101
|
Johnson JL, Erickson JW, Cerione RA. New insights into how the Rho guanine nucleotide dissociation inhibitor regulates the interaction of Cdc42 with membranes. J Biol Chem 2009; 284:23860-71. [PMID: 19581296 DOI: 10.1074/jbc.m109.031815] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The subcellular localization of the Rho family GTPases is of fundamental importance to their proper functioning in cells. The Rho guanine nucleotide dissociation inhibitor (RhoGDI) plays a key regulatory role by influencing the cellular localization of Rho GTPases and is essential for the transforming activity of oncogenic forms of Cdc42. However, the mechanism by which RhoGDI helps Cdc42 to undergo the transition between a membrane-associated protein and a soluble (cytosolic) species has been poorly understood. Here, we examine how RhoGDI influences the binding of Cdc42 to lipid bilayers. Despite having similar affinities for the signaling-inactive (GDP-bound) and signaling-active (GTP-bound) forms of Cdc42 in solution, we show that when RhoGDI interacts with Cdc42 along the membrane surface, it has a much higher affinity for GDP-bound Cdc42 compared with its GTP-bound counterpart. Interestingly, the rate for the dissociation of Cdc42.RhoGDI complexes from membranes is unaffected by the nucleotide-bound state of Cdc42. Moreover, the membrane release of Cdc42.RhoGDI complexes occurs at a similar rate as the release of Cdc42 alone, with the major effect of RhoGDI being to impede the re-association of Cdc42 with membranes. These findings lead us to propose a new model for how RhoGDI influences the ability of Cdc42 to move between membranes and the cytosol, which highlights the role of the membrane in helping RhoGDI to distinguish between the GDP- and GTP-bound forms of Cdc42 and holds important implications for how it functions as a key regulator of the cellular localization and signaling activities of this GTPase.
Collapse
Affiliation(s)
- Jared L Johnson
- Department of Chemistry, Cornell University, Ithaca, New York 14853, USA
| | | | | |
Collapse
|
102
|
Koh W, Sachidanandam K, Stratman AN, Sacharidou A, Mayo AM, Murphy EA, Cheresh DA, Davis GE. Formation of endothelial lumens requires a coordinated PKCepsilon-, Src-, Pak- and Raf-kinase-dependent signaling cascade downstream of Cdc42 activation. J Cell Sci 2009; 122:1812-22. [PMID: 19435802 DOI: 10.1242/jcs.045799] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In this study, we present data showing that Cdc42-dependent lumen formation by endothelial cells (ECs) in three-dimensional (3D) collagen matrices involves coordinated signaling by PKCepsilon in conjunction with the Src-family kinases (SFKs) Src and Yes. Activated SFKs interact with Cdc42 in multiprotein signaling complexes that require PKCepsilon during this process. Src and Yes are differentially expressed during EC lumen formation and siRNA suppression of either kinase, but not Fyn or Lyn, results in significant inhibition of EC lumen formation. Concurrent with Cdc42 activation, PKCepsilon- and SFK-dependent signaling converge to activate p21-activated kinase (Pak)2 and Pak4 in steps that are also required for EC lumen formation. Pak2 and Pak4 further activate two Raf kinases, B-Raf and C-Raf, leading to ERK1 and ERK2 (ERK1/2) activation, which all seem to be necessary for EC lumen formation. This work reveals a multicomponent kinase signaling pathway downstream of integrin-matrix interactions and Cdc42 activation involving PKCepsilon, Src, Yes, Pak2, Pak4, B-Raf, C-Raf and ERK1/2 to control EC lumen formation in 3D collagen matrices.
Collapse
Affiliation(s)
- Wonshill Koh
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | | | | | | | | | | | | | | |
Collapse
|
103
|
Src phosphorylation of RhoGDI2 regulates its metastasis suppressor function. Proc Natl Acad Sci U S A 2009; 106:5807-12. [PMID: 19321744 DOI: 10.1073/pnas.0810094106] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
RhoGDI2 is a suppressor of metastasis in human bladder cancer. Although diminished RhoGDI2 expression in tumors is associated with decreased patient survival, normal expression in some metastatic tumors led us to wonder whether other mechanisms regulate RhoGDI2 function. Protein interaction analysis identified Src as a novel RhoGDI2 interaction partner. Gene expression profiling and immunohistochemistry of human tumors revealed that Src levels diminish as a function of bladder cancer stage. In addition, diminished Src levels and RhoGDI2 levels appear mutually exclusive in individual tumors, indicating that both genes are likely involved in the same signaling pathway leading to metastasis suppression. Studies confirmed that activated Src kinase binds and phosphorylates RhoGDI2 in vitro and vivo. Mutagenesis revealed that Tyr-153 and, to a lesser degree, Tyr-24 were the primary Src phosphorylation sites. Phosphorylation decreased the amount of Rac1 in RhoGDI2 complexes and increased RhoGDI2 association with cell membranes. Stable expression of phosphomimetic Tyr-153 RhoGDI2 in metastatic human bladder cancer cell lines had no effect on primary tumor growth but suppressed metastasis more potently than WT RhoGDI2. These data suggest that phosphorylation by Src enhances RhoGDI2 metastasis suppression and that loss of Src relieves metastasis suppression in tumor cells that maintain RhoGDI2 expression. Our findings also suggest caution in using Src inhibitors in the hope of delaying progression in patients with bladder cancer.
Collapse
|
104
|
Knock GA, Snetkov VA, Shaifta Y, Connolly M, Drndarski S, Noah A, Pourmahram GE, Becker S, Aaronson PI, Ward JPT. Superoxide constricts rat pulmonary arteries via Rho-kinase-mediated Ca(2+) sensitization. Free Radic Biol Med 2009; 46:633-42. [PMID: 19103285 PMCID: PMC6016743 DOI: 10.1016/j.freeradbiomed.2008.11.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 10/21/2008] [Accepted: 11/21/2008] [Indexed: 01/09/2023]
Abstract
Reactive oxygen species play a key role in vascular disease, pulmonary hypertension, and hypoxic pulmonary vasoconstriction. We investigated contractile responses, intracellular Ca(2+) ([Ca(2+)](i)), Rho-kinase translocation, and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and of myosin light chain (MLC(20)) in response to LY83583, a generator of superoxide anion, in small intrapulmonary arteries (IPA) of rat. LY83583 caused concentration-dependent constrictions in IPA and greatly enhanced submaximal PGF(2alpha)-mediated preconstriction. In small femoral or mesenteric arteries of rat, LY83583 alone was without effect, but it relaxed a PGF(2)alpha-mediated preconstriction. Constrictions in IPA were inhibited by superoxide dismutase and tempol, but not catalase, and were endothelium and guanylate cyclase independent. Constrictions were also inhibited by the Rho-kinase inhibitor Y27632 and the Src-family kinase inhibitor SU6656. LY83583 did not raise [Ca(2+)](i), but caused a Y27632-sensitive constriction in alpha-toxin-permeabilized IPA. LY83583 triggered translocation of Rho-kinase from the nucleus to the cytosol in pulmonary artery smooth muscle cells and enhanced phosphorylation of MYPT-1 at Thr-855 and of MLC(20) at Ser-19 in IPA. This enhancement was inhibited by superoxide dismutase and abolished by Y27632. Hydrogen peroxide did not activate Rho-kinase. We conclude that in rat small pulmonary artery, superoxide triggers Rho-kinase-mediated Ca(2+) sensitization and vasoconstriction independent of hydrogen peroxide.
Collapse
|
105
|
Huang CY, Yang LC, Liu KY, Liao PH, Chou JIY, Chou MY, Lin WW, Yang JJ. RhoGDIbeta-induced hypertrophic growth in H9c2 cells is negatively regulated by ZAK. J Biomed Sci 2009; 16:11. [PMID: 19272173 PMCID: PMC2653512 DOI: 10.1186/1423-0127-16-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Accepted: 01/22/2009] [Indexed: 12/20/2022] Open
Abstract
We found that overexpression of RhoGDIβ, a Rho GDP dissociation inhibitor, induced hypertrophic growth and suppressed cell cycle progression in a cultured cardiomyoblast cell line. Knockdown of RhoGDIβ expression by RNA interference blocked hypertrophic growth. We further demonstrated that RhoGDIβ physically interacts with ZAK and is phosphorylated by ZAK in vitro, and this phosphorylation negatively regulates RhoGDIβ functions. Moreover, the ZAK-RhoGDIβ interaction may maintain ZAK in an inactive hypophosphorylated form. These two proteins could negatively regulate one another such that ZAK suppresses RhoGDIβ functions through phosphorylation and RhoGDIβ counteracts the effects of ZAK by physical interaction. Knockdown of ZAK expression in ZAK- and RhoGDIβ-expressing cells by ZAK-specific RNA interference restored the full functions of RhoGDIβ.
Collapse
Affiliation(s)
- Chih-Yang Huang
- Graduate Institute of Chinese Medical Science, China Medical University, Taichung 404, Taiwan.
| | | | | | | | | | | | | | | |
Collapse
|
106
|
An adaptor role for cytoplasmic Sam68 in modulating Src activity during cell polarization. Mol Cell Biol 2009; 29:1933-43. [PMID: 19139276 DOI: 10.1128/mcb.01707-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The Src-associated substrate during mitosis with a molecular mass of 68 kDa (Sam68) is predominantly nuclear and is known to associate with proteins containing the Src homology 3 (SH3) and SH2 domains. Although Sam68 is a Src substrate, little is known about the signaling pathway that link them. Src is known to be activated transiently after cell spreading, where it modulates the activity of small Rho GTPases. Herein we report that Sam68-deficient cells exhibit loss of cell polarity and cell migration. Interestingly, Sam68-deficient cells exhibited sustained Src activity after cell attachment, resulting in the constitutive tyrosine phosphorylation and activation of p190RhoGAP and its association with p120rasGAP. Consistently, we observed that Sam68-deficient cells exhibited deregulated RhoA and Rac1 activity. By using total internal reflection fluorescence microscopy, we observed Sam68 near the plasma membrane after cell attachment coinciding with phosphorylation of its C-terminal tyrosines and association with Csk. These findings show that Sam68 localizes near the plasma membrane during cell attachment and serves as an adaptor protein to modulate Src activity for proper signaling to small Rho GTPases.
Collapse
|
107
|
Zhao T, Wang D, Cheranov SY, Karpurapu M, Chava KR, Kundumani-Sridharan V, Johnson DA, Penn JS, Rao GN. A novel role for activating transcription factor-2 in 15(S)-hydroxyeicosatetraenoic acid-induced angiogenesis. J Lipid Res 2008; 50:521-533. [PMID: 18849464 DOI: 10.1194/jlr.m800388-jlr200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To investigate the mechanisms underlying 15(S)-HETE-induced angiogenesis, we have studied the role of the small GTPase, Rac1. We find that 15(S)-HETE activated Rac1 in human retinal microvascular endothelial cells (HRMVEC) in a time-dependent manner. Blockade of Rac1 by adenovirus-mediated expression of its dominant negative mutant suppressed HRMVEC migration as well as tube formation and Matrigel plug angiogenesis. 15(S)-HETE stimulated Src in HRMVEC in a time-dependent manner and blockade of its activation inhibited 15(S)-HETE-induced Rac1 stimulation in HRMVEC and the migration and tube formation of these cells as well as Matrigel plug angiogenesis. 15(S)-HETE stimulated JNK1 in Src-Rac1-dependent manner in HRMVEC and adenovirus-mediated expression of its dominant negative mutant suppressed the migration and tube formation of these cells and Matrigel plug angiogenesis. 15(S)-HETE activated ATF-2 in HRMVEC in Src-Rac1-JNK1-dependent manner and interference with its activation via adenovirus-mediated expression of its dominant negative mutant abrogated migration and tube formation of HRMVEC and Matrigel plug angiogenesis. In addition, 15(S)-HETE-induced MEK1 stimulation was found to be dependent on Src-Rac1 activation. Blockade of MEK1 activation inhibited 15(S)-HETE-induced JNK1 activity and ATF-2 phosphorylation. Together, these findings show that 15(S)-HETE activates ATF-2 via the Src-Rac1-MEK1-JNK1 signaling axis in HRMVEC leading to their angiogenic differentiation.
Collapse
Affiliation(s)
- Tieqiang Zhao
- T. Zhao and D. Wang contributed equally to this work; Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Dong Wang
- T. Zhao and D. Wang contributed equally to this work; Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Sergey Y Cheranov
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Manjula Karpurapu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Koteswara R Chava
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | | | - Dianna A Johnson
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - John S Penn
- Vanderbilt Eye Institute, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Gadiparthi N Rao
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163.
| |
Collapse
|
108
|
Stuart HC, Jia Z, Messenberg A, Joshi B, Underhill TM, Moukhles H, Nabi IR. Localized Rho GTPase activation regulates RNA dynamics and compartmentalization in tumor cell protrusions. J Biol Chem 2008; 283:34785-95. [PMID: 18845542 DOI: 10.1074/jbc.m804014200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
mRNA trafficking and local protein translation are associated with protrusive cellular domains, such as neuronal growth cones, and deregulated control of protein translation is associated with tumor malignancy. We show here that activated RhoA, but not Rac1, is enriched in pseudopodia of MSV-MDCK-INV tumor cells and that Rho, Rho kinase (ROCK), and myosin II regulate the microtubule-independent targeting of RNA to these tumor cell domains. ROCK inhibition does not affect pseudopodial actin turnover but significantly reduces the dynamics of pseudopodial RNA turnover. Gene array analysis shows that 7.3% of the total genes analyzed exhibited a greater than 1.6-fold difference between the pseudopod and cell body fractions. Of these, only 13.2% (261 genes) are enriched in pseudopodia, suggesting that only a limited number of total cellular mRNAs are enriched in tumor cell protrusions. Comparison of the tumor pseudopod mRNA cohort and a cohort of mRNAs enriched in neuronal processes identified tumor pseudopod-specific signaling networks that were defined by expression of M-Ras and the Shp2 protein phosphatase. Pseudopod expression of M-Ras and Shp2 mRNA were diminished by ROCK inhibition linking pseudopodial Rho/ROCK activation to the localized expression of specific mRNAs. Pseudopodial enrichment for mRNAs involved in protein translation and signaling suggests that local mRNA translation regulates pseudopodial expression of less stable signaling molecules as well as the cellular machinery to translate these mRNAs. Pseudopodial Rho/ROCK activation may impact on tumor cell migration and metastasis by stimulating the pseudopodial translocation of mRNAs and thereby regulating the expression of local signaling cascades.
Collapse
Affiliation(s)
- Heather C Stuart
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | | | | | | | | | | | | |
Collapse
|
109
|
Leve F, de Souza W, Morgado-Díaz JA. A cross-link between protein kinase A and Rho-family GTPases signaling mediates cell-cell adhesion and actin cytoskeleton organization in epithelial cancer cells. J Pharmacol Exp Ther 2008; 327:777-88. [PMID: 18791066 DOI: 10.1124/jpet.108.140798] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Disassembly of the apical junctional complex (AJC) together with actin cytoskeleton alterations are among the initial events for the development of epithelial cancer. The cell signaling pathways for these processes have been analyzed separately. However, the existence of a link between these two events has not been defined. In this study, using the extracellular calcium depletion model, we analyzed the signaling pathways regulating AJC disassembly together with actin cytoskeleton organization in colon adenocarcinoma cells (Caco-2). Changes in the location of AJC proteins were examined by immunofluorescence and immunoblotting, and tight junction (TJ) functionality was observed by measuring the transepithelial electrical resistance and permeation to ruthenium red. The actin cytoskeleton was stained with rhodamine-phalloidin and analyzed by confocal microscopy. Rho-GTPase activation was assessed by its translocation to the membrane (a hallmark of RhoA activation) and immunoblotting. Pharmacological inhibition of protein kinase A (PKA) with H-89 [N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide)] prevented AJC disassembly and actin disorganization at the apical and medial regions caused by calcium depletion. Rho inhibition using toxin A induced AJC disassembly and actin cytoskeleton reorganization. Y-27632 [(R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-ciclohexanecarboxamide], a Rho-associated kinase inhibitor, reversed redistribution of E-cadherin, but not of TJ proteins and actin disorganization caused by calcium depletion. Calcium depletion and forskolin treatment caused activation of Rho, as evidenced by their translocation to the membrane, an event concurrent to Rac and RhoGDI translocation, and this effect was also reverted by H-89. Thus, our findings demonstrate a central role of a regulatory cascade that integrates PKA and Rho-family GTPases in the AJC disassembly and actin organization in tumor epithelial cells.
Collapse
Affiliation(s)
- Fernanda Leve
- Divisão de Biologia Celular, Coordenação de Pesquisa, Instituto Nacional de Câncer, Rio de Janeiro, Brazil
| | | | | |
Collapse
|
110
|
Qiao J, Holian O, Lee BS, Huang F, Zhang J, Lum H. Phosphorylation of GTP dissociation inhibitor by PKA negatively regulates RhoA. Am J Physiol Cell Physiol 2008; 295:C1161-8. [PMID: 18768928 DOI: 10.1152/ajpcell.00139.2008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cAMP-PKA cascade is a recognized signaling pathway important in inhibition of inflammatory injury events such as endothelial permeability and leucocyte trafficking, and a critical target of regulation is believed to be inhibition of Rho proteins. Here, we hypothesize that PKA directly phosphorylates GTP dissociation inhibitor (GDI) to negatively regulate Rho activity. Amino acid analysis of GDIalpha showed two potential protein kinase A (PKA) phosphorylation motifs, Ser(174) and Thr(182). Using in vitro kinase assay and mass spectrometry, we found that the purified PKA catalytic subunit phosphorylated GDIalpha-GST fusion protein and PKA motif-containing GDIalpha peptide at Ser(174), but not Thr(182). Transfection of COS-7 cells with mutated full-length GDIalpha at Ser(174) to Ala(174) (GDIalpha-Ser(174A)) abrogated the ability of cAMP to phosphorylate GDIalpha. However, mutation of Thr(182) to Ala(182) (GDIalpha-Thr(182A)) did not abrogate, and cAMP increased phosphorylation of GDIalpha to a similar extent as wild-type GDIalpha transfectants. The mutant GDIalpha-Ser(174A), but not GDIalpha-Thr(182A), was unable to prevent cAMP-mediated inhibition of Rho-dependent serum-response element reporter activity. Furthermore, the mutant GDIalpha-Ser(174A) was unable to prevent the thrombin-induced RhoA activation. Coprecipitation studies indicated that neither mutation of the PKA consensus sites nor phosphorylation alter GDIalpha binding with RhoA, suggesting that phosphorylation of Ser(174) regulated preformed GDIalpha-RhoA complexes. The findings provide strong support that the selective phosphorylation at Ser(174) by PKA is a signaling pathway in the negative regulation of RhoA activity and therefore could be a potential protective mechanism for inflammatory injury.
Collapse
Affiliation(s)
- Jing Qiao
- Dept. of Pharmacology, Rush Univ. Medical Center, 1735 W. Harrison St., Cohn Research Bldg.; Rm 416, Chicago, IL 60612, USA
| | | | | | | | | | | |
Collapse
|
111
|
Knock GA, Snetkov VA, Shaifta Y, Drndarski S, Ward JPT, Aaronson PI. Role of src-family kinases in hypoxic vasoconstriction of rat pulmonary artery. Cardiovasc Res 2008; 80:453-62. [PMID: 18682436 PMCID: PMC2583063 DOI: 10.1093/cvr/cvn209] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Aims We investigated the role of src-family kinases (srcFKs) in hypoxic pulmonary vasoconstriction (HPV) and how this relates to Rho-kinase-mediated Ca2+ sensitization and changes in intracellular Ca2+ concentration ([Ca2+]i). Methods and results Intra-pulmonary arteries (IPAs) were obtained from male Wistar rats. HPV was induced in myograph-mounted IPAs. Auto-phosphorylation of srcFKs and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and myosin light-chain (MLC20) in response to hypoxia were determined by western blotting. Translocation of Rho-kinase and effects of siRNA knockdown of src and fyn were examined in cultured pulmonary artery smooth muscle cells (PASMCs). [Ca2+]i was estimated in Fura-PE3-loaded IPA. HPV was inhibited by two blockers of srcFKs, SU6656 and PP2. Hypoxia enhanced phosphorylation of three srcFK proteins at Tyr-416 (60, 59, and 54 kDa, corresponding to src, fyn, and yes, respectively) and enhanced srcFK-dependent tyrosine phosphorylation of multiple target proteins. Hypoxia caused a complex, time-dependent enhancement of MYPT-1 and MLC20 phosphorylation, both in the absence and presence of pre-constriction. The sustained component of this enhancement was blocked by SU6656 and the Rho-kinase inhibitor Y27632. In PASMCs, hypoxia caused translocation of Rho-kinase from the nucleus to the cytoplasm, and this was prevented by anti-src siRNA and to a lesser extent by anti-fyn siRNA. The biphasic increases in [Ca2+]i that accompany HPV were also inhibited by PP2. Conclusion Hypoxia activates srcFKs and triggers protein tyrosine phosphorylation in IPA. Hypoxia-mediated Rho-kinase activation, Ca2+ sensitization, and [Ca2+]i responses are depressed by srcFK inhibitors and/or siRNA knockdown, suggesting a central role of srcFKs in HPV.
Collapse
Affiliation(s)
- Greg A Knock
- Department of Asthma, Allergy and Respiratory Science, School of Medicine, King's College London, Room 3.20, Franklin Wilkins Building, Stamford Street, London SE1 9NH, UK.
| | | | | | | | | | | |
Collapse
|
112
|
Kim Y, Lee YS, Choe J, Lee H, Kim YM, Jeoung D. CD44-epidermal growth factor receptor interaction mediates hyaluronic acid-promoted cell motility by activating protein kinase C signaling involving Akt, Rac1, Phox, reactive oxygen species, focal adhesion kinase, and MMP-2. J Biol Chem 2008; 283:22513-28. [PMID: 18577517 DOI: 10.1074/jbc.m708319200] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hyaluronic acid (HA) is known to play an important role in motility of tumor cells. However, the molecular mechanisms associated with HA-promoted melanoma cell motility are not fully understood. Treatment of cells with HA was shown to increase the production of reactive oxygen species (ROS) in a CD44-dependent manner. Antioxidants, such as N-acetyl-l-cysteine and seleno-l-methionine, prevented HA from enhancing cell motility. Protein kinase C (PKC)-alpha and PKCdelta were responsible for increased Rac1 activity, production of ROS, and mediated HA-promoted cell motility. HA increased Rac1 activity via CD44, PKCalpha, and PKCdelta. Transfection with dominant negative and constitutive active Rac1 mutants demonstrated that Rac1 was responsible for the increased production of ROS and cell motility by HA. Inhibition of NADPH oxidase by diphenylene iodonium and down-regulation of p47Phox and p67Phox decreased the ROS level, suggesting that NADPH oxidase is the main source of ROS production. Rac1 increased phosphorylation of FAK. FAK functions downstream of and is necessary for HA-promoted cell motility. Secretion and expression of MMP-2 were increased by treatment with HA via the action of PKCalpha, PKCdelta, and Rac1 and the production of ROS and FAK. Ilomastat, an inhibitor of MMP-2, exerted a negative effect on HA-promoted cell motility. HA increased interaction between CD44 and epidermal growth factor receptor (EGFR). AG1478, an inhibitor of EGFR, decreased phosphorylation of PKCalpha, PKCdelta, and Rac1 activity and suppressed induction of p47Phox and p67Phox. These results suggest that CD44-EGFR interaction is necessary for HA-promoted cell motility by regulating PKC signaling. EGFR-Akt interaction promoted by HA was responsible for the increased production of ROS and HA-promoted cell motility. In summary, HA promotes CD44-EGFR interaction, which in turn activates PKC signaling, involving Akt, Rac1, Phox, and the production of ROS, FAK, and MMP-2, to enhance melanoma cell motility.
Collapse
Affiliation(s)
- Youngmi Kim
- School of Biological Sciences, College of Natural Sciences, Kangwon National University, Chunchon 200-701, Korea
| | | | | | | | | | | |
Collapse
|
113
|
Schramp M, Ying O, Kim TY, Martin GS. ERK5 promotes Src-induced podosome formation by limiting Rho activation. ACTA ACUST UNITED AC 2008; 181:1195-210. [PMID: 18573916 PMCID: PMC2442207 DOI: 10.1083/jcb.200801078] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Increased Src activity, often associated with tumorigenesis, leads to the formation of invasive adhesions termed podosomes. Podosome formation requires the function of Rho family guanosine triphosphatases and reorganization of the actin cytoskeleton. In addition, Src induces changes in gene expression required for transformation, in part by activating mitogen-activated protein kinase (MAPK) signaling pathways. We sought to determine whether MAPK signaling regulates podosome formation. Unlike extracellular signal–regulated kinase 1/2 (ERK1/2), ERK5 is constitutively activated in Src-transformed fibroblasts. ERK5-deficient cells expressing v-Src exhibited increased RhoA activation and signaling, which lead to cellular retraction and an inability to form podosomes or induce invasion. Addition of the Rho-kinase inhibitor Y27632 to ERK5-deficient cells expressing v-Src led to cellular extension and restored podosome formation. In Src-transformed cells, ERK5 induced the expression of a Rho GTPase-activating protein (RhoGAP), RhoGAP7/DLC-1, via activation of the transcription factor myocyte enhancing factor 2C, and RhoGAP7 expression restored podosome formation in ERK5-deficient cells. We conclude that ERK5 promotes Src-induced podosome formation by inducing RhoGAP7 and thereby limiting Rho activation.
Collapse
Affiliation(s)
- Mark Schramp
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | | | | | | |
Collapse
|
114
|
Ho TTG, Merajver SD, Lapière CM, Nusgens BV, Deroanne CF. RhoA-GDP regulates RhoB protein stability. Potential involvement of RhoGDIalpha. J Biol Chem 2008; 283:21588-98. [PMID: 18524772 DOI: 10.1074/jbc.m710033200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
RhoA plays a significant role in actin stress fibers formation. However, silencing RhoA alone or RhoA and RhoC did not completely suppress the stress fibers suggesting a residual "Rho-like" activity. RhoB, the third member of the Rho subclass, is a shortlived protein barely detectable in basal conditions. In various cell types, the silencing of RhoA induced a strong up-regulation of both total and active RhoB protein levels that were rescued by re-expressing RhoA and related to an enhanced half-life of the protein. The RhoA-dependent regulation of RhoB does not depend on the activity of RhoA but is mediated by its GDP-bound form. The stabilization of RhoB was not dependent on isoprenoid biosynthesis, Rho kinase, extracellular signal-regulated kinase, p38 mitogen-activated kinase, or phosphatidylinositol 3'-OH kinase pathways but required RhoGDIalpha. The forced expression of RhoGDIalpha increased RhoB half-life, whereas its knock-down antagonized the induction of RhoB following RhoA silencing. Moreover, a RhoA mutant (RhoAR68E) unable to bind RhoGDIalpha was significantly less efficient as compared with wild-type RhoA in reversing RhoB up-regulation upon RhoA silencing. These results suggest that, in basal conditions, RhoGDIalpha is rate-limiting and the suppression of RhoA makes it available to stabilize RhoB. Our results highlight RhoGDIalpha-dependent cross-talks that regulate the stability of RhoGTPases.
Collapse
Affiliation(s)
- T T Giang Ho
- Laboratory of Connective Tissues Biology, GIGA-R, University of Liège, Tour de Pathologie, Sart Tilman, Belgium
| | | | | | | | | |
Collapse
|
115
|
Gianni D, Bohl B, Courtneidge SA, Bokoch GM. The involvement of the tyrosine kinase c-Src in the regulation of reactive oxygen species generation mediated by NADPH oxidase-1. Mol Biol Cell 2008; 19:2984-94. [PMID: 18463161 DOI: 10.1091/mbc.e08-02-0138] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
NADPH oxidase (Nox) family enzymes are one of the main sources of cellular reactive oxygen species (ROS), which have been shown to function as second messenger molecules. To date, seven members of this family have been reported, including Nox1-5 and Duox1 and -2. With the exception of Nox2, the regulation of the Nox enzymes is still poorly understood. Nox1 is highly expressed in the colon, and it requires two cytosolic regulators, NoxO1 and NoxA1, as well as the binding of Rac1 GTPase, for its activity. In this study, we investigate the role of the tyrosine kinase c-Src in the regulation of ROS formation by Nox1. We show that c-Src induces Nox1-mediated ROS generation in the HT29 human colon carcinoma cell line through a Rac-dependent mechanism. Treatment of HT29 cells with the Src inhibitor PP2, expression of a kinase-inactive form of c-Src, and c-Src depletion by small interfering RNA (siRNA) reduce both ROS generation and the levels of active Rac1. This is associated with decreased Src-mediated phosphorylation and activation of the Rac1-guanine nucleotide exchange factor Vav2. Consistent with this, Vav2 siRNA that specifically reduces endogenous Vav2 protein is able to dramatically decrease Nox1-dependent ROS generation and abolish c-Src-induced Nox1 activity. Together, these results establish c-Src as an important regulator of Nox1 activity, and they may provide insight into the mechanisms of tumor formation in colon cancers.
Collapse
Affiliation(s)
- Davide Gianni
- Departments of Immunology and Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | | | | |
Collapse
|
116
|
Gimona M. The microfilament system in the formation of invasive adhesions. Semin Cancer Biol 2008; 18:23-34. [DOI: 10.1016/j.semcancer.2007.08.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 08/30/2007] [Accepted: 08/31/2007] [Indexed: 12/23/2022]
|
117
|
Abstract
Motile eukaryotic cells polarize in response to external signals. Numerous mechanisms have been suggested to account for this symmetry breaking and for the ensuing robust polarization. Implicated in this process are various proteins that are recruited to the plasma membrane and segregate at an emergent front or back of the polarizing cell. Among these are PI3K, PTEN, and members of the Rho family GTPases such as Cdc42, Rac, and Rho. Many such proteins, including the Rho GTPases, cycle between active membrane-bound forms and inactive cytosolic forms. In previous work, we have shown that this property, together with appropriate crosstalk, endows a biochemical circuit (Cdc42, Rac, and Rho) with the property of inherent polarizability. Here we show that this property is present in an even simpler system comprised of a single active/inactive protein pair with positive feedback to its own activation. The simplicity of this minimal system also allows us to explain the mechanism using insights from mathematical analysis. The basic idea resides in a well-known property of reaction-diffusion systems with bistable kinetics, namely, propagation of fronts. However, it crucially depends on exchange between active and inactive forms of the chemicals with unequal rates of diffusion, and overall conservation to pin the waves into a stable polar distribution. We refer to these dynamics as wave-pinning and we show that this phenomenon is distinct from Turing-instability-generated pattern formation that occurs in reaction-diffusion systems that appear to be very similar. We explain the mathematical basis of the phenomenon, relate it to spatial segregation of Rho GTPases, and show how it can account for spatial amplification and maintenance of polarity, as well as sensitivity to new stimuli typical in polarization of eukaryotic cells.
Collapse
|
118
|
Kweon SM, Cho YJ, Minoo P, Groffen J, Heisterkamp N. Activity of the Bcr GTPase-activating domain is regulated through direct protein/protein interaction with the Rho guanine nucleotide dissociation inhibitor. J Biol Chem 2007; 283:3023-3030. [PMID: 18070886 DOI: 10.1074/jbc.m705513200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cycling of Rac GTPases, alternating between an active GTP- and an inactive GDP-bound state, is controlled by guanine nucleotide exchange factors, GTPase-activating proteins (GAPs), and guanine nucleotide dissociation inhibitors (GDIs). Little is known about how these controlling activities are coordinated. Studies using null mutant mice have demonstrated that Bcr and Abr are two physiologically important GAPs for Rac. Here, we report that in the presence of RhoGDIalpha, Bcr is unable to convert Rac-GTP to Rac-GDP because RhoGDI forms a direct protein complex with Bcr. Interestingly, RhoGDIalpha binds to the GAP domain in Bcr and Abr, a domain that also binds to Rac-GTP and catalyzes conversion of the bound GTP to GDP on Rac. The presence of activated Rac diminished the Bcr/RhoGDIalpha interaction. Moreover, a Bcr mutant that lacks the ability to promote hydrolysis of Rac-GTP bound to its GAP domain did not bind to RhoGDIalpha in cell lysates, indicating that binding of RhoGDIalpha and Rac-GTP to the Bcr GAP domain is mutually exclusive. Our results provide the first identification of a protein that regulates BcrGAP activity.
Collapse
Affiliation(s)
- Soo-Mi Kweon
- Section of Molecular Carcinogenesis, Division of Hematology/Oncology, The Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, California 90027
| | - Young Jin Cho
- Section of Molecular Carcinogenesis, Division of Hematology/Oncology, The Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, California 90027
| | - Parviz Minoo
- Department of Pediatrics, University of Southern California, Los Angeles, California 90033
| | - John Groffen
- Section of Molecular Carcinogenesis, Division of Hematology/Oncology, The Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, California 90027; Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Nora Heisterkamp
- Section of Molecular Carcinogenesis, Division of Hematology/Oncology, The Saban Research Institute, Childrens Hospital Los Angeles, Los Angeles, California 90027; Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033.
| |
Collapse
|
119
|
Schunke D, Span P, Ronneburg H, Dittmer A, Vetter M, Holzhausen HJ, Kantelhardt E, Krenkel S, Müller V, Sweep FC, Thomssen C, Dittmer J. Cyclooxygenase-2Is a Target Gene of Rho GDP Dissociation Inhibitor β in Breast Cancer Cells. Cancer Res 2007; 67:10694-702. [DOI: 10.1158/0008-5472.can-07-1621] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
120
|
Schmandke A, Schmandke A, Strittmatter SM. ROCK and Rho: biochemistry and neuronal functions of Rho-associated protein kinases. Neuroscientist 2007; 13:454-69. [PMID: 17901255 PMCID: PMC2849133 DOI: 10.1177/1073858407303611] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Rho-associated protein kinases (ROCKs) play key roles in mediating the control of the actin cytoskeleton by Rho family GTPases in response to extracellular signals. Such signaling pathways contribute to diverse neuronal functions from cell migration to axonal guidance to dendritic spine morphology to axonal regeneration to cell survival. In this review, the authors summarize biochemical knowledge of ROCK function and categorize neuronal ROCK-dependent signaling pathways. Further study of ROCK signal transduction mechanisms and specificities will enhance our understanding of brain development, plasticity, and repair. The ROCK pathway also provides a potential site for therapeutic intervention to promote neuronal regeneration and to limit degeneration.
Collapse
Affiliation(s)
- André Schmandke
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Neurology Yale University School of Medicine, New Haven, CT 06510, USA
| | | | | |
Collapse
|
121
|
|
122
|
Sahu SN, Nunez S, Bai G, Gupta A. Interaction of Pyk2 and PTP-PEST with leupaxin in prostate cancer cells. Am J Physiol Cell Physiol 2007; 292:C2288-96. [PMID: 17329398 DOI: 10.1152/ajpcell.00503.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have identified the presence of leupaxin (LPXN), which belongs to the paxillin extended family of focal adhesion-associated adaptor proteins, in prostate cancer cells. Previous studies have demonstrated that LPXN is a component of the podosomal signaling complex found in osteoclasts, where LPXN was found to associate with the protein tyrosine kinases Pyk2 and c-Src and the cytosolic protein tyrosine phosphatase-proline-, glutamate-, serine-, and threonine-rich sequence (PTP-PEST). In the current study, LPXN was detectable as a 50-kDa protein in PC-3 cells, a bone-derived metastatic prostate cancer cell line. In PC-3 cells, LPXN was also found to associate with Pyk2, c-Src, and PTP-PEST. A siRNA-mediated inhibition of LPXN resulted in decreased in vitro PC-3 cell migration. A recombinant adenoviral-mediated overexpression of LPXN resulted in an increased association of Pyk2 with LPXN, whereas a similar adenoviral-mediated overexpression of PTP-PEST resulted in decreased association of Pyk2 and c-Src with LPXN. The overexpression of LPXN in PC-3 cells resulted in increased migration, as assessed by in vitro Transwell migration assays. On the contrary, the overexpression of PTP-PEST in PC-3 cells resulted in decreased migration. The overexpression of LPXN resulted in increased activity of Rho GTPase, which was decreased in PTP-PEST-overexpressing cells. The increase in Rho GTPase activity following overexpression of LPXN was inhibited in the presence of Y27632, a selective inhibitor of Rho GTPase. In conclusion, our data demonstrate that LPXN forms a signaling complex with Pyk2, c-Src, and PTP-PEST to regulate migration of prostate cancer cells.
Collapse
Affiliation(s)
- Surasri Nandan Sahu
- Dept. of Biomedical Sciences, Dental School, University of Maryland, Baltimore, MD 21201, USA
| | | | | | | |
Collapse
|
123
|
The matrix corroded: podosomes and invadopodia in extracellular matrix degradation. Trends Cell Biol 2007; 17:107-17. [PMID: 17275303 DOI: 10.1016/j.tcb.2007.01.002] [Citation(s) in RCA: 482] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 12/20/2006] [Accepted: 01/17/2007] [Indexed: 01/09/2023]
Abstract
Podosomes and invadopodia are unique actin-rich adhesions that establish close contact to the substratum but can also degrade components of the extracellular matrix. Accordingly, matrix degradation localized at podosomes or invadopodia is thought to contribute to cellular invasiveness in physiological and pathological situations. Cell types that form podosomes include monocytic, endothelial and smooth muscle cells, whereas invadopodia have been mostly observed in carcinoma cells. This review highlights important new developments in the field, discusses the common and divergent features of podosomes and invadopodia and summarizes current knowledge about matrix-degrading proteinases at these structures.
Collapse
|
124
|
Castaño J, Solanas G, Casagolda D, Raurell I, Villagrasa P, Bustelo XR, García de Herreros A, Duñach M. Specific phosphorylation of p120-catenin regulatory domain differently modulates its binding to RhoA. Mol Cell Biol 2006; 27:1745-57. [PMID: 17194753 PMCID: PMC1820477 DOI: 10.1128/mcb.01974-06] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
p120-catenin is an adherens junction-associated protein that controls E-cadherin function and stability. p120-catenin also binds intracellular proteins, such as the small GTPase RhoA. In this paper, we identify the p120-catenin N-terminal regulatory domain as the docking site for RhoA. Moreover, we demonstrate that the binding of RhoA to p120-catenin is tightly controlled by the Src family-dependent phosphorylation of p120-catenin on tyrosine residues. The phosphorylation induced by Src and Fyn tyrosine kinases on p120-catenin induces opposite effects on RhoA binding. Fyn, by phosphorylating a residue located in the regulatory domain of p120-catenin (Tyr112), inhibits the interaction of this protein with RhoA. By contrast, the phosphorylation of Tyr217 and Tyr228 by Src promotes a better affinity of p120-catenin towards RhoA. In agreement with these biochemical data, results obtained in cell lines support the important role of these phosphorylation sites in the regulation of RhoA activity by p120-catenin. Taken together, these observations uncover a new regulatory mechanism acting on p120-catenin that contributes to the fine-tuned regulation of the RhoA pathways during specific signaling events.
Collapse
Affiliation(s)
- Julio Castaño
- Unitat de Biofísica, Departament Bioquímica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain.
| | | | | | | | | | | | | | | |
Collapse
|