51
|
Abstract
Reversible protein phosphorylation on multiple sites is a key regulatory mechanism in most cellular processes. We consider here a kinase-phosphatase-substrate system with two sites, under mass-action kinetics, with no restrictions on the order of phosphorylation or dephosphorylation. We show that the concentrations of the four phosphoforms at steady state satisfy an algebraic formula-an invariant-that is independent of the other chemical species, such as free enzymes or enzyme-substrate complexes, and holds irrespective of the starting conditions and the total amounts of enzymes and substrate. Such invariants allow stringent quantitative predictions to be made without requiring any knowledge of site-specific parameter values. We introduce what we believe are novel methods from algebraic geometry-Gröbner bases, rational curves-to calculate invariants. These methods are particularly significant because they make it possible to treat parameters symbolically without having to specify their numerical values, and thereby allow us to sidestep the parameter problem. We anticipate that this approach will have much wider applications in biological modeling.
Collapse
|
52
|
Ren S, Yang G, He Y, Wang Y, Li Y, Chen Z. The conservation pattern of short linear motifs is highly correlated with the function of interacting protein domains. BMC Genomics 2008; 9:452. [PMID: 18828911 PMCID: PMC2576256 DOI: 10.1186/1471-2164-9-452] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 10/01/2008] [Indexed: 12/12/2022] Open
Abstract
Background Many well-represented domains recognize primary sequences usually less than 10 amino acids in length, called Short Linear Motifs (SLiMs). Accurate prediction of SLiMs has been difficult because they are short (often < 10 amino acids) and highly degenerate. In this study, we combined scoring matrixes derived from peptide library and conservation analysis to identify protein classes enriched of functional SLiMs recognized by SH2, SH3, PDZ and S/T kinase domains. Results Our combined approach revealed that SLiMs are highly conserved in proteins from functional classes that are known to interact with a specific domain, but that they are not conserved in most other protein groups. We found that SLiMs recognized by SH2 domains were highly conserved in receptor kinases/phosphatases, adaptor molecules, and tyrosine kinases/phosphatases, that SLiMs recognized by SH3 domains were highly conserved in cytoskeletal and cytoskeletal-associated proteins, that SLiMs recognized by PDZ domains were highly conserved in membrane proteins such as channels and receptors, and that SLiMs recognized by S/T kinase domains were highly conserved in adaptor molecules, S/T kinases/phosphatases, and proteins involved in transcription or cell cycle control. We studied Tyr-SLiMs recognized by SH2 domains in more detail, and found that SH2-recognized Tyr-SLiMs on the cytoplasmic side of membrane proteins are more highly conserved than those on the extra-cellular side. Also, we found that SH2-recognized Tyr-SLiMs that are associated with SH3 motifs and a tyrosine kinase phosphorylation motif are more highly conserved. Conclusion The interactome of protein domains is reflected by the evolutionary conservation of SLiMs recognized by these domains. Combining scoring matrixes derived from peptide libraries and conservation analysis, we would be able to find those protein groups that are more likely to interact with specific domains.
Collapse
Affiliation(s)
- Siyuan Ren
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, PR China.
| | | | | | | | | | | |
Collapse
|
53
|
Yadav SS, Miller WT. The evolutionarily conserved arrangement of domains in SRC family kinases is important for substrate recognition. Biochemistry 2008; 47:10871-80. [PMID: 18803405 DOI: 10.1021/bi800930e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The SH3-SH2-kinase domain arrangement in nonreceptor tyrosine kinases has been conserved throughout evolution. For Src family kinases, the relative positions of the domains are important for enzyme regulation; they permit the assembly of Src kinases into autoinhibited conformations. The SH3 and SH2 domains of Src family kinases have an additional role in determining the substrate specificity of the kinase. We addressed the question of whether the domain arrangement of Src family kinases has a role in substrate specificity by producing mutants with alternative arrangements. Our results suggest that changes in the positions of domains can lead to specific changes in the phosphorylation of Sam68 and Cas by Src. Phosphorylation of Cas by several mutants triggers downstream signaling leading to cell migration. The placement of the SH2 domain with respect to the catalytic domain of Src appears to be especially important for proper substrate recognition, while the placement of the SH3 domain is more flexible. The results suggest that the involvement of the SH3 and SH2 domains in substrate recognition is one reason for the strict conservation of the SH3-SH2-kinase architecture.
Collapse
Affiliation(s)
- Shalini S Yadav
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York 11794-8661, USA
| | | |
Collapse
|
54
|
Guiet R, Poincloux R, Castandet J, Marois L, Labrousse A, Le Cabec V, Maridonneau-Parini I. Hematopoietic cell kinase (Hck) isoforms and phagocyte duties – From signaling and actin reorganization to migration and phagocytosis. Eur J Cell Biol 2008; 87:527-42. [DOI: 10.1016/j.ejcb.2008.03.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 03/06/2008] [Accepted: 03/11/2008] [Indexed: 01/21/2023] Open
|
55
|
Solheim SA, Petsalaki E, Stokka AJ, Russell RB, Taskén K, Berge T. Interactions between the Fyn SH3-domain and adaptor protein Cbp/PAG derived ligands, effects on kinase activity and affinity. FEBS J 2008; 275:4863-74. [PMID: 18721137 DOI: 10.1111/j.1742-4658.2008.06626.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Csk-binding protein/phosphoprotein associated with glycosphingolipid-enriched domains is a transmembrane adaptor protein primarily involved in negative regulation of T-cell activation by recruitment of C-terminal Src kinase (Csk), a protein tyrosine kinase which represses Src kinase activity through C-terminal phosphorylation. Recruitment of Csk occurs via SH2-domain binding to PAG pTyr317, thus, the interaction is highly dependent on phosphorylation performed by the Src family kinase Fyn, which docks onto PAG using a dual-domain binding mode involving both SH3- and SH2-domains of Fyn. In this study, we investigated Fyn SH3-domain binding to 14-mer peptide ligands derived from Cbp/PAG-enriched microdomains sequence using biochemical, biophysical and computational techniques. Interaction kinetics and dissociation constants for the various ligands were determined by SPR. The local structural impact of ligand association has been evaluated using CD, and molecular modelling has been employed to investigate details of the interactions. We show that data from these investigations correlate with functional effects of ligand binding, assessed experimentally by kinase assays using full-length PAG proteins as substrates. The presented data demonstrate a potential method for modulation of Src family kinase tyrosine phosphorylation through minor changes of the substrate SH3-interacting motif.
Collapse
Affiliation(s)
- Silje A Solheim
- The Biotechnology Centre of Oslo, University of Oslo, Norway
| | | | | | | | | | | |
Collapse
|
56
|
Granum S, Andersen TCB, Sørlie M, Jørgensen M, Koll L, Berge T, Lea T, Fleckenstein B, Spurkland A, Sundvold-Gjerstad V. Modulation of Lck function through multisite docking to T cell-specific adapter protein. J Biol Chem 2008; 283:21909-19. [PMID: 18541536 DOI: 10.1074/jbc.m800871200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
T cell-specific adapter protein (TSAd), encoded by the SH2D2A gene, interacts with Lck through its C terminus and thus modulates Lck activity. Here we mapped Lck phosphorylation and interaction sites on TSAd and evaluated their functional importance. The three C-terminal TSAd tyrosines Tyr(280), Tyr(290), and Tyr(305) were phosphorylated by Lck and functioned as docking sites for the Lck Src homology 2 (SH2) domain. Binding affinities of the TSAd Tyr(P)(280) and Tyr(P)(290) phosphopeptides to the isolated Lck SH2 domain were similar to that observed for the Lck Tyr(P)(505) phosphopeptide, whereas the TSAd Tyr(P)(305) peptide displayed a 10-fold higher affinity. The proline-rich Lck SH3-binding site on TSAd as well as the Lck SH2 domain were required for efficient tyrosine phosphorylation of TSAd by Lck. Interaction sites on TSAd for both Lck SH2 and Lck SH3 were necessary for TSAd-mediated modulation of proximal TCR signaling events. We found that 20-30% of TSAd molecules are phosphorylated in activated T cells and that the proportion of TSAd to Lck molecules in such cells is approximately 1:1. Therefore, in activated T cells, a considerable number of Lck molecules may potentially be engaged by TSAd. In conclusion, Lck binds to TSAd prolines and phosphorylates and interacts with the three C-terminal TSAd tyrosines. We propose that through multivalent interactions with Lck, TSAd diverts Lck from phosphorylating other substrates, thus modulating its functional activity through substrate competition.
Collapse
Affiliation(s)
- Stine Granum
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Box 1105, Blindern, N-0317 Oslo, Norway.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
57
|
Cooper JA, Qian H. A mechanism for SRC kinase-dependent signaling by noncatalytic receptors. Biochemistry 2008; 47:5681-5688. [PMID: 18444664 DOI: 10.1021/bi8003044] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental issue in cell biology is how signals are transmitted across membranes. A variety of transmembrane receptors, including multichain immune recognition receptors, lack catalytic activity and require Src family kinases (SFKs) for signal transduction. However, many receptors only bind and activate SFKs after ligand-induced receptor dimerization. This presents a conundrum: How do SFKs sense the dimerization of receptors to which they are not already bound? Most proposals for resolving this enigma invoke additional players, such as lipid rafts or receptor conformational changes. Here we used simple thermodynamics to show that SFK activation is a natural outcome of clustering of receptors with SFK phosphorylation sites, provided that there is phosphorylation-dependent receptor-SFK association and an SFK bound to one receptor can phosphorylate the second receptor or its associated SFK in a dimer. A simple system of receptor, SFK, and an unregulated protein tyrosine phosphatase (PTP) can account for ligand-induced changes in phosphorylation observed in cells. We suggest that a core signaling system comprising a receptor with SFK phosphorylation sites, an SFK, and an unregulated PTP provides a robust mechanism for transmembrane signal transduction. Other events that regulate signaling in specific cases may have evolved for fine-tuning of this basic mechanism.
Collapse
Affiliation(s)
- Jonathan A Cooper
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Hong Qian
- Department of Applied Mathematics, University of Washington, Seattle, Washington 98195
| |
Collapse
|
58
|
Solheim SA, Torgersen KM, Taskén K, Berge T. Regulation of FynT Function by Dual Domain Docking on PAG/Cbp. J Biol Chem 2008; 283:2773-83. [DOI: 10.1074/jbc.m705215200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
|
59
|
Takatsuka A, Yagi R, Koike M, Oneyama C, Nada S, Schmedt C, Uchiyama Y, Okada M. Ablation of Csk in neural crest lineages causes corneal anomaly by deregulating collagen fibril organization and cell motility. Dev Biol 2008; 315:474-88. [PMID: 18262517 DOI: 10.1016/j.ydbio.2008.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 12/29/2007] [Accepted: 01/04/2008] [Indexed: 12/25/2022]
Abstract
Src family kinases (SFKs) have been implicated in the regulation of cell motility. To verify their in vivo roles during development, we generated mutant mice in which Csk, a negative regulator of SFKs, was inactivated in neural crest lineages using the Protein zero promoter in a Cre-loxP system. Inactivation of Csk caused deformities in various tissues of neural crest origins, including facial dysplasia and corneal opacity. In the cornea, the stromal collagen fibril was disorganized and there was an overproduction of collagen 1a1 and several metalloproteases. The corneal endothelium failed to overlie the central region of the eye and the peripheral endothelium displayed a disorganized cytoskeleton. Corneal mesenchymal cells cultured from mutant mice showed attenuated cell motility. In these cells, p130 Crk-associated substrate (Cas) was hyperphosphorylated and markedly downregulated. The expression of a dominant negative Cas (Cas Delta SD) could suppress the cell motility defects. Fluorescence resonance energy transfer analysis revealed that activation of Rac1 and Cdc42 was depolarized in Csk-inactivated cells, which was restored by the expression of either Csk or Cas Delta SD. These results demonstrate that the SFKs/Csk circuit plays crucial roles in corneal development by controlling stromal organization and by ensuring cell motility via the Cas-Rac/Cdc42 pathways.
Collapse
Affiliation(s)
- Atsuko Takatsuka
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | | | | | | | | | | | | |
Collapse
|
60
|
Shvartsman DE, Donaldson JC, Diaz B, Gutman O, Martin GS, Henis YI. Src kinase activity and SH2 domain regulate the dynamics of Src association with lipid and protein targets. ACTA ACUST UNITED AC 2007; 178:675-86. [PMID: 17698610 PMCID: PMC2064473 DOI: 10.1083/jcb.200701133] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Src functions depend on its association with the plasma membrane and with specific membrane-associated assemblies. Many aspects of these interactions are unclear. We investigated the functions of kinase, SH2, and SH3 domains in Src membrane interactions. We used FRAP beam-size analysis in live cells expressing a series of c-Src–GFP proteins with targeted mutations in specific domains together with biochemical experiments to determine whether the mutants can generate and bind to phosphotyrosyl proteins. Wild-type Src displays lipid-like membrane association, whereas constitutively active Src-Y527F interacts transiently with slower-diffusing membrane-associated proteins. These interactions require Src kinase activity and SH2 binding, but not SH3 binding. Furthermore, overexpression of paxillin, an Src substrate with a high cytoplasmic population, competes with membrane phosphotyrosyl protein targets for binding to activated Src. Our observations indicate that the interactions of Src with lipid and protein targets are dynamic and that the kinase and SH2 domain cooperate in the membrane targeting of Src.
Collapse
Affiliation(s)
- Dmitry E Shvartsman
- Department of Neurobiochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | | | | | | | | | | |
Collapse
|
61
|
Yadav SS, Miller WT. Cooperative activation of Src family kinases by SH3 and SH2 ligands. Cancer Lett 2007; 257:116-23. [PMID: 17719722 PMCID: PMC2045694 DOI: 10.1016/j.canlet.2007.07.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 07/06/2007] [Accepted: 07/10/2007] [Indexed: 11/21/2022]
Abstract
Src family nonreceptor tyrosine kinases are kept in a repressed state by intramolecular interactions involving the SH3 and SH2 domains of the enzymes. Ligands for these domains can displace the intramolecular associations and activate the kinases. Here, we carried out in vitro activation experiments with purified, down-regulated hematopoietic cell kinase (Hck), a Src family kinase. We show that SH3 and SH2 ligands act cooperatively to activate Src family kinases: the presence of one ligand lowers the concentration of the second ligand necessary for activation. To confirm the findings in intact cells, we studied Cas, a Src substrate that possesses SH2 and SH3 ligands. In contrast to wild-type Cas, mutant forms of Cas lacking the SH3 or SH2 ligands were unable to stimulate Src autophosphorylation when expressed in Cas-deficient fibroblasts. Cells expressing the Cas mutants also showed decreased amounts of activated Src at focal adhesions. The results suggest that proteins containing ligands for both SH3 and SH2 domains can produce a synergistic activation of Src family kinases.
Collapse
Affiliation(s)
| | - W. Todd Miller
- * To whom correspondence should be addressed: Dept. of Physiology and Biophysics, Basic Science Tower, T-6, School of Medicine, SUNY at Stony Brook, Stony Brook, NY 11794-8661, Tel.: 631-444-3533; Fax: 631-444-3432, E-mail:
| |
Collapse
|
62
|
Gunawardena J. Distributivity and processivity in multisite phosphorylation can be distinguished through steady-state invariants. Biophys J 2007; 93:3828-34. [PMID: 17704153 PMCID: PMC2084251 DOI: 10.1529/biophysj.107.110866] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multisite protein phosphorylation and dephosphorylation are key cellular regulatory mechanisms but their system properties have been difficult to study in vivo and in vitro. Here we show by mathematical analysis that steady-state invariants enable the mechanism of the kinase or the phosphatase to be determined from steady-state measurements. Invariants exist when both enzymes act distributively (i.e., nonprocessively), making at most one modification in each molecular encounter. For instance, in the sequential case, in any experiment involving the same ingredients, the quantity [S(i-1)][S(i+1)]/[S(i)](2) always has the same value, where [S(i)] denotes the steady-state concentration of the i-th phospho-form. For a two-site substrate, if either enzyme exhibits processivity, so that more than one modification can be made in each molecular encounter, the degree of processivity can be estimated from changes in this invariant. We discuss the experimental and theoretical challenges in extending these results.
Collapse
Affiliation(s)
- Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
63
|
Baldanzi G, Cutrupi S, Chianale F, Gnocchi V, Rainero E, Porporato P, Filigheddu N, van Blitterswijk WJ, Parolini O, Bussolino F, Sinigaglia F, Graziani A. Diacylglycerol kinase-alpha phosphorylation by Src on Y335 is required for activation, membrane recruitment and Hgf-induced cell motility. Oncogene 2007; 27:942-56. [PMID: 17700527 DOI: 10.1038/sj.onc.1210717] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Diacylglycerol (DAG) kinases (Dgk), which phosphorylate DAG to generate phosphatidic acid, act as either positive or negative key regulators of cell signaling. We previously showed that Src mediates growth factors-induced activation of Dgk-alpha, whose activity is required for cell motility, proliferation and angiogenesis. Here, we demonstrate that both hepatocytes growth factor (HGF) stimulation and v-Src transformation induce tyrosine phosphorylation of Dgk-alpha on Y335, through a mechanism requiring its proline-rich C-terminal sequence. Moreover, we show that both proline-rich sequence and phosphorylation of Y335 of Dgk-alpha mediate: (i) its enzymatic activation, (ii) its ability to interact respectively with SH3 and SH2 domains of Src, (iii) its recruitment to the membrane. In addition, we show that phosphorylation of Dgk-alpha on Y335 is required for HGF-induced motility, while its constitutive recruitment at the membrane by myristylation is sufficient to trigger spontaneous motility in absence of HGF. Providing the first evidence that tyrosine phosphorylation of Dgk-alpha is required for growth-factors-induced activation and membrane recruitment, these findings underscore its relevance as a rheostat, whose activation is a threshold to elicit growth factors-induced migratory signaling.
Collapse
Affiliation(s)
- G Baldanzi
- Department of Medical Sciences, University Amedeo Avogadro of Piemonte Oriental, Novara, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
64
|
Wang YH, Huang K, Lin X, Sun G. Subdomain Switching Reveals Regions That Harbor Substrate Specificity and Regulatory Properties of Protein Tyrosine Kinases. Biochemistry 2007; 46:10162-9. [PMID: 17691821 DOI: 10.1021/bi7007257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Csk and Src are two protein tyrosine kinases that share a similar overall multidomain structural organization and a high degree of sequence homology but have different substrate specificities and regulatory properties. In this study, we generated chimeric kinases of Csk and Src by switching the C-terminal lobes of their catalytic domains, and we characterized their substrate specificity and regulatory properties. First, both Csk and Src phosphorylate Src as a common substrate, but on different Tyr residues. The C-terminal lobes of the kinase catalytic domain determined the site of phosphorylation on Src. Furthermore, toward several physiological substrates of Src, the substrate specificity was also determined by the C-terminal lobe of the catalytic domain regardless of the regulatory domains and the N-terminal lobe of the catalytic domain. Second, Csk and Src represent two general regulatory strategies for protein tyrosine kinases. Csk catalytic domain is inactive and is positively regulated by the regulatory domains, while Src catalytic domain is active and suppressed by its interactions with the regulatory domains. The regulatory properties of the chimeric kinases were more complicated. The regulatory domains and the N-lobe did not fully determine the response to a regulatory ligand, suggesting that the C-lobe also contributes to such responses. On the other hand, the intrinsic kinase activity of the catalytic domain correlates with the identity of the N-lobe. These results demonstrate that the chimeric strategy is useful for detailed dissection of the mechanistic basis of substrate specificity and regulation of protein tyrosine kinases.
Collapse
Affiliation(s)
- Yue-Hao Wang
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island 02881, USA
| | | | | | | |
Collapse
|
65
|
Patwardhan P, Miller WT. Processive phosphorylation: mechanism and biological importance. Cell Signal 2007; 19:2218-26. [PMID: 17644338 PMCID: PMC2034209 DOI: 10.1016/j.cellsig.2007.06.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 05/31/2007] [Accepted: 06/12/2007] [Indexed: 01/13/2023]
Abstract
Recent proteomic data indicate that a majority of the phosphorylated proteins in a eucaryotic cell contain multiple sites of phosphorylation. In many signaling events, a single kinase phosphorylates multiple sites on a target protein. Processive phosphorylation occurs when a protein kinase binds once to a substrate and phosphorylates all of the available sites before dissociating. In this review, we discuss examples of processive phosphorylation by serine/threonine kinases and tyrosine kinases. We describe current experimental approaches for distinguishing processive from non-processive phosphorylation. Finally, we contrast the biological situations that are suited to regulation by processive and non-processive phosphorylation.
Collapse
Affiliation(s)
- Parag Patwardhan
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | | |
Collapse
|
66
|
Salazar C, Höfer T. Competition Effects Shape the Response Sensitivity and Kinetics of Phosphorylation Cycles in Cell Signaling. Ann N Y Acad Sci 2006; 1091:517-30. [PMID: 17341641 DOI: 10.1196/annals.1378.093] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Phosphorylation cycles are a core component of cell signaling networks. The response sensitivity and kinetics of these cycles are controlled by thermodynamic, kinetic, and structural factors, including binding affinities, catalytic activities, and the phosphorylation order of multiple sites. Based on mathematical models, we interpret the role of these factors in terms of competition effects. For the regulation of a single phosphorylation site, two kinds of competition effects turn out to shape behavior: the competition between kinase and phosphatase to bind the substrate, and the competition between the distinct phosphorylation forms of the substrate for binding to either enzyme. Depending on the concentrations and mutual affinities of the enzymes and the target, the response function can be graded, ultrasensitive, or biphasic. In multiply phosphorylatable proteins, additional factors generating competition effects are present and more complex responses can be obtained. For example, the combination of a cooperative kinetics with the conditions for zero-order ultrasensitivity may yield a bistable response. We show that a repeated competition between kinase and phosphatase for binding the substrate and/or between the phosphorylation and dephosphorylation reactions at each phosphorylation site generally result in a threshold response. The phosphorylation time is also strongly affected by the kinetic design of the cycle. In particular, threshold responses are generally associated with very long phosphorylation times. We also argue here that a description in terms of elementary binding and reaction steps is required for an appropriate analysis of these cycles in cell signaling.
Collapse
Affiliation(s)
- Carlos Salazar
- Theoretical Biophysics, Institute for Biology, Humboldt University, Invalidenstrasse 42, 10115 Berlin, Germany.
| | | |
Collapse
|
67
|
Chong YP, Chan AS, Chan KC, Williamson NA, Lerner EC, Smithgall TE, Bjorge JD, Fujita DJ, Purcell AW, Scholz G, Mulhern TD, Cheng HC. C-terminal Src kinase-homologous kinase (CHK), a unique inhibitor inactivating multiple active conformations of Src family tyrosine kinases. J Biol Chem 2006; 281:32988-99. [PMID: 16959780 DOI: 10.1074/jbc.m602951200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Src family of protein kinases (SFKs) mediates mitogenic signal transduction, and constitutive SFK activation is associated with tumorigenesis. To prevent constitutive SFK activation, the catalytic activity of SFKs in normal mammalian cells is suppressed mainly by two inhibitors called C-terminal Src kinase (CSK) and CSK-homologous kinase (CHK), which inactivate SFKs by phosphorylating a consensus tyrosine near the C terminus of SFKs (Y(T)). The phosphorylated Y(T) intramolecularly binds to the SH2 domain of SFKs. This interaction, known as pY(T)/SH2 interaction, together with binding between the SH2 kinase linker and the SH3 domain of SFKs (linker/SH3 interaction) stabilizes SFKs in a "closed" inactive conformation. We previously discovered an alternative mechanism CHK employs to inhibit SFKs. This mechanism, referred to as the non-catalytic inhibitory mechanism, involves tight binding of CHK to SFKs; the binding alone is sufficient to inhibit SFKs. Herein, we constructed multiple active conformations of an SFK member, Hck, by systematically disrupting the two inhibitory interactions. We found that CHK employs the non-catalytic mechanism to inactivate these active conformations of Hck. However, CHK does not bind Hck when it adopts the inactive conformation in which both inhibitory interactions are intact. These data indicate that binding of CHK to SFKs via the non-catalytic mechanism is governed by the conformations of SFKs. Although CSK is also an inhibitor of SFKs, it does not inhibit SFKs by a similar non-catalytic mechanism. Thus, the non-catalytic inhibitory mechanism is a unique property of CHK that allows it to down-regulate multiple active conformations of SFKs.
Collapse
Affiliation(s)
- Yuh-Ping Chong
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
68
|
Riggins RB, Thomas KS, Ta HQ, Wen J, Davis RJ, Schuh NR, Donelan SS, Owen KA, Gibson MA, Shupnik MA, Silva CM, Parsons SJ, Clarke R, Bouton AH. Physical and Functional Interactions between Cas and c-Src Induce Tamoxifen Resistance of Breast Cancer Cells through Pathways Involving Epidermal Growth Factor Receptor and Signal Transducer and Activator of Transcription 5b. Cancer Res 2006; 66:7007-15. [PMID: 16849545 DOI: 10.1158/0008-5472.can-05-3952] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High expression of the adaptor molecule Cas has been linked to resistance to the antiestrogen tamoxifen, both in tissue culture and in human tumors. The aim of this study was to elucidate the mechanism(s) by which overexpression of Cas confers resistance to tamoxifen. Cas overexpression in MCF-7 breast cancer cells was shown to alleviate both tamoxifen-mediated growth inhibition and induction of apoptosis. This enhancement of cell proliferation/survival occurred in the absence of detectable effects on estrogen receptor (ER) transcriptional activity under conditions where tamoxifen was present, indicating that Cas-dependent tamoxifen resistance is not the result of a switch to an ER-negative phenotype or enhanced responses to the partial agonist activity of tamoxifen. Instead, we present evidence, suggesting that Cas promotes tamoxifen resistance by deregulation of alternative cell proliferation pathways, particularly those mediated through enhanced c-Src protein tyrosine kinase activity arising from Cas/c-Src interactions. Overexpression of Cas was found to drive endogenous c-Src into complex with Cas, a process that has been shown previously to cause up-regulation of c-Src tyrosine kinase activity. MCF-7 cells overexpressing Cas exhibited increased phosphorylation of two c-Src substrates, Tyr845 in the kinase domain of the epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription (STAT) 5b. Importantly, Cas-dependent protection from the antiproliferative effects of tamoxifen was reversed by the expression of dominant inhibitory variants of these substrates (Y845F EGFR and COOH-terminally truncated STAT5b). Based on these findings, we suggest that the Cas/c-Src/EGFR/STAT5 signaling axis is a major regulator of tamoxifen-resistant breast cancer cell growth and survival.
Collapse
Affiliation(s)
- Rebecca B Riggins
- Department of Microbiology and Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
69
|
Achuthan A, Elsegood C, Masendycz P, Hamilton JA, Scholz GM. CpG DNA enhances macrophage cell spreading by promoting the Src-family kinase-mediated phosphorylation of paxillin. Cell Signal 2006; 18:2252-61. [PMID: 16809022 DOI: 10.1016/j.cellsig.2006.05.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 05/12/2006] [Accepted: 05/15/2006] [Indexed: 01/22/2023]
Abstract
Macrophages are an important component of the innate immune response to infection by microbial pathogens. The activation of macrophages by pathogens is largely mediated by Toll-like receptors (TLRs). Bacterial DNA, which contains unmethylated CpG dinucleotide motifs, is specifically recognised by TLR9 and triggers the activation of a complex network of intracellular signalling pathways that orchestrates the ensuing inflammatory responses of macrophages to the pathogen. Here, we have established that CpG DNA promotes reorganisation of the actin cytoskeleton and enhances cell spreading by primary mouse bone marrow macrophages. CpG DNA stimulation resulted in an approximately 70% increase in cell size. Notably, CpG DNA-induced cell spreading was dependent on the activity of Src-family kinases. Tyrosine phosphorylation of several proteins was increased in a Src-family kinase-dependent manner following CpG DNA stimulation of bone marrow macrophages, including the cytoskeletal protein paxillin. Paxillin was phosphorylated both in vitro and in vivo by the Src-family kinase Hck. Significantly, paxillin from CpG DNA-stimulated bone marrow macrophages had a greater capacity to bind the SH2 domain of the adapter protein Crk than did paxillin from unstimulated bone marrow macrophages. Furthermore, phosphorylation of paxillin by Hck created a binding site for Crk. We propose that the formation of paxillin-Crk complexes may mediate the cytoskeletal changes that underlie the increased cell spreading of macrophages following their activation by CpG DNA.
Collapse
Affiliation(s)
- Adrian Achuthan
- Arthritis and Inflammation Research Centre and Cooperative Research Centre for Chronic Inflammatory Diseases, Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Victoria 3050, Australia
| | | | | | | | | |
Collapse
|
70
|
Patwardhan P, Shen Y, Goldberg GS, Miller WT. Individual Cas phosphorylation sites are dispensable for processive phosphorylation by Src and anchorage-independent cell growth. J Biol Chem 2006; 281:20689-20697. [PMID: 16707485 PMCID: PMC2441569 DOI: 10.1074/jbc.m602311200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cas is a multidomain signaling protein that resides in focal adhesions. Cas possesses a large central substrate domain containing 15 repeats of the sequence YXXP, which are phosphorylated by Src. The phosphorylation sites are essential for the roles of Cas in cell migration and in regulation of the actin cytoskeleton. We showed previously that Src catalyzes the multisite phosphorylation of Cas via a processive mechanism. In this study, we created mutant forms of Cas to identify the determinants for processive phosphorylation. Mutants containing single or multiple YXXP mutations were phosphorylated processively by Src, suggesting that individual sites are dispensable. The results also suggest that there is no defined order to the Cas phosphorylation events. We also studied the effects of these mutations by reintroducing Cas into Cas-deficient fibroblasts. Mutants lacking some or all YXXP sites augment the ability of Src to promote anchorage-independent growth. On the other hand, deletion of YXXP sites compromises the ability of Cas to promote tumor cell migration.
Collapse
Affiliation(s)
- Parag Patwardhan
- Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, New York 11794
| | - Yongquan Shen
- Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084
| | - Gary S Goldberg
- Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084
| | - W Todd Miller
- Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, New York 11794.
| |
Collapse
|
71
|
Huang J, Sakai R, Furuichi T. The docking protein Cas links tyrosine phosphorylation signaling to elongation of cerebellar granule cell axons. Mol Biol Cell 2006; 17:3187-96. [PMID: 16687575 PMCID: PMC1483050 DOI: 10.1091/mbc.e05-12-1122] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Crk-associated substrate (Cas) is a tyrosine-phosphorylated docking protein that is indispensable for the regulation of the actin cytoskeletal organization and cell migration in fibroblasts. The function of Cas in neurons, however, is poorly understood. Here we report that Cas is dominantly enriched in the brain, especially the cerebellum, of postnatal mice. During cerebellar development, Cas is highly tyrosine phosphorylated and is concentrated in the neurites and growth cones of granule cells. Cas coimmunoprecipitates with Src family protein tyrosine kinases, Crk, and cell adhesion molecules and colocalizes with these proteins in granule cells. The axon extension of granule cells is inhibited by either RNA interference knockdown of Cas or overexpression of the Cas mutant lacking the YDxP motifs, which are tyrosine phosphorylated and thereby interact with Crk. These findings demonstrate that Cas acts as a key scaffold that links the proteins associated with tyrosine phosphorylation signaling pathways to the granule cell axon elongation.
Collapse
Affiliation(s)
- Jinhong Huang
- *Laboratory for Molecular Neurogenesis, Riken Brain Science Institute, Wako, Saitama 351-0198; and
| | - Ryuichi Sakai
- Growth Factor Division, National Cancer Center Research Institute, Chuo-ku, Tokyo 104-0045, Japan
| | - Teiichi Furuichi
- *Laboratory for Molecular Neurogenesis, Riken Brain Science Institute, Wako, Saitama 351-0198; and
| |
Collapse
|
72
|
Lee S, Ayrapetov MK, Kemble DJ, Parang K, Sun G. Docking-based Substrate Recognition by the Catalytic Domain of a Protein Tyrosine Kinase, C-terminal Src Kinase (Csk). J Biol Chem 2006; 281:8183-9. [PMID: 16439366 DOI: 10.1074/jbc.m508120200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Protein tyrosine kinases are key enzymes of mammalian signal transduction. Substrate specificity is a fundamental property that determines the specificity and fidelity of signaling by protein tyrosine kinases. However, how protein tyrosine kinases recognize the protein substrates is not well understood. C-terminal Src kinase (Csk) specifically phosphorylates Src family kinases on a C-terminal Tyr residue, which down-regulates their activities. We have previously determined that Csk recognizes Src using a substrate-docking site away from the active site. In the current study, we identified the docking determinants in Src recognized by the Csk substrate-docking site and demonstrated an interaction between the docking determinants of Src and the Csk substrate-docking site for this recognition. A similar mechanism was confirmed for Csk recognition of another Src family kinase, Yes. Although both Csk and MAP kinases used docking sites for substrate recognition, their docking sites consisted of different substructures in the catalytic domain. These results helped establish a docking-based substrate recognition mechanism for Csk. This model may provide a framework for understanding substrate recognition and specificity of other protein tyrosine kinases.
Collapse
Affiliation(s)
- Sungsoo Lee
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island 02881, USA
| | | | | | | | | |
Collapse
|
73
|
Binkowski BF, Miller RA, Belshaw PJ. Ligand-regulated peptides: a general approach for modulating protein-peptide interactions with small molecules. ACTA ACUST UNITED AC 2005; 12:847-55. [PMID: 16039531 DOI: 10.1016/j.chembiol.2005.05.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 04/28/2005] [Accepted: 05/18/2005] [Indexed: 10/25/2022]
Abstract
We engineered a novel ligand-regulated peptide (LiRP) system where the binding activity of intracellular peptides is controlled by a cell-permeable small molecule. In the absence of ligand, peptides expressed as fusions in an FKBP-peptide-FRB-GST LiRP scaffold protein are free to interact with target proteins. In the presence of the ligand rapamycin, or the nonimmunosuppressive rapamycin derivative AP23102, the scaffold protein undergoes a conformational change that prevents the interaction of the peptide with the target protein. The modular design of the scaffold enables the creation of LiRPs through rational design or selection from combinatorial peptide libraries. Using these methods, we identified LiRPs that interact with three independent targets: retinoblastoma protein, c-Src, and the AMP-activated protein kinase. The LiRP system should provide a general method to temporally and spatially regulate protein function in cells and organisms.
Collapse
Affiliation(s)
- Brock F Binkowski
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | | |
Collapse
|
74
|
Velazquez-Dones A, Hagopian JC, Ma CT, Zhong XY, Zhou H, Ghosh G, Fu XD, Adams JA. Mass spectrometric and kinetic analysis of ASF/SF2 phosphorylation by SRPK1 and Clk/Sty. J Biol Chem 2005; 280:41761-8. [PMID: 16223727 DOI: 10.1074/jbc.m504156200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Assembly of the spliceosome requires the participation of SR proteins, a family of splicing factors rich in arginine-serine dipeptide repeats. The repeat regions (RS domains) are polyphosphorylated by the SRPK and Clk/Sty families of kinases. The two families of kinases have distinct enzymatic properties, raising the question of how they may work to regulate the function of SR proteins in RNA metabolism in mammalian cells. Here we report the first mass spectral analysis of the RS domain of ASF/SF2, a prototypical SR protein. We found that SRPK1 was responsible for efficient phosphorylation of a short stretch of amino acids in the N-terminal portion of the RS domain of ASF/SF2 while Clk/Sty was able to transfer phosphate to all available serine residues in the RS domain, indicating that SR proteins may be phosphorylated by different kinases in a stepwise manner. Both kinases bind with high affinity and use fully processive catalytic mechanisms to achieve either restrictive or complete RS domain phosphorylation. These findings have important implications on the regulation of SR proteins in vivo by the SRPK and Clk/Sty families of kinases.
Collapse
Affiliation(s)
- Adolfo Velazquez-Dones
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla 92093, USA
| | | | | | | | | | | | | | | |
Collapse
|
75
|
Yokoyama N, deBakker CD, Zappacosta F, Huddleston MJ, Annan RS, Ravichandran KS, Miller WT. Identification of tyrosine residues on ELMO1 that are phosphorylated by the Src-family kinase Hck. Biochemistry 2005; 44:8841-9. [PMID: 15952790 PMCID: PMC2441568 DOI: 10.1021/bi0500832] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The SH3 and SH2 domains of hematopoietic cell kinase (Hck) play important roles in substrate targeting. To identify new components of Hck signaling pathways, we identified proteins that bind to the SH3 domain of Hck (Scott et al. (2002) J. Biol. Chem. 277, 28238). One such protein was ELMO1, the mammalian orthologue of the Caenorhabditis elegans gene, ced-12. ELMO1 is an approximately 80-kD protein containing a PH domain and a C-terminal Pro-rich sequence. In C. elegans, ced-12 is required for the engulfment of dying cells and for cell migration. In mammalian fibroblasts, ELMO1 binds to Dock180, and functions upstream of Rac during phagocytosis and cell migration. We previously showed that ELMO1 binds directly to the Hck SH3 domain and is phosphorylated by Hck. In this study, we used mass spectrometry to identify the following sites of ELMO1 phosphorylation: Tyr 18, Tyr 216, Tyr 511, Tyr 395, and Tyr 720. Mutant forms of ELMO1 lacking these sites were defective in their ability to promote phagocytosis and migration in fibroblasts. Single tyrosine mutations showed that Tyr 511 is particularly important in mediating these biological effects. These mutants displayed comparable binding to Dock180 and Crk as wild-type ELMO1, but gave a lowered activation of Rac. The data suggest that Src family kinase mediated tyrosine phosphorylation of ELMO1 might represent an important regulatory mechanism that controls signaling through the ELMO1/Crk/Dock180 pathway.
Collapse
Affiliation(s)
- Noriko Yokoyama
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
| | - Colin D. deBakker
- Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia 22908
| | - Francesca Zappacosta
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Michael J. Huddleston
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Roland S. Annan
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Kodi S. Ravichandran
- Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia 22908
| | - W. Todd Miller
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
- To whom correspondence should be addressed. Mailing address: Dept. of Physiology and Biophysics, Basic Science Tower, T-6, School of Medicine, SUNY at Stony Brook, Stony Brook, NY 11794-8661. Tel: 631-444-3533. Fax: 631-444-3432. E-mail:
| |
Collapse
|
76
|
Chong YP, Ia KK, Mulhern TD, Cheng HC. Endogenous and synthetic inhibitors of the Src-family protein tyrosine kinases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1754:210-20. [PMID: 16198159 DOI: 10.1016/j.bbapap.2005.07.027] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Revised: 07/14/2005] [Accepted: 07/15/2005] [Indexed: 12/28/2022]
Abstract
Src-family kinases (SFKs) are protooncogenic enzymes controlling mammalian cell growth and proliferation. The activity of SFKs is primarily regulated by two tyrosine phosphorylation sites: autophosphorylation of a conserved tyrosine (Y(A)) in the kinase domain results in activation while phosphorylation of the regulatory tyrosine (Y(T)) near the C-terminus leads to inactivation. The phosphorylated Y(T) (pY(T)) engages in intramolecular interactions that stabilise the inactive conformation of SFKs. These inhibitory intramolecular interactions include the binding of pY(T) to the SH2 domain and the binding of the SH2-kinase linker to the SH3 domain. Thus, SFKs are active upon (i) disruption of the inhibitory intramolecular interactions, (ii) autophosphorylation of Y(A) and/or (iii) dephosphorylation of pY(T). Since aberrant activation of SFKs contributes to cancer, SFKs in normal cells are kept inactive by multiple endogenous inhibitors classified as catalytic and non-catalytic inhibitors. The catalytic inhibitors include C-terminal Src kinase (CSK) and CSK-homologous kinase (CHK) that phosphorylate Y(T) of SFKs, as well as the protein tyrosine phosphatases that dephosphorylate pY(A) of the activated SFKs. The non-catalytic inhibitors inactivate SFKs by direct binding. CHK is unique among these inhibitors because it employs both catalytic and non-catalytic mechanisms to inhibit SFKs. Other known non-catalytic inhibitors include WASP, caveolin and RACK1, which function to down-regulate SFKs in specific subcellular locations. This review discusses how the various endogenous SFK inhibitors cooperate to regulate SFKs in normal cells. As chemical compounds that can selectively inhibit SFKs in vivo are potential anti-cancer therapeutics, this review also discusses how investigation into the inhibitory mechanisms of the endogenous inhibitors will benefit the design and screening of these compounds.
Collapse
Affiliation(s)
- Yuh-Ping Chong
- Department of Biochemistry and Molecular Biology, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria 3010, Australia
| | | | | | | |
Collapse
|
77
|
Liang F, Lee SY, Liang J, Lawrence DS, Zhang ZY. The role of protein-tyrosine phosphatase 1B in integrin signaling. J Biol Chem 2005; 280:24857-63. [PMID: 15866871 DOI: 10.1074/jbc.m502780200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-tyrosine phosphatase 1B (PTP1B) is a key negative regulator of insulin and leptin signaling and a novel therapeutic target for the treatment of type 2 diabetes, obesity, and other associated metabolic syndromes. Because PTP1B regulates multiple signal pathways and it can both enhance and antagonize a cellular event, it is important to establish the physiological relevance of PTP1B in these processes. In this study, we utilize potent and selective PTP1B inhibitors to delineate the role of PTP1B in integrin signaling. We show that down-regulation of PTP1B activity with small molecule inhibitors suppresses cell spreading and migration to fibronectin, increases Tyr(527) phosphorylation in Src, and decreases phosphorylation of FAK, p130(Cas), and ERK1/2. In addition, PTP1B "substrate-trapping" mutants bind Tyr(527)-phosphorylated Src and protect it from dephosphorylation by endogenous PTP1B. These results establish that PTP1B promotes integrin-mediated responses in fibroblasts by dephosphorylating the inhibitory pTyr(527) and thereby activating the Src kinase. We also show that PTP1B forms a complex with Src and p130(Cas), and that the proline-rich motif PPRPPK (residues 309-314) in PTP1B is essential for the complex formation. We suggest that the specificity of PTP1B for Src pTyr(527) is mediated by protein-protein interactions involving the docking protein p130(Cas) with both Src and PTP1B in addition to the interactions between the PTP1B active site and the pTyr(527) motif.
Collapse
Affiliation(s)
- Fubo Liang
- Departments of Molecular Pharmacology and Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | | | | | | | | |
Collapse
|
78
|
Nasertorabi F, Tars K, Becherer K, Kodandapani R, Liljas L, Vuori K, Ely KR. Molecular basis for regulation of Src by the docking protein p130Cas. J Mol Recognit 2005; 19:30-8. [PMID: 16245368 DOI: 10.1002/jmr.755] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The docking protein p130Cas (Cas) becomes tyrosine-phosphorylated in its central substrate domain in response to extracellular stimuli such as integrin-mediated cell adhesion, and transmits signals through interactions with various intracellular signaling molecules such as the adaptor protein Crk. Src-family kinases (SFKs) bind a specific site in the carboxyl-terminal region of Cas and subsequently SFKs phosphorylate progressively the substrate domain in Cas. In this study crystallography, mutagenesis and binding assays were used to understand the molecular basis for Cas interactions with SFKs. Tyrosine phosphorylation regulates binding of Cas to SFKs, and the primary site for this phosphorylation, Y762, has been proposed. A phosphorylated peptide corresponding to Cas residues 759MEDpYDYVHL767 containing the key phosphotyrosine was crystallized in complex with the SH3-SH2 domain of the SFK Lck. The results provide the first structural data for this protein-protein interaction. The motif in Cas 762pYDYV binds to the SH2 domain in a mode that mimics high-affinity ligands, involving dual contacts of Y762 and V765 with conserved residues in SFK SH2 domains. In addition, Y764 is in position to make an electrostatic contact after phosphorylation with a conserved SFK arginine that mediates interactions with other high-affinity SH2 binders. These new molecular data suggest that Cas may regulate activity of Src as a competing ligand to displace intramolecular interactions that occur in SFKs (between the C-terminal tail and the SH2 domain) and restrain and down-regulate the kinase in an inactive form.
Collapse
Affiliation(s)
- Fariborz Nasertorabi
- Cancer Center, The Burnham Institute for Medical Research, La Jolla, California 92037, USA
| | | | | | | | | | | | | |
Collapse
|
79
|
Medzihradszky KF, Zhang X, Chalkley RJ, Guan S, McFarland MA, Chalmers MJ, Marshall AG, Diaz RL, Allis CD, Burlingame AL. Characterization of Tetrahymena Histone H2B Variants and Posttranslational Populations by Electron Capture Dissociation (ECD) Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS). Mol Cell Proteomics 2004; 3:872-86. [PMID: 15199121 DOI: 10.1074/mcp.m400041-mcp200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This work describes the nature and sequence information content of the electron capture dissociation mass spectra for the intact Tetrahymena histone H2B. Two major variants of this protein were present bearing nominal modifications of both +42 and +84 Da. This work describes identification of the nature of these two modifications. For example, using gas-phase selection and isolation of the +42-Da modified species, from a background of two H2B variants each present in six or more posttranslationally modified isoforms, we were able to determine that this +42-Da modification isoform bears trimethylation rather than acetylation. LC-CIDMS analysis was also employed on digested preparations to obtain complementary detail of the nature of site-specific posttranslational modifications. This study establishes that integration of the information from these two datasets provides a comprehensive map of posttranslational occupancy for each particular covalent assemblage selected for structural investigation.
Collapse
Affiliation(s)
- K F Medzihradszky
- Department of Pharmaceutical Chemistry and Mass Spectrometry Facility, University of California, San Francisco, CA 94143-0446, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
80
|
Brábek J, Constancio SS, Shin NY, Pozzi A, Weaver AM, Hanks SK. CAS promotes invasiveness of Src-transformed cells. Oncogene 2004; 23:7406-15. [PMID: 15273716 DOI: 10.1038/sj.onc.1207965] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
CAS ('Crk-associated substrate') is an Src substrate found at sites of integrin-mediated cell adhesion and linked to cell motility and survival. In this study, the involvement of CAS in oncogenic transformation was evaluated through analysis of mouse embryo fibroblast populations expressing an activated Src mutant, either in the presence or absence of CAS expression. CAS was not found to be a critical determinant of either Src-mediated morphologic transformation or anchorage-independent growth. However, CAS had a profound effect on other aspects of oncogenic Src function. CAS expression led to a substantial increase in the phosphotyrosine content of FAK and paxillin, supporting a role for CAS as a positive regulator of Src activity at integrin adhesion sites. Importantly, CAS expression resulted in a striking enhancement of the capacity of Src-transformed cells to invade through Matrigel. The increased invasiveness was associated with increased activation of matrix metalloproteinase MMP-2 and formation of large actin-rich podosomal aggregates appearing as ring and belt structures. Thus, elevated CAS-associated tyrosine phosphorylation signaling events occurring at sites of integrin-mediated cell adhesion can have a major role in the development of an invasive cell phenotype.
Collapse
Affiliation(s)
- Jan Brábek
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37212, USA
| | | | | | | | | | | |
Collapse
|
81
|
Baldanzi G, Mitola S, Cutrupi S, Filigheddu N, van Blitterswijk WJ, Sinigaglia F, Bussolino F, Graziani A. Activation of diacylglycerol kinase α is required for VEGF-induced angiogenic signaling in vitro. Oncogene 2004; 23:4828-38. [PMID: 15122338 DOI: 10.1038/sj.onc.1207633] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Vascular endothelial growth factor-A (VEGF-A) promotes angiogenesis by stimulating migration, proliferation and organization of endothelium, through the activation of signaling pathways involving Src tyrosine kinase. As we had previously shown that Src-mediated activation of diacylglycerol kinase-alpha (Dgk-alpha) is required for hepatocytes growth factor-stimulated cell migration, we asked whether Dgk-alpha is involved in the transduction of angiogenic signaling. In PAE-KDR cells, an endothelial-derived cell line expressing VEGFR-2, VEGF-A165, stimulates the enzymatic activity of Dgk-alpha: activation is inhibited by R59949, an isoform-specific Dgk inhibitor, and is dependent on Src tyrosine kinase, with which Dgk-alpha forms a complex. Conversely in HUVEC, VEGF-A165-induced activation of Dgk is only partially sensitive to R59949, suggesting that also other isoforms may be activated, albeit still dependent on Src tyrosine kinase. Specific inhibition of Dgk-alpha, obtained in both cells by R59949 and in PAE-KDR by expression of Dgk-alpha dominant-negative mutant, impairs VEGF-A165-dependent chemotaxis, proliferation and in vitro angiogenesis. In addition, in HUVEC, specific downregulation of Dgk-alpha by siRNA impairs in vitro angiogenesis on matrigel, further suggesting the requirement for Dgk-alpha in angiogenic signaling in HUVEC. Thus, we propose that activation of Dgk-alpha generates a signal essential for both proliferative and migratory response to VEGF-A165, suggesting that it may constitute a novel pharmacological target for angiogenesis control.
Collapse
Affiliation(s)
- Gianluca Baldanzi
- Department of Medical Sciences, University Amedeo Avogadro of Piemonte Orientale, v. Solaroli 17, 28100, Novara, Italy
| | | | | | | | | | | | | | | |
Collapse
|
82
|
Goldberg GS, Alexander DB, Pellicena P, Zhang ZY, Tsudal H, Miller WT. Src phosphorylates Cas on tyrosine 253 to promote migration of transformed cells. J Biol Chem 2003; 278:46533-40. [PMID: 12972425 PMCID: PMC2441571 DOI: 10.1074/jbc.m307526200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cas is a member of the focal adhesion complex. Phosphorylation of Cas by Src is an important event leading to cell transformation. Using mass spectrometry, we have mapped 11 sites in Cas that are phosphorylated by Src. These sites are all located between residues 132 and 414 of Cas, in a region that is required for binding to a number of other proteins including Crk. We tested synthetic peptides modeled on Cas phosphorylation sites, and found that the sequence containing tyrosine 253 was phosphorylated by Src most efficiently. Using cells derived from Cas-deficient mice, we confirmed that Cas greatly enhanced the ability of Src to transform cells. Phosphorylation of Cas on tyrosine 253 was not required for Src to increase growth rate, suppress contact inhibition, or suppress anchorage dependence. Yet, in contrast to these growth characteristics, phosphorylation of Cas on tyrosine 253 was required for Src to promote cell migration. Thus, a single phosphorylation site on this focal adhesion adaptor protein can effectively separate cell migration from other transformed growth characteristics.
Collapse
Affiliation(s)
- Gary S. Goldberg
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
- To whom correspondence may be addressed: Dept. of Physiology and Biophysics, School of Medicine, Basic Science Tower T6, Health Science Complex, State University of New York at Stony Brook, Stony Brook, NY 11794-8661. Tel.: 631-444-3533; Fax: 631-444-3432; E-mail: or
| | - David B. Alexander
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
| | - Patricia Pellicena
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
| | - Zhong-Yin Zhang
- Department of Molecular Pharmacology, College of Medicine, Albert Einstein University, Bronx, New York 10461
| | - Hiroyuki Tsudal
- Division of Experimental Pathology and Chemotherapy, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - W. Todd Miller
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
- To whom correspondence may be addressed: Dept. of Physiology and Biophysics, School of Medicine, Basic Science Tower T6, Health Science Complex, State University of New York at Stony Brook, Stony Brook, NY 11794-8661. Tel.: 631-444-3533; Fax: 631-444-3432; E-mail: or
| |
Collapse
|
83
|
Aubol BE, Chakrabarti S, Ngo J, Shaffer J, Nolen B, Fu XD, Ghosh G, Adams JA. Processive phosphorylation of alternative splicing factor/splicing factor 2. Proc Natl Acad Sci U S A 2003; 100:12601-6. [PMID: 14555757 PMCID: PMC240664 DOI: 10.1073/pnas.1635129100] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
SR proteins, named for their multiple arginine/serine (RS) dipeptide repeats, are critical components of the spliceosome, influencing both constitutive and alternative splicing of pre-mRNA. SR protein function is regulated through phosphorylation of their RS domains by multiple kinases, including a family of evolutionarily conserved SR protein-specific kinases (SRPKs). The SRPK family of kinases is unique in that they are capable of phosphorylating repetitive RS domains with remarkable specificity and efficiency. Here, we carried out kinetic experiments specially developed to investigate how SRPK1 phosphorylates the model human SR protein, ASF/SF2. By using the start-trap strategy, we monitored the progress curve for ASF/SF2 phosphorylation in the absence and presence of an inhibitor peptide directed at the active site of SRPK1. ASF/SF2 modification is not altered when the inhibitor peptide (trap) is added with ATP (start). However, when the trap is added first and allowed to incubate for a specific delay time, the decrease in phosphate content of the enzyme-substrate complex follows a simple exponential decline corresponding to the release rate of SRPK1. These data demonstrate that SRPK1 phosphorylates a specific region within the RS domain of ASF/SF2 by using a fully processive catalytic mechanism, in which the splicing factor remains "locked" onto SRPK1 during RS domain modification.
Collapse
Affiliation(s)
- Brandon E. Aubol
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Sutapa Chakrabarti
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Jacky Ngo
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Jennifer Shaffer
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Brad Nolen
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Xiang-Dong Fu
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Gourisankar Ghosh
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
| | - Joseph A. Adams
- Departments of Pharmacology, Chemistry and Biochemistry, and Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0506
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
84
|
Sharma A, Antoku S, Fujiwara K, Mayer BJ. Functional interaction trap: a strategy for validating the functional consequences of tyrosine phosphorylation of specific substrates in vivo. Mol Cell Proteomics 2003; 2:1217-24. [PMID: 14519720 DOI: 10.1074/mcp.m300078-mcp200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein tyrosine phosphorylation controls diverse signaling pathways, and disregulated tyrosine kinase activity plays a direct role in human diseases such as cancer. Because activated kinases exert their effects by phosphorylating multiple substrate proteins, it is difficult or impossible to assess experimentally the contribution of a particular substrate to a cellular response or activity. To overcome this problem, we have developed a novel approach termed the "functional interaction trap," in which two proteins are induced to interact in a pairwise fashion through an engineered, highly specific binding interface. We show that the functional interaction trap can be used to direct a modified tyrosine kinase to specifically phosphorylate a single substrate of choice in vivo, permitting analysis of the resulting biological output. This strategy provides a powerful tool for validating the functional significance of tyrosine phosphorylation and other post-translational modifications identified by proteomic discovery efforts.
Collapse
Affiliation(s)
- Alok Sharma
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3301, USA
| | | | | | | |
Collapse
|
85
|
Master Z, Tran J, Bishnoi A, Chen SH, Ebos JML, Van Slyke P, Kerbel RS, Dumont DJ. Dok-R binds c-Abl and regulates Abl kinase activity and mediates cytoskeletal reorganization. J Biol Chem 2003; 278:30170-9. [PMID: 12777393 DOI: 10.1074/jbc.m301339200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dok-R, also known as Dok-2/FRIP, belongs to the DOK family of signaling molecules that become tyrosine-phosphorylated by several different receptor and cytoplasmic tyrosine kinases. Tyrosine phosphorylation of DOK proteins establishes high affinity binding sites for other signaling molecules leading to activation of a signaling cascade. Here we show that Dok-R associates with c-Abl directly via a constitutive SH3-mediated interaction and that this binding requires a PMMP motif in the proline-rich tail of Dok-R. The Dok-R-Abl interaction is further enhanced by an active c-Abl kinase, which requires the presence of its SH2 domain. Interaction of Dok-R with c-Abl also results in an increase in c-Abl tyrosine phosphorylation and kinase activity. Furthermore, we demonstrate that this increase in kinase activity correlates with a concomitant increase in c-Abl-mediated biological activity as measured by the formation of actin microspikes. Our data are the first to demonstrate that Dok-R and c-Abl interact in both a constitutive and inducible fashion and that Dok-R influences the intracellular kinase and biological activity of c-Abl.
Collapse
Affiliation(s)
- Zubin Master
- Division of Molecular and Cellular Biology, Sunnybrook and Women's College Health Sciences Centre, Toronto M4N 3M5, Canada
| | | | | | | | | | | | | | | |
Collapse
|
86
|
Konrad RJ, Gold G, Lee TN, Workman R, Broderick CL, Knierman MD. Glucose stimulates the tyrosine phosphorylation of Crk-associated substrate in pancreatic beta-cells. J Biol Chem 2003; 278:28116-22. [PMID: 12746446 DOI: 10.1074/jbc.m212899200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Several years ago, we demonstrated that glucose induced tyrosine phosphorylation of a 125-kDa protein (p125) in pancreatic beta-cells (Konrad, R. J., Dean, R. M., Young, R. A., Bilings, P. C., and Wolf, B. A. (1996) J. Biol. Chem. 271, 24179-24186). Glucose induced p125 tyrosine phosphorylation in beta-TC3 insulinoma cells, beta-HC9 cells, and in freshly isolated rat islets, whereas increased tyrosine phosphorylation was not observed with other fuel secretagogues. Initial efforts to identify p125 were unsuccessful, so a new approach was taken. The protein was purified from betaTC6,F7 cells via an immunodepletion method. After electrophoresis and colloidal Coomassie Blue staining, the area of the gel corresponding to p125 was excised and subjected to tryptic digestion. Afterward, mass spectrometry was performed and the presence of Crk-associated substrate (Cas) was detected. Commercially available antibodies against Cas were obtained and tested directly in beta-cells, confirming glucose-induced tyrosine phosphorylation of Cas. Further experiments demonstrated that in beta-cells the glucose-induced increase in Cas tyrosine phosphorylation occurs immediately and is not accompanied by increased focal adhesion kinase tyrosine phosphorylation. Finally, it is also demonstrated via Western blotting that Cas is present in normal isolated rat islets. Together, these results show that the identity of the previously described p125 beta-cell protein is Cas and that Cas undergoes rapid glucose-induced tyrosine phosphorylation in beta-cells.
Collapse
Affiliation(s)
- Robert J Konrad
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
| | | | | | | | | | | |
Collapse
|
87
|
Riggins RB, Quilliam LA, Bouton AH. Synergistic promotion of c-Src activation and cell migration by Cas and AND-34/BCAR3. J Biol Chem 2003; 278:28264-73. [PMID: 12740391 DOI: 10.1074/jbc.m303535200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The adapter molecule p130Cas (Cas) plays a role in cellular processes such as proliferation, survival, cell adhesion, and migration. The ability of Cas to promote migration has been shown to be dependent upon its carboxyl terminus, which contains a bipartite binding site for the protein tyrosine kinase c-Src (Src). The association between Src and Cas enhances Src kinase activity, and like Cas, Src plays an important role in cell proliferation and migration. In this study, we show that Src and Cas function cooperatively to promote cell migration in a manner that depends upon kinase-active Src. Another carboxyl-terminal binding partner of Cas, AND-34/BCAR3 (AND-34), functions synergistically with Cas to enhance Src activation and cell migration. The carboxyl-terminal guanine nucleotide exchange factor domain of AND-34, as well as the activity of its putative target Rap1, contribute to these events. A mechanism through which AND-34 may regulate Cas-dependent cell migration is suggested by the finding that Cas becomes redistributed from focal adhesions to lamellipodia located at the leading edge of AND-34 overexpressing cells. These data thus provide insight into how Cas and AND-34 may function together to stimulate Src signaling pathways and promote cell migration.
Collapse
Affiliation(s)
- Rebecca B Riggins
- Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, Virginia 22908-0735, USA
| | | | | |
Collapse
|
88
|
Abstract
Cytoplasmic tyrosine kinases do not occur as isolated catalytic domains. Instead, each kinase family possesses a characteristic array of additional domains that are appended to the catalytic domain. The combination and the arrangement of these modular domains are important in kinase regulation and function. This Account describes how the noncatalytic regions of Src family tyrosine kinases are involved in enzyme regulation, substrate selection, and multisite phosphorylation.
Collapse
|
89
|
Affiliation(s)
- Andrea Musacchio
- Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy
| |
Collapse
|
90
|
Schreiner SJ, Schiavone AP, Smithgall TE. Activation of STAT3 by the Src family kinase Hck requires a functional SH3 domain. J Biol Chem 2002; 277:45680-7. [PMID: 12244095 DOI: 10.1074/jbc.m204255200] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
STAT3 is a member of a family of transcription factors with Src homology 2 (SH2) domains that are activated by tyrosine phosphorylation in response to a wide variety of cytokines and growth factors. In this study, we investigated the mechanism of STAT3 activation by the Src family of nonreceptor tyrosine kinases, which have been linked to STAT activation in both normal and transformed cell types. Using Sf-9 insect cells, we demonstrate direct STAT3 tyrosine phosphorylation and stimulation of DNA binding activity by five members of the Src kinase family (Src, Hck, Lyn, Fyn, and Fgr). We also observed stable STAT3.Src family kinase complex formation in this system. Recombinant Src family kinase SH3 domains were sufficient for interaction with STAT3, suggesting a mechanistic basis for the Src kinase-STAT3 interaction. To test the contribution of Src family kinase SH3 domains to the recruitment and activation of STAT3 in vivo, we used Rat-2 fibroblasts expressing activated mutants of the myeloid Src family member Hck. Transformation of fibroblasts by an activated Hck mutant lacking the negative regulatory tail tyrosine residue (Hck-YF) induced strong DNA binding activity of endogenous STAT3. Inactivation of Hck SH3 function by Ala replacement of a conserved Trp residue (W93A mutant) completely abolished STAT3 activation by Hck-YF and reduced transforming activity by 50% without affecting Hck kinase activity. Finally, overexpression of STAT3 in Rat-2 cells transiently stimulated Hck and c-Src kinase activity in the absence of extracellular signals, an effect that was dependent upon a putative SH3 binding motif in STAT3. These results support a model in which Src family kinases recruit STAT3 through an SH3-dependent mechanism, resulting in transient kinase activation and STAT3 phosphorylation.
Collapse
Affiliation(s)
- Steven J Schreiner
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
| | | | | |
Collapse
|
91
|
Scott MP, Zappacosta F, Kim EY, Annan RS, Miller WT. Identification of novel SH3 domain ligands for the Src family kinase Hck. Wiskott-Aldrich syndrome protein (WASP), WASP-interacting protein (WIP), and ELMO1. J Biol Chem 2002; 277:28238-46. [PMID: 12029088 DOI: 10.1074/jbc.m202783200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The importance of the SH3 domain of Hck in kinase regulation, substrate phosphorylation, and ligand binding has been established. However, few in vivo ligands are known for the SH3 domain of Hck. In this study, we used mass spectrometry to identify approximately 25 potential binding partners for the SH3 domain of Hck from the monocyte cell line U937. Two major interacting proteins were the actin binding proteins Wiskott-Aldrich syndrome protein (WASP) and WASP-interacting protein (WIP). We also focused on a novel interaction between Hck and ELMO1, an 84-kDa protein that was recently identified as the mammalian ortholog of the Caenorhabditis elegans gene, ced-12. In mammalian cells, ELMO1 interacts with Dock180 as a component of the CrkII/Dock180/Rac pathway responsible for phagocytosis and cell migration. Using purified proteins, we confirmed that WASP-interacting protein and ELMO1 interact directly with the SH3 domain of Hck. We also show that Hck and ELMO1 interact in intact cells and that ELMO1 is heavily tyrosine-phosphorylated in cells that co-express Hck, suggesting that it is a substrate of Hck. The binding of ELMO1 to Hck is specifically dependent on the interaction of a polyproline motif with the SH3 domain of Hck. Our results suggest that these proteins may be novel activators/effectors of Hck.
Collapse
Affiliation(s)
- Margaret Porter Scott
- Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, New York 11794-8661, USA
| | | | | | | | | |
Collapse
|
92
|
Huang J, Hamasaki H, Nakamoto T, Honda H, Hirai H, Saito M, Takato T, Sakai R. Differential regulation of cell migration, actin stress fiber organization, and cell transformation by functional domains of Crk-associated substrate. J Biol Chem 2002; 277:27265-72. [PMID: 12011056 DOI: 10.1074/jbc.m203063200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Crk-associated substrate (Cas) is a unique docking protein that possesses a repetitive stretch of tyrosine-containing motifs and an Src homology 3 (SH3) domain. Embryonic fibroblasts lacking Cas demonstrated resistance to Src-induced transformation along with impaired actin bundling and cell motility, indicating critical roles of Cas in actin cytoskeleton organization, cell migration, and oncogenesis. To gain further insight into roles of each domain of Cas in these processes, a compensation assay was performed by expressing a series of Cas mutants in Cas-deficient fibroblasts. The results showed that motifs containing YDxP were indispensable for actin cytoskeleton organization and cell migration, suggesting that CrkII-mediated signaling regulates these biological processes. The C-terminal Src-binding domain played essential roles in cell migration and membrane localization of Cas, although it was dispensable in the organization of actin stress fibers. Furthermore, the Src-binding domain was also a prerequisite for Src transformation possibly, because of its crucial role in the phosphorylation of Cas during transformation. Overall, differential uses of the Cas domains in individual biological processes were demonstrated.
Collapse
Affiliation(s)
- Jinhong Huang
- Cancer Signal Transduction Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045
| | | | | | | | | | | | | | | |
Collapse
|
93
|
Kirsch KH, Kensinger M, Hanafusa H, August A. A p130Cas tyrosine phosphorylated substrate domain decoy disrupts v-crk signaling. BMC Cell Biol 2002; 3:18. [PMID: 12119061 PMCID: PMC117778 DOI: 10.1186/1471-2121-3-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2002] [Accepted: 07/15/2002] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The adaptor protein p130Cas (Cas) has been shown to be involved in different cellular processes including cell adhesion, migration and transformation. This protein has a substrate domain with up to 15 tyrosines that are potential kinase substrates, able to serve as docking sites for proteins with SH2 or PTB domains. Cas interacts with focal adhesion plaques and is phosphorylated by the tyrosine kinases FAK and Src. A number of effector molecules have been shown to interact with Cas and play a role in its function, including c-crk and v-crk, two adaptor proteins involved in intracellular signaling. Cas function is dependent on tyrosine phosphorylation of its substrate domain, suggesting that tyrosine phosphorylation of Cas in part regulates its control of adhesion and migration. To determine whether the substrate domain alone when tyrosine phosphorylated could signal, we have constructed a chimeric Cas molecule that is phosphorylated independently of upstream signals. RESULTS We found that a tyrosine phosphorylated Cas substrate domain acts as a dominant negative mutant by blocking Cas-mediated signaling events, including JNK activation by the oncogene v-crk in transient and stable lines and v-crk transformation. This block was the result of competition for binding partners as the chimera competed for binding to endogenous c-crk and exogenously expressed v-crk. CONCLUSION Our approach suggests a novel method to study adaptor proteins that require phosphorylation, and indicates that mere tyrosine phosphorylation of the substrate domain of Cas is not sufficient for its function.
Collapse
Affiliation(s)
- Kathrin H Kirsch
- Laboratory of Molecular Oncology, The Rockefeller University, NY, NY, 10021, USA
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, K-225, Boston, MA 02118, USA
| | - Margaret Kensinger
- Immunology Research Laboratories, Department of Veterinary Science, Penn State University, 115 Henning Building, University Park, PA 16802, USA
| | - Hidesaburo Hanafusa
- Laboratory of Molecular Oncology, The Rockefeller University, NY, NY, 10021, USA
- Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
| | - Avery August
- Immunology Research Laboratories, Department of Veterinary Science, Penn State University, 115 Henning Building, University Park, PA 16802, USA
- Laboratory of Molecular Oncology, The Rockefeller University, NY, NY, 10021, USA
| |
Collapse
|
94
|
Cary LA, Klinghoffer RA, Sachsenmaier C, Cooper JA. SRC catalytic but not scaffolding function is needed for integrin-regulated tyrosine phosphorylation, cell migration, and cell spreading. Mol Cell Biol 2002; 22:2427-40. [PMID: 11909938 PMCID: PMC133722 DOI: 10.1128/mcb.22.8.2427-2440.2002] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Src family kinases (SFKs) are crucial for signaling through a variety of cell surface receptors, including integrins. There is evidence that integrin activation induces focal adhesion kinase (FAK) autophosphorylation at Y397 and that Src binds to and is activated by FAK to carry out subsequent phosphorylation events. However, it has also been suggested that Src functions as a scaffolding molecule through its SH2 and SH3 domains and that its kinase activity is not necessary. To examine the role of SFKs in integrin signaling, we have expressed various Src molecules in fibroblasts lacking other SFKs. In cells plated on fibronectin, FAK could indeed autophosphorylate at Y397 independently of Src but with lower efficiency than when Src was present. This step was promoted by kinase-inactive Src, but Src kinase activity was required for full rescue. Src kinase activity was also required for phosphorylation of additional sites on FAK and for other integrin-directed functions, including cell migration and spreading on fibronectin. In contrast, Src mutations in the SH2 or SH3 domain greatly reduced binding to FAK, Cas, and paxillin but had little effect on tyrosine phosphorylation or biological assays. Furthermore, our indirect evidence indicates that Src kinase activity does not need to be regulated to promote cell migration and FAK phosphorylation. Although Src clearly plays important roles in integrin signaling, it was not concentrated in focal adhesions. These results indicate that the primary role of Src in integrin signaling is as a kinase. Indirect models for Src function are proposed.
Collapse
Affiliation(s)
- Leslie A Cary
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
| | | | | | | |
Collapse
|
95
|
Abstract
Many of the signaling pathways and regulatory systems in eukaryotic cells are controlled by proteins with multiple interaction domains that mediate specific protein-protein and protein-phospholipid interactions, and thereby determine the biological output of receptors for external and intrinsic signals. Here, we discuss the basic features of interaction domains, and suggest that rather simple binary interactions can be used in sophisticated ways to generate complex cellular responses.
Collapse
Affiliation(s)
- Tony Pawson
- Samuel Lumenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5G 1 X5.
| | | | | |
Collapse
|