1
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Zhang EL, Van Petten J, Eitzen G. RhoGDI in RBL-2H3 cells acts as a negative regulator of Rho GTPase signaling to inhibit granule exocytosis. J Leukoc Biol 2024; 116:1498-1514. [PMID: 38943612 PMCID: PMC11599123 DOI: 10.1093/jleuko/qiae150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 05/28/2024] [Accepted: 06/27/2024] [Indexed: 07/01/2024] Open
Abstract
Mast cells are hematopoietic-derived immune cells that possess numerous cytoplasmic granules containing immune mediators such as cytokines and histamine. Antigen stimulation triggers mast cell granule exocytosis, releasing granule contents in a process known as degranulation. We have shown that Rho GTPase signaling is an essential component of granule exocytosis, however, the proteins that regulate Rho GTPases during this process are not well defined. Here we examined the role of Rho guanine-nucleotide dissociation inhibitors (RhoGDIs) in regulating Rho GTPase signaling using RBL-2H3 cells as a mast cell model. We found that RBL-2H3 cells express two RhoGDI isoforms which are primarily localized to the cytosol. Knockdown of RhoGDI1 and RhoGDI2 greatly reduced the levels of all Rho GTPases tested: RhoA, RhoG, Rac1, Rac2, and Cdc42. The reduction in Rho GTPase levels was accompanied by an increase in their membrane-localized fraction and an elevation in the levels of active Rho GTPases. All RhoGDI knockdown strains had altered resting cell morphology, although each strain was activation competent when stimulated. Live cell imaging revealed that the RhoGDI1/2 double knockdown (DKD) strain maintained its activated state for prolonged periods of time compared to the other strains. Only the RhoGDI1/2 DKD strain showed a significant increase in granule exocytosis. Conversely, RhoGDI overexpression in RBL-2H3 cells did not noticeably affect Rho GTPases or degranulation. Based on these results, RhoGDIs act as negative regulators of Rho GTPases during mast cell degranulation, and inhibit exocytosis by sequestering Rho GTPases in the cytosol.
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Affiliation(s)
- Eric L Zhang
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Jennifer Van Petten
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Gary Eitzen
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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2
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Medina Gomez S, Visco I, Merino F, Bieling P, Linser R. Transient Structural Properties of the Rho GDP-Dissociation Inhibitor. Angew Chem Int Ed Engl 2024; 63:e202403941. [PMID: 38853146 PMCID: PMC7616425 DOI: 10.1002/anie.202403941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 06/11/2024]
Abstract
Rho GTPases, master spatial regulators of a wide range of cellular processes, are orchestrated by complex formation with guanine nucleotide dissociation inhibitors (RhoGDIs). These have been thought to possess an unstructured N-terminus that inhibits nucleotide exchange of their client upon binding/folding. Via NMR analyses, molecular dynamics simulations, and biochemical assays, we reveal instead pertinent structural properties transiently maintained both, in the presence and absence of the client, imposed onto the terminus context-specifically by modulating interactions with the surface of the folded C-terminal domain. These observations revise the long-standing textbook picture of the GTPases' mechanism of membrane extraction. Rather than by a disorder-to-order transition upon binding of an inhibitory peptide, the intricate and highly selective extraction process of RhoGTPases is orchestrated via a dynamic ensemble bearing preformed transient structural properties, suitably modulated by the specific surrounding along the multi-step process.
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Affiliation(s)
- Sara Medina Gomez
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany
| | - Ilaria Visco
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Felipe Merino
- Department of Protein Evolution, Max Planck Institute of Developmental Biology, Max-Planck-Ring 5, 72076, Tübingen, Germany
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Rasmus Linser
- Department of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany
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3
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The Dual Function of RhoGDI2 in Immunity and Cancer. Int J Mol Sci 2023; 24:ijms24044015. [PMID: 36835422 PMCID: PMC9960019 DOI: 10.3390/ijms24044015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/10/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
RhoGDI2 is a guanine nucleotide dissociation inhibitor (GDI) specific for the Rho family of small GTPases. It is highly expressed in hematopoietic cells but is also present in a large array of other cell types. RhoGDI2 has been implicated in multiple human cancers and immunity regulation, where it can display a dual role. Despite its involvement in various biological processes, we still do not have a clear understanding of its mechanistic functions. This review sheds a light on the dual opposite role of RhoGDI2 in cancer, highlights its underappreciated role in immunity and proposes ways to explain its intricate regulatory functions.
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4
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Ahmad Mokhtar AM, Ahmed SBM, Darling NJ, Harris M, Mott HR, Owen D. A Complete Survey of RhoGDI Targets Reveals Novel Interactions with Atypical Small GTPases. Biochemistry 2021; 60:1533-1551. [PMID: 33913706 PMCID: PMC8253491 DOI: 10.1021/acs.biochem.1c00120] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/16/2021] [Indexed: 01/07/2023]
Abstract
There are three RhoGDIs in mammalian cells, which were initially defined as negative regulators of Rho family small GTPases. However, it is now accepted that RhoGDIs not only maintain small GTPases in their inactive GDP-bound form but also act as chaperones for small GTPases, targeting them to specific intracellular membranes and protecting them from degradation. Studies to date with RhoGDIs have usually focused on the interactions between the "typical" or "classical" small GTPases, such as the Rho, Rac, and Cdc42 subfamily members, and either the widely expressed RhoGDI-1 or the hematopoietic-specific RhoGDI-2. Less is known about the third member of the family, RhoGDI-3 and its interacting partners. RhoGDI-3 has a unique N-terminal extension and is found to localize in both the cytoplasm and the Golgi. RhoGDI-3 has been shown to target RhoB and RhoG to endomembranes. In order to facilitate a more thorough understanding of RhoGDI function, we undertook a systematic study to determine all possible Rho family small GTPases that interact with the RhoGDIs. RhoGDI-1 and RhoGDI-2 were found to have relatively restricted activity, mainly binding members of the Rho and Rac subfamilies. RhoGDI-3 displayed wider specificity, interacting with the members of Rho, Rac, and Cdc42 subfamilies but also forming complexes with "atypical" small Rho GTPases such as Wrch2/RhoV, Rnd2, Miro2, and RhoH. Levels of RhoA, RhoB, RhoC, Rac1, RhoH, and Wrch2/RhoV bound to GTP were found to decrease following coexpression with RhoGDI-3, confirming its role as a negative regulator of these small Rho GTPases.
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Affiliation(s)
| | | | | | | | - Helen R. Mott
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Darerca Owen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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5
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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: 3.0] [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.
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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;
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6
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Ota T, Jiang YS, Fujiwara M, Tatsuka M. Apoptosis‑independent cleavage of RhoGDIβ at Asp19 during PMA‑stimulated differentiation of THP‑1 cells to macrophages. Mol Med Rep 2017; 15:1722-1726. [PMID: 28260067 PMCID: PMC5365007 DOI: 10.3892/mmr.2017.6199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 01/05/2017] [Indexed: 01/19/2023] Open
Abstract
Rho GDP-dissociation inhibitor β (RhoGDIβ), a regulator of the Rho family of proteins, is expressed abundantly in the hematopoietic cell lineage. During apoptosis of hematopoietic cells, RhoGDIβ is cleaved by caspase-3 at Asp19 and this cleaved form (Δ19-RhoGDIβ) has been implicated in the apoptotic pathway. To clarify the role of RhoGDIβ in hematopoietic cells, the present study performed immunoblotting and immunofluorescence staining to examine the expression of RhoGDIβ and ∆19-RhoGDIβ during phorbol 12-myristate 13-acetate (PMA)-stimulated differentiation of human THP-1 monocytic cells to macrophages. During differentiation of the THP-1 cells to macrophages, the expression of RhoGDIβ remained stable; however, the expression of Δ19-RhoGDIβ increased, particularly in well-spreading, non-apoptotic cells, which differentiated into macrophages. These results suggested that Δ19-RhoGDIβ has an apoptosis-independent role in the PMA-induced differentiation of THP-1 cells to macrophages.
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Affiliation(s)
- Takahide Ota
- Division of Tumor Biology, Department of Life Science, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa 920‑02, Japan
| | - Yong-Sheng Jiang
- Department of Oncology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Mamoru Fujiwara
- Department of Life Sciences, Life and Environmental Sciences, Prefectural University of Hiroshima, Shoubara, Hiroshima 727‑0023, Japan
| | - Masaaki Tatsuka
- Department of Life Sciences, Life and Environmental Sciences, Prefectural University of Hiroshima, Shoubara, Hiroshima 727‑0023, Japan
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7
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Kuhlmann N, Wroblowski S, Knyphausen P, de Boor S, Brenig J, Zienert AY, Meyer-Teschendorf K, Praefcke GJK, Nolte H, Krüger M, Schacherl M, Baumann U, James LC, Chin JW, Lammers M. Structural and Mechanistic Insights into the Regulation of the Fundamental Rho Regulator RhoGDIα by Lysine Acetylation. J Biol Chem 2015; 291:5484-5499. [PMID: 26719334 DOI: 10.1074/jbc.m115.707091] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Indexed: 11/06/2022] Open
Abstract
Rho proteins are small GTP/GDP-binding proteins primarily involved in cytoskeleton regulation. Their GTP/GDP cycle is often tightly connected to a membrane/cytosol cycle regulated by the Rho guanine nucleotide dissociation inhibitor α (RhoGDIα). RhoGDIα has been regarded as a housekeeping regulator essential to control homeostasis of Rho proteins. Recent proteomic screens showed that RhoGDIα is extensively lysine-acetylated. Here, we present the first comprehensive structural and mechanistic study to show how RhoGDIα function is regulated by lysine acetylation. We discover that lysine acetylation impairs Rho protein binding and increases guanine nucleotide exchange factor-catalyzed nucleotide exchange on RhoA, these two functions being prerequisites to constitute a bona fide GDI displacement factor. RhoGDIα acetylation interferes with Rho signaling, resulting in alteration of cellular filamentous actin. Finally, we discover that RhoGDIα is endogenously acetylated in mammalian cells, and we identify CBP, p300, and pCAF as RhoGDIα-acetyltransferases and Sirt2 and HDAC6 as specific deacetylases, showing the biological significance of this post-translational modification.
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Affiliation(s)
- Nora Kuhlmann
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Sarah Wroblowski
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Philipp Knyphausen
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Susanne de Boor
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Julian Brenig
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Anke Y Zienert
- the Institute for Genetics, Zülpicher Strasse 47a, University of Cologne, 50674 Cologne, Germany
| | - Katrin Meyer-Teschendorf
- the Institute for Genetics, Zülpicher Strasse 47a, University of Cologne, 50674 Cologne, Germany
| | - Gerrit J K Praefcke
- the Institute for Genetics, Zülpicher Strasse 47a, University of Cologne, 50674 Cologne, Germany,; the Paul-Ehrlich-Institute, Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany, and
| | - Hendrik Nolte
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Marcus Krüger
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany
| | - Magdalena Schacherl
- the Institute for Biochemistry, Zülpicher Strasse 47, University of Cologne, 50674 Cologne, Germany
| | - Ulrich Baumann
- the Institute for Biochemistry, Zülpicher Strasse 47, University of Cologne, 50674 Cologne, Germany
| | - Leo C James
- the Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Jason W Chin
- the Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Michael Lammers
- From the Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), Joseph-Stelzmann-Strasse 26, University of Cologne, 50931 Cologne, Germany,.
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8
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Griner EM, Dancik GM, Costello JC, Owens C, Guin S, Edwards MG, Brautigan DL, Theodorescu D. RhoC Is an Unexpected Target of RhoGDI2 in Prevention of Lung Colonization of Bladder Cancer. Mol Cancer Res 2014; 13:483-92. [PMID: 25516960 DOI: 10.1158/1541-7786.mcr-14-0420] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
UNLABELLED RhoGDI2 (ARHGDIB) suppresses metastasis in a variety of cancers but the mechanism is unclear, thus hampering development of human therapeutics. RhoGDI2 is a guanine nucleotide dissociation inhibitor (GDI) for the Rho family of GTPases thought to primarily bind to Rac1; however, Rac1 activation was not decreased by RhoGDI2 expression in bladder cancer cells. To better understand the GTPase-binding partners for RhoGDI2, a mass spectrometry-based proteomic approach was used in bladder cancer cells. As expected, endogenous RhoGDI2 coimmunoprecipitates with Rac1 and unexpectedly also with RhoC. Further analysis demonstrated that RhoGDI2 negatively regulates RhoC, as knockdown of RhoGDI2 increased RhoC activation in response to serum stimulation. Conversely, overexpression of RhoGDI2 decreased RhoC activation. RhoC promoted bladder cancer cell growth and invasion, as knockdown increased cell doubling time, decreased invasion through Matrigel, and decreased colony formation in soft agar. Importantly, RhoC knockdown reduced in vivo lung colonization by bladder cancer cells following tail vein injection in immunocompromised mice. Finally, unbiased transcriptome analysis revealed a set of genes regulated by RhoGDI2 overexpression and RhoC knockdown in bladder cancer cells. IMPLICATIONS RhoGDI2 suppresses bladder cancer metastatic colonization via negative regulation of RhoC activity, providing a rationale for the development of therapeutics that target RhoC signaling.
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Affiliation(s)
- Erin M Griner
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology University of Virginia, Charlottesville, Virginia
| | - Garrett M Dancik
- Department of Mathematics and Computer Science, Eastern Connecticut State University, Willimantic, Connecticut
| | - James C Costello
- Department of Surgery and Pharmacology University of Colorado, Aurora, Colorado
| | - Charles Owens
- Department of Surgery and Pharmacology University of Colorado, Aurora, Colorado
| | - Sunny Guin
- Department of Surgery and Pharmacology University of Colorado, Aurora, Colorado
| | - Michael G Edwards
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado, Aurora, Colorado
| | - David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology University of Virginia, Charlottesville, Virginia
| | - Dan Theodorescu
- Department of Surgery and Pharmacology University of Colorado, Aurora, Colorado. University of Colorado Comprehensive Cancer Center, Aurora, Colorado.
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9
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Cdc42: An important regulator of neuronal morphology. Int J Biochem Cell Biol 2012; 44:447-51. [DOI: 10.1016/j.biocel.2011.11.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 12/21/2022]
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10
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Abramovitz A, Gutman M, Nachliel E. Structural coupling between the Rho-insert domain of Cdc42 and the geranylgeranyl binding site of RhoGDI. Biochemistry 2012; 51:715-23. [PMID: 22206343 DOI: 10.1021/bi201211v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The small GTPase proteins are components of the intracellular signaling system, alternating between active (membrane-bound and GTP-loaded) and inactive (GDP-loaded and cytosolic) states. In the inactive state, the proteins are soluble in the cytoplasm. To compensate for the energetic penalty of extraction of the hydrophobic moiety from the membrane phase, the inactive state is stabilized via formation of a complex with the RhoGDI proteins that provide a hydrophobic pocket for the binding of the hydrophobic moieties. The signals delivered by the Rho subfamily involve a specific, short, highly exposed α-helix (Rho-insert), located close to the GDP binding site. Upon simulating the complex in solution, we observed that the Rho-insert domain of Cdc42 can assume two basic orientations. One is the canonical one, as detected in both crystals and NMR spectra of concentrated protein solutions. The second orientation appears only in the RhoGDI-Cdc42 complex where the GER moiety of Cdc42 is properly inserted into the specific binding site of RhoGDI. Any impairment of the GER-RhoGDI interactions, such as insertion of specific mutations in the hydrophobic binding site, abolished the coupling between the proteins and the Rho-insert domain, preserving its canonical orientation as in the crystalline structure. The noncanonical conformation of the Rho-insert domain is not a simulation artifact, as it appears in crystals of plant Rho proteins (ROP4, ROP5, and ROP7). In accord with the notion that the Rho-insert domain participates in downstream signaling, we propose that the deformation of the Rho-insert is part of the signal transmissions.
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Affiliation(s)
- Adel Abramovitz
- Laser Laboratory for Fast Reactions, Biochemistry and Molecular Biology department, Tel Aviv University, Tel Aviv, Israel 69978
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11
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Garcia-Mata R, Boulter E, Burridge K. The 'invisible hand': regulation of RHO GTPases by RHOGDIs. Nat Rev Mol Cell Biol 2011; 12:493-504. [PMID: 21779026 DOI: 10.1038/nrm3153] [Citation(s) in RCA: 425] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The 'invisible hand' is a term originally coined by Adam Smith in The Theory of Moral Sentiments to describe the forces of self-interest, competition and supply and demand that regulate the resources in society. This metaphor continues to be used by economists to describe the self-regulating nature of a market economy. The same metaphor can be used to describe the RHO-specific guanine nucleotide dissociation inhibitor (RHOGDI) family, which operates in the background, as an invisible hand, using similar forces to regulate the RHO GTPase cycle.
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Affiliation(s)
- Rafael Garcia-Mata
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA.
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12
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Comparison of the antibacterial properties of phage endolysins SAL-1 and LysK. Antimicrob Agents Chemother 2011; 55:1764-7. [PMID: 21263051 DOI: 10.1128/aac.01097-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In spite of the high degree of amino acid sequence similarity between the newly discovered phage endolysin SAL-1 and the phage endolysin LysK, SAL-1 has an approximately 2-fold-lower MIC against several Staphylococcus aureus strains and higher bacterial cell-wall-hydrolyzing activity than LysK. The amino acid residue change contributing the most to this enhanced enzymatic activity is a change from glutamic acid to glutamine at the 114th residue.
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13
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Moissoglu K, McRoberts KS, Meier JA, Theodorescu D, Schwartz MA. Rho GDP dissociation inhibitor 2 suppresses metastasis via unconventional regulation of RhoGTPases. Cancer Res 2009; 69:2838-44. [PMID: 19276387 PMCID: PMC2701105 DOI: 10.1158/0008-5472.can-08-1397] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rho GDP dissociation inhibitor 2 (RhoGDI2) has been identified as a metastasis suppressor in bladder and possibly other cancers. This protein is a member of a family of proteins that maintain Rho GTPases in the cytoplasm and inhibit their activation and function. To understand the mechanism of metastasis suppression, we compared effects of RhoGDI1 and RhoGDI2. Despite showing much stronger inhibition of metastasis, RhoGDI2 is a weak inhibitor of Rho GTPase membrane targeting and function. However, point mutants that increase or decrease the affinity of RhoGDI2 for GTPases abolished its ability to inhibit metastasis. Surprisingly, metastasis suppression correlates with increased rather than decreased Rac1 activity. These data show that RhoGDI2 metastasis inhibition works through Rho GTPases but via a mechanism distinct from inhibition of membrane association.
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Affiliation(s)
- Konstadinos Moissoglu
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
| | - Kevin S. McRoberts
- Departments of Urology and Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Jeremy A. Meier
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
| | - Dan Theodorescu
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Departments of Urology and Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
- Mellon Urologic Cancer Research Institute, University of Virginia, Charlottesville, VA 22908, USA
| | - Martin A. Schwartz
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Departments of Microbiology, Cell Biology and Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
- Mellon Urologic Cancer Research Institute, University of Virginia, Charlottesville, VA 22908, USA
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14
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Menotta M, Amicucci A, Basili G, Polidori E, Stocchi V, Rivero F. Molecular and functional characterization of a Rho GDP dissociation inhibitor in the filamentous fungus Tuber borchii. BMC Microbiol 2008; 8:57. [PMID: 18400087 PMCID: PMC2362126 DOI: 10.1186/1471-2180-8-57] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 04/09/2008] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Small GTPases of the Rho family function as tightly regulated molecular switches that govern important cellular functions in eukaryotes. Several families of regulatory proteins control their activation cycle and subcellular localization. Members of the guanine nucleotide dissociation inhibitor (GDI) family sequester Rho GTPases from the plasma membrane and keep them in an inactive form. RESULTS We report on the characterization the RhoGDI homolog of Tuber borchii Vittad., an ascomycetous ectomycorrhizal fungus. The Tbgdi gene is present in two copies in the T. borchii genome. The predicted amino acid sequence shows high similarity to other known RhoGDIs. Real time PCR analyses revealed an increased expression of Tbgdi during the phase preparative to the symbiosis instauration, in particular after stimulation with root exudates extracts, that correlates with expression of Tbcdc42. In a translocation assay TbRhoGDI was able to solubilize TbCdc42 from membranes. Surprisingly, TbRhoGDI appeared not to interact with S. cerevisiae Cdc42, precluding the use of yeast as a surrogate model for functional studies. To study the role of TbRhoGDI we performed complementation experiments using a RhoGDI null strain of Dictyostelium discoideum, a model organism where the roles of Rho signaling pathways are well established. For comparison, complementation with mammalian RhoGDI1 and LyGDI was also studied in the null strain. Although interacting with Rac1 isoforms, TbRhoGDI was not able to revert the defects of the D. discoideum RhoGDI null strain, but displayed an additional negative effect on the cAMP-stimulated actin polymerization response. CONCLUSION T. borchii expresses a functional RhoGDI homolog that appears as an important modulator of cytoskeleton reorganization during polarized apical growth that antecedes symbiosis instauration. The specificity of TbRhoGDI actions was underscored by its inability to elicit a growth defect in S. cerevisiae or to compensate the loss of a D. discoideum RhoGDI. Knowledge of the cell signaling at the basis of cytoskeleton reorganization of ectomycorrhizal fungi is essential for improvements in the production of mycorrhized plant seedlings used in timberland extension programs and fruit body production.
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Affiliation(s)
- Michele Menotta
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Antonella Amicucci
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Giorgio Basili
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Emanuela Polidori
- Istituto di Ricerca sull'Attività Motoria, Università degli Studi di Urbino "Carlo Bo," Via I Maggetti 26, 61029 Urbino (PU), Italy
| | - Vilberto Stocchi
- Istituto di Chimica Biologica "G. Fornaini," Università degli Studi di Urbino "Carlo Bo," Via Saffi 2, 61029 Urbino (PU), Italy
| | - Francisco Rivero
- Center for Biochemistry, Medical Faculty, University of Cologne. Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- The Hull York Medical School and Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK
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15
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Choi MR, Groot M, Drexler HCA. Functional implications of caspase-mediated RhoGDI2 processing during apoptosis of HL60 and K562 leukemia cells. Apoptosis 2007; 12:2025-35. [PMID: 17726646 DOI: 10.1007/s10495-007-0121-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
RhoGDI2, a cytosolic regulator of Rho GTPase, is cleaved during apoptosis in a caspase-3 dependent fashion. By using 2D-gel electrophoresis, mass spectrometry and Western blotting we investigate in this paper the functional consequences of RhoGDI2 processing. We can show that loss of the N-terminal 19 amino acids results in a shift of the isoelectric point of the truncated RhoGDI2 (NDelta19) to a more basic value due to the removal of 9 acidic amino acids from the N-terminus, which may be responsible for enhanced retention of the N-terminally truncated protein within the nuclear compartment. Fusion of the p53 nuclear export signaling sequence MFRELNEALELK to NDelta19 (NDelta19NES) abolished its apoptosis promoting properties, while overexpression of NDelta19 significantly increased the susceptibility to apoptosis induction by the proteasome inhibitor PSI and by staurosporine. These results suggest that cleavage of RhoGDI2 by caspase-3 is not a functionally irrelevant bystander effect of caspase activation during apoptosis, but rather expedites progression of the apoptotic process.
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MESH Headings
- Amino Acid Sequence
- Apoptosis/genetics
- Apoptosis/physiology
- Caspases/physiology
- Electrophoresis, Gel, Two-Dimensional
- Guanine Nucleotide Dissociation Inhibitors/genetics
- Guanine Nucleotide Dissociation Inhibitors/metabolism
- HL-60 Cells
- Humans
- K562 Cells
- Leukemia, Erythroblastic, Acute/metabolism
- Leukemia, Erythroblastic, Acute/pathology
- Leukemia, Promyelocytic, Acute/metabolism
- Leukemia, Promyelocytic, Acute/pathology
- Molecular Sequence Data
- RNA Processing, Post-Transcriptional
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Tumor Cells, Cultured
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
- U937 Cells
- rho Guanine Nucleotide Dissociation Inhibitor beta
- rho-Specific Guanine Nucleotide Dissociation Inhibitors
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Affiliation(s)
- Mi-Ran Choi
- Max-Planck-Institute for Heart and Lung Research, Parkstr.1, Bad Nauheim 61231, Germany
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16
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Cole KC, McLaughlin HW, Johnson DI. Use of bimolecular fluorescence complementation to study in vivo interactions between Cdc42p and Rdi1p of Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:378-87. [PMID: 17220465 PMCID: PMC1828923 DOI: 10.1128/ec.00368-06] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Saccharomyces cerevisiae Cdc42p functions as a GTPase molecular switch, activating multiple signaling pathways required to regulate cell cycle progression and the actin cytoskeleton. Regulatory proteins control its GTP binding and hydrolysis and its subcellular localization, ensuring that Cdc42p is appropriately activated and localized at sites of polarized growth during the cell cycle. One of these, the Rdi1p guanine nucleotide dissociation inhibitor, negatively regulates Cdc42p by extracting it from cellular membranes. In this study, the technique of bimolecular fluorescence complementation (BiFC) was used to study the dynamic in vivo interactions between Cdc42p and Rdi1p. The BiFC data indicated that Cdc42p and Rdi1p interacted in the cytoplasm and around the periphery of the cell at the plasma membrane and that this interaction was enhanced at sites of polarized cell growth during the cell cycle, i.e., incipient bud sites, tips and sides of small- and medium-sized buds, and the mother-bud neck region. In addition, a ring-like structure containing the Cdc42p-Rdi1p complex transiently appeared following release from G1-phase cell cycle arrest. A homology model of the Cdc42p-Rdi1p complex was used to introduce mutations that were predicted to affect complex formation. These mutations resulted in altered BiFC interactions, restricting the complex exclusively to either the plasma membrane or the cytoplasm. Data from these studies have facilitated the temporal and spatial modeling of Rdi1p-dependent extraction of Cdc42p from the plasma membrane during the cell cycle.
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Affiliation(s)
- Karen C Cole
- Department of Microbiology and Molecular Genetics, University of Vermont, 202 Stafford Hall, 95 Carrigan Drive, Burlington, VT 05405, USA
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17
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Pechlivanis M, Kuhlmann J. Hydrophobic modifications of Ras proteins by isoprenoid groups and fatty acids--More than just membrane anchoring. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:1914-31. [PMID: 17110180 DOI: 10.1016/j.bbapap.2006.09.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2006] [Revised: 09/26/2006] [Accepted: 09/29/2006] [Indexed: 01/25/2023]
Abstract
During the last years, post-translational modification of peripheral membrane proteins with hydrophobic side groups has been attributed to a couple of additional functions than just simple anchoring into lipid bilayers. In particular isoprenylation and N- and S-acylation did quicken interest in terms of specific recognition elements for protein-protein interactions and as hydrophobic switches that allow for temporal regulated association with distinct target structures. Furthermore new insights into the heterogeneity of natural membranes have connected the physical properties of e.g. farnesyl or palmitoyl side chains with a preference for such sub-compartments as lipid rafts or caveolae. In this review the impact of the two frequently realized modifications by isoprenylation and S-acylation on the process of cellular signal transduction is exemplified with proteins of the Ras and Rab family of small GTP-binding proteins.
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Affiliation(s)
- Markos Pechlivanis
- Department of Structural Biology, Max Planck Institute for Molecular Physiology, D-44227 Dortmund, Germany
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18
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Dovas A, Couchman J. RhoGDI: multiple functions in the regulation of Rho family GTPase activities. Biochem J 2005; 390:1-9. [PMID: 16083425 PMCID: PMC1184558 DOI: 10.1042/bj20050104] [Citation(s) in RCA: 324] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
RhoGDI (Rho GDP-dissociation inhibitor) was identified as a down-regulator of Rho family GTPases typified by its ability to prevent nucleotide exchange and membrane association. Structural studies on GTPase-RhoGDI complexes, in combination with biochemical and cell biological results, have provided insight as to how RhoGDI exerts its effects on nucleotide binding, the membrane association-dissociation cycling of the GTPase and how these activities are controlled. Despite the initial negative roles attributed to RhoGDI, recent evidence has come to suggest that it may also act as a positive regulator necessary for the correct targeting and regulation of Rho activities by conferring cues for spatial restriction, guidance and availability to effectors. These potential functions are discussed in the context of RhoGDI-associated multimolecular complexes, the newly emerged shuttling capability and the importance of the particular membrane microenvironment that represents the site of action for GTPases. All these results point to a wider role for RhoGDI than initially perceived, making it a binding partner that can tightly control Rho GTPases, but which also allows them to reach their full spectrum of activities.
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Affiliation(s)
- Athanassios Dovas
- Division of Biomedical Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - John R. Couchman
- Division of Biomedical Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
- To whom correspondence should be addressed (email )
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19
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DerMardirossian C, Bokoch GM. GDIs: central regulatory molecules in Rho GTPase activation. Trends Cell Biol 2005; 15:356-63. [PMID: 15921909 DOI: 10.1016/j.tcb.2005.05.001] [Citation(s) in RCA: 489] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 04/11/2005] [Accepted: 05/10/2005] [Indexed: 11/20/2022]
Abstract
The GDP dissociation inhibitors (GDIs) are pivotal regulators of Rho GTPase function. GDIs control the access of Rho GTPases to regulatory guanine nucleotide exchange factors and GTPase-activating proteins, to effector targets and to membranes where such effectors reside. We discuss here our current understanding of how Rho GTPase-GDI complexes are regulated by various proteins, lipids and enzymes that exert GDI displacement activity. We propose that phosphorylation mediated by diverse kinases might provide a means of controlling and coordinating Rho GTPase activation.
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Affiliation(s)
- Céline DerMardirossian
- Departments of Immunology and Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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20
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Ferland RJ, Li X, Buhlmann JE, Bu X, Walsh CA, Lim B. Characterization of Rho-GDIγ and Rho-GDIα mRNA in the developing and mature brain with an analysis of mice with targeted deletions of Rho-GDIγ. Brain Res 2005; 1054:9-21. [PMID: 16054116 DOI: 10.1016/j.brainres.2005.04.088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 04/26/2005] [Accepted: 04/28/2005] [Indexed: 11/15/2022]
Abstract
Rho-GDIs are a family of Rho GDP-dissociation inhibitors that are critical in modulating the activity of the small GTPases, Cdc42 and RhoA. Two Rho-GDI isoforms are expressed in the brain, Rho-GDIgamma and Rho-GDIalpha. Here, we describe the expression of both of these isoforms in the developing and mature brain. The mRNA expression patterns of Rho-GDIgamma and Rho-GDIalpha were almost identical in the brain with expression in the developing and mature cerebral cortex, striatum, and hippocampus. In addition, we generated mice with targeted deletions of Rho-GDIgamma that are viable and fertile and have no obvious phenotypic abnormalities. Mutant brains looked histologically normal and demonstrated normal patterns of dendritogenesis and neuronal layering as determined by Golgi staining. Mutant mice had normal sleep/wake patterns and sleep EEGs and showed normal hippocampal-dependent learning as assayed by the Morris water maze task. Based on the co-expression of Rho-GDIalpha and Rho-GDIgamma in identical populations of cells in the brain, the lack of phenotype caused by targeted deletion of Rho-GDIgamma may not be surprising given that Rho-GDIalpha may compensate for the loss of Rho-GDIgamma. Whether deletion of both Rho-GDIalpha and Rho-GDIgamma, thereby eliminating all GDI activity in the brain, would produce an observable phenotype remains to be determined.
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Affiliation(s)
- Russell J Ferland
- Department of Neurology, Beth Israel Deaconess Medical Center, Howard Hughes Medical Institute, Harvard Medical School, NRB 266, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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21
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Ota T, Maeda M, Suto S, Tatsuka M. LyGDI functions in cancer metastasis by anchoring Rho proteins to the cell membrane. Mol Carcinog 2004; 39:206-20. [PMID: 15057873 DOI: 10.1002/mc.20006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Rho family GTPases play an important role in a number of processes related to metastasis, and RhoGDP dissociation, inhibitors (RhoGDIs) regulate Rho family proteins. We cloned genomic DNA from colon carcinoma SW480 cells capable of transforming nonmetastatic ras-transformed 1-1ras1000 cells into metastatic cells. This DNA contained a truncated human ras homolog gene family GDP dissociation inhibitor beta (ARHGDIB) gene, resulting in a C-terminal truncated form of LyGDI (Delta C-LyGDI, 166-201 deletion), a member of the RhoGDIs. The stable expression of Delta C-LyGDI induced pulmonary metastasis in 1-1ras1000 cells, whereas expression of full-length LyGDI did not induce metastasis. Delta C-LyGDI was preferentially localized in the membrane, detected in a NP-40-insoluble fraction, and co-purified with radixin, moesin, Rac1, Cdc42, and RhoA. In Delta C-LyGDI transfectant, an activation state of Rac1 was elevated and Delta C-LyGDI was associated with Rac1-GTP. In keeping with the observed localization of Rac1 to the cell membrane and the elevated level of Rac1-GTP, Delta C-LyGDI transfectants were found to be more invasive than mock transfectant. These results suggest that LyGDI functions in the cell membrane to afford spatial regulation of Rho family GTPase signaling through ezrin radixin moesin (ERM) proteins during metastasis.
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Affiliation(s)
- Takahide Ota
- Division of Molecular Oncology and Virology, Medical Research Institute, Kanazawa Medical University, Ishikawa, Japan
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22
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Kale TA, Raab C, Yu N, Aquino E, Dean DC, Distefano MD. Synthesis of high specific activity 35S-labelled N-methanesulfonyl farnesylcysteine and a photoactive analog. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.638] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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23
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Rivero F, Illenberger D, Somesh BP, Dislich H, Adam N, Meyer AK. Defects in cytokinesis, actin reorganization and the contractile vacuole in cells deficient in RhoGDI. EMBO J 2002; 21:4539-49. [PMID: 12198156 PMCID: PMC126189 DOI: 10.1093/emboj/cdf449] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rho GDP-dissociation inhibitors (RhoGDIs) modulate the cycling of Rho GTPases between active GTP-bound and inactive GDP-bound states. We identified two RhoGDI homologues in DICTYOSTELIUM: GDI1 shares 51-58% similarity to RhoGDIs from diverse species. GDI2 is more divergent (40-44% similarity) and lacks the N-terminal regulatory arm characteristic for RhoGDI proteins. Both are cytosolic proteins and do not relocalize upon reorganization of the actin cytoskeleton. Using a two-hybrid approach, we identified Rac1a/1b/1c, RacB, RacC and RacE as interacting partners for GDI1. Cells lacking GDI1 are multinucleate, grow slowly and display a moderate pinocytosis defect, but rates of phagocytosis are unaffected. Mutant cells present prominent actin-rich protrusions, and large vacuoles that are continuous with the contractile vacuole system. The actin polymerization response upon stimulation with cAMP was reduced, but the motile behavior toward the chemoattractant was unaffected. Our results indicate that GDI1 plays a central role in the regulation of signal transduction cascades mediated by Rho GTPases.
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Affiliation(s)
- Francisco Rivero
- Institut für Biochemie I, Medizinische Fakultät, University of Cologne, Joseph-Stelzmann-Strasse 52, D-50931 Köln and
Department of Pharmacology and Toxicology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany Corresponding author e-mail:
| | - Daria Illenberger
- Institut für Biochemie I, Medizinische Fakultät, University of Cologne, Joseph-Stelzmann-Strasse 52, D-50931 Köln and
Department of Pharmacology and Toxicology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany Corresponding author e-mail:
| | | | | | - Nicola Adam
- Institut für Biochemie I, Medizinische Fakultät, University of Cologne, Joseph-Stelzmann-Strasse 52, D-50931 Köln and
Department of Pharmacology and Toxicology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany Corresponding author e-mail:
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24
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Golovanov AP, Chuang TH, DerMardirossian C, Barsukov I, Hawkins D, Badii R, Bokoch GM, Lian LY, Roberts GC. Structure-activity relationships in flexible protein domains: regulation of rho GTPases by RhoGDI and D4 GDI. J Mol Biol 2001; 305:121-35. [PMID: 11114252 DOI: 10.1006/jmbi.2000.4262] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The guanine dissociation inhibitors RhoGDI and D4GDI inhibit guanosine 5'-diphosphate dissociation from Rho GTPases, keeping these small GTPases in an inactive state. The GDIs are made up of two domains: a flexible N-terminal domain of about 70 amino acid residues and a folded 134-residue C-terminal domain. Here, we characterize the conformation of the N-terminal regions of both RhoGDI and D4GDI using a series of NMR experiments which include (15)N relaxation and amide solvent accessibility measurements. In each protein, two regions with tendencies to form helices are identified: residues 36 to 58 and 9 to 20 in RhoGDI, and residues 36 to 57 and 20 to 25 in D4GDI. To examine the functional roles of the N-terminal domain of RhoGDI, in vitro and in vivo functional assays have been carried out with N-terminally truncated proteins. These studies show that the first 30 amino acid residues are not required for inhibition of GDP dissociation but appear to be important for GTP hydrolysis, whilst removal of the first 41 residues completely abolish the ability of RhoGDI to inhibit GDP dissociation. The combination of structural and functional studies allows us to explain why RhoGDI and D4GDI are able to interact in similar ways with the guanosine 5'-diphosphate-bound GTPase, but differ in their ability to regulate GTP-bound forms; these functional differences are attributed to the conformational differences of the N-terminal domains of the guanosine 5'-diphosphate dissociation inhibitors. Therefore, the two transient helices, appear to be associated with different biological effects of RhoGDI, providing a clear example of structure-activity relationships in a flexible protein domain.
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Affiliation(s)
- A P Golovanov
- Department of Biochemistry and Biological NMR Centre, University of Leicester, Leicester, LE1 7RH, UK
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25
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Hoffman GR, Nassar N, Cerione RA. Structure of the Rho family GTP-binding protein Cdc42 in complex with the multifunctional regulator RhoGDI. Cell 2000; 100:345-56. [PMID: 10676816 DOI: 10.1016/s0092-8674(00)80670-4] [Citation(s) in RCA: 393] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The RhoGDI proteins serve as key multifunctional regulators of Rho family GTP-binding proteins. The 2.6 A X-ray crystallographic structure of the Cdc42/RhoGDI complex reveals two important sites of interaction between GDI and Cdc42. First, the amino-terminal regulatory arm of the GDI binds to the switch I and II domains of Cdc42 leading to the inhibition of both GDP dissociation and GTP hydrolysis. Second, the geranylgeranyl moiety of Cdc42 inserts into a hydrophobic pocket within the immunoglobulin-like domain of the GDI molecule leading to membrane release. The structural data demonstrate how GDIs serve as negative regulators of small GTP-binding proteins and how the isoprenoid moiety is utilized in this critical regulatory interaction.
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Affiliation(s)
- G R Hoffman
- Department of Molecular Medicine, Veterinary Medical Center, Cornell University, Ithaca, New York 14853, USA
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26
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Bischoff F, Vahlkamp L, Molendijk A, Palme K. Localization of AtROP4 and AtROP6 and interaction with the guanine nucleotide dissociation inhibitor AtRhoGDI1 from Arabidopsis. PLANT MOLECULAR BIOLOGY 2000; 42:515-30. [PMID: 10798620 DOI: 10.1023/a:1006341210147] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The small GTPases of the Rho family play a key role in actin cytoskeletal organization. In plants, a novel Rho subfamily, called ROP (Rho of plants), has been found. In Arabidopsis, 12 ROP GTPases have been identified which differ mainly at their C-termini. To test the localization of two members of this subfamily (AtROP4 and AtROP6), we have generated translational fusions with the green fluorescent protein (GFP). Microscopic analysis of transiently transfected BY2 cells revealed a predominant localization of AtROP4 in the perinuclear region, while AtROP6 was localized almost exclusively to the plasma membrane. Swapping of the AtROP4 and AtROP6 C-termini produced a change in localization. As RhoGDIs are known to bind to the C-terminus of GTPases of the Rho family, we searched for Arabidopsis RhoGDI genes. We identified the AtRhoGDI1 gene and mapped it to chromosome 3. AtRhoGDI1 encodes a 22.5 kDa protein which contains highly conserved amino acids in the isoprene binding pocket and exhibits 29% to 37% similarity to known mammalian RhoGDI homologues. The AtRhoGDI1 gene was expressed in all tissues studied. Using the yeast two-hybrid system, we showed specific interaction of AtRhoGDI1 with both AtROP4 and AtROP6 as well as with their GTP-locked mutants, but not with a GTPase of the RAB family. Recombinant GST-AtRhoGDI1 could bind GFP-AtROP4 from transgenic tobacco BY2 cell extracts, confirming the interaction observed with the two-hybrid system.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Blotting, Northern
- Blotting, Western
- Cells, Cultured
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- Gene Expression
- Green Fluorescent Proteins
- Guanine Nucleotide Dissociation Inhibitors/genetics
- Guanine Nucleotide Dissociation Inhibitors/metabolism
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microscopy, Fluorescence
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Toxic
- Protein Binding
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Saccharomyces cerevisiae/genetics
- Sequence Homology, Amino Acid
- Tissue Distribution
- Nicotiana/cytology
- Transfection
- Two-Hybrid System Techniques
- rho GTP-Binding Proteins/genetics
- rho GTP-Binding Proteins/metabolism
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Affiliation(s)
- F Bischoff
- Max-Delbrück-Laboratorium in der Max-Planck Gesellschaft, Köln-Vogelsang, Germany
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27
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Lian LY, Barsukov I, Golovanov AP, Hawkins DI, Badii R, Sze KH, Keep NH, Bokoch GM, Roberts GC. Mapping the binding site for the GTP-binding protein Rac-1 on its inhibitor RhoGDI-1. Structure 2000; 8:47-55. [PMID: 10673424 DOI: 10.1016/s0969-2126(00)00080-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Members of the Rho family of small GTP-binding proteins, such as Rho, Rac and Cdc42, have a role in a wide range of cell responses. These proteins function as molecular switches by virtue of a conformational change between the GTP-bound (active) and GDP-bound (inactive) forms. In addition, most members of the Rho and Rac subfamilies cycle between the cytosol and membrane. The cytosolic guanine nucleotide dissociation inhibitors, RhoGDIs, regulate both the GDP/GTP exchange cycle and the membrane association/dissociation cycle. RESULTS We have used NMR spectroscopy and site-directed mutagenesis to identify the regions of human RhoGDI-1 that are involved in binding Rac-1. The results emphasise the importance of the flexible regions of both proteins in the interaction. At least one specific region (residues 46-57) of the flexible N-terminal domain of RhoGDI, which has a tendency to form an amphipathic helix in the free protein, makes a major contribution to the binding energy of the complex. In addition, the primary site of Rac-1 binding on the folded domain of RhoGDI involves the beta4-beta5 and beta6-beta7 loops, with a slight movement of the 3(10) helix accompanying the interaction. This binding site is on the same face of the protein as the binding site for the isoprenyl group of post-translationally modified Rac-1, but is distinct from this site. CONCLUSIONS Isoprenylated Rac-1 appears to interact with three distinct sites on RhoGDI. The isoprenyl group attached to the C terminus of Rac-1 binds in a pocket in the folded domain of RhoGDI. This is distinct from the major site on this domain occupied by Rac-1 itself, which involves two loops at the opposite end to the isoprenyl-binding site. It is probable that the flexible C-terminal region of Rac-1 extends from the site at which Rac-1 contacts the folded domain of RhoGDI to allow the isoprenyl group to bind in the pocket at the other end of the RhoGDI molecule. Finally, the flexible N terminus of RhoGDI-1, and particularly residues 48-58, makes a specific interaction with Rac-1 which contributes substantially to the binding affinity.
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Affiliation(s)
- L Y Lian
- Department of Biochemistry and Biological NMR Centre, University of Leicester, Leicester, LE1 7RH, UK.
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Togawa A, Miyoshi J, Ishizaki H, Tanaka M, Takakura A, Nishioka H, Yoshida H, Doi T, Mizoguchi A, Matsuura N, Niho Y, Nishimune Y, Nishikawa SI, Takai Y. Progressive impairment of kidneys and reproductive organs in mice lacking Rho GDIalpha. Oncogene 1999; 18:5373-80. [PMID: 10498891 DOI: 10.1038/sj.onc.1202921] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Rho small G protein family members regulate various actin cytoskeleton-dependent cell functions. The Rho GDI (GDP dissociation inhibitor) family, consisting of Rho GDIalpha, -beta, and -gamma, is a regulator that keeps the Rho family members in the cytosol as the GDP-bound inactive form and translocates the GDP-bound form from the membranes to the cytosol after the GTP-bound form accomplishes their functions. Rho GDIalpha is ubiquitously expressed in mouse tissues and shows GDI activity on all the Rho family members in vitro. We have generated mice lacking Rho GDIalpha by homologous recombination to clarify its in vivo function. Rho GDIalpha -/- mice showed several abnormal phenotypes. Firstly, Rho GDIalpha -/- mice were initially viable but developed massive proteinuria mimicking nephrotic syndrome, leading to death due to renal failure within a year. Histologically, degeneration of tubular epithelial cells and dilatation of distal and collecting tubules were readily detected in the kidneys. Secondly, Rho GDIalpha -/- male mice were infertile and showed impaired spermatogenesis with vacuolar degeneration of seminiferous tubules in their testes. Thirdly, Rho GDIalpha -/- embryos derived from Rho GDIalpha -/- female mice were defective in the postimplantation development. In addition, these morphological and functional abnormalities showed age-dependent progression. These results suggest that the signaling pathways of the Rho family members regulated by Rho GDIalpha play important roles in maintaining the structure and physiological function of at least kidneys and reproductive systems in adult mice.
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Affiliation(s)
- A Togawa
- Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, c/o JCR Pharmaceuticals Co., Ltd., 2-2-10 Murotani, Nishi-ku, Kobe 651-2241, Japan
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29
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Abstract
The small G proteins of the Ras family act as bimodal relays in the transfer of intracellular signals. This is a dynamic phenomenon involving a cascade of protein-protein interactions modulated by chemical modifications, structural rearrangements and intracellular relocalisations. Most of the small G proteins could be operationally defined as proteins having two conformational states, each of which interacts with different cellular partners. These two states are determined by the nature of the bound nucleotide, GDP or GTP. This capacity to cycle between a GDP-bound conformation and a GTP-bound conformation enables them to filter, to amplify or to temporise the upstream signals that they receive. Thus the control of this cycle is crucial. Membrane anchoring of the proteins in the Ras family is a prerequisite for their activity. Most of the proteins in the Rho/Rac and Rab subfamilies of Ras proteins cycle between cytosol and membranes. Then the control of membrane association/dissociation is an other important regulation level. This review will describe one family of crucial regulators acting on proteins in the Rho/Rac family-the Rho guanine nucleotide dissociation inhibitors, or RhoGDIs. As yet, only three RhoGDIs have been described: RhoGDI-1, RhoGDI-2 (or D4/Ly-GDI) and RhoGDI-3. RhoGDI 1 and 2 are cytosolic and participate in the regulation of both the GDP/GTP cycle and the membrane association/dissociation cycle of Rho/Rac proteins. The non-cytosolic RhoGDI-3 seems to act in a slightly different way.
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Affiliation(s)
- B Olofsson
- CNRS UPR 9063, Laboratoire d'Enzymologie et Biochimie Structurales, Gif sur Yvette, France.
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30
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Zalcman G, Dorseuil O, Garcia-Ranea JA, Gacon G, Camonis J. RhoGAPs and RhoGDIs, (His)stories of two families. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1999; 22:85-113. [PMID: 10081066 DOI: 10.1007/978-3-642-58591-3_5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- G Zalcman
- Institut Curie, INSERM U-248, Paris, France
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31
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Abstract
Cdc42p is an essential GTPase that belongs to the Rho/Rac subfamily of Ras-like GTPases. These proteins act as molecular switches by responding to exogenous and/or endogenous signals and relaying those signals to activate downstream components of a biological pathway. The 11 current members of the Cdc42p family display between 75 and 100% amino acid identity and are functional as well as structural homologs. Cdc42p transduces signals to the actin cytoskeleton to initiate and maintain polarized gorwth and to mitogen-activated protein morphogenesis. In the budding yeast Saccharomyces cerevisiae, Cdc42p plays an important role in multiple actin-dependent morphogenetic events such as bud emergence, mating-projection formation, and pseudohyphal growth. In mammalian cells, Cdc42p regulates a variety of actin-dependent events and induces the JNK/SAPK protein kinase cascade, which leads to the activation of transcription factors within the nucleus. Cdc42p mediates these processes through interactions with a myriad of downstream effectors, whose number and regulation we are just starting to understand. In addition, Cdc42p has been implicated in a number of human diseases through interactions with its regulators and downstream effectors. While much is known about Cdc42p structure and functional interactions, little is known about the mechanism(s) by which it transduces signals within the cell. Future research should focus on this question as well as on the detailed analysis of the interactions of Cdc42p with its regulators and downstream effectors.
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Affiliation(s)
- D I Johnson
- Department of Microbiology & Molecular Genetics and the Markey Center for Molecular Genetics, University of Vermont, Burlington, Vermont 05405,
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32
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Bilodeau D, Lamy S, Desrosiers RR, Gingras D, Béliveau R. Regulation of Rho protein binding to membranes by rhoGDI: inhibition of releasing activity by physiological ionic conditions. Biochem Cell Biol 1999. [DOI: 10.1139/o99-004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Rho GDP dissociation inhibitor (GDI) is an ubiquitously expressed regulatory protein involved in the cycling of Rho proteins between membrane-bound and soluble forms. Here, we characterized the Rho solubilization activity of a glutathione S-transferase (GST) - GDI fusion protein in a cell-free system derived from rat kidney. Addition of GST-GDI to kidney brush border membranes resulted in the specific release of Cdc42 and RhoA from the membranes, while RhoB and Ras were not extracted. The release of Cdc42 and RhoA by GST-GDI was dose dependent and saturable with about 50% of both RhoA and Cdc42 extracted. The unextracted Rho proteins were tightly bound to membranes and could not be solubilized by repeated GST-GDI treatment. These results demonstrated that kidney brush border membranes contained two populations of RhoA and Cdc42. Furthermore, the GST-GDI solubilizing activity on membrane-bound Cdc42 and RhoA was abolished at physiological conditions of salt and temperature in all tissues examined. When using bead-immobilized GST-GDI, KCl did not reduced the binding of Rho proteins. However, washing brush border membranes with KCl prior treatment by GST-GDI inhibited the extraction of Rho proteins. Taken together, these results suggest that the binding of GDI to membrane-bound Cdc42 and RhoA occurs easily under physiological ionic strength conditions, but a complementary factor is required to extract these proteins from membranes. These observations suggest that the shuttling activity of GDI upon Rho proteins could be normally downregulated under physiological conditions.Key words: rhoGDI, rho proteins, ionic strength, kidney.
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33
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Adra CN, Iyengar AR, Syed FA, Kanaan IN, Rilo HL, Yu W, Kheraj R, Lin SR, Horiuchi T, Khan S, Weremowicz S, Lim B, Morton CC, Higgs DR. Human ARHGDIG, a GDP-dissociation inhibitor for Rho proteins: genomic structure, sequence, expression analysis, and mapping to chromosome 16p13.3. Genomics 1998; 53:104-9. [PMID: 9787082 DOI: 10.1006/geno.1998.5482] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
GDP-dissociation inhibitors (GDIs) play a primary role in modulating the activity of GTPases. We recently reported the identification of a new GDI for the Rho-related GTPases named RhoGDIgamma. This gene is now designated ARHGDIG by HUGO. Here, in a detailed analysis of tissue expression of ARHGDIG, we observe high levels in the entire brain, with regional variations. The mRNA is also present at high levels in kidney and pancreas and at moderate levels in spinal cord, stomach, and pituitary gland. In other tissues examined, the mRNA levels are very low (lung, trachea, small intestine, colon, placenta) or undetectable. RT-PCR analysis of total RNA isolated from exocrine pancreas and islets shows that the gene is expressed in both tissues. We also report the genomic structure of ARHGDIG. The gene spans over 4 kb and is organized into six exons and five introns. The upstream region lacks a canonical TATA box and contains several putative binding sites for ubiquitous and tissue-specific factors active in central nervous system development. Using FISH, we have mapped the gene to chromosome band 16p13.3. This band is rich in deletion mutants of genes involved in several human diseases, notably polycystic kidney disease, alpha-thalassemia, tuberous sclerosis, mental retardation, and cancer. The promoter structure and the chromosomal location of RhoGDIgamma suggest its importance and underscore the need for further investigation into its biology.
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Affiliation(s)
- C N Adra
- Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, USA.
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Gorvel JP, Chang TC, Boretto J, Azuma T, Chavrier P. Differential properties of D4/LyGDI versus RhoGDI: phosphorylation and rho GTPase selectivity. FEBS Lett 1998; 422:269-73. [PMID: 9490022 DOI: 10.1016/s0014-5793(98)00020-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RhoA/B/C and CDC42/Rac, which form two subgroups of the rho guanosine triphosphatase (GTPase) family, regulate various aspects of actin cytoskeleton organisation. In cytosol, guanosine diphosphate (GDP) dissociation inhibitor (GDI) interacts with and maintains rho GTPases in their inactive GDP-bound form. RhoGDI is a ubiquitously expressed GDI, whereas D4/LyGDI is hematopoietic cell-specific and 10-fold less potent than RhoGDI in binding to and regulating rho GTPases. We have combined microanalytical liquid chromatography with the use of specific antibodies in order to separate D4/LyGDI and RhoDGI-complexes from the cytosol of U937 cells and to demonstrate that the two GDIs associate with different rho protein partners. RhoGDI can form a complex with CDC42Hs, RhoA, Rac1 and Rac2, while none of these GTPases was found to interact with D4/LyGDI. In addition, we found that stimulation of U937 cells with phorbol ester leads to phosphorylation of D4/LyGDI. Our results suggest that LyGDI forms complexes with specific rho GTPases expressed in hematopoietic cells where it may regulate specific pathways.
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Affiliation(s)
- J P Gorvel
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, France
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35
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Affiliation(s)
- L Van Aelst
- Cold Spring Harbor Laboratory, New York 11724, USA. vanaelst@.cshl.org
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36
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Gosser YQ, Nomanbhoy TK, Aghazadeh B, Manor D, Combs C, Cerione RA, Rosen MK. C-terminal binding domain of Rho GDP-dissociation inhibitor directs N-terminal inhibitory peptide to GTPases. Nature 1997; 387:814-9. [PMID: 9194563 DOI: 10.1038/42961] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Rho GDP-dissociation inhibitors (GDIs) negatively regulate Rho-family GTPases. The inhibitory activity of GDI derives both from an ability to bind the carboxy-terminal isoprene of Rho family members and extract them from membranes, and from inhibition of GTPase cycling between the GTP- and GDP-bound states. Here we demonstrate that these binding and inhibitory functions of rhoGDI can be attributed to two structurally distinct regions of the protein. A carboxy-terminal folded domain of relative molecular mass 16,000 (M[r] 16K) binds strongly to the Rho-family member Cdc42, yet has little effect on the rate of nucleotide dissociation from the GTPase. The solution structure of this domain shows a beta-sandwich motif with a narrow hydrophobic cleft that binds isoprenes, and an exposed surface that interacts with the protein portion of Cdc42. The amino-terminal region of rhoGDI is unstructured in the absence of target and contributes little to binding, but is necessary to inhibit nucleotide dissociation from Cdc42. These results lead to a model of rhoGDI function in which the carboxy-terminal binding domain targets the amino-terminal inhibitory region to GTPases, resulting in membrane extraction and inhibition of nucleotide cycling.
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Affiliation(s)
- Y Q Gosser
- Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York 10021, USA
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37
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Keep NH, Barnes M, Barsukov I, Badii R, Lian LY, Segal AW, Moody PC, Roberts GC. A modulator of rho family G proteins, rhoGDI, binds these G proteins via an immunoglobulin-like domain and a flexible N-terminal arm. Structure 1997; 5:623-33. [PMID: 9195882 DOI: 10.1016/s0969-2126(97)00218-9] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The rho family of small G proteins, including rho, rac and cdc42, are involved in many cellular processes, including cell transformation by ras and the organization of the actin cytoskeleton. Additionally, rac has a role in the regulation of phagocyte NADPH oxidase. Guanine nucleotide dissociation inhibitors (GDIs) of the rhoGDI family bind to these G proteins and regulate their activity by preventing nucleotide dissociation and by controlling their interaction with membranes. RESULTS We report the structure of rhoGDI, determined by a combination of X-ray crystallography and NMR spectroscopy. NMR spectroscopy and selective proteolysis show that the N-terminal 50-60 residues of rhoGDI are flexible and unstructured in solution. The 2.5 A crystal structure of the folded core of rhoGDI, comprising residues 59-204, shows it to have an immunoglobulin-like fold, with an unprecedented insertion of two short beta strands and a 310 helix. There is an unusual pocket between the beta sheets of the immunoglobulin fold which may bind the C-terminal isoprenyl group of rac. NMR spectroscopy shows that the N-terminal arm is necessary for binding rac, although it remains largely flexible even in the complex. CONCLUSIONS The rhoGDI structure is notable for the existence of both a structured and a highly flexible domain, both of which appear to be required for the interaction with rac. The immunoglobulin-like fold of the structured domain is unusual for a cytoplasmic protein. The presence of equivalent cleavage sites in rhoGDI and the closely related D4/Ly-GDI (rhoGDI-2) suggest that proteolytic cleavage between the flexible and structured regions of rhoGDI may have a role in the regulation of the activity of members of this family. There is no detectable similarity between the structure of rhoGDI and the recently reported structure of rabGDI, which performs the same function as rhoGDI for the rab family of small G proteins.
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Affiliation(s)
- N H Keep
- Department of Medicine, University College London, Rayne Institute, 5 University Street, London, WC1E 6JJ, UK
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38
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Adra CN, Manor D, Ko JL, Zhu S, Horiuchi T, Van Aelst L, Cerione RA, Lim B. RhoGDIgamma: a GDP-dissociation inhibitor for Rho proteins with preferential expression in brain and pancreas. Proc Natl Acad Sci U S A 1997; 94:4279-84. [PMID: 9113980 PMCID: PMC20713 DOI: 10.1073/pnas.94.9.4279] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/1996] [Accepted: 02/27/1997] [Indexed: 02/04/2023] Open
Abstract
GDP-dissociation inhibitors (GDIs) play a primary role in modulating the activation of GTPases and may also be critical for the cellular compartmentalization of GTPases. RhoGDI and GDI/D4 are two currently known GDIs for the Rho-subfamily of GTPases. Using their cDNAs to screen a human brain cDNA library under low stringency, we have cloned a homologous cDNA preferentially expressed at high levels in brain and pancreas. The predicted protein, named RhoGDIgamma, is approximately 50% identical to GDI/D4 and RhoGDI. It binds to CDC42 and RhoA with less affinity compared with RhoGDI and does not bind with Rac1, Rac2, or Ras. RhoGDIgamma functions as a GDI for CDC42 but with approximately 20 times less efficiency than RhoGDI. Immunohistochemical studies showed a diffuse punctate distribution of the protein in the cytoplasm with concentration around the nucleus in cytoplasmic vesicles. Overexpression of the protein in baby hamster kidney cells caused the cells to round up with loss of stress fibers. A distinct hydrophobic amino terminus in RhoGDIgamma, not seen in the other two RhoGDIs, could provide a mechanism for localization of the GDI to specific membranous compartment thus determining function distinct from RhoGDI or GDI/D4. Our results provide evidence that there is a family of GDIs for the Rho-related GTPases and that they differ in binding affinity, target specificity, and tissue expression. We propose that RhoGDI be renamed RhoGDIalpha and GDID4 be renamed RhoGDIbeta. The new GDI should widen the scope of investigation of this important class of regulatory protein.
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Affiliation(s)
- C N Adra
- Harvard Institutes of Medicine, HIM955, Beth Israel Hospital, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
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39
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Zalcman G, Closson V, Camonis J, Honoré N, Rousseau-Merck MF, Tavitian A, Olofsson B. RhoGDI-3 is a new GDP dissociation inhibitor (GDI). Identification of a non-cytosolic GDI protein interacting with the small GTP-binding proteins RhoB and RhoG. J Biol Chem 1996; 271:30366-74. [PMID: 8939998 DOI: 10.1074/jbc.271.48.30366] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. We have reported that the transient expression of the endogenous RhoB protein is regulated during the cell cycle, contrasting with the permanent RhoA protein expression (). Using the yeast two-hybrid system to characterize proteins interacting with RhoB, we identified a new mouse Rho GDP dissociation inhibitor, referenced as RhoGDI-3. The NH2-terminal alpha helix of RhoGDI-3 is strongly amphipatic and differs thus from that found in previously described bovine, human, and yeast RhoGDI proteins and mouse and human D4/Ly-GDIs. Contrary to the cytosolic localization of all known GDI proteins, acting on Rab or Rho, RhoGDI-3 is associated to a Triton X-100-insoluble membranous or cytoskeletal subcellular fraction. In the two-hybrid system, RhoGDI-3 interacts specifically with GDP- and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show a growth-regulated expression in mammalian cells. No interaction is found with RhoA, RhoC, or Rac1 proteins. We show that GDI-3 is able to inhibit GDP/GTP exchange of RhoB and to release GDP-bound but not GTP-bound RhoB from cell membranes.
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Affiliation(s)
- G Zalcman
- Unité INSERM 248, Section de Recherche, Institut Curie, 26 rue d'Ulm, 75231 Paris Cedex 05, France
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40
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Nomanbhoy TK, Cerione R. Characterization of the interaction between RhoGDI and Cdc42Hs using fluorescence spectroscopy. J Biol Chem 1996; 271:10004-9. [PMID: 8626553 DOI: 10.1074/jbc.271.17.10004] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The GDP-dissociation-inhibitor (GDI) for Rho-like GTP-binding proteins is capable of three different biochemical activities. These are the inhibition of GDP dissociation, the inhibition of GTP hydrolysis, and the stimulation of the release of GTP-binding proteins from membranes. In order to better understand how GDI interactions with Rho-like proteins mediate these different effects, we have set out to develop a direct fluorescence spectroscopic assay for the binding of the GDI to the Rho-like protein, Cdc42Hs. We show here that when the GDI interacts with Cdc42Hs that contains bound N-methylanthraniloyl GDP (Mant-GDP), there is an approximately 20% quenching of the Mant fluorescence. The GDI-induced quenching is only observed when Mant-GDP is bound to Spodoptera frugiperda-expressed Cdc42Hs and is not detected when the Mant nucleotide is bound to Escherichia coli-expressed Cdc42Hs and thus shows the same requirement for isoprenylated GTP-binding protein as that observed when assaying GDI activity. A truncated Cdc42Hs mutant that lacks 8 amino acids from the carboxyl terminus and is insensitive to GDI regulation also does not show changes in the fluorescence of its bound Mant-GDP upon GDI addition. Thus, the GDI-induced quenching of Mant-GDP provides a direct read-out for the binding of the GDI to Cdc42Hs. Titration profiles of the GDI-induced quenching of the Mant-GDP fluorescence are saturable and are well fit to a simple 1:1 binding model for Cdc42Hs-GDI interactions with an apparent Kd value of 30 nM. A very similar Kd value (28 nM) is measured when titrating the GDI-induced quenching of the fluorescence of Mant-guanylyl imidotriphosphate, bound to Cdc42Hs. These results suggest that the GDI can bind to the GDP-bound and GTP-bound forms of Cdc42Hs equally well. We also have used the fluorescence assay for GDI interactions to demonstrate that the differences in functional potency observed between the GDI molecule and a related human leukemic protein, designated LD4, are due to differences in their binding affinities for Cdc42Hs. This, together with the results from studies using GDI/LD4 chimeras, allow us to conclude that a limit region within the carboxyl-terminal domain of the GDI molecule is responsible for its ability to bind with higher affinity (compared with LD4) to Cdc42Hs.
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Affiliation(s)
- T K Nomanbhoy
- Department of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA
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