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A current overview of RhoA, RhoB, and RhoC functions in vascular biology and pathology. Biochem Pharmacol 2022; 206:115321. [DOI: 10.1016/j.bcp.2022.115321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 11/24/2022]
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Huang Q, Xie J, Seetharaman J. Crystal Structure of Schizosaccharomyces pombe Rho1 Reveals Its Evolutionary Relationship with Other Rho GTPases. BIOLOGY 2022; 11:biology11111627. [PMID: 36358328 PMCID: PMC9687936 DOI: 10.3390/biology11111627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/23/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
Simple Summary Rho family of proteins are involved in cytoskeletal organization, cell mobility and polarity, and are implicated in cancer morphogenesis. The structure and function of the Rho homologs from higher-level organisms are well studied, but not from the lower-level organisms. Such as over 95% of the known structures of Rho GTPases are from higher-order mammalian organisms, with only three structures of Rho homologs reported to date from lower-level, single-celled organisms. In this paper we report the crystal structure of Rho1 from Schizosaccharomyces pombe, also called fission yeast (SpRho1), in complex with GDP in the presence of Mg2+ at 2.63-Å resolution, to broaden our understanding of Rho homologs in lower-level organisms. Although the overall structure is similar to that of known Rho homologs, we observed subtle differences at the Switch I and II regions, in β2 and β3, and in the Rho insert domain and loop from Phe107 to Pro112. Combined with literature and sequence analyses, we suggest that the Switch regions and Rho insert domain may contribute to downstream kinase activation in different species through their interactions with different effectors and regulators; and the conservation and divergence of Rho GTPases among difference species and provide evolutionary insight for SpRho1. While many studies have reported the evolutionary development of Rho GTPases based on their amino acid sequences, the present study, for the first time, explores these evolutionary aspects based on structure. Our analysis indicates that SpRho is evolutionarily closer to HsRhoC than HsRhoA, as previously believed. Abstract The Rho protein, a homolog of Ras, is a member of the Ras superfamily of small GTPases. Rho family proteins are involved in cytoskeletal organization, cell mobility, and polarity, and are implicated in cancer morphogenesis. Although Rho homologs from higher-order mammalian organisms are well studied, there are few studies examining Rho proteins in lower-level single-celled organisms. Here, we report on the crystal structure of Rho1 from Schizosaccharomyces pombe (SpRho1) in complex with GDP in the presence of Mg2+ at a 2.78 Å resolution. The overall structure is similar to that of known Rho homologs, including human RhoA, human RhoC, and Aspergillus fumigatus Rho1 (AfRho1), with some exceptions. We observed subtle differences at the Switch I and II regions, in β2 and β3, and in the Rho insert domain and loop from Phe107 to Pro112. Our analysis suggests that SpRho is evolutionarily closer to HsRhoC than HsRhoA, as previously believed.
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Affiliation(s)
- Qingqing Huang
- Department of Biological Sciences, 14 Science Drive 4, National University of Singapore, Singapore 117543, Singapore
| | - Jiarong Xie
- Department of Biological Sciences, 14 Science Drive 4, National University of Singapore, Singapore 117543, Singapore
| | - Jayaraman Seetharaman
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Correspondence:
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3
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Electrostatic Forces Mediate the Specificity of RHO GTPase-GDI Interactions. Int J Mol Sci 2021; 22:ijms222212493. [PMID: 34830380 PMCID: PMC8622166 DOI: 10.3390/ijms222212493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 01/13/2023] Open
Abstract
Three decades of research have documented the spatiotemporal dynamics of RHO family GTPase membrane extraction regulated by guanine nucleotide dissociation inhibitors (GDIs), but the interplay of the kinetic mechanism and structural specificity of these interactions is as yet unresolved. To address this, we reconstituted the GDI-controlled spatial segregation of geranylgeranylated RHO protein RAC1 in vitro. Various biochemical and biophysical measurements provided unprecedented mechanistic details for GDI function with respect to RHO protein dynamics. We determined that membrane extraction of RHO GTPases by GDI occurs via a 3-step mechanism: (1) GDI non-specifically associates with the switch regions of the RHO GTPases; (2) an electrostatic switch determines the interaction specificity between the C-terminal polybasic region of RHO GTPases and two distinct negatively-charged clusters of GDI1; (3) a non-specific displacement of geranylgeranyl moiety from the membrane sequesters it into a hydrophobic cleft, effectively shielding it from the aqueous milieu. This study substantially extends the model for the mechanism of GDI-regulated RHO GTPase extraction from the membrane, and could have implications for clinical studies and drug development.
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4
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Conformational Insights into the Control of CNF1 Toxin Activity by Peptidyl-Prolyl Isomerization: A Molecular Dynamics Perspective. Int J Mol Sci 2021; 22:ijms221810129. [PMID: 34576292 PMCID: PMC8467853 DOI: 10.3390/ijms221810129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/11/2021] [Accepted: 09/14/2021] [Indexed: 12/18/2022] Open
Abstract
The cytotoxic necrotizing factor 1 (CNF1) toxin from uropathogenic Escherichia coli constitutively activates Rho GTPases by catalyzing the deamidation of a critical glutamine residue located in the switch II (SWII). In crystallographic structures of the CNF1 catalytic domain (CNF1CD), surface-exposed P768 and P968 peptidyl-prolyl imide bonds (X-Pro) adopt an unusual cis conformation. Here, we show that mutation of each proline residue into glycine abrogates CNF1CD in vitro deamidase activity, while mutant forms of CNF1 remain functional on RhoA in cells. Using molecular dynamics simulations coupled to protein-peptide docking, we highlight the long-distance impact of peptidyl-prolyl cis-trans isomerization on the network of interactions between the loops bordering the entrance of the catalytic cleft. The energetically favorable isomerization of P768 compared with P968, induces an enlargement of loop L1 that fosters the invasion of CNF1CD catalytic cleft by a peptide encompassing SWII of RhoA. The connection of the P968 cis isomer to the catalytic cysteine C866 via a ladder of stacking interactions is alleviated along the cis-trans isomerization. Finally, the cis-trans conversion of P768 favors a switch of the thiol side chain of C866 from a resting to an active orientation. The long-distance impact of peptidyl-prolyl cis-trans isomerizations is expected to have implications for target modification.
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Mosaddeghzadeh N, Ahmadian MR. The RHO Family GTPases: Mechanisms of Regulation and Signaling. Cells 2021; 10:1831. [PMID: 34359999 PMCID: PMC8305018 DOI: 10.3390/cells10071831] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 12/27/2022] Open
Abstract
Much progress has been made toward deciphering RHO GTPase functions, and many studies have convincingly demonstrated that altered signal transduction through RHO GTPases is a recurring theme in the progression of human malignancies. It seems that 20 canonical RHO GTPases are likely regulated by three GDIs, 85 GEFs, and 66 GAPs, and eventually interact with >70 downstream effectors. A recurring theme is the challenge in understanding the molecular determinants of the specificity of these four classes of interacting proteins that, irrespective of their functions, bind to common sites on the surface of RHO GTPases. Identified and structurally verified hotspots as functional determinants specific to RHO GTPase regulation by GDIs, GEFs, and GAPs as well as signaling through effectors are presented, and challenges and future perspectives are discussed.
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Affiliation(s)
| | - Mohammad Reza Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich Heine University, Universitätsstrasse 1, Building 22.03.05, 40225 Düsseldorf, Germany;
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6
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High Throughput strategies Aimed at Closing the GAP in Our Knowledge of Rho GTPase Signaling. Cells 2020; 9:cells9061430. [PMID: 32526908 PMCID: PMC7348934 DOI: 10.3390/cells9061430] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/05/2020] [Accepted: 06/07/2020] [Indexed: 12/21/2022] Open
Abstract
Since their discovery, Rho GTPases have emerged as key regulators of cytoskeletal dynamics. In humans, there are 20 Rho GTPases and more than 150 regulators that belong to the RhoGEF, RhoGAP, and RhoGDI families. Throughout development, Rho GTPases choregraph a plethora of cellular processes essential for cellular migration, cell–cell junctions, and cell polarity assembly. Rho GTPases are also significant mediators of cancer cell invasion. Nevertheless, to date only a few molecules from these intricate signaling networks have been studied in depth, which has prevented appreciation for the full scope of Rho GTPases’ biological functions. Given the large complexity involved, system level studies are required to fully grasp the extent of their biological roles and regulation. Recently, several groups have tackled this challenge by using proteomic approaches to map the full repertoire of Rho GTPases and Rho regulators protein interactions. These studies have provided in-depth understanding of Rho regulators specificity and have contributed to expand Rho GTPases’ effector portfolio. Additionally, new roles for understudied family members were unraveled using high throughput screening strategies using cell culture models and mouse embryos. In this review, we highlight theses latest large-scale efforts, and we discuss the emerging opportunities that may lead to the next wave of discoveries.
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7
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Ohta K, Matsumoto Y, Yumine N, Nishio M. The V protein of human parainfluenza virus type 2 promotes RhoA-induced filamentous actin formation. Virology 2018; 524:90-96. [DOI: 10.1016/j.virol.2018.08.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/14/2018] [Accepted: 08/17/2018] [Indexed: 10/28/2022]
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8
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Zhang C, Adamos C, Oh MJ, Baruah J, Ayee MAA, Mehta D, Wary KK, Levitan I. oxLDL induces endothelial cell proliferation via Rho/ROCK/Akt/p27 kip1 signaling: opposite effects of oxLDL and cholesterol loading. Am J Physiol Cell Physiol 2017; 313:C340-C351. [PMID: 28701359 DOI: 10.1152/ajpcell.00249.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 07/05/2017] [Accepted: 07/05/2017] [Indexed: 12/19/2022]
Abstract
Oxidized modifications of LDL (oxLDL) play a key role in the development of endothelial dysfunction and atherosclerosis. However, the underlying mechanisms of oxLDL-mediated cellular behavior are not completely understood. Here, we compared the effects of two major types of oxLDL, copper-oxidized LDL (Cu2+-oxLDL) and lipoxygenase-oxidized LDL (LPO-oxLDL), on proliferation of human aortic endothelial cells (HAECs). Cu2+-oxLDL enhanced HAECs' proliferation in a dose- and degree of oxidation-dependent manner. Similarly, LPO-oxLDL also enhanced HAEC proliferation. Mechanistically, both Cu2+-oxLDL and LPO-oxLDL enhance HAEC proliferation via activation of Rho, Akt phosphorylation, and a decrease in the expression of cyclin-dependent kinase inhibitor 1B (p27kip1). Both Cu2+-oxLDL or LPO-oxLDL significantly increased Akt phosphorylation, whereas an Akt inhibitor, MK2206, blocked oxLDL-induced increase in HAEC proliferation. Blocking Rho with C3 or its downstream target ROCK with Y27632 significantly inhibited oxLDL-induced Akt phosphorylation and proliferation mediated by both Cu2+- and LPO-oxLDL. Activation of RhoA was blocked by Rho-GDI-1, which also abrogated oxLDL-induced Akt phosphorylation and HAEC proliferation. In contrast, blocking Rac1 in these cells had no effect on oxLDL-induced Akt phosphorylation or cell proliferation. Moreover, oxLDL-induced Rho/Akt signaling downregulated cell cycle inhibitor p27kip1 Preloading these cells with cholesterol, however, prevented oxLDL-induced Akt phosphorylation and HAEC proliferation. These findings provide a new understanding of the effects of oxLDL on endothelial proliferation, which is essential for developing new treatments against neovascularization and progression of atherosclerosis.
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Affiliation(s)
- Chongxu Zhang
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois; and
| | - Crystal Adamos
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois; and
| | - Myung-Jin Oh
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois; and
| | - Jugajyoti Baruah
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois
| | - Manuela A A Ayee
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois; and
| | - Dolly Mehta
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois
| | - Kishore K Wary
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois
| | - Irena Levitan
- Division of Pulmonary and Critical Care, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois; and
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9
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Vilar M. Structural Characterization of the p75 Neurotrophin Receptor: A Stranger in the TNFR Superfamily. VITAMINS AND HORMONES 2016; 104:57-87. [PMID: 28215307 DOI: 10.1016/bs.vh.2016.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Although p75 neurotrophin receptor (p75NTR) was the founding member of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), it is an atypical TNFRSF protein. p75NTR like TNF-R1 and Fas-R contain an extracellular domain with four cysteine-rich domains (CRD) and a death domain (DD) in the intracellular region. While TNFRSF proteins are activated by trimeric TNFSF ligands, p75NTR forms dimers activated by dimeric neurotrophins that are structurally unrelated to TNFSF proteins. In addition, although p75NTR shares with other members the interaction with the TNF receptor-associated factors to activate the NF-κB and cell death pathways, p75NTR does not interact with the DD-containing proteins FADD, TRADD, or MyD88. By contrast, the DD of p75NTR is able to recruit several protein interactors via a full catalog of DD interactions not described before in the TNFRSF. p75-DD forms homotypic symmetrical DD-DD complexes with itself and with the related p45-DD; forms heterotypic DD-CARD interactions with the RIP2-CARD domain, and forms a new interaction between a DD and RhoGDI. All these features, in addition to its promiscuous interactions with several ligands and coreceptors, its processing by α- and γ-secretases, the dimeric nature of its transmembrane domain and its "special" juxtamembrane region, make p75NTR a truly stranger in the TNFR superfamily. In this chapter, I will summarize the known structural aspects of p75NTR and I will analyze from a structural point of view, the similitudes and differences between p75NTR and the other members of the TNFRSF.
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Affiliation(s)
- M Vilar
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of Valencia (IBV-CSIC), València, Spain.
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10
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A disappearing act performed by magnesium: the nucleotide exchange mechanism of Ran GTPase by quantum mechanics/molecular mechanics studies. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1953-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Lin Z, Tann JY, Goh ETH, Kelly C, Lim KB, Gao JF, Ibanez CF. Structural basis of death domain signaling in the p75 neurotrophin receptor. eLife 2015; 4:e11692. [PMID: 26646181 PMCID: PMC4739766 DOI: 10.7554/elife.11692] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 12/06/2015] [Indexed: 12/30/2022] Open
Abstract
Death domains (DDs) mediate assembly of oligomeric complexes for activation of downstream signaling pathways through incompletely understood mechanisms. Here we report structures of complexes formed by the DD of p75 neurotrophin receptor (p75NTR) with RhoGDI, for activation of the RhoA pathway, with caspase recruitment domain (CARD) of RIP2 kinase, for activation of the NF-kB pathway, and with itself, revealing how DD dimerization controls access of intracellular effectors to the receptor. RIP2 CARD and RhoGDI bind to p75NTR DD at partially overlapping epitopes with over 100-fold difference in affinity, revealing the mechanism by which RIP2 recruitment displaces RhoGDI upon ligand binding. The p75NTR DD forms non-covalent, low-affinity symmetric dimers in solution. The dimer interface overlaps with RIP2 CARD but not RhoGDI binding sites, supporting a model of receptor activation triggered by separation of DDs. These structures reveal how competitive protein-protein interactions orchestrate the hierarchical activation of downstream pathways in non-catalytic receptors. DOI:http://dx.doi.org/10.7554/eLife.11692.001 Cells have proteins called receptors on their surface that can bind to specific molecules on the outside of the cell. Typically, this binding activates the receptor and the activated receptor then triggers some biochemical changes inside the cell. For many receptors, the portion of the receptor inside the cell is essentially an enzyme that can trigger a biochemical change by itself. Some receptors, however, lack any enzymatic activity, and it is often unclear how these ‘non-catalytic receptors’ trigger changes inside a cell. A protein called p75 neurotrophin receptor (or p75NTR for short) is a non-catalytic receptor that is expressed when neurons are injured and its activity leads to the death of the neurons and related cells. Inhibiting this non-catalytic receptor is an attractive strategy for limiting the damage caused by diseases of the nervous system. However, the molecular mechanisms behind the activity of p75NTR are not well understood. Previous biochemical studies set out to answer the question of how p75NTR engages with components of the signaling machinery inside the cell, and found several components that interact with this receptor. Now, Lin et al. have tried to gain a more detailed understanding of those interactions at a molecular level. This involved solving the three-dimensional structures of three protein complexes that involve part of p75NTR (called the “death domain”) and one of two signaling components (called RhoGDI and RIP2). Two of the protein complexes showed that RIP2 and RhoGDI bind to the receptor’s death domain at partially overlapping sites, although RIP2 binds about 100 times more strongly than RhoGDI.A third protein complex showed an interaction between two copies of the death domain, which involves a surface of the receptor that overlaps with RIP2’s, but not RhoGDI’s, binding site. These structures, together with the results of other experiments, allowed Lin et al. to propose a model that could explain how p75NTR is activated. First, the two death domains must be separated. Next, RIP2 is recruited to the receptor, and outcompetes and displaces RhoGDI. This change in protein-protein interactions switches the receptor’s signaling from one pathway to the other. Now that these structures are available, they can be used in future experiments to design specific changes in the receptor that would allow researchers to dissect its different activities. DOI:http://dx.doi.org/10.7554/eLife.11692.002
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Affiliation(s)
- Zhi Lin
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Jason Y Tann
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Eddy T H Goh
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Claire Kelly
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Kim Buay Lim
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Jian Fang Gao
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Carlos F Ibanez
- Department of Physiology, National University of Singapore, Singapore, Singapore.,Life Sciences Institute, National University of Singapore, Singapore, Singapore.,Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
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12
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Knyphausen P, Kuhlmann N, de Boor S, Lammers M. Lysine-acetylation as a fundamental regulator of Ran function: Implications for signaling of proteins of the Ras-superfamily. Small GTPases 2015; 6:189-95. [PMID: 26507377 PMCID: PMC4905271 DOI: 10.1080/21541248.2015.1103399] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The small GTP-binding protein Ran is involved in the regulation of essential cellular processes in interphase but also in mitotic cells: Ran controls the nucleocytoplasmic transport of proteins and RNA, it regulates mitotic spindle formation and nuclear envelope assembly. Deregulations in Ran dependent processes were implicated in the development of severe diseases such as cancer and neurodegenerative disorders. To understand how Ran-function is regulated is therefore of highest importance. Recently, several lysine-acetylation sites in Ran were identified by quantitative mass-spectrometry, some being located in highly important regions such as the P-loop, switch I, switch II and the G5/SAK motif. We recently reported that lysine-acetylation regulates nearly all aspects of Ran-function such as RCC1 catalyzed nucleotide exchange, intrinsic nucleotide hydrolysis, its interaction with NTF2 and the formation of import- and export-complexes. As a hint for its biological importance, we identified Ran-specific lysine-deacetylases (KDACs) and -acetyltransferases (KATs). Also for other small GTPases such as Ras, Rho, Cdc42, and for many effectors and regulators thereof, lysine-acetylation sites were discovered. However, the functional impact of lysine-acetylation as a regulator of protein function has only been marginally investigated so far. We will discuss recent findings of lysine-acetylation as a novel modification to regulate Ras-protein signaling.
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Affiliation(s)
- Philipp Knyphausen
- a Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD ); University of Cologne ; Cologne , Germany
| | - Nora Kuhlmann
- a Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD ); University of Cologne ; Cologne , Germany
| | - Susanne de Boor
- a Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD ); University of Cologne ; Cologne , Germany
| | - Michael Lammers
- a Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD ); University of Cologne ; Cologne , Germany
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Mejuch T, van Hattum H, Triola G, Jaiswal M, Waldmann H. Specificity of Lipoprotein Chaperones for the Characteristic Lipidated Structural Motifs of their Cognate Lipoproteins. Chembiochem 2015; 16:2460-5. [PMID: 26503308 DOI: 10.1002/cbic.201500355] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Indexed: 11/08/2022]
Abstract
Lipoprotein-binding chaperones mediate intracellular transport of lipidated proteins and determine their proper localisation and functioning. Understanding of the exact structural parameters that determine recognition and transport by different chaperones is of major interest. We have synthesised several lipid-modified peptides, representative of different lipoprotein classes, and have investigated their binding to the relevant chaperones PDEδ, UNC119a, UNC119b, and galectins-1 and -3. Our results demonstrate that PDEδ recognises S-isoprenylated C-terminal peptidic structures but not N-myristoylated peptides. In contrast, UNC119 proteins bind only mono-N-myristoylated, but do not recognise doubly lipidated and S-isoprenylated peptides at the C terminus. For galectins-1 and -3, neither binding to N-acylated, nor to C-terminally prenylated peptides could be determined. These results shed light on the specificity of the chaperone-mediated cellular lipoprotein transport systems.
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Affiliation(s)
- Tom Mejuch
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Hilde van Hattum
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Gemma Triola
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Mamta Jaiswal
- Department of Structural Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Herbert Waldmann
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany. .,Department of Chemistry and Chemical Biology, Technical University of Dortmund, Otto-Hahn-Strasse 6, 44227, Dortmund, Germany.
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14
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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: 63] [Impact Index Per Article: 7.0] [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.
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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
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15
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Tnimov Z, Abankwa D, Alexandrov K. RhoGDI facilitates geranylgeranyltransferase-I-mediated RhoA prenylation. Biochem Biophys Res Commun 2014; 452:967-73. [PMID: 25223799 DOI: 10.1016/j.bbrc.2014.09.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 09/07/2014] [Indexed: 11/28/2022]
Abstract
Protein prenylation is a post-translational modification where farnesyl or geranylgeranyl groups are enzymatically attached to a C-terminal cysteine residue. This modification is essential for the activity of small cellular GTPases, as it allows them to associate with intracellular membranes. Dissociated from membranes, prenylated proteins need to be transported through the aqueous cytoplasm by protein carriers that shield the hydrophobic anchor from the solvent. One such carrier is Rho GDP dissociation inhibitor (RhoGDI). Recently, it was shown that prenylated Rho proteins that are not associated with RhoGDI are subjected to proteolysis in the cell. We hypothesized that the role of RhoGDI might be not only to associate with prenylated proteins but also to regulate the prenylation process in the cell. This idea is supported by the fact that RhoGDI binds both unprenylated and prenylated Rho proteins with high affinity in vitro, and hence, these interactions may affect the kinetics of prenylation. We addressed this question experimentally and found that RhoGDI increased the catalytic efficiency of geranylgeranyl transferase-I in RhoA prenylation. Nevertheless, we did not observe formation of a ternary RhoGDI∗RhoA∗GGTase-I complex, indicating sequential operation of geranylgeranyltransferase-I and RhoGDI. Our results suggest that RhoGDI accelerates Rho prenylation by kinetically trapping the reaction product, thereby increasing the rate of product release.
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Affiliation(s)
- Zakir Tnimov
- Department of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia
| | - Daniel Abankwa
- Department of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia
| | - Kirill Alexandrov
- Department of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia.
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16
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Pick E. Role of the Rho GTPase Rac in the activation of the phagocyte NADPH oxidase: outsourcing a key task. Small GTPases 2014; 5:e27952. [PMID: 24598074 PMCID: PMC4114928 DOI: 10.4161/sgtp.27952] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 11/19/2022] Open
Abstract
The superoxide-generating NADPH oxidase of phagocytes consists of the membrane-associated cytochrome b 558 (a heterodimer of Nox2 and p22(phox)) and 4 cytosolic components: p47(phox), p67(phox), p40(phox), and the small GTPase, Rac, in complex with RhoGDI. Superoxide is produced by the NADPH-driven reduction of molecular oxygen, via a redox gradient located in Nox2. Electron flow in Nox2 is initiated by interaction with cytosolic components, which translocate to the membrane, p67(phox) playing the central role. The participation of Rac is expressed in the following sequence: (1) Translocation of the RacGDP-RhoGDI complex to the membrane; (2) Dissociation of RacGDP from RhoGDI; (3) GDP to GTP exchange on Rac, mediated by a guanine nucleotide exchange factor; (4) Binding of RacGTP to p67(phox); (5) Induction of a conformational change in p67(phox), promoting interaction with Nox2. The particular involvement of Rac in NADPH oxidase assembly serves as a paradigm for signaling by Rho GTPases, in general.
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Affiliation(s)
- Edgar Pick
- Julius Friedrich Cohnheim Laboratory of Phagocyte Research; Department of Clinical Microbiology and Immunology; Sackler School of Medicine; Tel Aviv University; Tel Aviv, Israel
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17
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Agarwal NK, Kazyken D, Sarbassov DD. Rictor encounters RhoGDI2: the second pilot is taking a lead. Small GTPases 2013; 4:102-5. [PMID: 23354413 DOI: 10.4161/sgtp.23346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rictor's role in cell migration has been first indicated in the original chemotaxis studies in Dictyostelium and more recent studies reported that rictor is required for migration of cancer cells. How rictor promotes cell migration remains poorly characterized. Based on our proteomics study we have identified a novel functional role of rictor in regulation of cell migration. Here, we discuss our recent finding that rictor by suppressing RhoGDI2 maintains activity of the Rac1/cdc42 GTPases and promotes cell migration. Our finding outlines a critical role of rictor in the regulation of RhoGDI2 activity. This study opens new avenues in the investigation of cancer metastasis by analyzing the rictor dependent post-translational modification of RhoGDI2.
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Affiliation(s)
- Nitin K Agarwal
- Department of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
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18
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Jobichen C, Pal K, Swaminathan K. Crystal structure of mouse RhoA:GTPγS complex in a centered lattice. ACTA ACUST UNITED AC 2012; 13:241-5. [PMID: 23001747 DOI: 10.1007/s10969-012-9143-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 09/11/2012] [Indexed: 11/24/2022]
Abstract
RhoA, a member of the Rho sub-family of small GTPases, plays a significant signaling role in cell morphogenesis, migration, neuronal development, cell division and adhesion. So far, 4 structures of RhoA:GDP/GTP analogs and 14 structures of RhoA in complex with other proteins have been reported. All RhoA:GDP/GTP analog complexes have been crystallized in primitive lattices and RhoA is monomeric. This is the first time a RhoA:GTP analog complex has been crystallized as a dimer in a centered lattice. The present structure reveals structural differences in the switch-I (residues 28-42) and switch-II (residues 61-66) regions, which play important roles in interactions with downstream targets to transduce signals, when compared to the previously reported structures.
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Affiliation(s)
- Chacko Jobichen
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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19
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Ard R, Mulatz K, Abramovici H, Maillet JC, Fottinger A, Foley T, Byham MR, Iqbal TA, Yoneda A, Couchman JR, Parks RJ, Gee SH. Diacylglycerol kinase ζ regulates RhoA activation via a kinase-independent scaffolding mechanism. Mol Biol Cell 2012; 23:4008-19. [PMID: 22918940 PMCID: PMC3469516 DOI: 10.1091/mbc.e12-01-0026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The dissociation of individual Rho GTPases from RhoGDI ensures appropriate responses to cellular signals. The enzyme diacylglycerol kinase ζ (DGKζ) serves as a scaffold to assemble a signaling complex that functions as a RhoA-specific RhoGDI dissociation factor. DGKζ deficiency impairs RhoA activation and stress fiber formation in fibroblasts. Rho GTPases share a common inhibitor, Rho guanine nucleotide dissociation inhibitor (RhoGDI), which regulates their expression levels, membrane localization, and activation state. The selective dissociation of individual Rho GTPases from RhoGDI ensures appropriate responses to cellular signals, but the underlying mechanisms are unclear. Diacylglycerol kinase ζ (DGKζ), which phosphorylates diacylglycerol to yield phosphatidic acid, selectively dissociates Rac1 by stimulating PAK1-mediated phosphorylation of RhoGDI on Ser-101/174. Similarly, phosphorylation of RhoGDI on Ser-34 by protein kinase Cα (PKCα) selectively releases RhoA. Here we show DGKζ is required for RhoA activation and Ser-34 phosphorylation, which were decreased in DGKζ-deficient fibroblasts and rescued by wild-type DGKζ or a catalytically inactive mutant. DGKζ bound directly to the C-terminus of RhoA and the regulatory arm of RhoGDI and was required for efficient interaction of PKCα and RhoA. DGKζ-null fibroblasts had condensed F-actin bundles and altered focal adhesion distribution, indicative of aberrant RhoA signaling. Two targets of the RhoA effector ROCK showed reduced phosphorylation in DGKζ-null cells. Collectively our findings suggest DGKζ functions as a scaffold to assemble a signaling complex that functions as a RhoA-selective, GDI dissociation factor. As a regulator of Rac1 and RhoA activity, DGKζ is a critical factor linking changes in lipid signaling to actin reorganization.
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Affiliation(s)
- Ryan Ard
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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20
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Chandra A, Grecco HE, Pisupati V, Perera D, Cassidy L, Skoulidis F, Ismail SA, Hedberg C, Hanzal-Bayer M, Venkitaraman AR, Wittinghofer A, Bastiaens PIH. The GDI-like solubilizing factor PDEδ sustains the spatial organization and signalling of Ras family proteins. Nat Cell Biol 2011; 14:148-58. [PMID: 22179043 DOI: 10.1038/ncb2394] [Citation(s) in RCA: 254] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 11/04/2011] [Indexed: 12/31/2022]
Abstract
We identify a role for the GDI-like solubilizing factor (GSF) PDEδ in modulating signalling through Ras family G proteins by sustaining their dynamic distribution in cellular membranes. We show that the GDI-like pocket of PDEδ binds and solubilizes farnesylated Ras proteins, thereby enhancing their diffusion in the cytoplasm. This mechanism allows more effective trapping of depalmitoylated Ras proteins at the Golgi and polycationic Ras proteins at the plasma membrane to counter the entropic tendency to distribute these proteins over all intracellular membranes. Thus, PDEδ activity augments K/Hras signalling by enriching Ras at the plasma membrane; conversely, PDEδ down-modulation randomizes Ras distributions to all membranes in the cell and suppresses regulated signalling through wild-type Ras and also constitutive oncogenic Ras signalling in cancer cells. Our findings link the activity of PDEδ in determining Ras protein topography to Ras-dependent signalling.
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Affiliation(s)
- Anchal Chandra
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
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21
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Bielnicki JA, Shkumatov AV, Derewenda U, Somlyo AV, Svergun DI, Derewenda ZS. Insights into the molecular activation mechanism of the RhoA-specific guanine nucleotide exchange factor, PDZRhoGEF. J Biol Chem 2011; 286:35163-75. [PMID: 21816819 PMCID: PMC3186380 DOI: 10.1074/jbc.m111.270918] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 07/07/2011] [Indexed: 11/06/2022] Open
Abstract
PDZRhoGEF (PRG) belongs to a small family of RhoA-specific nucleotide exchange factors that mediates signaling through select G-protein-coupled receptors via Gα(12/13) and activates RhoA by catalyzing the exchange of GDP to GTP. PRG is a multidomain protein composed of PDZ, regulators of G-protein signaling-like (RGSL), Dbl-homology (DH), and pleckstrin-homology (PH) domains. It is autoinhibited in cytosol and is believed to undergo a conformational rearrangement and translocation to the membrane for full activation, although the molecular details of the regulation mechanism are not clear. It has been shown recently that the main autoregulatory elements of PDZRhoGEF, the autoinhibitory "activation box" and the "GEF switch," which is required for full activation, are located directly upstream of the catalytic DH domain and its RhoA binding surface, emphasizing the functional role of the RGSL-DH linker. Here, using a combination of biophysical and biochemical methods, we show that the mechanism of PRG regulation is yet more complex and may involve an additional autoinhibitory element in the form of a molten globule region within the linker between RGSL and DH domains. We propose a novel, two-tier model of autoinhibition where the activation box and the molten globule region act synergistically to impair the ability of RhoA to bind to the catalytic DH-PH tandem. The molten globule region and the activation box become less ordered in the PRG-RhoA complex and dissociate from the RhoA-binding site, which may constitute a critical step leading to PRG activation.
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Affiliation(s)
- Jakub A. Bielnicki
- From the Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia 22908 and
| | - Alexander V. Shkumatov
- the European Molecular Biology Laboratory, Hamburg Outstation, EMBL c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany
| | - Urszula Derewenda
- From the Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia 22908 and
| | - Avril V. Somlyo
- From the Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia 22908 and
| | - Dmitri I. Svergun
- the European Molecular Biology Laboratory, Hamburg Outstation, EMBL c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany
| | - Zygmunt S. Derewenda
- From the Department of Molecular Physiology and Biological Physics University of Virginia, Charlottesville, Virginia 22908 and
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22
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Momotani K, Artamonov MV, Utepbergenov D, Derewenda U, Derewenda ZS, Somlyo AV. p63RhoGEF couples Gα(q/11)-mediated signaling to Ca2+ sensitization of vascular smooth muscle contractility. Circ Res 2011; 109:993-1002. [PMID: 21885830 DOI: 10.1161/circresaha.111.248898] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE In normal and diseased vascular smooth muscle (SM), the RhoA pathway, which is activated by multiple agonists through G protein-coupled receptors (GPCRs), plays a central role in regulating basal tone and peripheral resistance. This occurs through inhibition of myosin light chain phosphatase, leading to increased phosphorylation of the myosin regulatory light chain. Although it is thought that specific agonists and GPCRs may couple to distinct RhoA guanine nucleotide exchange factors (GEFs), thus raising the possibility of selective targeting of specific GEFs for therapeutic use, this notion is largely unexplored for SM contraction. OBJECTIVE We examine whether p63RhoGEF, known to couple specifically to Gα(q/11) in vitro, is functional in blood vessels as a mediator of RhoA activation and if it is selectively activated by Gα(q/11) coupled agonists. METHODS AND RESULTS We find that p63RhoGEF is present across SM tissues and demonstrate that silencing of the endogenous p63RhoGEF in mouse portal vein inhibits contractile force induced by endothelin-1 to a greater extent than the predominantly Gα(12/13)-mediated thromboxane analog U46619. This is because endothelin-1 acts on Gα(q/11) as well as Gα(12/13). Introduction of the exogenous isolated pleckstrin-homology (PH) domain of p63RhoGEF (residues 331-580) into permeabilized rabbit portal vein inhibited Ca2+ sensitized force and activation of RhoA, when phenylephrine was used as an agonist. This reinforces the results based on endothelin-1, because phenylephrine is thought to act exclusively through Gα(q/11). CONCLUSION We demonstrate that p63RhoGEF selectively couples Gα(q/11) but not Gα(12/13), to RhoA activation in blood vessels and cultured cells and thus mediates the physiologically important Ca2+ sensitization of force induced with Gα(q/11)-coupled agonists. Our results suggest that signaling through p63RhoGEF provides a novel mechanism for selective regulation of blood pressure.
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Affiliation(s)
- Ko Momotani
- University of Virginia, Charlottesville, VA 22908-0736, USA
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23
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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: 406] [Impact Index Per Article: 31.2] [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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24
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Zheng M, Cierpicki T, Burdette AJ, Utepbergenov D, Janczyk PŁ, Derewenda U, Stukenberg PT, Caldwell KA, Derewenda ZS. Structural features and chaperone activity of the NudC protein family. J Mol Biol 2011; 409:722-41. [PMID: 21530541 DOI: 10.1016/j.jmb.2011.04.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/07/2011] [Accepted: 04/07/2011] [Indexed: 11/19/2022]
Abstract
The NudC family consists of four conserved proteins with representatives in all eukaryotes. The archetypal nudC gene from Aspergillus nidulans is a member of the nud gene family that is involved in the maintenance of nuclear migration. This family also includes nudF, whose human orthologue, Lis1, codes for a protein essential for brain cortex development. Three paralogues of NudC are known in vertebrates: NudC, NudC-like (NudCL), and NudC-like 2 (NudCL2). The fourth distantly related member of the family, CML66, contains a NudC-like domain. The three principal NudC proteins have no catalytic activity but appear to play as yet poorly defined roles in proliferating and dividing cells. We present crystallographic and NMR studies of the human NudC protein and discuss the results in the context of structures recently deposited by structural genomics centers (i.e., NudCL and mouse NudCL2). All proteins share the same core CS domain characteristic of proteins acting either as cochaperones of Hsp90 or as independent small heat shock proteins. However, while NudC and NudCL dimerize via an N-terminally located coiled coil, the smaller NudCL2 lacks this motif and instead dimerizes as a result of unique domain swapping. We show that NudC and NudCL, but not NudCL2, inhibit the aggregation of several target proteins, consistent with an Hsp90-independent heat shock protein function. Importantly, and in contrast to several previous reports, none of the three proteins is able to form binary complexes with Lis1. The availability of structural information will be of help in further studies on the cellular functions of the NudC family.
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Affiliation(s)
- Meiying Zheng
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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25
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Zazueta-Novoa V, Martínez-Cadena G, Wessel GM, Zazueta-Sandoval R, Castellano L, García-Soto J. Concordance and interaction of guanine nucleotide dissociation inhibitor (RhoGDI) with RhoA in oogenesis and early development of the sea urchin. Dev Growth Differ 2011; 53:427-39. [PMID: 21492154 DOI: 10.1111/j.1440-169x.2011.01261.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rho GTPases are Ras-related GTPases that regulate a variety of cellular processes. In the sea urchin Strongylocentrotus purpuratus, RhoA in the oocyte associates with the membrane of the cortical granules and directs their movement from the cytoplasm to the cell cortex during maturation to an egg. RhoA also plays an important role regulating the Na(+) -H(+) exchanger activity, which determines the internal pH of the cell during the first minutes of embryogenesis. We investigated how this activity may be regulated by a guanine-nucleotide dissociation inhibitor (RhoGDI). The sequence of this RhoA regulatory protein was identified in the genome on the basis of its similarity to other RhoGDI species, especially for key segments in the formation of the isoprenyl-binding pocket and in interactions with the Rho GTPase. We examined the expression and the subcellular localization of RhoGDI during oogenesis and in different developmental stages. We found that RhoGDI mRNA levels were high in eggs and during cleavage divisions until blastula, when it disappeared, only to reappear in gastrula stage. RhoGDI localization overlaps the presence of RhoA during oogenesis and in embryonic development, reinforcing the regulatory premise of the interaction. By use of recombinant protein interactions in vitro, we also find that these two proteins selectively interact. These results support the hypothesis of a functional relationship in vivo and now enable mechanistic insight for the cellular and organelle rearrangements that occur during oogenesis and embryonic development.
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Affiliation(s)
- Vanesa Zazueta-Novoa
- Department of Biology, Natural and Exact Sciences Division, Guanajuato Campus, University of Guanajuato, Box 187, Guanajuato, Gto. 36000, Mèxico
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26
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Cho HJ, Baek KE, Yoo J. RhoGDI2 as a therapeutic target in cancer. Expert Opin Ther Targets 2010; 14:67-75. [PMID: 20001211 DOI: 10.1517/14728220903449251] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IMPORTANCE OF THE FIELD Rho GDP dissociation inhibitor 2 (RhoGDI2) has been identified as a regulator of Rho GTPases that play important roles in the development of numerous aspects of the malignant phenotype, including cell cycle progression, resistance to apoptotic stimuli, neovascularization, tumor cell motility, invasiveness, and metastasis. Although RhoGDI2 has been known to be expressed only in hematopoietic tissues, recent studies suggest that this protein is also aberrantly expressed in several human cancers and contributes to aggressive phenotypes, such as invasion and metastasis. Hence, RhoGDI2 appears to be a target of interest for therapeutic manipulation. AREAS COVERED IN THIS REVIEW Here, we summarize the role of RhoGDI2 in human cancers, specifically metastasis-related processes, and discuss its potential as a therapeutic target. WHAT THE READER WILL GAIN RhoGDI2 modulates the invasiveness and metastatic ability of cancer cells through regulation of Rac1 activity. TAKE HOME MESSAGE RhoGDI2 may be a useful marker for tumor progression in human cancers, and interruption of the RhoGDI2-mediated cancer cell invasion and metastasis by an interfacial inhibitor may be a powerful therapeutic approach to cancer.
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Affiliation(s)
- Hee Jun Cho
- Gyeongsang National University, College of Natural Sciences, Research Institute of Life Science, Department of Microbiology, Jinju 660-701, Korea
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27
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Bielek H, Anselmo A, Dermardirossian C. Morphological and proliferative abnormalities in renal mesangial cells lacking RhoGDI. Cell Signal 2009; 21:1974-83. [PMID: 19765647 DOI: 10.1016/j.cellsig.2009.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 09/09/2009] [Indexed: 11/28/2022]
Abstract
The regulation of Rho GTPase activities and expression is critical in the development and function of the kidney. Rho GTPase activities and cytosol-membrane cycling are regulated by Rho GDP Dissociation Inhibitor (RhoGDI), and RhoGDI knockout mice develop defects in kidney structure and function that lead to death due to renal failure. It is therefore important to understand the changes in RhoGDI-regulated Rho GTPase activities and cell morphology that lead to kidney failure in RhoGDI (-/-) mice. Here, we characterize a renal mesangial cell line derived from the RhoGDI (-/-) mouse in which we verify the absence of GDI proteins. In the absence of RhoGDI, we show an increase in the specific activity of Rac1, and to a lesser extent, RhoA and Cdc42 GTPases in these cells. This is accompanied by a compensatory decrease in the steady-state protein levels of Rho GTPases. Morphological analysis of RhoGDI (-/-) mesangial cells reveals a decrease in cell spreading and in focal contacts compared to wild-type cells. Finally, RhoGDI (-/-) mesangial cells show a decreased ability to proliferate and survive. These functional and structural changes are likely to contribute to the defects in renal architecture and function observed in the RhoGDI (-/-) mouse.
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Affiliation(s)
- Heike Bielek
- Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, United States
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28
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Ho C, Shanmugasundararaj S, Miller KW, Malinowski SA, Cook AC, Slater SJ. Interaction of anesthetics with the Rho GTPase regulator Rho GDP dissociation inhibitor. Biochemistry 2008; 47:9540-52. [PMID: 18702520 DOI: 10.1021/bi800544d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The physiological effects of anesthetics have been ascribed to their interaction with hydrophobic sites within functionally relevant CNS proteins. Studies have shown that volatile anesthetics compete for luciferin binding to the hydrophobic substrate binding site within firefly luciferase and inhibit its activity (Franks, N. P., and Lieb, W. R. (1984) Nature 310, 599-601). To assess whether anesthetics also compete for ligand binding to a mammalian signal transduction protein, we investigated the interaction of the volatile anesthetic, halothane, with the Rho GDP dissociation inhibitor (RhoGDIalpha), which binds the geranylgeranyl moiety of GDP-bound Rho GTPases. Consistent with the existence of a discrete halothane binding site, the intrinsic tryptophan fluorescence of RhoGDIalpha was quenched by halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) in a saturable, concentration-dependent manner. Bromine quenching of tryptophan fluorescence is short-range and W192 and W194 of the RhoGDIalpha are located within the geranylgeranyl binding pocket, suggesting that halothane binds within this region. Supporting this, N-acetyl-geranylgeranyl cysteine reversed tryptophan quenching by halothane. Short chain n-alcohols ( n < 6) also reversed tryptophan quenching, suggesting that RhoGDIalpha may also bind n-alkanols. Consistent with this, E193 was photolabeled by 3-azibutanol. This residue is located in the vicinity of, but outside, the geranylgeranyl chain binding pocket, suggesting that the alcohol binding site is distinct from that occupied by halothane. Supporting this, N-acetyl-geranylgeranyl cysteine enhanced E193 photolabeling by 3-azibutanol. Overall, the results suggest that halothane binds to a site within the geranylgeranyl chain binding pocket of RhoGDIalpha, whereas alcohols bind to a distal site that interacts allosterically with this pocket.
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Affiliation(s)
- Cojen Ho
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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29
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Berken A, Wittinghofer A. Structure and function of Rho-type molecular switches in plants. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:380-93. [PMID: 18272378 DOI: 10.1016/j.plaphy.2007.12.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Indexed: 05/20/2023]
Abstract
Molecular switches of the Rho family, in concert with their associated regulators and effectors are well known as important control elements of vital signaling pathways in eucaryotic organisms. Yet, this knowledge has so far been established mainly from animal and fungal studies. However, during the recent years, the Rho switch has gone increasingly green as well, and it turned out that the homologous system in plants holds some distinctive features regarding structures, functions and molecular mechanisms for signal transduction. In this review, we give an overview about the structural characteristics of the Rho proteins of plants, termed ROP, highlighting some exciting differences to their animal and fungal counterparts. We further address the unique regulators and effectors of the ROPs and discuss the structural basis for the function and interaction of those proteins in ROP controlled reaction cascades. We finally intend to stimulate the demand for future three-dimensional structures that advance our understanding of the ROP switch in plants.
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Affiliation(s)
- Antje Berken
- Max Planck Institute of Molecular Physiology, Structural Biology Department, Otto Hahn Strasse 11, 44227 Dortmund, Germany.
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30
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Aragoni MC, Arca M, Devillanova FA, Garau A, Isaia F, Lippolis V, Mancini A. The nature of the chemical bond in linear three-body systems: from i3- to mixed chalcogen/halogen and trichalcogen moieties. Bioinorg Chem Appl 2007; 2007:17416. [PMID: 18389065 PMCID: PMC2276819 DOI: 10.1155/2007/17416] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 10/17/2006] [Accepted: 10/17/2006] [Indexed: 11/29/2022] Open
Abstract
The 3 centre-4 electrons (3c-4e) and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I(3) (-) and related electron-rich (22 shell electrons) systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD). Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall) has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I(3) (-) anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom.
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Affiliation(s)
- M. Carla Aragoni
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Massimiliano Arca
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Francesco A. Devillanova
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Alessandra Garau
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Francesco Isaia
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Vito Lippolis
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
| | - Annalisa Mancini
- Dipartimento di Chimica Inorganica ed Analitica, Universitá degli Studi di Cagliari, S.S. 554 Bivio per Sestu, Monserrato, Cagliari 09042, Italy
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31
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Ota T, Maeda M, Sakita-Suto S, Zhou X, Murakami M, Takegami T, Tatsuka M. RhoGDIbeta lacking the N-terminal regulatory domain suppresses metastasis by promoting anoikis in v-src-transformed cells. Clin Exp Metastasis 2006; 23:323-34. [PMID: 17111235 DOI: 10.1007/s10585-006-9041-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Accepted: 09/29/2006] [Indexed: 10/23/2022]
Abstract
Rho guanine nucleotide dissociation inhibitors (RhoGDIs) regulate the activity of Rho family GTPases. RhoGDIbeta (LyGDI/GDID4/RhoGDI2) has two caspase cleavage sites after Asp19 and Asp55. The resulting cleavage products, DeltaN(1-19)RhoGDIbeta and DeltaN(1-55)RhoGDIbeta, are expressed in cells under conditions that activate caspases. DeltaN(1-19)RhoGDIbeta, which can inhibit GDP dissociation, is implicated in the process of apoptosis, whereas the physiological roles for DeltaN(1-55)RhoGDIbeta, which lacks the ability to inhibit GDP dissociation, are largely unknown. To explore the roles of DeltaN(1-55)RhoGDIbeta, we examined the phenotypes of v-src-transformed metastatic fibroblasts transfected with plasmids for expressing DeltaN(1-55)RhoGDIbeta. Although the expression of DeltaN(1-55)RhoGDIbeta had no effect on the rate of growth in vitro, it suppressed experimental metastasis and decreased the rate of growth in vivo. In addition, DeltaN(1-55)RhoGDIbeta-expressing cells had enhanced adhesion to fibronectin, laminin, and collagens but reduced retention in the lung after intravenous injection. Also, the expression of DeltaN(1-55)RhoGDIbeta promoted anoikis without affecting the levels of activated Rac1 or Cdc42. Furthermore, DeltaN(1-55)RhoGDIbeta did not affect the expression or phosphorylation of focal adhesion kinase, p44/p42 mitogen-activated protein kinases, or Akt1 before or after induction of anoikis. Thus, DeltaN(1-55)RhoGDIbeta appears to promote anoikis by undefined mechanisms, thereby suppressing metastasis in v-src-transformed fibroblasts.
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Affiliation(s)
- Takahide Ota
- Division of Molecular Oncology and Virology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan.
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32
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Roberts GCK. Folding and unfolding for binding: large-scale protein dynamics in protein–protein interactions. Biochem Soc Trans 2006; 34:971-4. [PMID: 17052239 DOI: 10.1042/bst0340971] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The role of dynamics in the function of proteins, from enzymes to signalling proteins, is widely recognized. In many cases, the dynamic process is a relatively localized one, involving motion of a limited number of key residues, while in others large-scale domain movements may be involved. These motions all take place within the context of a folded protein; however, there is increasing evidence for the existence of some proteins where a transition between folded and unfolded structures is required for function.
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Affiliation(s)
- G C K Roberts
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, Henry Wellcome Building, University of Leicester, P.O. Box 138, Lancaster Road, Leicester LE1 9HN, UK.
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33
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Abstract
Rho GTPase activation is partially regulated at the level of guanine nucleotide dissociation inhibitors, or GDIs. The binding of Rho GTPases to GDIs has been shown to dramatically reduce the action of guanine nucleotide exchange factors (GEFs) to initiate Rho GTPase activation. The GDI-GTPase complex thus serves as a major point of regulation of Rho GTPase activity and function. It is likely that specific mechanisms exist to dissociate individual members of the Rho GTPase family from cytosolic Rho GDI complexes to facilitate the activation process. Such dissociation would likely be tightly coupled to GEF-mediated guanine nucleotide exchange and membrane association of the activated GTPase, resulting in effector binding and functional responses. Accumulating evidence suggests that the phosphorylation of either the Rho GTPases themselves and/or phosphorylation of GDIs might serve as a mechanism for regulating the formation and/or dissociation of Rho GTPase-GDI complexes. Indeed, the selective release of Rac1 from RhoGDI complexes induced by the p21-activated kinase-regulated phosphorylation of RhoGDI has been reported. We describe here methods for the analysis of RhoGDI phosphorylation and regulation by p21-activated kinase 1 (Pak1).
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34
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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: 313] [Impact Index Per Article: 16.5] [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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35
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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: 480] [Impact Index Per Article: 25.3] [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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36
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Dvorsky R, Ahmadian MR. Always look on the bright site of Rho: structural implications for a conserved intermolecular interface. EMBO Rep 2005; 5:1130-6. [PMID: 15577926 PMCID: PMC1299188 DOI: 10.1038/sj.embor.7400293] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 10/08/2004] [Indexed: 01/30/2023] Open
Abstract
The signalling functions of Rho-family GTPases are based on the formation of distinctive protein-protein complexes. Invaluable insights into the structure-function relationships of the Rho GTPases have been obtained through the resolution of several of their structures in complex with regulators and downstream effectors. In this review, we use these complexes to compare the binding and specificity-determining sites of the Rho GTPases. Although the properties that characterize these sites are diverse, some fundamental conserved principles that govern their intermolecular interactions have emerged. Notably, all of the interacting partners of the Rho GTPases, irrespective of their function, bind to a common set of conserved amino acids that are clustered on the surface of the switch regions. This conserved region and its specific structural characteristics exemplify the convergence of the Rho GTPases on a consensus binding site.
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Affiliation(s)
- Radovan Dvorsky
- Department of Structural Biology, Max Planck Institute for Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Mohammad Reza Ahmadian
- Department of Structural Biology, Max Planck Institute for Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
- Tel: +49 231 133 2105; Fax: +49 231 133 2199;
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37
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Johannessen BR, Skov LK, Kastrup JS, Kristensen O, Bolwig C, Larsen JN, Spangfort M, Lund K, Gajhede M. Structure of the house dust mite allergen Der f 2: implications for function and molecular basis of IgE cross-reactivity. FEBS Lett 2005; 579:1208-12. [PMID: 15710415 DOI: 10.1016/j.febslet.2004.11.115] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 11/23/2004] [Accepted: 11/24/2004] [Indexed: 11/21/2022]
Abstract
The X-ray structure of the group 2 major allergen from Dermatophagoides farinae (Der f 2) was determined to 1.83 A resolution. The overall Der f 2 structure comprises a single domain of immunoglobulin fold with two anti-parallel beta-sheets. A large hydrophobic cavity is formed in the interior of Der f 2. Structural comparisons to distantly related proteins suggest a role in lipid binding. Immunoglobulin E (IgE) cross-reactivity between group 2 house dust mite major allergens can be explained by conserved surface areas representing IgE binding epitopes.
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Affiliation(s)
- Birthe R Johannessen
- Biostructural Research, Department of Medicinal Chemistry, Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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38
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Papaharalambus C, Sajjad W, Syed A, Zhang C, Bergo MO, Alexander RW, Ahmad M. Tumor necrosis factor alpha stimulation of Rac1 activity. Role of isoprenylcysteine carboxylmethyltransferase. J Biol Chem 2005; 280:18790-6. [PMID: 15647276 DOI: 10.1074/jbc.m410081200] [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] [Indexed: 11/06/2022] Open
Abstract
We have previously demonstrated that both isoprenylcysteine carboxylmethyltransferase (ICMT) and one of its substrates, the RhoGTPase Rac1, are critical for the tumor necrosis factor alpha (TNF alpha) stimulation of vascular cell adhesion molecule-1 expression in endothelial cells (EC). Here, we have shown that ICMT regulates TNF alpha stimulation of Rac1 activity. TNF alpha stimulation of EC increased the membrane association of Rac1, an event that is essential for Rac1 activity. ICMT inhibitor N-acetyl-S-farnesyl-L-cysteine (AFC) blocked the accumulation of Rac1 into the membrane both in resting and TNF alpha-stimulated conditions. Similarly, the membrane-associated Rac1 was lower in Icmt-deficient versus wild-type mouse embryonic fibroblasts (MEFs). TNF alpha also increased the level of GTP-Rac1, the active form of Rac1, in EC. AFC completely suppressed the TNF alpha stimulation of increase in GTP-Rac1 levels. Confocal microscopy revealed resting EC Rac1 was present in the plasma membrane and also in the perinuclear region. AFC mislocalized Rac1, both from the plasma membrane and the perinuclear region. Mislocalization of Rac1 was also observed in Icmt-deficient versus wild-type MEFs. To determine the consequences of ICMT inhibition, we investigated the effect of AFC on p38 mitogen-activated protein (MAP) kinase phosphorylation, which is downstream of Rac1. AFC inhibited the TNF alpha stimulation of p38 MAP kinase phosphorylation in EC. TNF alpha stimulation of p38 MAP kinase phosphorylation was also significantly attenuated in Icmt-deficient versus wild-type MEFs. To understand the mechanism of inhibition of Rac1 activity, we examined the effect of ICMT inhibition on the interaction of Rac1 with its inhibitor, Rho guanine nucleotide dissociation inhibitor (RhoGDI). The association of Rac1 with its inhibitor RhoGDI was dramatically increased in the Icmt-deficient versus wild-type MEFs both in resting as well as in TNF alpha-stimulated conditions, suggesting that RhoGDI was involved in inhibiting Rac1 activity under the conditions of ICMT inhibition. These results suggest that ICMT regulates Rac1 activity by controlling the interaction of Rac1 with RhoGDI. We hypothesize that ICMT regulates the release of Rac1 from RhoGDI.
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Affiliation(s)
- Christopher Papaharalambus
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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39
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Budge PJ, Lebowitz J, Graham BS. Antiviral activity of RhoA-derived peptides against respiratory syncytial virus is dependent on formation of peptide dimers. Antimicrob Agents Chemother 2004; 47:3470-7. [PMID: 14576104 PMCID: PMC253766 DOI: 10.1128/aac.47.11.3470-3477.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A synthetic peptide containing amino acids 77 to 95 of the intracellular GTPase RhoA has previously been shown to inhibit replication of respiratory syncytial virus (RSV) in cultured cells. We show that residues 80 to 90 of RhoA are sufficient for this activity and that the cysteine residue at position 83 is critical. Further studies with an optimal peptide sequence containing amino acids 80 to 94 of RhoA revealed that the antiviral potency of the peptide is dependent on the oxidation of cysteine 83. Size-exclusion chromatography and sedimentation equilibrium studies of the peptide comprising residues 80 to 94 revealed that it is capable of forming aggregates in both reduced and oxidized states. A peptide (83A) in which the cysteine residue is replaced by an alanine does not form dimers or higher-order aggregates and did not inhibit RSV replication at any concentration tested. These data indicate that formation of peptide multimers is necessary for the antiviral activities of RhoA-derived peptides and suggest that the observed antiviral activities of these peptides may be unrelated to the biological functions of their parent molecule.
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Affiliation(s)
- Philip J Budge
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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40
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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: 1.3] [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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41
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Somlyo AP, Somlyo AV. Ca2+ sensitivity of smooth muscle and nonmuscle myosin II: modulated by G proteins, kinases, and myosin phosphatase. Physiol Rev 2003; 83:1325-58. [PMID: 14506307 DOI: 10.1152/physrev.00023.2003] [Citation(s) in RCA: 1509] [Impact Index Per Article: 71.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ca2+ sensitivity of smooth muscle and nonmuscle myosin II reflects the ratio of activities of myosin light-chain kinase (MLCK) to myosin light-chain phosphatase (MLCP) and is a major, regulated determinant of numerous cellular processes. We conclude that the majority of phenotypes attributed to the monomeric G protein RhoA and mediated by its effector, Rho-kinase (ROK), reflect Ca2+ sensitization: inhibition of myosin II dephosphorylation in the presence of basal (Ca2+ dependent or independent) or increased MLCK activity. We outline the pathway from receptors through trimeric G proteins (Galphaq, Galpha12, Galpha13) to activation, by guanine nucleotide exchange factors (GEFs), from GDP. RhoA. GDI to GTP. RhoA and hence to ROK through a mechanism involving association of GEF, RhoA, and ROK in multimolecular complexes at the lipid cell membrane. Specific domains of GEFs interact with trimeric G proteins, and some GEFs are activated by Tyr kinases whose inhibition can inhibit Rho signaling. Inhibition of MLCP, directly by ROK or by phosphorylation of the phosphatase inhibitor CPI-17, increases phosphorylation of the myosin II regulatory light chain and thus the activity of smooth muscle and nonmuscle actomyosin ATPase and motility. We summarize relevant effects of p21-activated kinase, LIM-kinase, and focal adhesion kinase. Mechanisms of Ca2+ desensitization are outlined with emphasis on the antagonism between cGMP-activated kinase and the RhoA/ROK pathway. We suggest that the RhoA/ROK pathway is constitutively active in a number of organs under physiological conditions; its aberrations play major roles in several disease states, particularly impacting on Ca2+ sensitization of smooth muscle in hypertension and possibly asthma and on cancer neoangiogenesis and cancer progression. It is a potentially important therapeutic target and a subject for translational research.
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Affiliation(s)
- Andrew P Somlyo
- Dept. of Molecular Physiology and Biological Physics, Univ. of Virginia, PO Box 800736, Charlottesville, VA 22908-0736.
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42
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Genth H, Gerhard R, Maeda A, Amano M, Kaibuchi K, Aktories K, Just I. Entrapment of Rho ADP-ribosylated by Clostridium botulinum C3 exoenzyme in the Rho-guanine nucleotide dissociation inhibitor-1 complex. J Biol Chem 2003; 278:28523-7. [PMID: 12750364 DOI: 10.1074/jbc.m301915200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RhoA, -B, and -C are ADP-ribosylated by Clostridium botulinum exoenzyme C3 to induce redistribution of the actin filaments in intact cells, a finding that has led to the notion that the ADP-ribosylation blocks coupling of Rho to the downstream effectors. ADP-ribosylation, however, does not alter nucleotide binding, intrinsic, and GTPase-activating protein-stimulated GTPase activity. ADP-ribosylated Rho is even capable of activating the effector protein ROK in a recombinant system. Treatment of cells with a cell-permeable chimeric C3 toxin led to complete localization of modified Rho to the cytosolic fraction based on the complexation of ADP-ribosylated Rho with the guanine-nucleotide dissociation inhibitor-1 (GDI-1). The modified complex turned out to be resistant to phosphatidylinositol 4,5-bisphosphate- and GTPgammaS-induced release of Rho from GDI-1. Thus, ADP-ribosylation leads to entrapment of Rho in the GDI-1 complex. The increased stability of the GDI complex prevented binding of Rho to membrane-associated players of the GTPase cycle such as the activating guanine nucleotide exchange factors and effector proteins.
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Affiliation(s)
- Harald Genth
- Institut für Toxikologie, Medizinische Hochschule D-30625 Hannover, Germany.
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43
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Brunet N, Morin A, Olofsson B. RhoGDI-3 regulates RhoG and targets this protein to the Golgi complex through its unique N-terminal domain. Traffic 2002; 3:342-57. [PMID: 11967128 DOI: 10.1034/j.1600-0854.2002.30504.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Guanine nucleotide dissociation inhibitors (GDIs) regulate both GDP/GTP and membrane association/dissociation cycles of Rho/Rac and Rab proteins.RhoGDI-3 is distinguishable from other rhoGDI proteins by its partial association with a detergent-resistant subcellular fraction. Here, we investigate the activity of this unusual rhoGDI using confocal laser scanning microscopy, immuno-isolation, and rhoGDI-3 mutants. We establish that the noncytosolic fraction of rhoGDI-3 is associated with the Golgi apparatus. The domain involved in this association is the unique N-terminal segment of rhoGDI-3 predicted to form an amphipathic alpha helix. This peptide is indispensable for Golgi association of rhoGDI-3 and sufficient to address a green fluorescent protein to the Golgi apparatus. Site-directed mutations, decreasing the hydrophobic surface of the helix, localize rhoGDI-3 into the cytoplasm. We establish that rhoGDI-3 is able to inhibit activation of the RhoG protein and to target this protein to the Golgi apparatus. Furthermore, we demonstrate the importance of the rhoGDI-3 N-terminal segment for both Golgi targeting and stability of the cytoplasmic RhoG/rhoGDI-3 complex. RhoGDI-3 is the first example of a GDI directly involved in the delivery of a Rho protein to a specific subcellular compartment.
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Affiliation(s)
- Nicolas Brunet
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS UPR 9063, F-91198 Gif-sur-Yvette, France
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44
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Derewenda U, Li J, Derewenda Z, Dauter Z, Mueller GA, Rule GS, Benjamin DC. The crystal structure of a major dust mite allergen Der p 2, and its biological implications. J Mol Biol 2002; 318:189-97. [PMID: 12054778 DOI: 10.1016/s0022-2836(02)00027-x] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The crystal structure of the common house mite (Dermatophagoides sp.) Der p 2 allergen was solved at 2.15 A resolution using the MAD phasing technique, and refined to an R-factor of 0.209. The refined atomic model, which reveals an immunoglobulin-like tertiary fold, differs in important ways from the previously described NMR structure, because the two beta-sheets are significantly further apart and create an internal cavity, which is occupied by a hydrophobic ligand. This interaction is structurally reminiscent of the binding of a prenyl group by a regulatory protein, the Rho guanine nucleotide exchange inhibitor. The crystal structure suggests that binding of non-polar molecules may be essential to the physiological function of the Der p 2 protein.
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Affiliation(s)
- U Derewenda
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
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45
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Patel JC, Hall A, Caron E. Vav regulates activation of Rac but not Cdc42 during FcgammaR-mediated phagocytosis. Mol Biol Cell 2002; 13:1215-26. [PMID: 11950933 PMCID: PMC102263 DOI: 10.1091/mbc.02-01-0002] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Phagocytosis is the process whereby cells direct the spatially localized, receptor-driven engulfment of particulate materials. It proceeds via remodeling of the actin cytoskeleton and shares many of the core cytoskeletal components involved in adhesion and migration. Small GTPases of the Rho family have been widely implicated in coordinating actin dynamics in response to extracellular signals and during diverse cellular processes, including phagocytosis, yet the mechanisms controlling their recruitment and activation are not known. We show herein that in response to ligation of Fc receptors for IgG (FcgammaR), the guanine nucleotide exchange factor Vav translocates to nascent phagosomes and catalyzes GTP loading on Rac, but not Cdc42. The Vav-induced Rac activation proceeds independently of Cdc42 function, suggesting distinct roles for each GTPase during engulfment. Moreover, inhibition of Vav exchange activity or of Cdc42 activity does not prevent Rac recruitment to sites of particle attachment. We conclude that Rac is recruited to Fcgamma membrane receptors in its inactive, GDP-bound state and that Vav regulates phagocytosis through subsequent catalysis of GDP/GTP exchange on Rac.
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Affiliation(s)
- Jayesh C Patel
- Medical Research Council Laboratory for Molecular Cell Biology, Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
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46
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Del Pozo MA, Kiosses WB, Alderson NB, Meller N, Hahn KM, Schwartz MA. Integrins regulate GTP-Rac localized effector interactions through dissociation of Rho-GDI. Nat Cell Biol 2002; 4:232-9. [PMID: 11862216 DOI: 10.1038/ncb759] [Citation(s) in RCA: 273] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The proper function of Rho GTPases requires precise spatial and temporal regulation of effector interactions. Integrin-mediated cell adhesion modulates the interaction of GTP-Rac with its effectors by controlling GTP-Rac membrane targeting. Here, we show that the translocation of GTP-Rac to membranes is independent of effector interactions, but instead requires the polybasic sequence near the carboxyl terminus. Cdc42 also requires integrin-mediated adhesion for translocation to membranes. A recently developed fluorescence resonance energy transfer (FRET)-based assay yields the surprising result that, despite its uniform distribution, the interaction of activated V12-Rac with a soluble, cytoplasmic effector domain is enhanced at specific regions near cell edges and is induced locally by integrin stimulation. This enhancement requires Rac membrane targeting. We show that Rho-GDI, which associates with cytoplasmic GTP-Rac, blocks effector binding. Release of Rho-GDI after membrane translocation allows Rac to bind to effectors. Thus, Rho-GDI confers spatially restricted regulation of Rac-effector interactions.
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Affiliation(s)
- Miguel Angel Del Pozo
- Division of Vascular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA.
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Forget MA, Desrosiers RR, Gingras D, Béliveau R. Phosphorylation states of Cdc42 and RhoA regulate their interactions with Rho GDP dissociation inhibitor and their extraction from biological membranes. Biochem J 2002; 361:243-54. [PMID: 11772396 PMCID: PMC1222304 DOI: 10.1042/0264-6021:3610243] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Rho GDP dissociation inhibitor (RhoGDI) regulates the activation-inactivation cycle of Rho small GTPases, such as Cdc42 and RhoA, by extracting them from the membrane. To study the roles of Mg(2+), phosphatidylinositol 4,5-bisphosphate (PIP(2)), ionic strength and phosphorylation on the interactions of RhoGDI with Cdc42 and RhoA, we developed a new, efficient and reliable method to produce prenylated Rho proteins using the yeast Saccharomyces cerevisiae. It has been previously reported that protein kinase A (PKA)-treatment of isolated membranes increased RhoA extraction from membranes by RhoGDI [Lang, Gesbert, Delespine-Carmagnat, Stancou, Pouchelet and Bertoglio (1996) EMBO J. 16, 510-519]. In the present study, we used an in vitro affinity chromatography system to show that phosphorylation of RhoA and Cdc42 significantly increased their interaction with RhoGDI under physiological conditions of ionic strength. This increase was independent of the nucleotide (GDP or guanosine 5'-[gamma-thio]triphosphate) loaded on to the Rho proteins, as well as of Mg(2+) and PIP(2). Moreover, dephosphorylation of rat brain membranes by alkaline phosphatase significantly decreased the extraction of RhoA and Cdc42 by RhoGDI. Subsequent re-phosphorylation by PKA restored the extraction levels, indicating the reversibility of this process. These results clearly demonstrate that the phosphorylation states of Cdc42 and RhoA regulate their interactions with RhoGDI and, consequently, their extraction from rat brain membranes. We therefore suggest that phosphorylation is a mechanism of regulation of Cdc42 and RhoA activity that is independent of GDP-GTP cycling.
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Affiliation(s)
- Marie-Annick Forget
- Laboratoire de médecine moléculaire, Hôpital Sainte-Justine-Université du Québec à Montréal, P.O. Box 8888, Centre-ville station, Montréal, Québec, Canada H3C 3P8
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Mamoon AM, Baker RC, Farley JM. Activation of phospholipase D in porcine tracheal smooth muscle: role of phosphatidylinositol 3-kinase and RhoA activation. Eur J Pharmacol 2001; 433:7-16. [PMID: 11755129 DOI: 10.1016/s0014-2999(01)01439-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Muscarinic receptor agonists transiently activate phospholipase D in tracheal smooth muscle. Muscarinic activation of phospholipase D in this tissue is dependent on activation of protein kinase C and an unidentified pathway that is not protein kinase C dependent. Cholinergic agents have also been shown to activate phospholipase D by pathways linked to the small G protein, RhoA. This study explores the relationship between muscarinic activation of phophatidylinositol 3-kinase and activation of RhoA, and examines whether phospholipase D activation is dependent on either pathway in tracheal smooth muscle. Wortmannin or 2-(4-morphonyl)-8-phenyl-4H-1-benzopyran-4-one (LY-294002), putative specific inhibitors of phophatidylinositol 3-kinase, significantly inhibit acetylcholine-induced formation of phosphatidylethanol and also block acetylcholine-induced translocation of RhoA to the membrane. In previous experiments calphostin C, a protein kinase C inhibitor, partially inhibited both acetylcholine-induced and phorbol-12-myristate-13-acetate (PMA)-induced phosphatidylethanol formation. In the present study calphostin C did not block acetylcholine-induced RhoA translocation to the membrane. However, the Rho kinase inhibitor, N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide (Y-27632), significantly inhibited acetylcholine-induced phosphatidylethanol formation, but had no effect on activation of phospholipase D by PMA. Acetylcholine treatment also stimulated the phosphorylation of the 110-kDa subunit of phosphatidylinositol 3-kinase. Phosphorylation of phosphatidylinositol 3-kinase 110-kDa subunit could be blocked by wortmannin in a concentration-dependent manner, and acetylcholine-induced phosphatidylinositol 3-kinase activity was significantly inhibited by wortmannin. LY-294002 also inhibited acetylcholine-induced phosphorylation of 110-kDa subunit and activation of phosphatidylinositol 3-kinase. These results suggest that acetylcholine stimulation translocates RhoA to the membrane by a phosphatidylinositol 3-kinase-dependent mechanism and acetylcholine-induced phospholipase D stimulation is at least partly mediated via phosphatidylinositol 3-kinase, however, protein kinase C appears to activate phospholipase D independent of phosphatidylinositol 3-kinase or RhoA activation in porcine tracheal smooth muscle.
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Affiliation(s)
- A M Mamoon
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
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Gibson RM, Wilson-Delfosse AL. RhoGDI-binding-defective mutant of Cdc42Hs targets to membranes and activates filopodia formation but does not cycle with the cytosol of mammalian cells. Biochem J 2001; 359:285-94. [PMID: 11583574 PMCID: PMC1222146 DOI: 10.1042/0264-6021:3590285] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have identified a mutant of the human G-protein Cdc42Hs, R66E, that fails to form a detectable complex with the GDP-dissociation inhibitor RhoGDI in cell-free systems or in intact cells. This point mutant is prenylated, binds guanine nucleotide and interacts with GTPase-activating protein in a manner indistinguishable from wild-type Cdc42Hs. Immunofluorescence localization studies revealed that this RhoGDI-binding-defective mutant is found predominantly in the Golgi apparatus, with a staining pattern similar to that of the wild-type protein. However, unlike wild-type Cdc42Hs, which is distributed in both the microsomal membrane and cytosolic fractions, studies using differential centrifugation show that prenylated R66E Cdc42Hs is found exclusively in association with lipid bilayers. Additionally, whereas the overexpression of RhoGDI results in an apparent translocation of wild-type Cdc42Hs from the Golgi apparatus into the cytosol, identical RhoGDI-overexpression conditions do not alter the Golgi localization of the R66E mutant. Furthermore, overexpression of this RhoGDI-binding-defective mutant of Cdc42Hs seems to activate redistribution of the actin cytoskeleton and filopodia formation in fibroblasts in a manner indistinguishable from the wild-type protein. Taken together, these results suggest that the interaction of Cdc42Hs with RhoGDI is not essential for proper membrane targeting of nascent prenylated Cdc42Hs in mammalian cells; neither is this interaction an essential part of the mechanism by which Cdc42Hs activates filopodia formation. However, it does seem that redistribution of Cdc42Hs to the cytosolic compartment is absolutely dependent on RhoGDI interaction.
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Affiliation(s)
- R M Gibson
- Department of Pharmacology, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4965, USA
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Gong MC, Gorenne I, Read P, Jia T, Nakamoto RK, Somlyo AV, Somlyo AP. Regulation by GDI of RhoA/Rho-kinase-induced Ca2+ sensitization of smooth muscle myosin II. Am J Physiol Cell Physiol 2001; 281:C257-69. [PMID: 11401849 DOI: 10.1152/ajpcell.2001.281.1.c257] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We characterized the role of guanine nucleotide dissociation inhibitor (GDI) in RhoA/Rho-kinase-mediated Ca2+ sensitization of smooth muscle. Endogenous contents (approximately 2-4 microM) of RhoA and RhoGDI were near stoichiometric, whereas a supraphysiological GDI concentration was required to relax Ca2+ sensitization of force by GTP and guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). GDI also inhibited Ca2+ sensitization by GTP. G14V RhoA, by alpha-adrenergic and muscarinic agonists, and extracted RhoA from membranes. GTPgammaS translocated Rho-kinase to a Triton X-114-extractable membrane fraction. GTP. G14V RhoA complexed with GDI also induced Ca2+ sensitization, probably through in vivo dissociation of GTP. RhoA from the complex, because it was reversed by addition of excess GDI. GDI did not inhibit Ca2+ sensitization by phorbol ester. Constitutively active Cdc42 and Rac1 inhibited Ca2+ sensitization by GTP. G14V RhoA. We conclude that 1) the most likely in vivo function of GDI is to prevent perpetual "recycling" of GDP. RhoA to GTP. RhoA; 2) nucleotide exchange (GTP for GDP) on complexed GDP. RhoA/GDI can precede translocation of RhoA to the membrane; 3) activation of Rho-kinase exposes a hydrophobic domain; and 4) Cdc42 and Rac1 can inhibit Ca2+ sensitization by activated GTP. RhoA.
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Affiliation(s)
- M C Gong
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
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