1
|
Schaefer A, Hodge RG, Zhang H, Hobbs GA, Dilly J, Huynh M, Goodwin CM, Zhang F, Diehl JN, Pierobon M, Baldelli E, Javaid S, Guthrie K, Rashid NU, Petricoin EF, Cox AD, Hahn WC, Aguirre AJ, Bass AJ, Der CJ. RHOA L57V drives the development of diffuse gastric cancer through IGF1R-PAK1-YAP1 signaling. Sci Signal 2023; 16:eadg5289. [PMID: 38113333 PMCID: PMC10791543 DOI: 10.1126/scisignal.adg5289] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 11/03/2023] [Indexed: 12/21/2023]
Abstract
Cancer-associated mutations in the guanosine triphosphatase (GTPase) RHOA are found at different locations from the mutational hotspots in the structurally and biochemically related RAS. Tyr42-to-Cys (Y42C) and Leu57-to-Val (L57V) substitutions are the two most prevalent RHOA mutations in diffuse gastric cancer (DGC). RHOAY42C exhibits a gain-of-function phenotype and is an oncogenic driver in DGC. Here, we determined how RHOAL57V promotes DGC growth. In mouse gastric organoids with deletion of Cdh1, which encodes the cell adhesion protein E-cadherin, the expression of RHOAL57V, but not of wild-type RHOA, induced an abnormal morphology similar to that of patient-derived DGC organoids. RHOAL57V also exhibited a gain-of-function phenotype and promoted F-actin stress fiber formation and cell migration. RHOAL57V retained interaction with effectors but exhibited impaired RHOA-intrinsic and GAP-catalyzed GTP hydrolysis, which favored formation of the active GTP-bound state. Introduction of missense mutations at KRAS residues analogous to Tyr42 and Leu57 in RHOA did not activate KRAS oncogenic potential, indicating distinct functional effects in otherwise highly related GTPases. Both RHOA mutants stimulated the transcriptional co-activator YAP1 through actin dynamics to promote DGC progression; however, RHOAL57V additionally did so by activating the kinases IGF1R and PAK1, distinct from the FAK-mediated mechanism induced by RHOAY42C. Our results reveal that RHOAL57V and RHOAY42C drive the development of DGC through distinct biochemical and signaling mechanisms.
Collapse
Affiliation(s)
- Antje Schaefer
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Richard G. Hodge
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Haisheng Zhang
- Division of Molecular and Cellular Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - G. Aaron Hobbs
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Julien Dilly
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Minh Huynh
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Craig M. Goodwin
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Feifei Zhang
- Division of Molecular and Cellular Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - J. Nathaniel Diehl
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mariaelena Pierobon
- Center for Applied Proteomics and Molecular Medicine, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Elisa Baldelli
- Center for Applied Proteomics and Molecular Medicine, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Sehrish Javaid
- Program in Oral and Craniofacial Biomedicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Karson Guthrie
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Naim U. Rashid
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Emanuel F. Petricoin
- Center for Applied Proteomics and Molecular Medicine, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Adrienne D. Cox
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Program in Oral and Craniofacial Biomedicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William C. Hahn
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Andrew J. Aguirre
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Adam J. Bass
- Division of Molecular and Cellular Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Herbert Irving Comprehensive Cancer Center at Columbia University, New York, NY 10032, USA
| | - Channing J. Der
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Program in Oral and Craniofacial Biomedicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| |
Collapse
|
2
|
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: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [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.
Collapse
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
| |
Collapse
|
3
|
Sugioka K. Symmetry-breaking of animal cytokinesis. Semin Cell Dev Biol 2021; 127:100-109. [PMID: 34955355 DOI: 10.1016/j.semcdb.2021.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 12/24/2022]
Abstract
Cytokinesis is a mechanism that separates dividing cells via constriction of a supramolecular structure, the contractile ring. In animal cells, three modes of symmetry-breaking of cytokinesis result in unilateral cytokinesis, asymmetric cell division, and oriented cell division. Each mode of cytokinesis plays a significant role in tissue patterning and morphogenesis by the mechanisms that control the orientation and position of the contractile ring relative to the body axis. Despite its significance, the mechanisms involved in the symmetry-breaking of cytokinesis remain unclear in many cell types. Classical embryologists have identified that the geometric relationship between the mitotic spindle and cell cortex induces cytokinesis asymmetry; however, emerging evidence suggests that a concerted flow of compressional cell-cortex materials (cortical flow) is a spindle-independent driving force in spatial cytokinesis control. This review provides an overview of both classical and emerging mechanisms of cytokinesis asymmetry and their roles in animal development.
Collapse
Affiliation(s)
- Kenji Sugioka
- Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T1Z3, Canada; Department of Zoology, The University of British Columbia, Vancouver, BC V6T1Z3, Canada.
| |
Collapse
|
4
|
Schneid S, Wolff F, Buchner K, Bertram N, Baygün S, Barbosa P, Mangal S, Zanin E. The BRCT domains of ECT2 have distinct functions during cytokinesis. Cell Rep 2021; 34:108805. [PMID: 33657383 DOI: 10.1016/j.celrep.2021.108805] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 12/18/2020] [Accepted: 02/08/2021] [Indexed: 12/28/2022] Open
Abstract
During cell division, the guanine nucleotide exchange factor (GEF) ECT2 activates RhoA in a narrow zone at the cell equator in anaphase. ECT2 consists of three BRCT domains (BRCT0, 1, and 2), a catalytic GEF, and a pleckstrin homology (PH) domain. How the conserved BRCT domains spatially and temporally control ECT2 activity remains unclear. We reveal that each BRCT domain makes distinct contributions to the ECT2 function. We find that BRCT0 contributes to, and BRCT1 is essential for, ECT2 activation in anaphase. BRCT2 integrates two functions: GEF inhibition and RACGAP1 binding, which together limit ECT2 activity to a narrow zone at the cell equator. BRCT2-dependent control of active RhoA zone dimension functions in addition to the inhibitory signal of the astral microtubules. Our analysis provides detailed mechanistic insights into how ECT2 activity is regulated and how that regulation ensures, together with other signaling pathways, successful cell division.
Collapse
Affiliation(s)
- Sandra Schneid
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Friederike Wolff
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Kristina Buchner
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Nils Bertram
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Seren Baygün
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Pedro Barbosa
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Sriyash Mangal
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany
| | - Esther Zanin
- Department Biology II, Ludwig-Maximilians University, Planegg-Martinsried, Munich 82152, Germany.
| |
Collapse
|
5
|
Kosibaty Z, Murata Y, Minami Y, Noguchi M, Sakamoto N. ECT2 promotes lung adenocarcinoma progression through extracellular matrix dynamics and focal adhesion signaling. Cancer Sci 2020; 112:703-714. [PMID: 33215807 PMCID: PMC7893990 DOI: 10.1111/cas.14743] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
Lung adenocarcinoma (LAC) is the most prevalent form of lung cancer. Epithelial cell transforming sequence 2 (ECT2) is a guanine nucleotide exchange factor that has been implicated in oncogenic and malignant phenotypes of LAC. Here, we identified an oncogenic role of ECT2 in the extracellular matrix (ECM) dynamics of LAC cells. We showed that suppression of ECT2 decreased adhesion and spreading of LAC cells on ECM components. Morphologically, ECT2-depleted cells exhibited a rounded shape and cytoskeletal changes. Examination of transcriptional changes by RNA sequencing revealed a total of 1569 and 828 genes whose expressions were altered (absolute fold change and a difference of >2 fold) in response to suppression of ECT2 in two LAC cells (Calu-3 and NCI-H2342), respectively, along with 298 genes that were common to both cell lines. Functional enrichment analysis of common genes demonstrated a significant enrichment of focal adhesions. In accord with this observation, we found that ECT2 suppression decreased the expression level of proteins involved in focal adhesion signaling including focal adhesion kinase (FAK), Crk, integrin β1, paxillin, and p130Cas. FAK knockdown leads to impaired cell proliferation, adhesion, and spreading of LAC cells. Moreover, in LAC cells, ECT2 binds to and stabilizes FAK and is associated with the formation of the focal adhesions. Our findings provide new insights into the underlying role of ECT2 in cell-ECM dynamics during LAC progression and suggest that ECT2 could be a promising therapeutic avenue for lung cancer.
Collapse
Affiliation(s)
- Zeinab Kosibaty
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Yoshihiko Murata
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Yuko Minami
- Department of Pathology, National Hospital Organization, Ibaraki Higashi National Hospital, Ibaraki, Japan
| | - Masayuki Noguchi
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Noriaki Sakamoto
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| |
Collapse
|
6
|
Castillo-Kauil A, García-Jiménez I, Cervantes-Villagrana RD, Adame-García SR, Beltrán-Navarro YM, Gutkind JS, Reyes-Cruz G, Vázquez-Prado J. Gα s directly drives PDZ-RhoGEF signaling to Cdc42. J Biol Chem 2020; 295:16920-16928. [PMID: 33023908 PMCID: PMC7863908 DOI: 10.1074/jbc.ac120.015204] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/24/2020] [Indexed: 12/16/2022] Open
Abstract
Gα proteins promote dynamic adjustments of cell shape directed by actin-cytoskeleton reorganization via their respective RhoGEF effectors. For example, Gα13 binding to the RGS-homology (RH) domains of several RH-RhoGEFs allosterically activates these proteins, causing them to expose their catalytic Dbl-homology (DH)/pleckstrin-homology (PH) regions, which triggers downstream signals. However, whether additional Gα proteins might directly regulate the RH-RhoGEFs was not known. To explore this question, we first examined the morphological effects of expressing shortened RH-RhoGEF DH/PH constructs of p115RhoGEF/ARHGEF1, PDZ-RhoGEF (PRG)/ARHGEF11, and LARG/ARHGEF12. As expected, the three constructs promoted cell contraction and activated RhoA, known to be downstream of Gα13 Intriguingly, PRG DH/PH also induced filopodia-like cell protrusions and activated Cdc42. This pathway was stimulated by constitutively active Gαs (GαsQ227L), which enabled endogenous PRG to gain affinity for Cdc42. A chemogenetic approach revealed that signaling by Gs-coupled receptors, but not by those coupled to Gi or Gq, enabled PRG to bind Cdc42. This receptor-dependent effect, as well as CREB phosphorylation, was blocked by a construct derived from the PRG:Gαs-binding region, PRG-linker. Active Gαs interacted with isolated PRG DH and PH domains and their linker. In addition, this construct interfered with GαsQ227L's ability to guide PRG's interaction with Cdc42. Endogenous Gs-coupled prostaglandin receptors stimulated PRG binding to membrane fractions and activated signaling to PKA, and this canonical endogenous pathway was attenuated by PRG-linker. Altogether, our results demonstrate that active Gαs can recognize PRG as a novel effector directing its DH/PH catalytic module to gain affinity for Cdc42.
Collapse
Affiliation(s)
- Alejandro Castillo-Kauil
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Irving García-Jiménez
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | | | - Sendi Rafael Adame-García
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Yarely Mabell Beltrán-Navarro
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - J Silvio Gutkind
- Moores Cancer Center and Department of Pharmacology, University of California, San Diego, La Jolla, California, USA
| | - Guadalupe Reyes-Cruz
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - José Vázquez-Prado
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico.
| |
Collapse
|
7
|
Liu J, Zhou M, Ouyang Y, Du L, Xu L, Li H. Identification of potential biomarkers and their clinical significance in gastric cancer using bioinformatics analysis methods. PeerJ 2020; 8:e9174. [PMID: 33062405 PMCID: PMC7527772 DOI: 10.7717/peerj.9174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/21/2020] [Indexed: 01/07/2023] Open
Abstract
Background Alternative splicing (AS) is an important mechanism for regulating gene expression and proteome diversity. Tumor-alternative splicing can reveal a large class of new splicing-associated potential new antigens that may affect the immune response and can be used for immunotherapy. Methods The RNA-seq transcriptome data and clinical information of stomach adenocarcinoma (STAD) cohort were downloaded from The Cancer Genome Atlas (TCGA) database data portal, and data of splicing events were obtained from the SpliceSeq database. Predicting genes were validated by Asian cancer research group (ACRG) cohort and Oncomine database. RT-qPCR was used to analysis the expression of ECT2 in STAD. Results A total of 32,166 AS events were identified, among which 2,042 AS events were significantly associated with patients survival. Biological pathway analysis indicated that these genes play an important role in regulating gastric cancer-related processes such as GTPase activity and PI3K-Akt signaling pathway. Next, we derived a risk signature, using alternate acceptor, that is an independent prognostic marker. Moreover, high ECT2 expression was associated with poorer prognosis in STAD. Multivariate survival analysis demonstrated that high ECT2 expression was an independent risk factor for overall survival. Gene set enrichment analysis revealed that high ECT2 expression was enriched for hallmarks of malignant tumors. The ACRG cohort and Oncomine also showed that high ECT2 expression was associated with poorer prognosis in gastric cancer patients. Finally, RT-qPCR showed ECT2 expression was higher in STAD compared to the normal tissues. Conclusion This study excavated the alternative splicing events in gastric cancer, and found ECT2 might be a biomarkers for diagnosis and prognosis.
Collapse
Affiliation(s)
- Jie Liu
- Gastroenterology, Jining No.1 People's Hospital, Jining, China
| | - Miao Zhou
- Gastroenterology, Jining No.1 People's Hospital, Jining, China
| | - Yangyang Ouyang
- Gastroenterology, Jining No.1 People's Hospital, Jining, China
| | - Laifeng Du
- General Medicine, Jining Prison Hospital, Jining, China
| | - Lingbo Xu
- Obstetrical, Jining No.1 People's Hospital, Jining, China
| | - Hongyun Li
- Gastroenterology, Jining No.1 People's Hospital, Jining, China
| |
Collapse
|
8
|
Humphries BA, Wang Z, Yang C. MicroRNA Regulation of the Small Rho GTPase Regulators-Complexities and Opportunities in Targeting Cancer Metastasis. Cancers (Basel) 2020; 12:E1092. [PMID: 32353968 PMCID: PMC7281527 DOI: 10.3390/cancers12051092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 02/07/2023] Open
Abstract
The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.
Collapse
Affiliation(s)
- Brock A. Humphries
- Center for Molecular Imaging, Department of Radiology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Zhishan Wang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| | - Chengfeng Yang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| |
Collapse
|
9
|
Beaudet D, Pham N, Skaik N, Piekny A. Importin binding mediates the intramolecular regulation of anillin during cytokinesis. Mol Biol Cell 2020; 31:1124-1139. [PMID: 32238082 PMCID: PMC7353161 DOI: 10.1091/mbc.e20-01-0006] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains a nuclear localization signal (NLS) that binds to importin and is required for its function during cytokinesis. Here we reveal the mechanism whereby importin binding favors a conformation required for anillin's recruitment to the equatorial cortex. Active RhoA binds to the RhoA-binding domain causing an increase in accessibility of the nearby C2 domain containing the NLS. Importin binding subsequently stabilizes a conformation that favors interactions for cortical recruitment. In addition to revealing a novel mechanism for the importin-mediated regulation of a cortical protein, we also show how importin binding positively regulates protein function.
Collapse
Affiliation(s)
- Daniel Beaudet
- Department of Bioengineering, McGill University, Montreal, QC, Canada, H3A 0G4
| | - Nhat Pham
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Noha Skaik
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| |
Collapse
|
10
|
Structure and regulation of human epithelial cell transforming 2 protein. Proc Natl Acad Sci U S A 2019; 117:1027-1035. [PMID: 31888991 DOI: 10.1073/pnas.1913054117] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Epithelial cell transforming 2 (Ect2) protein activates Rho GTPases and controls cytokinesis and many other cellular processes. Dysregulation of Ect2 is associated with various cancers. Here, we report the crystal structure of human Ect2 and complementary mechanistic analyses. The data show the C-terminal PH domain of Ect2 folds back and blocks the canonical RhoA-binding site at the catalytic center of the DH domain, providing a mechanism of Ect2 autoinhibition. Ect2 is activated by binding of GTP-bound RhoA to the PH domain, which suggests an allosteric mechanism of Ect2 activation and a positive-feedback loop reinforcing RhoA signaling. This bimodal RhoA binding of Ect2 is unusual and was confirmed with Förster resonance energy transfer (FRET) and hydrogen-deuterium exchange mass spectrometry (HDX-MS) analyses. Several recurrent cancer-associated mutations map to the catalytic and regulatory interfaces, and dysregulate Ect2 in vitro and in vivo. Together, our findings provide mechanistic insights into Ect2 regulation in normal cells and under disease conditions.
Collapse
|
11
|
Kosibaty Z, Murata Y, Minami Y, Dai T, Kano J, Matsuoka R, Nakano N, Noguchi M. Cytoplasmic expression of epithelial cell transforming sequence 2 in lung adenocarcinoma and its implications for malignant progression. J Transl Med 2019; 99:551-567. [PMID: 30542068 DOI: 10.1038/s41374-018-0142-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 08/14/2018] [Accepted: 08/20/2018] [Indexed: 12/20/2022] Open
Abstract
Epithelial cell transforming sequence 2 (ECT2), a guanine nucleotide exchange factor, is predominantly localized in the nucleus of non-transformed cells and functions to regulate cytokinesis. ECT2 is also localized in the cytoplasm of cancer cells. Aberrant cytoplasmic expression of ECT2 is thought to drive tumor growth and invasion. In this study, we investigated the cytoplasmic expression of ECT2 and its prognostic and biological significance in lung adenocarcinoma. Western blotting of cellular fractions from the nucleus and cytoplasm was performed to determine the subcellular localization of ECT2 in lung adenocarcinoma cell lines. The cytoplasmic expression of ECT2 in 167 lung adenocarcinomas was evaluated by immunohistochemistry and its clinical significance was examined using Kaplan-Meier curves and Cox regression analysis. Scraping cytology specimens of 13 fresh lung adenocarcinomas were used to assess the subcellular localization of ECT2 and its phosphorylation at Thr790 (P-ECT2(T790)). We found that ECT2 was localized in both the nucleus and cytoplasm of lung adenocarcinoma cell lines and tumor tissues. Cytoplasmic expression of ECT2 was detected by immunohistochemistry in 83 (50%) of the lung adenocarcinomas, and was found to increase during cancer progression. It was expressed in 30 (29%) small adenocarcinomas ( ≤ 2 cm in diameter) and 53 (82%) advanced adenocarcinomas ( > 2 cm in diameter). Cytoplasmic positivity for ECT2 was associated with a poor outcome in terms of both disease-free and overall survival (both P < 0.001), and was an independent prognostic factor for overall survival (P = 0.025). Immunocytochemical staining for P-ECT2(T790) demonstrated cytoplasmic and membrane positivity in Calu-3 cells and scraping cytology specimens. Positive P-ECT2(T790) staining was correlated with cytoplasmic ECT2 expression in 6 of 13 scraped cytology specimens tested. In conclusion, our findings indicate that cytoplasmic ECT2 expression could promote the malignant progression of lung adenocarcinoma and may represent a potent therapeutic target for patients with lung adenocarcinoma.
Collapse
Affiliation(s)
- Zeinab Kosibaty
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yoshihiko Murata
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Yuko Minami
- Department of Pathology, National Hospital Organization, Ibaraki Higashi National Hospital, Ibaraki, Japan
| | - Tomoko Dai
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Junko Kano
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Ryota Matsuoka
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Noriyuki Nakano
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Masayuki Noguchi
- Department of Pathology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
| |
Collapse
|
12
|
Huff LP, Kikuchi DS, Faidley E, Forrester SJ, Tsai MZ, Lassègue B, Griendling KK. Polymerase-δ-interacting protein 2 activates the RhoGEF epithelial cell transforming sequence 2 in vascular smooth muscle cells. Am J Physiol Cell Physiol 2019; 316:C621-C631. [PMID: 30726115 DOI: 10.1152/ajpcell.00208.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Polymerase-δ-interacting protein 2 (Poldip2) controls a wide variety of cellular functions and vascular pathologies. To mediate these effects, Poldip2 interacts with numerous proteins and generates reactive oxygen species via the enzyme NADPH oxidase 4 (Nox4). We have previously shown that Poldip2 can activate the Rho family GTPase RhoA, another signaling node within the cell. In this study, we aimed to better understand how Poldip2 activates Rho family GTPases and the functions of the involved proteins in vascular smooth muscle cells (VSMCs). RhoA is activated by guanine nucleotide exchange factors. Using nucleotide-free RhoA (isolated from bacteria) to pulldown active RhoGEFs, we found that the RhoGEF epithelial cell transforming sequence 2 (Ect2) is activated by Poldip2. Ect2 is a critical RhoGEF for Poldip2-mediated RhoA activation, because siRNA against Ect2 prevented Poldip2-mediated RhoA activity (measured by rhotekin pulldowns). Surprisingly, we were unable to detect a direct interaction between Poldip2 and Ect2, as they did not coimmunoprecipitate. Nox4 is not required for Poldip2-driven Ect2 activation, as Poldip2 overexpression induced Ect2 activation in Nox4 knockout VSMCs similar to wild-type cells. However, antioxidant treatment blocked Poldip2-induced Ect2 activation. This indicates a novel reactive oxygen species-driven mechanism by which Poldip2 regulates Rho family GTPases. Finally, we examined the function of these proteins in VSMCs, using siRNA against Poldip2 or Ect2 and determined that Poldip2 and Ect2 are both essential for vascular smooth muscle cell cytokinesis and proliferation.
Collapse
Affiliation(s)
- Lauren Parker Huff
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Daniel Seicho Kikuchi
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Elizabeth Faidley
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Steven J Forrester
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Michelle Z Tsai
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Bernard Lassègue
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| | - Kathy K Griendling
- Department of Medicine, Division of Cardiology, Emory University School of Medicine , Atlanta, Georgia
| |
Collapse
|
13
|
Li Y, Cai X, Chen B, Gu H, Liu C. Overexpression of epithelial cell transforming 2 protein in colorectal carcinoma predicts a poor prognosis. Exp Ther Med 2017; 14:4862-4868. [PMID: 29109759 PMCID: PMC5663027 DOI: 10.3892/etm.2017.5132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 02/17/2017] [Indexed: 02/07/2023] Open
Abstract
Epithelial cell transforming 2 (Ect2) protein is a member of the human diffuse B-cell lymphoma family of guanine nucleotide exchange factors, which activate the Ras homolog gene family of small GTPases; however, the clinical implications of Ect2 in colorectal carcinoma (CRC) are unclear. The present study aimed to determine the relationship between Ect2 expression and prognosis in patients with CRC. Western blot analysis and immunohistochemistry assays were used to determine the expression of Ect2 in CRC and paired non-cancerous tissues from 66 patients. The correlation between Ect2 expression and clinicopathological parameters was assessed using χ2 tests. Patient survival was determined using the Kaplan-Meier method and log-rank test. Cox regression was used for multivariate analysis of prognostic factors. Results demonstrated that Ect2 protein was highly expressed in human CRC samples [29/45 (64.45%)] and significantly correlated with a poor prognosis (P<0.05). Compared with normal tissues, CRC tissues demonstrated higher expression levels of Ect2 mRNA [44/66 (66.67%)]. In addition, highly-expressed Ect2 was significantly associated with recurrence (P=0.023) and invasion (P=0.008) of CRC. High Ect2 expression levels in patients were associated with poorer overall survival (OS) and disease-free survival (DFS) compared with lower expression levels of Ect2. Based on multivariate analysis, Ect2 overexpression was significantly correlated with OS and DFS (P=0.015 and 0.020, respectively). In conclusion, Ect2 overexpression is an independent and important prognostic factor for OS and DFS in patients with CRC.
Collapse
Affiliation(s)
- Yiming Li
- Division of Breast Surgery, Department of Surgical Oncology, General Surgery, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China.,Department of General Surgery, 202 Hospital of People's Liberation Army, Shenyang, Liaoning 110812, P.R. China
| | - Xiangjun Cai
- Department of General Surgery, 202 Hospital of People's Liberation Army, Shenyang, Liaoning 110812, P.R. China
| | - Bo Chen
- Division of Breast Surgery, Department of Surgical Oncology, General Surgery, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Hanbo Gu
- Department of General Surgery, 202 Hospital of People's Liberation Army, Shenyang, Liaoning 110812, P.R. China
| | - Caigang Liu
- Division of Breast Surgery, Department of Surgical Oncology, General Surgery, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| |
Collapse
|
14
|
Schaefer A, Reinhard NR, Hordijk PL. Toward understanding RhoGTPase specificity: structure, function and local activation. Small GTPases 2015; 5:6. [PMID: 25483298 DOI: 10.4161/21541248.2014.968004] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Cell adhesion and migration are regulated through the concerted action of cytoskeletal dynamics and adhesion proteins, the activity of which is governed by RhoGTPases. Specific RhoGTPase signaling requires spatio-temporal activation and coordination of subsequent protein-protein and protein-lipid interactions. The nature, location and duration of these interactions are dependent on polarized extracellular triggers, such as cell-cell contact, and intracellular modifying events, such as phosphorylation. RhoA, RhoB, and RhoC are highly homologous GTPases that, however, succeed in generating specific intracellular responses. Here, we discuss the key features that contribute to this specificity. These not only include the well-studied switch regions, the conformation of which is nucleotide-dependent, but also additional regions and seemingly small differences in primary sequence that also contribute to specific interactions. These differences translate into differential surface charge distribution, local exposure of amino acid side-chains and isoform-specific post-translational modifications. The available evidence supports the notion that multiple regions in RhoA/B/C cooperate to provide specificity in binding to regulators and effectors. These specific interactions are highly regulated in time and space. We therefore subsequently discuss current approaches means to visualize and analyze localized GTPase activation using biosensors that allow imaging of isoform-specific, localized regulation.
Collapse
Affiliation(s)
- Antje Schaefer
- a Department of Molecular Cell Biology Sanquin Research and Landsteiner Laboratory; Academic Medical Center; Swammerdam Institute for Life Sciences ; University of Amsterdam ; Amsterdam , The Netherlands
| | | | | |
Collapse
|
15
|
Yamasaki T, Ariyoshi W, Okinaga T, Adachi Y, Hosokawa R, Mochizuki S, Sakurai K, Nishihara T. The dectin 1 agonist curdlan regulates osteoclastogenesis by inhibiting nuclear factor of activated T cells cytoplasmic 1 (NFATc1) through Syk kinase. J Biol Chem 2014; 289:19191-203. [PMID: 24821724 DOI: 10.1074/jbc.m114.551416] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Several immune system cell surface receptors are reported to be associated with osteoclastogenesis. Dectin 1, a lectin receptor for β-glucan, is found predominantly on cells of the myeloid lineage. In this study, we examined the effect of the dectin 1 agonist curdlan on osteoclastogenesis. In mouse bone marrow cells and dectin 1-overexpressing RAW 264.7 cells (d-RAWs), curdlan suppressed receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation, bone resorption, and actin ring formation in a dose-dependent manner. This was achieved within non-growth inhibitory concentrations at the early stage. Conversely, curdlan had no effect on macrophage colony-stimulating factor-induced differentiation. Furthermore, curdlan inhibited RANKL-induced nuclear factor of activated T cell cytoplasmic 1 (NFATc1) expression, thereby decreasing osteoclastogenesis-related marker gene expression, including tartrate-resistant acid phosphatase, osteoclast stimulatory transmembrane protein, cathepsin K, and matrix metallopeptidase 9. Curdlan inhibited RANKL-induced c-fos expression, followed by suppression of NFATc1 autoamplification, without significantly affecting the NF-κB signaling pathway. We also observed that curdlan treatment decreased Syk protein in d-RAWs. Inhibition of the dectin 1-Syk kinase pathway by Syk-specific siRNA or chemical inhibitors suppressed osteoclast formation and NFATc1 expression stimulated by RANKL. In conclusion, our results demonstrate that curdlan potentially inhibits osteoclast differentiation, especially NFATc1 expression, and that Syk kinase plays a crucial role in the transcriptional pathways. This suggests that the activation of dectin 1-Syk kinase interaction critically regulates the genes required for osteoclastogenesis.
Collapse
Affiliation(s)
- Toru Yamasaki
- From the Division of Infections and Molecular Biology, Department of Health Promotion, Division of Oral Reconstruction and Rehabilitation, Department of Oral Functions, Kyushu Dental University, Kitakyushu, Fukuoka 803-8580, Japan
| | - Wataru Ariyoshi
- From the Division of Infections and Molecular Biology, Department of Health Promotion,
| | - Toshinori Okinaga
- From the Division of Infections and Molecular Biology, Department of Health Promotion
| | - Yoshiyuki Adachi
- the Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan, and
| | - Ryuji Hosokawa
- Division of Oral Reconstruction and Rehabilitation, Department of Oral Functions, Kyushu Dental University, Kitakyushu, Fukuoka 803-8580, Japan
| | - Shinichi Mochizuki
- the Department of Chemistry and Biochemistry, The University of Kitakyushu, Kitakyushu, Fukuoka 808-0135, Japan
| | - Kazuo Sakurai
- the Department of Chemistry and Biochemistry, The University of Kitakyushu, Kitakyushu, Fukuoka 808-0135, Japan
| | - Tatsuji Nishihara
- From the Division of Infections and Molecular Biology, Department of Health Promotion
| |
Collapse
|
16
|
Huff LP, Decristo MJ, Trembath D, Kuan PF, Yim M, Liu J, Cook DR, Miller CR, Der CJ, Cox AD. The Role of Ect2 Nuclear RhoGEF Activity in Ovarian Cancer Cell Transformation. Genes Cancer 2014; 4:460-75. [PMID: 24386507 DOI: 10.1177/1947601913514851] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 11/07/2013] [Indexed: 11/15/2022] Open
Abstract
Ect2, a Rho guanine nucleotide exchange factor (RhoGEF), is atypical among RhoGEFs in its predominantly nuclear localization in interphase cells. One current model suggests that Ect2 mislocalization drives cellular transformation by promoting aberrant activation of cytoplasmic Rho family GTPase substrates. However, in ovarian cancers, where Ect2 is both amplified and overexpressed at the mRNA level, we observed that the protein is highly expressed and predominantly nuclear and that nuclear but not cytoplasmic Ect2 increases with advanced disease. Knockdown of Ect2 in ovarian cancer cell lines impaired their anchorage-independent growth without affecting their growth on plastic. Restoration of Ect2 expression rescued the anchorage-independent growth defect, but not if either the DH catalytic domain or the nuclear localization sequences of Ect2 were mutated. These results suggested a novel mechanism whereby Ect2 could drive transformation in ovarian cancer cells by acting as a RhoGEF specifically within the nucleus. Interestingly, Ect2 had an intrinsically distinct GTPase specificity profile in the nucleus versus the cytoplasm. Nuclear Ect2 bound preferentially to Rac1, while cytoplasmic Ect2 bound to RhoA but not Rac. Consistent with nuclear activation of endogenous Rac, Ect2 overexpression was sufficient to recruit Rac effectors to the nucleus, a process that required a functional Ect2 catalytic domain. Furthermore, expression of active nuclearly targeted Rac1 rescued the defect in transformed growth caused by Ect2 knockdown. Our work suggests a novel mechanism of Ect2-driven transformation, identifies subcellular localization as a regulator of GEF specificity, and implicates activation of nuclear Rac1 in cellular transformation.
Collapse
Affiliation(s)
- Lauren P Huff
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Molly J Decristo
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Dimitri Trembath
- Department of Pathology & Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Pei Fen Kuan
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC, USA
| | - Margaret Yim
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, USA
| | - Jinsong Liu
- Department of Pathology, MD Anderson Cancer Center, Houston, TX, USA
| | - Danielle R Cook
- School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | - C Ryan Miller
- Department of Pathology & Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA ; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Channing J Der
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA ; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Adrienne D Cox
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA ; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA ; Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA
| |
Collapse
|
17
|
Cook DR, Rossman KL, Der CJ. Rho guanine nucleotide exchange factors: regulators of Rho GTPase activity in development and disease. Oncogene 2013; 33:4021-35. [PMID: 24037532 DOI: 10.1038/onc.2013.362] [Citation(s) in RCA: 286] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/25/2013] [Accepted: 06/26/2013] [Indexed: 12/16/2022]
Abstract
The aberrant activity of Ras homologous (Rho) family small GTPases (20 human members) has been implicated in cancer and other human diseases. However, in contrast to the direct mutational activation of Ras found in cancer and developmental disorders, Rho GTPases are activated most commonly in disease by indirect mechanisms. One prevalent mechanism involves aberrant Rho activation via the deregulated expression and/or activity of Rho family guanine nucleotide exchange factors (RhoGEFs). RhoGEFs promote formation of the active GTP-bound state of Rho GTPases. The largest family of RhoGEFs is comprised of the Dbl family RhoGEFs with 70 human members. The multitude of RhoGEFs that activate a single Rho GTPase reflects the very specific role of each RhoGEF in controlling distinct signaling mechanisms involved in Rho activation. In this review, we summarize the role of Dbl RhoGEFs in development and disease, with a focus on Ect2 (epithelial cell transforming squence 2), Tiam1 (T-cell lymphoma invasion and metastasis 1), Vav and P-Rex1/2 (PtdIns(3,4,5)P3 (phosphatidylinositol (3,4,5)-triphosphate)-dependent Rac exchanger).
Collapse
Affiliation(s)
- D R Cook
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
| | - K L Rossman
- 1] Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA [2] Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
| | - C J Der
- 1] Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA [2] Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA [3] Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
| |
Collapse
|
18
|
Muha V, Müller HAJ. Functions and Mechanisms of Fibroblast Growth Factor (FGF) Signalling in Drosophila melanogaster. Int J Mol Sci 2013; 14:5920-37. [PMID: 23493057 PMCID: PMC3634451 DOI: 10.3390/ijms14035920] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/05/2013] [Accepted: 03/12/2013] [Indexed: 01/19/2023] Open
Abstract
Intercellular signalling via growth factors plays an important role in controlling cell differentiation and cell movements during the development of multicellular animals. Fibroblast Growth Factor (FGF) signalling induces changes in cellular behaviour allowing cells in the embryo to move, to survive, to divide or to differentiate. Several examples argue that FGF signalling is used in multi-step morphogenetic processes to achieve and maintain a transitional state of the cells required for the control of cell fate. In the genetic model Drosophila melanogaster, FGF signalling via the receptor tyrosine kinases Heartless (Htl) and Breathless (Btl) is particularly well studied. These FGF receptors affect gene expression, cell shape and cell–cell interactions during mesoderm layer formation, caudal visceral muscle (CVM) formation, tracheal morphogenesis and glia differentiation. Here, we will address the current knowledge of the biological functions of FGF signalling in the fly on the tissue, at a cellular and molecular level.
Collapse
Affiliation(s)
- Villö Muha
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD15EH, Scotland, UK.
| | | |
Collapse
|
19
|
Chan E, Nance J. Mechanisms of CDC-42 activation during contact-induced cell polarization. J Cell Sci 2013; 126:1692-702. [PMID: 23424200 DOI: 10.1242/jcs.124594] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polarization of early embryos provides a foundation to execute essential patterning and morphogenetic events. In Caenorhabditis elegans, cell contacts polarize early embryos along their radial axis by excluding the cortical polarity protein PAR-6 from sites of cell contact, thereby restricting PAR-6 to contact-free cell surfaces. Radial polarization requires the cortically enriched Rho GTPase CDC-42, which in its active form recruits PAR-6 through direct binding. The Rho GTPase activating protein (RhoGAP) PAC-1, which localizes specifically to cell contacts, triggers radial polarization by inactivating CDC-42 at these sites. The mechanisms responsible for activating CDC-42 at contact-free surfaces are unknown. Here, in an overexpression screen of Rho guanine nucleotide exchange factors (RhoGEFs), which can activate Rho GTPases, we identify CGEF-1 and ECT-2 as RhoGEFs that act through CDC-42 to recruit PAR-6 to the cortex. We show that ECT-2 and CGEF-1 localize to the cell surface and that removing their activity causes a reduction in levels of cortical PAR-6. Through a structure-function analysis, we show that the tandem DH-PH domains of CGEF-1 and ECT-2 are sufficient for GEF activity, but that regions outside of these domains target each protein to the cell surface. Finally, we provide evidence suggesting that the N-terminal region of ECT-2 may direct its in vivo preference for CDC-42 over another known target, the Rho GTPase RHO-1. We propose that radial polarization results from a competition between RhoGEFs, which activate CDC-42 throughout the cortex, and the RhoGAP PAC-1, which inactivates CDC-42 at cell contacts.
Collapse
Affiliation(s)
- Emily Chan
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | | |
Collapse
|
20
|
He X, Kuo YC, Rosche TJ, Zhang X. Structural basis for autoinhibition of the guanine nucleotide exchange factor FARP2. Structure 2013; 21:355-64. [PMID: 23375260 DOI: 10.1016/j.str.2013.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 12/09/2012] [Accepted: 01/01/2013] [Indexed: 12/21/2022]
Abstract
FARP2 is a Dbl-family guanine nucleotide exchange factor (GEF) that contains a 4.1, ezrin, radixin and moesin (FERM) domain, a Dbl-homology (DH) domain and two pleckstrin homology (PH) domains. FARP2 activates Rac1 or Cdc42 in response to upstream signals, thereby regulating processes such as neuronal axon guidance and bone homeostasis. How the GEF activity of FARP2 is regulated remained poorly understood. We have determined the crystal structures of the catalytic DH domain and the DH-PH-PH domains of FARP2. The structures reveal an auto-inhibited conformation in which the GEF substrate-binding site is blocked collectively by the last helix in the DH domain and the two PH domains. This conformation is stabilized by multiple interactions among the domains and two well-structured inter-domain linkers. Our cell-based activity assays confirm the suppression of the FARP2 GEF activity by these auto-inhibitory elements.
Collapse
Affiliation(s)
- Xiaojing He
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75063, USA
| | | | | | | |
Collapse
|
21
|
Weeks A, Okolowsky N, Golbourn B, Ivanchuk S, Smith C, Rutka JT. ECT2 and RASAL2 mediate mesenchymal-amoeboid transition in human astrocytoma cells. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:662-74. [PMID: 22683310 DOI: 10.1016/j.ajpath.2012.04.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 04/04/2012] [Accepted: 04/10/2012] [Indexed: 11/28/2022]
Abstract
Malignant astrocytomas are highly invasive brain tumors. The Rho family of cytoskeletal GTPases are key regulators of astrocytoma migration and invasion; expression of the guanine nucleotide exchange factor ECT2 is elevated in primary astrocytomas and predicts both survival and malignancy. Mice bearing orthotopically implanted astrocytoma cells with diminished ECT2 levels following ECT2 knockdown exhibit longer survival. Although ECT2 is normally expressed in the nucleus, we show that ECT2 is aberrantly localized to the cytoplasm in both astrocytoma cell lines and primary human astrocytomas, and colocalizes with RAC1 and CDC42 at the leading edge of migrating astrocytoma cells. Inhibition of ECT2 expression by RNA interference resulted in decreased RAC1 and CDC42 activity, but no change in RHO activity, suggesting that ECT2 is capable of activating these pro-migratory Rho family members. ECT2 overexpression in astrocytoma cells resulted in a transition to an amoeboid phenotype that was abolished with the ROCK inhibitor, Y-27632. Cytoplasmic fractionation of astrocytoma cells followed by ECT2 immunoprecipitation and mass spectrometry were used to identify protein-binding partners that modulate the activity of ECT2 toward RAC1 and RHO/ROCK. We identified RASAL2 as an ECT2-interacting protein that regulates RHO activity in astrocytoma cells. RASAL2 knockdown leads to a conversion to an amoeboid phenotype. Our studies reveal that ECT2 has a novel role in mesenchymal-amoeboid transition in human astrocytoma cells.
Collapse
Affiliation(s)
- Adrienne Weeks
- Division of Neurosurgery, Department of Surgery, Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | | | | | | | | | | |
Collapse
|
22
|
Fortin SP, Ennis MJ, Schumacher CA, Zylstra-Diegel CR, Williams BO, Ross JTD, Winkles JA, Loftus JC, Symons MH, Tran NL. Cdc42 and the guanine nucleotide exchange factors Ect2 and trio mediate Fn14-induced migration and invasion of glioblastoma cells. Mol Cancer Res 2012; 10:958-68. [PMID: 22571869 DOI: 10.1158/1541-7786.mcr-11-0616] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Malignant glioblastomas are characterized by their ability to infiltrate into normal brain. We previously reported that binding of the multifunctional cytokine TNF-like weak inducer of apoptosis (TWEAK) to its receptor fibroblast growth factor-inducible 14 (Fn14) induces glioblastoma cell invasion via Rac1 activation. Here, we show that Cdc42 plays an essential role in Fn14-mediated activation of Rac1. TWEAK-treated glioma cells display an increased activation of Cdc42, and depletion of Cdc42 using siRNA abolishes TWEAK-induced Rac1 activation and abrogates glioma cell migration and invasion. In contrast, Rac1 depletion does not affect Cdc42 activation by Fn14, showing that Cdc42 mediates TWEAK-stimulated Rac1 activation. Furthermore, we identified two guanine nucleotide exchange factors (GEF), Ect2 and Trio, involved in TWEAK-induced activation of Cdc42 and Rac1, respectively. Depletion of Ect2 abrogates both TWEAK-induced Cdc42 and Rac1 activation, as well as subsequent TWEAK-Fn14-directed glioma cell migration and invasion. In contrast, Trio depletion inhibits TWEAK-induced Rac1 activation but not TWEAK-induced Cdc42 activation. Finally, inappropriate expression of Fn14 or Ect2 in mouse astrocytes in vivo using an RCAS vector system for glial-specific gene transfer in G-tva transgenic mice induces astrocyte migration within the brain, corroborating the in vitro importance of the TWEAK-Fn14 signaling cascade in glioblastoma invasion. Our results suggest that the TWEAK-Fn14 signaling axis stimulates glioma cell migration and invasion through two GEF-GTPase signaling units, Ect2-Cdc42 and Trio-Rac1. Components of the Fn14-Rho GEF-Rho GTPase signaling pathway present innovative drug targets for glioma therapy.
Collapse
Affiliation(s)
- Shannon P Fortin
- Cancer and Cell Biology Division, The Translational Genomics Research Institute, Phoenix, AZ 85004, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Frenette P, Haines E, Loloyan M, Kinal M, Pakarian P, Piekny A. An anillin-Ect2 complex stabilizes central spindle microtubules at the cortex during cytokinesis. PLoS One 2012; 7:e34888. [PMID: 22514687 PMCID: PMC3325936 DOI: 10.1371/journal.pone.0034888] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 03/09/2012] [Indexed: 12/31/2022] Open
Abstract
Cytokinesis occurs due to the RhoA-dependent ingression of an actomyosin ring. During anaphase, the Rho GEF (guanine nucleotide exchange factor) Ect2 is recruited to the central spindle via its interaction with MgcRacGAP/Cyk-4, and activates RhoA in the central plane of the cell. Ect2 also localizes to the cortex, where it has access to RhoA. The N-terminus of Ect2 binds to Cyk-4, and the C-terminus contains conserved DH (Dbl homologous) and PH (Pleckstrin Homology) domains with GEF activity. The PH domain is required for Ect2's cortical localization, but its molecular function is not known. In cultured human cells, we found that the PH domain interacts with anillin, a contractile ring protein that scaffolds actin and myosin and interacts with RhoA. The anillin-Ect2 interaction may require Ect2's association with lipids, since a novel mutation in the PH domain, which disrupts phospholipid association, weakens their interaction. An anillin-RacGAP50C (homologue of Cyk-4) complex was previously described in Drosophila, which may crosslink the central spindle to the cortex to stabilize the position of the contractile ring. Our data supports an analogous function for the anillin-Ect2 complex in human cells and one hypothesis is that this complex has functionally replaced the Drosophila anillin-RacGAP50C complex. Complexes between central spindle proteins and cortical proteins could regulate the position of the contractile ring by stabilizing microtubule-cortical interactions at the division plane to ensure the generation of active RhoA in a discrete zone.
Collapse
Affiliation(s)
- Paul Frenette
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Eric Haines
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Michael Loloyan
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Mena Kinal
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Paknoosh Pakarian
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, Quebec, Canada
- * E-mail:
| |
Collapse
|
24
|
Su KC, Takaki T, Petronczki M. Targeting of the RhoGEF Ect2 to the equatorial membrane controls cleavage furrow formation during cytokinesis. Dev Cell 2012; 21:1104-15. [PMID: 22172673 DOI: 10.1016/j.devcel.2011.11.003] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 11/09/2011] [Accepted: 11/09/2011] [Indexed: 12/16/2022]
Abstract
In animal cells, formation of the cytokinetic furrow requires activation of the GTPase RhoA by the guanine nucleotide exchange factor Ect2. How Ect2, which is associated with the spindle midzone, controls RhoA activity at the equatorial cortex during anaphase is not understood. Here, we show that Ect2 concentrates at the equatorial membrane during cytokinesis in live cells. Ect2 membrane association requires a pleckstrin homology domain and a polybasic cluster that bind to phosphoinositide lipids. Both guanine nucleotide exchange function and membrane targeting of Ect2 are essential for RhoA activation and cleavage furrow formation in human cells. Membrane localization of Ect2 is spatially confined to the equator by centralspindlin, Ect2's spindle midzone anchor complex, and is temporally coordinated with chromosome segregation through the activation state of CDK1. We propose that targeting of Ect2 to the equatorial membrane represents a key step in the delivery of the cytokinetic signal to the cortex.
Collapse
Affiliation(s)
- Kuan-Chung Su
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Hertfordshire EN6 3LD, UK
| | | | | |
Collapse
|
25
|
Cook DR, Solski PA, Bultman SJ, Kauselmann G, Schoor M, Kuehn R, Friedman LS, Cowley DO, Van Dyke T, Yeh JJ, Johnson L, Der CJ. The ect2 rho Guanine nucleotide exchange factor is essential for early mouse development and normal cell cytokinesis and migration. Genes Cancer 2011; 2:932-42. [PMID: 22701760 PMCID: PMC3374631 DOI: 10.1177/1947601912437035] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/14/2011] [Accepted: 12/18/2011] [Indexed: 12/23/2022] Open
Abstract
Ect2 is a member of the human Dbl family of guanine nucleotide exchange factors (RhoGEFs) that serve as activators of Rho family small GTPases. Although Ect2 is one of at least 25 RhoGEFs that can activate the RhoA small GTPase, cell culture studies using established cell lines determined that Ect2 is essential for mammalian cell cytokinesis and proliferation. To address the function of Ect2 in normal mammalian development, we performed gene targeting to generate Ect2 knockout mice. The heterozygous Ect2(+/-) mice showed normal development and life span, indicating that Ect2 haplodeficiency was not deleterious for development or growth. In contrast, Ect2(-/-) embryos were not found at birth or postimplantation stages. Ect2(-/-) blastocysts were recovered at embryonic day 3.5 but did not give rise to viable outgrowths in culture, indicating that Ect2 is required for peri-implantation development. To further assess the importance of Ect2 in normal cell physiology, we isolated primary fibroblasts from Ect2(fl/fl) embryos (MEFs) and ablated Ect2 using adenoviral delivery of Cre recombinase. We observed a significant increase in multinucleated cells and accumulation of cells in G2/M phase, consistent with a role for Ect2 in cytokinesis. Ect2 deficiency also caused enlargement of the cytoplasm and impaired cell migration. Finally, although Ect2-dependent activation of RhoA has been implicated in cytokinesis, Ect2 can also activate Rac1 and Cdc42 to cause growth transformation. Surprisingly, ectopic expression of constitutively activated RhoA, Rac1, or Cdc42, known substrates of Ect2, failed to phenocopy Ect2 and did not rescue the defect in cytokinesis caused by loss of Ect2. In summary, our results establish the unique role of Ect2 in development and normal cell proliferation.
Collapse
Affiliation(s)
- Danielle R. Cook
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Patricia A. Solski
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Scott J. Bultman
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | | | - Ralf Kuehn
- TaconicArtemis GmbH, Cologne, Germany
- Institute of Developmental Genetics, Helmholtz Center Munich, Munich, Germany
- Institute of Developmental Genetics, Helmholtz Center Munich, Munich,Germany
| | - Lori S. Friedman
- Exelixis Inc., South San Francisco, CA, USA
- Genentech Inc., South San Francisco, CA, USA
| | - Dale O. Cowley
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Terry Van Dyke
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jen Jen Yeh
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Leisa Johnson
- Exelixis Inc., South San Francisco, CA, USA
- Genentech Inc., South San Francisco, CA, USA
| | - Channing J. Der
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| |
Collapse
|
26
|
APC(cdh1) mediates degradation of the oncogenic Rho-GEF Ect2 after mitosis. PLoS One 2011; 6:e23676. [PMID: 21886810 PMCID: PMC3158779 DOI: 10.1371/journal.pone.0023676] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 07/23/2011] [Indexed: 01/10/2023] Open
Abstract
Background Besides regulation of actin cytoskeleton-dependent functions, Rho GTPase pathways are essential to cell cycle progression and cell division. Rho, Rac and Cdc42 regulate G1 to S phase progression and are involved in cytokinesis. RhoA GDP/GTP cycling is required for normal cytokinesis and recent reports have shown that the exchange factor Ect2 and the GTPase activating protein MgcRacGAP regulate RhoA activity during mitosis. We previously showed that the transcription factors E2F1 and CUX1 regulate expression of MgcRacGAP and Ect2 as cells enter S-phase. Methodology/Principal Findings We now report that Ect2 is subject to proteasomal degradation after mitosis, following ubiquitination by the APC/C complex and its co-activator Cdh1. A proper nuclear localization of Ect2 is necessary for its degradation. APC-Cdh1 assembles K11-linked poly-ubiquitin chains on Ect2, depending upon a stretch of ∼25 amino acid residues that contain a bi-partite NLS, a conventional D-box and two TEK-like boxes. Site-directed mutagenesis of target sequences generated stabilized Ect2 proteins. Furthermore, such degradation-resistant mutants of Ect2 were found to activate RhoA and subsequent signalling pathways and are able to transform NIH3T3 cells. Conclusions/Significance Our results identify Ect2 as a bona fide cell cycle-regulated protein and suggest that its ubiquitination-dependent degradation may play an important role in RhoA regulation at the time of mitosis. Our findings raise the possibility that the overexpression of Ect2 that has been reported in some human tumors might result not only from deregulated transcription, but also from impaired degradation.
Collapse
|
27
|
Justilien V, Jameison L, Der CJ, Rossman KL, Fields AP. Oncogenic activity of Ect2 is regulated through protein kinase C iota-mediated phosphorylation. J Biol Chem 2010; 286:8149-8157. [PMID: 21189248 DOI: 10.1074/jbc.m110.196113] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Rho GTPase guanine nucleotide exchange factor Ect2 is genetically and biochemically linked to the PKCι oncogene in non-small cell lung cancer (NSCLC). Ect2 is overexpressed and mislocalized to the cytoplasm of NSCLC cells where it binds the oncogenic PKCι-Par6 complex, leading to activation of the Rac1 small GTPase. Here, we identify a previously uncharacterized phosphorylation site on Ect2, threonine 328, that serves to regulate the oncogenic activity of Ect2 in NSCLC cells. PKCι directly phosphorylates Ect2 at Thr-328 in vitro, and RNAi-mediated knockdown of either PKCι or Par6 leads to a decrease in phospho-Thr-328 Ect2, indicating that PKCι regulates Thr-328 Ect2 phosphorylation in NSCLC cells. Both wild-type Ect2 and a phosphomimetic T328D Ect2 mutant bind the PKCι-Par6 complex, activate Rac1, and restore transformed growth and invasion when expressed in NSCLC cells made deficient in endogenous Ect2 by RNAi-mediated knockdown. In contrast, a phosphorylation-deficient T328A Ect2 mutant fails to bind the PKCι-Par6 complex, activate Rac1, or restore transformation. Our data support a model in which PKCι-mediated phosphorylation regulates Ect2 binding to the oncogenic PKCι-Par6 complex thereby activating Rac1 activity and driving transformed growth and invasion.
Collapse
Affiliation(s)
- Verline Justilien
- From the Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, Florida 32224 and
| | - Lee Jameison
- From the Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, Florida 32224 and
| | - Channing J Der
- the Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Kent L Rossman
- the Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Alan P Fields
- From the Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, Florida 32224 and.
| |
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Dominico Vigil
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Department of Pharmacology, Chapel Hill, North Carolina 27599, USA
| | | | | | | |
Collapse
|
29
|
The myriad roles of Anillin during cytokinesis. Semin Cell Dev Biol 2010; 21:881-91. [PMID: 20732437 DOI: 10.1016/j.semcdb.2010.08.002] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 06/03/2010] [Accepted: 08/03/2010] [Indexed: 11/21/2022]
Abstract
Anillin is a highly conserved multidomain protein that interacts with cytoskeletal components as well as their regulators. Throughout phylogeny, Anillins contribute to cytokinesis, the cell shape change that occurs at the end of meiosis and mitosis to separate a cell into daughter cells. Failed cytokinesis results in binucleation, which can lead to genomic instability. Study of Anillin in several model organisms has provided us with insight into how the cytoskeleton is coordinated to ensure that cytokinesis occurs with high fidelity. Here we review Anillin's interacting partners and the relevance of these interactions in vivo. We also discuss questions of how these interactions are coordinated, and finally provide some perspective regarding Anillin's role in cancer.
Collapse
|
30
|
Singh A, Boyer JL, Der CJ, Zohn IE. Transformation by a nucleotide-activated P2Y receptor is mediated by activation of Galphai, Galphaq and Rho-dependent signaling pathways. J Mol Signal 2010; 5:11. [PMID: 20653955 PMCID: PMC2917412 DOI: 10.1186/1750-2187-5-11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 07/23/2010] [Indexed: 11/14/2022] Open
Abstract
Background Nucleotide-actived P2Y receptors play critical roles in the growth of tumor cells by regulating cellular proliferation, differentiation and survival. Results Here we demonstrate that an avian P2Y purinoceptor (tP2YR) with unique pharmacological and signal transduction properties induces morphologic and growth transformation of rodent fibroblasts. tP2YR induced a transformed phenotype similar to the mas oncogene, a G protein-coupled receptor which causes transformation by activation of Rac-dependent pathways. tP2YR-transformed cells exhibited increased steady-state activation of Rac1 and RhoA. Like activated Rho GTPases, tP2YR cooperated with activated Raf and caused synergistic transformation of NIH3T3 cells. Our data indicate that the ability of tP2YR to cause transformation is due to its unique ability among purinergic receptors to simultaneously activate Gαq and Gαi. Co-expression of constitutively activated mutants of these two Gα subunits caused the same transformed phenotype as tP2YR and Mas. Furthermore, transformation by both tP2YR and Mas was blocked by pharmacological inhibition of GαI by pertussis toxin (PTX) indicating an essential role for Gαi in transformation by these G-protein coupled receptors. Conclusions Our data suggest that coordinated activation of Gαq and Gαi may link the tP2YR and possibility the Mas oncogene with signaling pathways resulting in activation of Rho family proteins to promote cellular transformation.
Collapse
Affiliation(s)
- Anurag Singh
- Linebergher Comprehensive Cancer Center, University of North Carolina at Chapel Hill, NC 27599, USA.
| | | | | | | |
Collapse
|
31
|
Fields AP, Justilien V. The guanine nucleotide exchange factor (GEF) Ect2 is an oncogene in human cancer. ACTA ACUST UNITED AC 2009; 50:190-200. [PMID: 19896966 DOI: 10.1016/j.advenzreg.2009.10.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Alan P Fields
- Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, FL, USA.
| | | |
Collapse
|
32
|
Justilien V, Fields AP. Ect2 links the PKCiota-Par6alpha complex to Rac1 activation and cellular transformation. Oncogene 2009; 28:3597-607. [PMID: 19617897 PMCID: PMC2762483 DOI: 10.1038/onc.2009.217] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein kinase Ciota (PKCiota) promotes non-small cell lung cancer (NSCLC) by binding to Par6alpha and activating a Rac1-Pak-Mek1,2-Erk1,2 signaling cascade. The mechanism by which the PKCiota-Par6alpha complex regulates Rac1 is unknown. Here we show that epithelial cell transforming sequence 2 (Ect2), a guanine nucleotide exchange factor for Rho family GTPases, is coordinately amplified and overexpressed with PKCiota in NSCLC tumors. RNA interference-mediated knockdown of Ect2 inhibits Rac1 activity and blocks transformed growth, invasion and tumorigenicity of NSCLC cells. Expression of constitutively active Rac1 (RacV12) restores transformation to Ect2-deficient cells. Interestingly, the role of Ect2 in transformation is distinct from its well-established role in cytokinesis. In NSCLC cells, Ect2 is mislocalized to the cytoplasm where it binds the PKCiota-Par6alpha complex. RNA interference-mediated knockdown of either PKCiota or Par6alpha causes Ect2 to redistribute to the nucleus, indicating that the PKCiota-Par6alpha complex regulates the cytoplasmic localization of Ect2. Our data indicate that Ect2 and PKCiota are genetically and functionally linked in NSCLC, acting to coordinately drive tumor cell proliferation and invasion through formation of an oncogenic PKCiota-Par6alpha-Ect2 complex.
Collapse
Affiliation(s)
- V Justilien
- Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, FL 32224, USA
| | | |
Collapse
|
33
|
van Impel A, Schumacher S, Draga M, Herz HM, Grosshans J, Müller HAJ. Regulation of the Rac GTPase pathway by the multifunctional Rho GEF Pebble is essential for mesoderm migration in the Drosophila gastrula. Development 2009; 136:813-22. [PMID: 19176590 PMCID: PMC2685947 DOI: 10.1242/dev.026203] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2009] [Indexed: 01/09/2023]
Abstract
The Drosophila guanine nucleotide exchange factor Pebble (Pbl) is essential for cytokinesis and cell migration during gastrulation. In dividing cells, Pbl promotes Rho1 activation at the cell cortex, leading to formation of the contractile actin-myosin ring. The role of Pbl in fibroblast growth factor-triggered mesoderm spreading during gastrulation is less well understood and its targets and subcellular localization are unknown. To address these issues we performed a domain-function study in the embryo. We show that Pbl is localized to the nucleus and the cell cortex in migrating mesoderm cells and found that, in addition to the PH domain, the conserved C-terminal tail of the protein is crucial for cortical localization. Moreover, we show that the Rac pathway plays an essential role during mesoderm migration. Genetic and biochemical interactions indicate that during mesoderm migration, Pbl functions by activating a Rac-dependent pathway. Furthermore, gain-of-function and rescue experiments suggest an important regulatory role of the C-terminal tail of Pbl for the selective activation of Rho1-versus Rac-dependent pathways.
Collapse
Affiliation(s)
- Andreas van Impel
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, UK
| | | | | | | | | | | |
Collapse
|
34
|
Seguin L, Liot C, Mzali R, Harada R, Siret A, Nepveu A, Bertoglio J. CUX1 and E2F1 regulate coordinated expression of the mitotic complex genes Ect2, MgcRacGAP, and MKLP1 in S phase. Mol Cell Biol 2009; 29:570-81. [PMID: 19015243 PMCID: PMC2612504 DOI: 10.1128/mcb.01275-08] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/13/2008] [Accepted: 11/03/2008] [Indexed: 01/19/2023] Open
Abstract
Rho GTPases are critical for mitosis progression and completion of cytokinesis. During mitosis, the GDP/GTP cycle of Rho GTPases is regulated by the exchange factor Ect2 and the GTPase activating protein MgcRacGAP which associates with the kinesin MKLP1 in the centralspindlin complex. We report here that expression of Ect2, MgcRacGAP, and MKLP1 is tightly regulated during cell cycle progression. These three genes share similar cell cycle-related signatures within their promoter regions: (i) cell cycle gene homology region (CHR) sites located at -20 to +40 nucleotides of their transcription start sites that are required for repression in G(1), (ii) E2F binding elements, and (iii) tandem repeats of target sequences for the CUX1 transcription factor. CUX1 and E2F1 bind these three promoters upon S-phase entry, as demonstrated by chromatin immunoprecipitation, and regulate transcription of these genes, as established using promoter-luciferase reporter constructs and expression of activated or dominant negative transcription factors. Overexpression of either E2F1 or CUX1 increased the levels of the endogenous proteins whereas small interfering RNA knockdown of E2F1 or use of a dominant negative E2F1 reduced their expression levels. Thus, CUX1, E2F, and CHR elements provide the transcriptional controls that coordinate induction of Ect2, MgcRacGAP, and MKLP1 in S phase, leading to peak expression of these interacting proteins in G(2)/M, at the time they are required to regulate cytokinesis.
Collapse
Affiliation(s)
- Laetitia Seguin
- INSERM U749, Faculté de Pharmacie Paris XI, 92296 Châtenay-Malabry, France
| | | | | | | | | | | | | |
Collapse
|
35
|
Salhia B, Tran NL, Chan A, Wolf A, Nakada M, Rutka F, Ennis M, McDonough WS, Berens ME, Symons M, Rutka JT. The guanine nucleotide exchange factors trio, Ect2, and Vav3 mediate the invasive behavior of glioblastoma. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1828-38. [PMID: 19008376 DOI: 10.2353/ajpath.2008.080043] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Malignant gliomas are characterized by their ability to invade normal brain tissue. We have previously shown that the small GTPase Rac1 plays a role in both migration and invasion in gliomas. Here, we aim to identify Rac-activating guanine nucleotide exchange factors (GEFs) that mediate glioblastoma invasiveness. Using a brain tumor expression database, we identified three GEFs, Trio, Ect2, and Vav3, that are expressed at higher levels in glioblastoma versus low-grade glioma. The expression of these GEFs is also associated with poor patient survival. Quantitative real-time polymerase chain reaction and immunohistochemical analyses on an independent set of tumors confirmed that these GEFs are overexpressed in glioblastoma as compared with either nonneoplastic brain or low-grade gliomas. In addition, depletion of Trio, Ect2, and Vav3 by siRNA oligonucleotides suppresses glioblastoma cell migration and invasion. Depletion of either Ect2 or Trio also reduces the rate of cell proliferation. These results suggest that targeting GEFs may present novel strategies for anti-invasive therapy for malignant gliomas.
Collapse
Affiliation(s)
- Bodour Salhia
- Arthur and Sonia Labatt Brain Tumor Research Centre, Cancer and Cell Biology Division, The Hospital for Sick Children, the University of Toronto, Toronto, Canada
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
Cleavage furrow formation in animal cells results from a local increase in cortical contractility. During anaphase, the spindle contains, in addition to astral arrays of microtubules, a set of bundled microtubules known as the central spindle. Each of these populations of microtubules, the astral arrays and the central spindle bundles, is sufficient to direct cleavage furrow formation, yet in wild-type situations these sets of microtubules co-operate to induce furrow formation at the same site, between the segregating chromosomes. These pathways have distinct genetic requirements that reflect their differential control of cortical actomyosin. We review our current understanding of the molecular mechanisms of furrow formation, with particular emphasis on the central spindle-independent pathway.
Collapse
|
37
|
Mikawa M, Su L, Parsons SJ. Opposing roles of p190RhoGAP and Ect2 RhoGEF in regulating cytokinesis. Cell Cycle 2008; 7:2003-12. [PMID: 18642445 DOI: 10.4161/cc.7.13.6128] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Evidence suggests that p190RhoGAP (p190), a GTPase activating protein (GAP) specific for Rho, plays a role in cytokinesis. First, ectopic expression of p190 induces a multinucleated cellular phenotype. Second, endogenous p190 localizes to the cleavage furrow of dividing cells. Lastly, its levels are reduced in late mitosis by ubiquitin-mediated proteasomal degradation, consistent with the idea that low levels of p190 and high levels of active Rho are required for completion of cytokinesis. As with p190, RhoA and the RhoGEF, ECT2, have been localized to the cleavage furrow. These findings raise the question of whether p190 and ECT2 cooperate antagonistically to regulate the activity of Rho and contraction of the actomyosin ring during cytokinesis. Here we demonstrate ECT2 can, in a dose-dependent manner, reduce multinucleation induced by p190. Furthermore, endogenous p190 and ECT2 colocalize at the cleavage furrow of dividing cells and stably associate with one another in co-immunoprecipitation assays. Functional and physical interactions between p190 and ECT2 are reflected in the levels of Rho activity, as assessed by Rho pull-down assays. Together, these results suggest that co-regulation of Rho activity by p190RhoGAP and ECT2 in the cleavage furrow determines whether cells properly complete cytokinesis.
Collapse
Affiliation(s)
- Masahito Mikawa
- Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, Virginia 22908, USA
| | | | | |
Collapse
|
38
|
Yohe ME, Rossman K, Sondek J. Role of the C-terminal SH3 domain and N-terminal tyrosine phosphorylation in regulation of Tim and related Dbl-family proteins. Biochemistry 2008; 47:6827-39. [PMID: 18537266 DOI: 10.1021/bi702543p] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dbl-related oncoproteins are guanine nucleotide exchange factors (GEFs) specific for Rho-family GTPases and typically possess tandem Dbl (DH) and pleckstrin homology (PH) domains that act in concert to catalyze exchange. Although the exchange potential of many Dbl-family proteins is constitutively activated by truncation, the precise mechanisms of regulation for many Dbl-family proteins are unknown. Tim and Vav are distantly related Dbl-family proteins that are similarly regulated; their Dbl homology (DH) domains interact with N-terminal helices to exclude and prevent activation of Rho GTPases. Phosphorylation, substitution, or deletion of the blocking helices relieves this autoinhibition. Here we show that two other Dbl-family proteins, Ngef and Wgef, which like Tim contain a C-terminal SH3 domain, are also activated by tyrosine phosphorylation of a blocking helix. Consequently, basal autoinhibition of DH domains by direct steric exclusion using short N-terminal helices likely represents a conserved mechanism of regulation for the large family of Dbl-related proteins. N-Terminal truncation or phosphorylation of many other Dbl-family GEFs leads to their activation; similar autoinhibition mechanisms could explain some of these events. In addition, we show that the C-terminal SH3 domain binding to a polyproline region N-terminal to the DH domain of the Tim subgroup of Dbl-family proteins provides a unique mechanism of regulated autoinhibition of exchange activity that is functionally linked to the interactions between the autoinhibitory helix and the DH domain.
Collapse
Affiliation(s)
- Marielle E Yohe
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA
| | | | | |
Collapse
|
39
|
Hosseinpour F, Timsit Y, Koike C, Matsui K, Yamamoto Y, Moore R, Negishi M. Overexpression of the Rho-guanine nucleotide exchange factor ECT2 inhibits nuclear translocation of nuclear receptor CAR in the mouse liver. FEBS Lett 2007; 581:4937-42. [PMID: 17904126 PMCID: PMC2367110 DOI: 10.1016/j.febslet.2007.09.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 09/10/2007] [Accepted: 09/13/2007] [Indexed: 11/29/2022]
Abstract
Various drugs such as phenobarbital (PB) trigger translocation of constitutive active/adrostane receptor (CAR) from the cytoplasm into the nucleus of mouse liver cells without directly binding to the receptor. We have now characterized the guanine nucleotide exchange factor epithelial cell-transforming gene 2 (ECT2) as a PB-inducible factor as well as a cellular signal that represses PB-triggered nuclear translocation of CAR. When CFP-tagged ECT2 was co-expressed with YFP-tagged CAR in the liver of Car(-/-) mice, ECT2 repressed CAR nuclear translocation. Coexpression of various deletion mutants delineated this repressive activity to the tandem Dbl homology/pleckstrin homology domains of ECT2 and to their cytosolic expression. CAR directly bound to the PH domain. Thus, ECT2 may comprise a part of the PB response signal regulating the intracellular trafficking of CAR.
Collapse
Affiliation(s)
- Fardin Hosseinpour
- Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, United States
| | | | | | | | | | | | | |
Collapse
|
40
|
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.
Collapse
Affiliation(s)
- Marielle E Yohe
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
Cytokinesis is a sequential process that occurs in three phases: assembly of the cytokinetic apparatus, furrow progression and fission (abscission) of the newly formed daughter cells. The ingression of the cleavage furrow is dependent on the constriction of an equatorial actomyosin ring in many cell types. Recent studies have demonstrated that this structure is highly dynamic and undergoes active polymerization and depolymerization throughout the furrowing process. Despite much progress in the identification of contractile ring components, little is known regarding the mechanism of its assembly and structural rearrangements. PIP2 (phosphatidylinositol 4,5-bisphosphate) is a critical regulator of actin dynamics and plays an essential role in cell motility and adhesion. Recent studies have indicated that an elevation of PIP2 at the cleavage furrow is a critical event for furrow stability. In this review we discuss the role of PIP2-mediated signalling in the structural maintenance of the contractile ring and furrow progression. In addition, we address the role of other phosphoinositides, PI(4)P (phosphatidylinositol 4-phosphate) and PIP3 (phosphatidylinositol 3,4,5-triphosphate) in these processes.
Collapse
Affiliation(s)
- Michael R Logan
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada H3A 2B2
| | | |
Collapse
|
42
|
Scoumanne A, Chen X. The epithelial cell transforming sequence 2, a guanine nucleotide exchange factor for Rho GTPases, is repressed by p53 via protein methyltransferases and is required for G1-S transition. Cancer Res 2006; 66:6271-9. [PMID: 16778203 DOI: 10.1158/0008-5472.can-06-0121] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The epithelial cell transforming sequence 2 (ECT2), a member of the Dbl family of guanine nucleotide exchange factor for Rho GTPases, is required for cytokinesis. The tumor suppressor p53 plays a crucial role in coordinating cellular processes, such as cell cycle arrest and apoptosis, in response to stress signals. Here, we showed that ECT2 is negatively regulated by wild-type p53 but not tumor-derived mutant p53 or other p53 family members. In addition, ECT2 is down-regulated in multiple cell lines by DNA damage agents and Nutlin-3, an MDM2 antagonist, in a p53-dependent manner. We also showed that the activity of the ECT2 promoter is repressed by wild-type p53, and to a lesser extent, by p21. In addition, the second activation domain in p53 is necessary for the efficient repression of ECT2. Importantly, we found that the ECT2 gene is bound by p53 in vivo in response to DNA damage and Nutlin-3 treatment. Furthermore, we provided evidence that inhibition of protein methyltransferases, especially arginine methyltransferases, relieve the repression of ECT2 induced by DNA damage or Nutlin-3 in a p53-dependent manner. Finally, we generated multiple cell lines in which ECT2 is inducibly knocked down and found that ECT2 knockdown triggers cell cycle arrest in G1. Taken together, we uncovered a novel function for ECT2 and provided a novel mechanism by which p53 represses gene expression via protein methyltransferases.
Collapse
Affiliation(s)
- Ariane Scoumanne
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | | |
Collapse
|
43
|
Dadke D, Jarnik M, Pugacheva EN, Singh MK, Golemis EA. Deregulation of HEF1 impairs M-phase progression by disrupting the RhoA activation cycle. Mol Biol Cell 2006; 17:1204-17. [PMID: 16394104 PMCID: PMC1382310 DOI: 10.1091/mbc.e05-03-0237] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The focal adhesion-associated signaling protein HEF1 undergoes a striking relocalization to the spindle at mitosis, but a function for HEF1 in mitotic signaling has not been demonstrated. We here report that overexpression of HEF1 leads to failure of cells to progress through cytokinesis, whereas depletion of HEF1 by small interfering RNA (siRNA) leads to defects earlier in M phase before cleavage furrow formation. These defects can be explained mechanistically by our determination that HEF1 regulates the activation cycle of RhoA. Inactivation of RhoA has long been known to be required for cytokinesis, whereas it has recently been determined that activation of RhoA at the entry to M phase is required for cellular rounding. We find that increased HEF1 sustains RhoA activation, whereas depleted HEF1 by siRNA reduces RhoA activation. Furthermore, we demonstrate that chemical inhibition of RhoA is sufficient to reverse HEF1-dependent cellular arrest at cytokinesis. Finally, we demonstrate that HEF1 associates with the RhoA-GTP exchange factor ECT2, an orthologue of the Drosophila cytokinetic regulator Pebble, providing a direct means for HEF1 control of RhoA. We conclude that HEF1 is a novel component of the cell division control machinery and that HEF1 activity impacts division as well as cell attachment signaling events.
Collapse
Affiliation(s)
- Disha Dadke
- Division of Basic Science, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | | | | | | |
Collapse
|
44
|
Shetty RS, Bose SC, Nickell MD, McIntyre JC, Hardin DH, Harris AM, McClintock TS. Transcriptional changes during neuronal death and replacement in the olfactory epithelium. Mol Cell Neurosci 2005; 30:90-107. [PMID: 16027002 DOI: 10.1016/j.mcn.2005.06.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 06/10/2005] [Accepted: 06/13/2005] [Indexed: 11/30/2022] Open
Abstract
The olfactory epithelium has the unusual ability to replace its neurons. We forced replacement of mouse olfactory sensory neurons by bulbectomy. Microarray, bioinformatics, and in situ hybridization techniques detected a rapid shift in favor of pro-apoptotic proteins, a progressive immune response by macrophages and dendritic cells, and identified or predicted 439 mRNAs enriched in olfactory sensory neurons, including gene silencing factors and sperm flagellar proteins. Transcripts encoding cell cycle regulators, axonogenesis proteins, and transcription factors and signaling proteins that promote proliferation and differentiation were increased at 5--7 days after bulbectomy and were expressed by basal progenitor cells or immature neurons. The transcription factors included Nhlh 1, Hes 6, Lmyc 1, c-Myc, Mxd 4, Id 1, Nmyc 1, Cited 2, c-Myb, Mybl 1, Tead 2, Dp 1, Gata 2, Lmo 1, and Sox1 1. The data reveal significant similarities with embryonic neurogenesis and make several mechanistic predictions, including the roles of the transcription factors in the olfactory sensory neuron lineage.
Collapse
Affiliation(s)
- Ranjit S Shetty
- Department of Physiology, Cellular and Molecular Neuroscience of Sensory Systems Training Program, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA
| | | | | | | | | | | | | |
Collapse
|
45
|
Kostenko EV, Mahon GM, Cheng L, Whitehead IP. The Sec14 Homology Domain Regulates the Cellular Distribution and Transforming Activity of the Rho-specific Guanine Nucleotide Exchange Factor Dbs. J Biol Chem 2005; 280:2807-17. [PMID: 15531584 DOI: 10.1074/jbc.m411139200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Dbs is a Rho-specific guanine nucleotide exchange factor that was identified in a screen for proteins whose overexpression cause deregulated growth in murine fibroblasts. Dbs contains multiple recognizable motifs including a centrally located Rho-specific guanine nucleotide exchange factor domain, a COOH-terminal Src homology 3 domain, two spectrin-like repeats, and a recently identified NH(2)-terminal Sec14 homology domain. The transforming potential of Dbs is substantially activated by the removal of inhibitory sequences that lie outside of the core catalytic sequences, and in this current study we mapped this inhibition to the Sec14 domain. Surprisingly removal of the NH(2) terminus did not alter the catalytic activity of Dbs in vivo but rather altered its subcellular distribution. Whereas full-length Dbs was distributed primarily in a perinuclear structure that coincides with a marker for the Golgi apparatus, removal of the Sec14 domain was associated with translocation of Dbs to the cell periphery where it accumulated within membrane ruffles and lamellipodia. However, translocation of Dbs and the concomitant changes in the actin cytoskeleton were not sufficient to fully activate Dbs transformation. The Sec14 domain also forms intramolecular contacts with the pleckstrin homology domain, and these contacts must also be relieved to achieve full transforming activity. Collectively these observations suggest that the Sec14 domain regulates Dbs transformation through at least two distinct mechanisms, neither of which appears to directly influence the in vivo exchange activity of the protein.
Collapse
Affiliation(s)
- Elena V Kostenko
- Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA
| | | | | | | |
Collapse
|
46
|
Kim JE, Billadeau DD, Chen J. The tandem BRCT domains of Ect2 are required for both negative and positive regulation of Ect2 in cytokinesis. J Biol Chem 2004; 280:5733-9. [PMID: 15545273 DOI: 10.1074/jbc.m409298200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epithelial cell transforming protein 2 (Ect2) is a guanine nucleotide exchange factor (GEF) for Rho GTPases, molecular switches essential for the control of cytokinesis in mammalian cells. Aside from the canonical Dbl homology/pleckstrin homology cassette found in virtually all Dbl family members, Ect2 contains N-terminal tandem BRCT domains. In this study, we address the role of the Ect2 BRCT domains in the regulation of Ect2 activity and cytokinesis. First, we show that the depletion of endogenous Ect2 by small interfering RNA induces multinucleation, suggesting that Ect2 is required for cytokinesis. In addition, we provide evidence that Ect2 normally exists in an inactive conformation, which is at least partially due to an intramolecular interaction between the BRCT domains and the C-terminal domain of Ect2. This intramolecular interaction masks the catalytic domain responsible for guanine nucleotide exchange toward RhoA. Consistent with a role in regulating Ect2 GEF activity, overexpression of an N-terminal Ect2 containing the tandem BRCT domains, but not single BRCT domain or BRCT domain mutant, leads to a failure in cytokinesis. Surprisingly, although ectopically expressed wild-type Ect2 rescues the multinucleation resulting from the depletion of endogenous Ect2, expression of a BRCT mutant of Ect2 failed to restore proper cytokinesis in these cells. Taken together, the results of our study indicate that the tandem BRCT domains of Ect2 play dual roles in the regulation of Ect2. Whereas these domains negatively regulate Ect2 GEF activity in interphase cells, they are also required for the proper function of Ect2 during cytokinesis.
Collapse
Affiliation(s)
- Ja-Eun Kim
- Department of Oncology Research, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA
| | | | | |
Collapse
|