724; and
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Ying Hu
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Hongtao Qin
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724; and
| | | | - Yi Zhong
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724; and
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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7
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Mattoo S, Durrant E, Chen MJ, Xiao J, Lazar CS, Manning G, Dixon JE, Worby CA. Comparative analysis of Histophilus somni immunoglobulin-binding protein A (IbpA) with other fic domain-containing enzymes reveals differences in substrate and nucleotide specificities. J Biol Chem 2011; 286:32834-42. [PMID: 21795713 PMCID: PMC3173180 DOI: 10.1074/jbc.m111.227603] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 07/23/2011] [Indexed: 11/25/2022] Open
Abstract
A new family of adenylyltransferases, defined by the presence of a Fic domain, was recently discovered to catalyze the addition of adenosine monophosphate (AMP) to Rho GTPases (Yarbrough, M. L., Li, Y., Kinch, L. N., Grishin, N. V., Ball, H. L., and Orth, K. (2009) Science 323, 269-272; Worby, C. A., Mattoo, S., Kruger, R. P., Corbeil, L. B., Koller, A., Mendez, J. C., Zekarias, B., Lazar, C., and Dixon, J. E. (2009) Mol. Cell 34, 93-103). This adenylylation event inactivates Rho GTPases by preventing them from binding to their downstream effectors. We reported that the Fic domain(s) of the immunoglobulin-binding protein A (IbpA) from the pathogenic bacterium Histophilus somni adenylylates mammalian Rho GTPases, RhoA, Rac1, and Cdc42, thereby inducing host cytoskeletal collapse, which allows H. somni to breach alveolar barriers and cause septicemia. The IbpA-mediated adenylylation occurs on a functionally critical tyrosine in the switch 1 region of these GTPases. Here, we conduct a detailed characterization of the IbpA Fic2 domain and compare its activity with other known Fic adenylyltransferases, VopS (Vibrio outer protein S) from the bacterial pathogen Vibrio parahaemolyticus and the human protein HYPE (huntingtin yeast interacting protein E; also called FicD). We also included the Fic domains of the secreted protein, PfhB2, from the opportunistic pathogen Pasteurella multocida, in our analysis. PfhB2 shares a common domain architecture with IbpA and contains two Fic domains. We demonstrate that the PfhB2 Fic domains also possess adenylyltransferase activity that targets the switch 1 tyrosine of Rho GTPases. Comparative kinetic and phylogenetic analyses of IbpA-Fic2 with the Fic domains of PfhB2, VopS, and HYPE reveal important aspects of their specificities for Rho GTPases and nucleotide usage and offer mechanistic insights for determining nucleotide and substrate specificities for these enzymes. Finally, we compare the evolutionary lineages of Fic proteins with those of other known adenylyltransferases.
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Affiliation(s)
- Seema Mattoo
- From the Howard Hughes Medical Institute and Department of Pharmacology and
| | - Eric Durrant
- the Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0721 and
| | - Mark J. Chen
- the Razavi Newman Center for Bioinformatics, Salk Institute, La Jolla, California 92037
| | - Junyu Xiao
- the Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0721 and
| | - Cheri S. Lazar
- the Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0721 and
| | - Gerard Manning
- the Razavi Newman Center for Bioinformatics, Salk Institute, La Jolla, California 92037
| | - Jack E. Dixon
- From the Howard Hughes Medical Institute and Department of Pharmacology and
- the Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0721 and
| | - Carolyn A. Worby
- the Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0721 and
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8
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Zhou Z, Kim J, Insolera R, Peng X, Fink DJ, Mata M. Rho GTPase regulation of α-synuclein and VMAT2: implications for pathogenesis of Parkinson's disease. Mol Cell Neurosci 2011; 48:29-37. [PMID: 21699982 PMCID: PMC3163163 DOI: 10.1016/j.mcn.2011.06.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/06/2011] [Accepted: 06/01/2011] [Indexed: 12/15/2022] Open
Abstract
Accumulation of α-synuclein (Asyn) in neuronal perikarya and dystrophic neurites is characteristic of idiopathic and familial Parkinson's disease. In this study, we investigated the relationship between α-synuclein expression and neurite outgrowth-maturation using MN9D dopaminergic cells and demonstrated key features of Asyn regulation in hippocampal neurons. Neurite elongation elicited by inhibition of Rho GTPase activity with C3 transferase or by db-cAMP treatment was associated with marked reduction of α-synuclein mRNA and protein expression. Rho inhibition resulted in reduction of transcription factor SRF in the nuclear fraction and retention of MKL-1 - the SRF co-transactivator of SRE - in cytosol, indicating that these effects of Rho inhibition may be mediated though reduction of SRF-SRE transcription. Inhibition of Rho GTPase activity led to decreased nuclear localization of GATA2, a key regulator of α-synuclein promoter activity. Rho inhibition-induced neurite extension was associated with increased VMAT2 and SNARE proteins synaptophysin and synapsin I. These results indicate that in the MN9D dopaminergic cell line, α-synuclein transcription and levels of synaptic vesicle associated proteins are inversely correlated with neurite growth. We confirm that in mature hippocampal neurons inhibition of RhoA and knock down of SRF by siRNA also lead to decrease GATA2 and Asyn. The results suggest that RhoA signaling may be potential therapeutic target for the treatment of synucleinopathies.
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Affiliation(s)
- Zhigang Zhou
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
| | - Jeeyong Kim
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
| | - Ryan Insolera
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
| | - Xiangmin Peng
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
| | - David J. Fink
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
| | - Marina Mata
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, 5031 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109
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9
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Qadota H, Miyauchi T, Nahabedian JF, Stirman JN, Lu H, Amano M, Benian GM, Kaibuchi K. PKN-1, a homologue of mammalian PKN, is involved in the regulation of muscle contraction and force transmission in C. elegans. J Mol Biol 2011; 407:222-31. [PMID: 21277858 PMCID: PMC3086710 DOI: 10.1016/j.jmb.2011.01.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 01/13/2011] [Accepted: 01/14/2011] [Indexed: 11/22/2022]
Abstract
To examine the in vivo functions of protein kinase N (PKN), one of the effectors of Rho small guanosine triphosphatases (GTPases), we used the nematode Caenorhabditis elegans as a genetic model system. We identified a C. elegans homologue (pkn-1) of mammalian PKN and confirmed direct binding to C. elegans Rho small GTPases. Using a green fluorescent protein reporter, we showed that pkn-1 is mainly expressed in various muscles and is localized at dense bodies and M lines. Overexpression of the PKN-1 kinase domain and loss-of-function mutations by genomic deletion of pkn-1 resulted in a loopy Unc phenotype, which has been reported in many mutants of neuronal genes. The results of mosaic analysis and body wall muscle-specific expression of the PKN-1 kinase domain suggests that this loopy phenotype is due to the expression of PKN-1 in body wall muscle. The genomic deletion of pkn-1 also showed a defect in force transmission. These results suggest that PKN-1 functions as a regulator of muscle contraction-relaxation and as a component of the force transmission mechanism.
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Affiliation(s)
- Hiroshi Qadota
- Division of Signal Transduction, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
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10
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Chen Z, Guo L, Sprang SR, Sternweis PC. Modulation of a GEF switch: autoinhibition of the intrinsic guanine nucleotide exchange activity of p115-RhoGEF. Protein Sci 2011; 20:107-17. [PMID: 21064165 PMCID: PMC3047067 DOI: 10.1002/pro.542] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 10/28/2010] [Accepted: 10/29/2010] [Indexed: 12/13/2022]
Abstract
p115-RhoGEF (p115) belongs to the family of RGS-containing guanine nucleotide exchange factors for Rho GTPases (RGS-RhoGEFs) that are activated by G12 class heterotrimeric G protein α subunits. All RGS-RhoGEFs possess tandemly linked Dbl-homology (DH) and plekstrin-homology (PH) domains, which bind and catalyze the exchange of GDP for GTP on RhoA. We have identified that the linker region connecting the N-terminal RGS-homology (RH) domain and the DH domain inhibits the intrinsic guanine nucleotide exchange (GEF) activity of p115, and determined the crystal structures of the DH/PH domains in the presence or absence of the inhibitory linker region. An N-terminal extension of the canonical DH domain (the GEF switch), which is critical to GEF activity, is well folded in the crystal structure of DH/PH alone, but becomes disordered in the presence of the linker region. The linker region is completely disordered in the crystal structure and partially disordered in the molecular envelope calculated from measurements of small angle x-ray scattering (SAXS). It is possible that Gα subunits activate p115 in part by relieving autoinhibition imposed by the linker region.
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Affiliation(s)
- Zhe Chen
- Department of Pharmacology, The University of Texas Southwestern Medical CenterDallas, Texas 75390
| | - Liang Guo
- BioCAT, Advanced Photon Source, Argonne National Laboratory9700 South Cass Avenue, Argonne, Illinois 60439
| | - Stephen R Sprang
- Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of MontanaMissoula, Montana 59812
| | - Paul C Sternweis
- Department of Pharmacology, The University of Texas Southwestern Medical CenterDallas, Texas 75390
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11
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Khusial PR, Vadla B, Krishnan H, Ramlall TF, Shen Y, Ichikawa H, Geng JG, Goldberg GS. Src activates Abl to augment Robo1 expression in order to promote tumor cell migration. Oncotarget 2010; 1:198-209. [PMID: 21301049 PMCID: PMC3058788 DOI: 10.18632/oncotarget.126] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/16/2010] [Indexed: 11/25/2022] Open
Abstract
Cell migration is an essential step in cancer invasion and metastasis. A number of orchestrated cellular events involving tyrosine kinases and signaling receptors enable cancer cells to dislodge from primary tumors and colonize elsewhere in the body. For example, activation of the Src and Abl kinases can mediate events that promote tumor cell migration. Also, activation of the Robo1 receptor can induce tumor cell migration. However, while the importance of Src, Abl, and Robo1 in cell migration have been demonstrated, molecular mechanisms by which they collectively influence cell migration have not been clearly elucidated. In addition, little is known about mechanisms that control Robo1 expression. We report here that Src activates Abl to stabilize Robo1 in order to promote cell migration. Inhibition of Abl kinase activity by siRNA or kinase blockers decreased Robo1 protein levels and suppressed the migration of transformed cells. We also provide evidence that Robo1 utilizes Cdc42 and Rac1 GTPases to induce cell migration. In addition, inhibition of Robo1 signaling can suppress transformed cell migration in the face of robust Src and Abl kinase activity. Therefore, inhibitors of Src, Abl, Robo1 and small GTPases may target a coordinated pathway required for tumor cell migration.
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Affiliation(s)
- P Raaj Khusial
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
| | - Bhaskar Vadla
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
- Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
| | - Harini Krishnan
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
- Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
| | - Trudy F Ramlall
- Department of Biochemistry and Program in Structural Biology, Weill Medical College of Cornell University, New York, New York 10065, USA
| | - Yongquan Shen
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
| | - Hitoshi Ichikawa
- Genetcis Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Jian-Guo Geng
- Vascular Biology Center, Division of Hematology, Oncology, and Transplantation, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Gary S Goldberg
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
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12
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Khusial PR, Vadla B, Krishnan H, Ramlall TF, Shen Y, Ichikawa H, Geng JG, Goldberg GS. Src activates Abl to augment Robo1 expression in order to promote tumor cell migration. Oncotarget 2010; 1:198-209. [PMID: 21301049 PMCID: PMC3058788 DOI: 10.18632/oncotarget.100710] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/16/2010] [Indexed: 01/09/2023] Open
Abstract
Cell migration is an essential step in cancer invasion and metastasis. A number of orchestrated cellular events involving tyrosine kinases and signaling receptors enable cancer cells to dislodge from primary tumors and colonize elsewhere in the body. For example, activation of the Src and Abl kinases can mediate events that promote tumor cell migration. Also, activation of the Robo1 receptor can induce tumor cell migration. However, while the importance of Src, Abl, and Robo1 in cell migration have been demonstrated, molecular mechanisms by which they collectively influence cell migration have not been clearly elucidated. In addition, little is known about mechanisms that control Robo1 expression. We report here that Src activates Abl to stabilize Robo1 in order to promote cell migration. Inhibition of Abl kinase activity by siRNA or kinase blockers decreased Robo1 protein levels and suppressed the migration of transformed cells. We also provide evidence that Robo1 utilizes Cdc42 and Rac1 GTPases to induce cell migration. In addition, inhibition of Robo1 signaling can suppress transformed cell migration in the face of robust Src and Abl kinase activity. Therefore, inhibitors of Src, Abl, Robo1 and small GTPases may target a coordinated pathway required for tumor cell migration.
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Affiliation(s)
- P Raaj Khusial
- Molecular Biology Department, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA
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13
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Blair HC, Yaroslavskiy BB, Robinson LJ, Mapara MY, Pangrazio A, Guo L, Chen K, Vezzoni P, Tolar J, Orchard PJ. Osteopetrosis with micro-lacunar resorption because of defective integrin organization. J Transl Med 2009; 89:1007-17. [PMID: 19546854 DOI: 10.1038/labinvest.2009.58] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In vitro differentiated monocytes were used to characterize the cellular defect in a type of osteopetrosis with minimally functional osteoclasts, in which defects associated with common causes of osteopetrosis were excluded by gene sequencing. Monocytes from the blood of a 28-year-old patient were differentiated in media with RANKL and CSF-1. Cell fusion, acid compartments within cells, and tartrate resistant acid phosphatase (TRAP) activity were normal. However, the osteoclasts made abnormally small pits on the dentine. Phalloidin labeling showed that the cell attachments lacked the peripheral ring structure that supports lacunar resorption. Instead, the osteoclasts had clusters of podosomes near the center of cell attachments. Antibody to the alphavbeta3 integrin pair or to the C-terminal of beta3 did not label podosomes, but antibody to alphav labeled them. Western blots using antibody to the N-terminal of beta3 showed a protein of reduced size. Integrins beta1 and beta5 were upregulated, but, in contrast to observations in beta3 defects, alpha2 had not increased. The rho-GTP exchange protein Vav3, a key attachment organizing protein, did not localize normally with peripheral attachment structures. Vav3 forms of 70 kD and 90 kD were identified on western blots. However, the proteins beta3 integrin, Vav3, Plekhm1, and Src, implicated in attachment defects, had normal exon sequences. In this new type of osteopetrosis, the integrin-organizing complex is dysfunctional, and at least two attachment proteins may be partially degraded.
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14
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Blasius AL, Brandl K, Crozat K, Xia Y, Khovananth K, Krebs P, Smart NG, Zampolli A, Ruggeri ZM, Beutler BA. Mice with mutations of Dock7 have generalized hypopigmentation and white-spotting but show normal neurological function. Proc Natl Acad Sci U S A 2009; 106:2706-11. [PMID: 19202056 PMCID: PMC2650330 DOI: 10.1073/pnas.0813208106] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Indexed: 12/30/2022] Open
Abstract
The classical recessive coat color mutation misty (m) arose spontaneously on the DBA/J background and causes generalized hypopigmentation and localized white-spotting in mice, with a lack of pigment on the belly, tail tip, and paws. Here we describe moonlight (mnlt), a second hypopigmentation and white-spotting mutation identified on the C57BL/6J background, which yields a phenotypic copy of m/m coat color traits. We demonstrate that the 2 mutations are allelic. m/m and mnlt/mnlt phenotypes both result from mutations that truncate the dedicator of cytokinesis 7 protein (DOCK7), a widely expressed Rho family guanine nucleotide exchange factor. Although Dock7 is transcribed at high levels in the developing brain and has been implicated in both axon development and myelination by in vitro studies, we find no requirement for DOCK7 in neurobehavioral function in vivo. However, DOCK7 has non-redundant role(s) related to the distribution and function of dermal and follicular melanocytes.
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Affiliation(s)
| | | | | | - Yu Xia
- Departments of Genetics and
| | | | | | | | - Antonella Zampolli
- Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Zaverio M. Ruggeri
- Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
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15
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Grassart A, Dujeancourt A, Lazarow PB, Dautry-Varsat A, Sauvonnet N. Clathrin-independent endocytosis used by the IL-2 receptor is regulated by Rac1, Pak1 and Pak2. EMBO Rep 2008; 9:356-62. [PMID: 18344974 PMCID: PMC2288760 DOI: 10.1038/embor.2008.28] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 01/30/2008] [Accepted: 01/30/2008] [Indexed: 01/14/2023] Open
Abstract
There are several endocytic pathways, which are either dependent on or independent of clathrin. This study focuses on a poorly characterized mechanism-clathrin- and caveolae-independent endocytosis-used by the interleukin-2 receptor beta (IL-2R beta). We address the question of its regulation in comparison with the clathrin-dependent pathway. First, we show that Ras-related C3 botulinum toxin substrate 1 (Rac1) is specifically required for IL-2R beta entry, and we identify p21-activated kinases (Paks) as downstream targets. By RNA interference, we show that Pak1 and Pak2 are both necessary for IL-2R beta uptake, in contrast to the clathrin-dependent route. We observe that cortactin, a partner of actin and dynamin-two essential endocytic factors-is required for IL-2R beta uptake. Furthermore, we find that cortactin acts downstream from Paks, suggesting control of its function by these kinases. Thus, we describe a cascade composed of Rac1, Paks and cortactin specifically regulating IL-2R beta internalization. This study indicates Paks as the first specific regulators of the clathrin-independent endocytosis pathway.
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Affiliation(s)
- Alexandre Grassart
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, CNRS URA 2582, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Annick Dujeancourt
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, CNRS URA 2582, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Paul B Lazarow
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, CNRS URA 2582, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Alice Dautry-Varsat
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, CNRS URA 2582, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Nathalie Sauvonnet
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, CNRS URA 2582, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
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16
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Abstract
Rho-associated protein kinases (ROCKs) play key roles in mediating the control of the actin cytoskeleton by Rho family GTPases in response to extracellular signals. Such signaling pathways contribute to diverse neuronal functions from cell migration to axonal guidance to dendritic spine morphology to axonal regeneration to cell survival. In this review, the authors summarize biochemical knowledge of ROCK function and categorize neuronal ROCK-dependent signaling pathways. Further study of ROCK signal transduction mechanisms and specificities will enhance our understanding of brain development, plasticity, and repair. The ROCK pathway also provides a potential site for therapeutic intervention to promote neuronal regeneration and to limit degeneration.
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Affiliation(s)
- André Schmandke
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Neurology Yale University School of Medicine, New Haven, CT 06510, USA
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17
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Chaplet M, Detry C, Deroanne C, Fisher L, Castronovo V, Bellahcéne A. Zoledronic acid up-regulates bone sialoprotein expression in osteoblastic cells through Rho GTPase inhibition. Biochem J 2004; 384:591-8. [PMID: 15324309 PMCID: PMC1134145 DOI: 10.1042/bj20040380] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 07/14/2004] [Accepted: 08/23/2004] [Indexed: 02/07/2023]
Abstract
Clinical practice reveals that osteoporotic women treated with BPs (bisphosphonates) show an increased bone mass density and a reduced risk of fractures. However, the mechanisms leading to these beneficial effects of BPs are still poorly understood. We hypothesized that ZOL (zoledronic acid), a potent third-generation BP, may induce the expression of proteins associated with the bone-forming potential of osteoblastic cells such as BSP (bone sialo-protein). Expression of BSP gene is up-regulated by hormones that promote bone formation and has been associated with de novo bone mineralization. Using real-time reverse transcriptase-PCR and Western-blot analysis, we demonstrated that ZOL increased BSP expression in Saos-2 osteoblast-like cells. Nuclear run-on and mRNA decay assays showed no effect at the transcriptional level but a stabilization of BSP transcripts in ZOL-treated cells. ZOL effect on BSP expression occurred through an interference with the mevalonate pathway since it was reversed by either mevalonate pathway intermediates or a Rho GTPase activator. We showed that ZOL impaired membrane localization of RhoA in Saos-2 cells indicating reduced prenylation of this protein. By the use of small interfering RNAs directed to RhoA and Rac1, we identified both Rho GTPases as negative regulators of BSP expression in Saos-2 cells. Our study demonstrates that ZOL induces BSP expression in osteoblast-like cells through inactivation of Rho GTPases and provides a potential mechanism to explain the favourable effects of ZOL treatment on bone mass and integrity.
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Key Words
- bisphosphonate
- bone sialoprotein
- osteoblast-like cells
- post-transcriptional regulation
- rho gtpase
- zoledronic acid
- bp, bisphosphonate
- bsp, bone sialoprotein
- cnf-1, cytotoxic necrotizing factor-1
- drb, 5,6-dichloro-1-β-d-ribofuranosylbenz-imidazole
- foh, farnesol
- fpp, farnesyldiphosphate
- gapdh, glyceraldehyde-3-phosphate dehydrogenase
- ggoh, geranylgeraniol
- ggpp, geranylgeranyldiphosphate
- rt, reverse transcriptase
- sirna, small interfering rna
- zol, zoledronic acid
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Affiliation(s)
- Michaël Chaplet
- *Metastasis Research Laboratory, Center of Experimental Cancer Research, University of Liège, 4000 Liège, Belgium
| | - Cédric Detry
- *Metastasis Research Laboratory, Center of Experimental Cancer Research, University of Liège, 4000 Liège, Belgium
| | - Christophe Deroanne
- †Laboratory of Connective Tissues Biology, Center of Experimental Cancer Research, University of Liège, 4000 Liège, Belgium
| | - Larry W. Fisher
- ‡Craniofacial and Skeletal Diseases Branch, N.I.D.C.R., National Institutes of Health, H.H.S., Bethesda, MD 20892-4320, U.S.A
| | - Vincent Castronovo
- *Metastasis Research Laboratory, Center of Experimental Cancer Research, University of Liège, 4000 Liège, Belgium
| | - Akeila Bellahcéne
- *Metastasis Research Laboratory, Center of Experimental Cancer Research, University of Liège, 4000 Liège, Belgium
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18
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Arnaud M, Mzali R, Gesbert F, Crouin C, Guenzi C, Vermot-Desroches C, Wijdenes J, Courtois G, Bernard O, Bertoglio J. Interaction of the tyrosine phosphatase SHP-2 with Gab2 regulates Rho-dependent activation of the c-fos serum response element by interleukin-2. Biochem J 2004; 382:545-56. [PMID: 15170389 PMCID: PMC1133811 DOI: 10.1042/bj20040103] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Revised: 05/17/2004] [Accepted: 06/01/2004] [Indexed: 12/27/2022]
Abstract
Gab2 (Grb2-associated binder-2), a member of the IRS (insulin receptor substrate)/Gab family of adapter proteins, undergoes tyrosine phosphorylation in response to cytokine or growth factor stimulation and serves as a docking platform for many signal transduction effectors, including the tyrosine phosphatase SHP-2 [SH2 (Src homology 2)-domain-containing tyrosine phosphatase]. Here, we report that, following IL-2 (interleukin-2) stimulation of human T lymphocytes, SHP-2 binds tyrosine residues 614 and 643 of human Gab2 through its N- and C-terminal SH2 domains respectively. However, the sole mutation of Tyr-614 into phenylalanine is sufficient to prevent Gab2 from recruiting SHP-2. Expression of the Gab2 Tyr-614-->Phe (Y614F) mutant, defective in SHP-2 association, prevents ERK (extracellular-signal-regulated kinase) activation and expression of a luciferase reporter plasmid driven by the c-fos SRE (serum response element), indicating that interaction of SHP-2 with Gab2 is required for ERK activation in response to IL-2. Further investigation of IL-2-dependent induction of SRE showed that expression of a constitutively active mutant of the RhoA GTPase synergizes with IL-2 for SRE-driven transcription, whereas a dominant-negative mutant reduces the IL-2 response. Thus, in response to IL-2, full induction of the SRE requires ERK-dependent as well as Rho-dependent signals that target the Ets-box and the CArG-box respectively. We also report that the synergy between Gab2/SHP-2 and RhoA for IL-2-dependent CArG-box-driven transcription depends upon MEK (mitogen-activated protein kinase/ERK kinase) activation, and is likely to involve regulation of the serum response factor co-activator MAL. Our studies thus provide new insights into the role of Gab2 and SHP-2 in IL-2 signal transduction.
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Key Words
- c-fos
- grb2-associated binder 2 (gab2)
- interleukin 2 (il-2)
- mitogen-activated protein (map) kinase
- rho gtpase
- serum response element (sre)
- sh2-domain-containing tyrosine phosphatase (shp-2)
- ecl, enhanced chemiluminescence
- erk, extracellular-signal-regulated kinase
- gab2, grb2-associated binder-2
- gst, glutathione s-transferase
- ha, haemagglutinin
- il, interleukin
- iptg, isopropyl β-d-thiogalactoside
- irs, insulin receptor substrate
- jak, janus kinase
- mapk, mitogen-activated protein kinase
- mek, mapk/erk kinase
- pdgf-r, platelet-derived growth factor receptor
- pi3k, phosphoinositide 3-kinase
- sre, serum response element
- srf, serum response factor
- sh2, src homology 2
- shp-2, sh2-domain-containing tyrosine phosphatase
- stat, signal transduction and activators of transcription
- tcf, ternary complex factor
- y614f, etc., a mutant bearing a replacement of tyr-614 with phenylalanine, etc
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Affiliation(s)
- Mary Arnaud
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Rym Mzali
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Franck Gesbert
- †Unité de Biologie des Interactions Cellulaires, Institut Pasteur, 25 rue du docteur Roux, 75015 Paris, France
| | - Catherine Crouin
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Christine Guenzi
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | | | - John Wijdenes
- ‡Diaclone, 1 Boulevard A. Fleming, 25020 Besançon, France
| | - Geneviève Courtois
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Olivier Bernard
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Jacques Bertoglio
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
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19
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Buck KB, Zheng JQ. Growth cone turning induced by direct local modification of microtubule dynamics. J Neurosci 2002; 22:9358-67. [PMID: 12417661 PMCID: PMC6758015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023] Open
Abstract
Pathfinding by nerve growth cones depends on attractive and repulsive turning in response to a variety of guidance cues. Here we present direct evidence to demonstrate an essential and instructive role for microtubules (MTs) in growth cone steering. First, both growth cone attraction and repulsion induced by diffusible cues in culture can be completely blocked by low concentrations of drugs that specifically inhibit dynamic microtubule ends in the growth cone. Second, direct focal photoactivated release of the microtubule-stabilizing drug taxol on one side of the growth cone consistently induces attraction (turning toward the site of application). Using the focal pipette application method, we also show that local MT stabilization by taxol induces growth cone attraction, whereas local MT destabilization by the microtubule-disrupting drug nocodazole induces repulsion (turning away). Finally, the microtubule-initiated attractive turning requires the participation of the actin cytoskeleton: local microtubule stabilization induces preferential protrusion of lamellipodia before the attractive turning, and the attraction can be abolished by inhibition of either actin polymerization or the Rho family GTPases. Together, these results demonstrate a novel steering mechanism for growth cones in which local and selective modification of dynamic microtubules can initiate and instruct directional steering. With the subsequent concerted activity of the actin cytoskeleton, this microtubule-initiated mechanism provides the growth cone with the additional means to efficiently navigate through its environment.
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Affiliation(s)
- Kenneth B Buck
- Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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20
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Abstract
Tip-growing pollen tubes provide a useful model system to study polar growth. Although roles for tip-focused calcium gradient and tip-localized Rho-family GTPase in pollen tube growth is established, the existence and function of tip-localized F-actin have been controversial. Using the green fluorescent protein-tagged actin-binding domain of mouse talin, we found a dynamic form of tip-localized F-actin in tobacco pollen tubes, termed short actin bundles (SABs). The dynamics of SABs during polar growth in pollen tubes is regulated by Rop1At, a Rop GTPase belonging to the Rho family. When overexpressed, Rop1At transformed SAB into a network of fine filaments and induced a transverse actin band behind the tip, leading to depolarized growth. These changes were due to ectopic Rop1At localization to the apical region of the plasma membrane and were suppressed by guanine dissociation inhibitor overexpression, which removed ectopically localized Rop1At. Rop GTPase-activating protein (RopGAP1) overexpression, or Latrunculin B treatments, also recovered normal actin organization and tip growth in Rop1At-overexpressing tubes. Moreover, overexpression of RopGAP1 alone disrupted SABs and inhibited growth. Finally, SAB oscillates and appears at the tip before growth. Together, these results indicate that the dynamics of tip actin are essential for tip growth and provide the first direct evidence to link Rho GTPase to actin organization in controlling cell polarity and polar growth in plants.
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Affiliation(s)
- Ying Fu
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Guang Wu
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Zhenbiao Yang
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
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21
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Abstract
Cell binding to extracellular matrix (ECM) components changes cytoskeletal organization by the activation of Rho family GTPases. Tenascin-C, a developmentally regulated matrix protein, modulates cellular responses to other matrix proteins, such as fibronectin (FN). Here, we report that tenascin-C markedly altered cell phenotype on a three-dimensional fibrin matrix containing FN, resulting in suppression of actin stress fibers and induction of actin-rich filopodia. This distinct morphology was associated with complete suppression of the activation of RhoA, a small GTPase that induces actin stress fiber formation. Enforced activation of RhoA circumvented the effects of tenascin. Effects of active Rho were reversed by a Rho inhibitor C3 transferase. Suppression of GTPase activation allows tenascin-C expression to act as a regulatory switch to reverse the effects of adhesive proteins on Rho function. This represents a novel paradigm for the regulation of cytoskeletal organization by ECM.
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Affiliation(s)
- Melissa B. Wenk
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014
| | - Kim S. Midwood
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014
| | - Jean E. Schwarzbauer
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014
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22
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Jantsch-Plunger V, Gönczy P, Romano A, Schnabel H, Hamill D, Schnabel R, Hyman AA, Glotzer M. CYK-4: A Rho family gtpase activating protein (GAP) required for central spindle formation and cytokinesis. J Cell Biol 2000; 149:1391-404. [PMID: 10871280 PMCID: PMC2175131 DOI: 10.1083/jcb.149.7.1391] [Citation(s) in RCA: 325] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
During cytokinesis of animal cells, the mitotic spindle plays at least two roles. Initially, the spindle positions the contractile ring. Subsequently, the central spindle, which is composed of microtubule bundles that form during anaphase, promotes a late step in cytokinesis. How the central spindle assembles and functions in cytokinesis is poorly understood. The cyk-4 gene has been identified by genetic analysis in Caenorhabditis elegans. Embryos from cyk-4(t1689ts) mutant hermaphrodites initiate, but fail to complete, cytokinesis. These embryos also fail to assemble the central spindle. We show that the cyk-4 gene encodes a GTPase activating protein (GAP) for Rho family GTPases. CYK-4 activates GTP hydrolysis by RhoA, Rac1, and Cdc42 in vitro. RNA-mediated interference of RhoA, Rac1, and Cdc42 indicates that only RhoA is essential for cytokinesis and, thus, RhoA is the likely target of CYK-4 GAP activity for cytokinesis. CYK-4 and a CYK-4:GFP fusion protein localize to the central spindle and persist at cell division remnants. CYK-4 localization is dependent on the kinesin-like protein ZEN-4/CeMKLP1 and vice versa. These data suggest that CYK-4 and ZEN-4/CeMKLP1 cooperate in central spindle assembly. Central spindle localization of CYK-4 could accelerate GTP hydrolysis by RhoA, thereby allowing contractile ring disassembly and completion of cytokinesis.
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Affiliation(s)
| | - Pierre Gönczy
- European Molecular Biology Lab, Heidelberg D-69117, Germany
| | - Alper Romano
- Research Institute of Molecular Pathology, A-1030 Vienna, Austria
| | - Heinke Schnabel
- Technical University Braunschweig, D-38106, Braunschweig, Germany
| | | | - Ralf Schnabel
- Technical University Braunschweig, D-38106, Braunschweig, Germany
| | | | - Michael Glotzer
- Research Institute of Molecular Pathology, A-1030 Vienna, Austria
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23
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Lehmann M, Fournier A, Selles-Navarro I, Dergham P, Sebok A, Leclerc N, Tigyi G, McKerracher L. Inactivation of Rho signaling pathway promotes CNS axon regeneration. J Neurosci 1999; 19:7537-47. [PMID: 10460260 PMCID: PMC6782492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/1999] [Revised: 06/02/1999] [Accepted: 06/14/1999] [Indexed: 02/13/2023] Open
Abstract
Regeneration in the CNS is blocked by many different growth inhibitory proteins. To foster regeneration, we have investigated a strategy to block the neuronal response to growth inhibitory signals. Here, we report that injured axons regrow directly on complex inhibitory substrates when Rho GTPase is inactivated. Treatment of PC12 cells with C3 enzyme to inactivate Rho and transfection with dominant negative Rho allowed neurite growth on inhibitory substrates. Primary retinal neurons treated with C3 extended neurites on myelin-associated glycoprotein and myelin substrates. To explore regeneration in vivo, we crushed optic nerves of adult rat. After C3 treatment, numerous cut axons traversed the lesion to regrow in the distal white matter of the optic nerve. These results indicate that targeting signaling mechanisms converging to Rho stimulates axon regeneration on inhibitory CNS substrates.
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Affiliation(s)
- M Lehmann
- Département de Pathologie et Biologie Cellulaire, Université de Montréal, Succursale Centreville, Montréal, Québec H3C 3J7, Canada
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24
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Abstract
The PKN family of PKC-related protein kinases constitutes the major Rho GTPase-associated protein kinase activities detected in mammalian tissues. However, the biological functions of these kinases are unknown. We have identified a closely related PKN homolog in Drosophila (Pkn) that binds specifically to GTP-activated Rho1 and Rac1 GTPases through distinct binding sites on Pkn. The interaction of Pkn with either of these GTPases results in increased kinase activity, suggesting that Pkn is a shared Rho/Rac effector target. Characterization of a loss-of-function mutant of Drosophila Pkn revealed that this kinase is required specifically for the epidermal cell shape changes during the morphogenetic process of dorsal closure of the developing embryo. Moreover, Pkn, as well as the Rho1 GTPase, mediate a pathway for cell shape changes in dorsal closure that is independent of the previously reported Rac GTPase-mediated Jun amino (N)-terminal kinase (JNK) cascade that regulates gene expression required for dorsal closure. Thus, it appears that distinct but coordinated Rho- and Rac-mediated signaling pathways regulate the cell shape changes required for dorsal closure and that Pkn provides a GTPase effector function for cell shape changes in vivo, which acts together with a Rac-JNK transcriptional pathway in the morphogenesis of the Drosophila embryo.
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Affiliation(s)
- Y Lu
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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