Our Research

The interactions between cells and their surrounding extracellular matrix play a central role in the development of multi-cellular animals. Early studies from our lab established that the matrix protein, fibronectin, binds to specific cell surface receptors 1; 2. These receptors are members of a widely distributed protein family3-5, now termed integrins. This protein family is essential for the normal development and functioning of both vertebrates and invertebrates. Many integrins recognize short peptide sequences in proteins such as fibrinogen and fibronectin. These peptides can therefore inhibit integrin function and represent prototypes of a novel class of therapeutics6-9. Furthermore, we used a combination of biochemical and genetic approaches to map ligand binding sites in integrins and to understand the mechanism of binding10-18.

Integrin receptors also transmit information in both directions across the plasma membrane. For example, the anchorage dependence of cell growth is mediated by signals emanating from integrins. Conversely, intracellular signaling events are reflected on the cell surface by changes in the conformation and ligand binding affinity of integrin receptors19; 20. This process, termed "inside-out" signal transduction, seems to be a general property of this receptor family. Inside-out signaling not only controls adhesive functions, but also regulates cell migration21,22 and the assembly of an extracellular fibronectin matrix23. Integrin cytoplasmic domains play a central role in integrin activation24-26. Conversely, when integrins bind ligands they change conformation27-29and long range propagation30of these conformational changes leads to intracellular signaling events31. Integrin signaling into cells also depends on their cytoplasmic domains26,32-37. To understand the structure of the cytoplasmic domains and how they interact with intracellular partners to generate integrin-dependent signals we've utilized a combination of synthetic38 and recombinant36,37,39,40 approaches to generate model protein mimics of the integrin cytoplasmic domains. Through the use of these model proteins the interactions of integrins with the actin cytoskeleton have been anayzed40 and the capacity of one of those interactions to regulate integrin activation has been established37. Furthermore, a4 integrins play a pivotal role in chronic inflammation because they markedly enhance the migration of leukocytes. The cytoplasmic domains of a4 integrins bind an adaptor, paxillin, via a central 9 amino acid motif36,41. This interaction accounts for the unusual signaling properties of this integrin36,41. A current focus is to understand how paxillin binding to a4 regulates cellular behaviors and to analyze the mechanisms of regulation and consequences of the integrin interactions with actin binding proteins, such as talin. In addition, a major emphasis will be on the effects of these interactions on the structure of these tails, as we now know that structural analysis of the model proteins is accessible by multi-dimensional nuclear magnetic resonance spectroscopy42.


We have developed genetic strategies for analysis of integrin signaling that depends on the use of integrin affinity for extracellular ligands as a selectable marker. This method has been validated for use in integrin structure-function studies, and for somatic cell genetic approaches to analyze signaling pathways17. In addition, such a strategy was used to develop novel expression cloning schemes that defined a new pathway involve the suppression of integrin activation by activated H-Ras via a MAP kinase pathway43. This pathway is probably involved in the control of cell migration and may be dysregulated during malignant transformation. More recent studies have established that the activity of this pathway can be opposed by another Ras family member, R-Ras via an apparently novel effector44,45. A current focus is to understand the downstream events in this suppressor pathway and to identify the R-Ras effectors responsible for reversal of suppression. The suppressor pathway can also be opposed by a an anti-apoptotic protein, PEA-15 46 even though PEA-15 promotes the activity of the ERK MAP kinase pathway47. We therefore have an active interest in identification of binding partners of PEA-15 and to understand how this protein can regulate MAP kinase signaling In another expression cloning scheme, complementation of dominant suppression, implicated a regulator of amino acid transport, CD 98, in integrin signaling48. CD98 binds to integrin cytoplasmic domains49 and distinct domains of this protein are responsible for its effects on integrins and amino acid transport50. A current focus is to analyze the mechanism by which CD 98 regulates integrins by analysis of mice with a disruption of the CD98 gene and recently derived CD98 null ES cells.

Recent Publications:

α4 Integrin Signaling

  • Han,J., Liu,S., Rose,D.M., Schlaepfer,D.D., McDonald,H., and Ginsberg,M.H. 2001. Phosphorylation of the integrin alpha4 cytoplasmic domain regulates paxillin binding. J.Biol.Chem. 276:40903-40909.
  • Liu,S., Slepak,M., and Ginsberg,M.H. 2001. Binding of Paxillin to the alpha 9 Integrin Cytoplasmic Domain Inhibits Cell Spreading. J.Biol.Chem. 276:37086-37092.
  • Rose,D.M., Grabovsky,V., Alon,R., and Ginsberg,M.H. 2001. The Affinity of Integrin alpha(4)beta(1) Governs Lymphocyte Migration. J.Immunol. 167:2824-2830.          Ambroise,Y., Yaspan,B., Ginsberg,M.H., and Boger,D.L. 2002. Inhibitors of cell migration that inhibit intracellular paxillin/alpha4 binding. A well-documented use of positional scanning libraries. Chem.Biol. 9:1219-1226.
  • Liu,S., Kiosses,W., Rose,D.M., Slepak,M., Salgia,R., Griffin,J.D., Turner,C.E., Schwartz,M.A., and Ginsberg,M.H. 2002. A fragment of Paxillin binds the alpha 4 integrin cytoplasmic domain (Tail) and selectively inhibits alpha 4-mediated cell migration. J.Biol.Chem. 277:20887-20894.
  • Goldfinger,L.E., Han,J., Kiosses,W.B., Howe,A.K., and Ginsberg,M.H. 2003. Spatial restriction of alpha4 integrin phosphorylation regulates lamellipodial stability and {alpha}4{beta}1-dependent cell migration. J Cell Biol 162:731-741.
  • Han,J., Rose,D.M., Woodside,D.G., Goldfinger,L.E., and Ginsberg,M.H. 2003. Integrin alpha4 beta1-dependent T cell migration requires both phosphorylation and de-phosphorylation of the alpha4 cytoplasmic domain to regulate the reversible binding of paxillin. J Biol Chem. 278:34845-34853.
  • Rose,D.M., Liu,S., Woodside,D.G., Han,J., Schlaepfer,D.D., and Ginsberg,M.H. 2003. Paxillin Binding to the {alpha}4 integrin subunit stimulates LFA-1 (Integrin {alpha}L{beta}2)-dependent T Cell migration by augmenting the activation of focal adhesion kinase/proline-rich tyrosine kinase-2. J Immunol 170:5912-5918.
  • Alon,R., Feigelson,S.W., Manevich,E., Rose,D.M., Schmitz,J., Overby,D.R., Winter,E., Grabovsky,V., Shinder,V., Matthews,B.D. et al. 2005. {alpha}4{beta}1-dependent adhesion strengthening under mechanical strain is regulated by paxillin association with the {alpha}4-cytoplasmic domain. J Cell Biol 171:1073-1084.
  • Hsia,D.A., Lim,S.T., Bernard-Trifilo,J.A., Mitra,S.K., Tanaka,S., den Hertog,J., Streblow,D.N., Ilic,D., Ginsberg,M.H., and Schlaepfer,D.D. 2005. Integrin {alpha}4{beta}1 Promotes Focal Adhesion Kinase-Independent Cell Motility via {alpha}4 Cytoplasmic Domain-Specific Activation of c-Src. Mol.Cell Biol 25:9700-9712.
  • Nishiya,N., Kiosses,W.B., Han,J., and Ginsberg,M.H. 2005. An [alpha]4 integrin-paxillin-Arf-GAP complex restricts Rac activation to the leading edge of migrating cells. Nat Cell Biol 4:343-352.
  • Feral,C.C., Rose,D.M., Han,J., Fox,N.E., Silverman,G.J., Kaushansky,K., and Ginsberg,M.H. 2006. Blocking the alpha4 integrin-paxillin interaction selectively impairs mononuclear leukocyte recruitment to an inflammatory site . J.Clin.Invest 116:715-723.

Integrin Cytoplasmic Domain Binding Proteins

  • Calderwood,D.A., Huttenlocher,A., Kiosses,W.B., Schwartz,M.A., and Ginsberg,M.H. 2001. Increased Filamin Binding to Integrin Beta Cytoplasmic Domains Inhbits Membrane Protrusion, Cell Polarization, and Cell Migration. Nat.Cell Biol. 12:1060-1068.
  • Felding-Habermann,B., O'Toole,T.E., Smith,J.W., Fransvea,E., Ruggeri,Z.M., Ginsberg,M.H., Hughes,P.E., Pampori,N., Shattil,S.J., Saven,A. et al. 2001. Integrin activation controls metastasis in human breast cancer. Proc.Natl.Acad.Sci.USA 98:1853-1858.
  • Ginsberg,M.H., Yaspan,B., Forsyth,J., Ulmer,T.S., Campbell,I.D., and Slepak,M. 2001. A membrane-distal segment of the integrin alpha IIb cytoplasmic domain regulates integrin activation. J.Biol.Chem. 276:22514-22521.
  • Ulmer,T.S., Yaspan,B., Ginsberg,M.H., and Campbell,I.D. 2001. NMR Analysis of Structure and Dynamics of the Cytosolic Tails of Integrin alphaIIbbeta3 in Aqueous Solution. Biochemistry 40:7498-7508.
  • Woodside,D.G., Obergfell,A., Leng,L., Wilsbacher,J.L., Miranti,C.K., Brugge,J.S., Shattil,S.J., and Ginsberg,M.H. 2001. Activation of Syk protein Tyrosine Kinase Through Interaction With Integrin Beta Cytoplasmic Domains. Curr.Biol. 22:1799-1804.
  • Yan,B., Calderwood,D.A., Yaspan,B., and Ginsberg,M.H. 2001. Calpain cleavage promotes talin binding to the Beta3 integrin cytoplasmic domain. J.Biol.Chem. 276:28164-28170.
  • Calderwood,D.A., Yan,B., de Pereda,J.M., Garcia-Alvarez,B., Fujioka,Y., Liddington,R.C., and Ginsberg,M.H. 2002. The phosphotyrosine binding (PTB)-like domain of talin activates integrins. J.Biol.Chem. 277:21749-21758.
  • Lin,J.Y., Pollack,J.R., Chou,F.L., Rees,C.A., Christian,A.T., Bedford,J.S., Brown,P.O., and Ginsberg,M.H. 2002. Physical mapping of genes in somatic cell radiation hybrids by comparative genomic hybridization to cDNA microarrays. Genome Biol. 3:RESEARCH0026.
  • Woodside,D.G., Obergfell,A., Talapatra,A., Calderwood,D.A., Shattil,S.J., and Ginsberg,M.H. 2002. The N-terminal SH2 domains of Syk and ZAP-70 mediate phosphotyrosine-independent binding to integrin beta cytoplasmic domains. J.Biol.Chem. 277:39401-39408.
  • Arias-Salgado,E.G., Lizano,S., Sarkar,S., Brugge,J.S., Ginsberg,M.H., and Shattil,S.J. 2003. Src kinase activation by direct interaction with the integrin beta cytoplasmic domain. Proc.Natl.Acad.Sci.USA 100:13298-13302.
  • Calderwood,D.A., Fujioka,Y., de Pereda,J.M., Garcia-Alvarez,B., Nakamoto,T., Margolis,B., McGlade,C.J., Liddington,R.C., and Ginsberg,M.H. 2003. Integrin beta cytoplasmic domain interactions with phosphotyrosine-binding domains: A structural prototype for diversity in integrin signaling. Proc.Natl.Acad.Sci.USA 100:2272-2277.
  • Garcia-Alvarez,B., de Pereda,J.M., Calderwood,D.A., Critchley,D.R., Ulmer,T.S., Campbell,I.D., Ginsberg,M.H., and Liddington,R.C. 2003. Structural Determinants of Integrin Interaction with Talin. Mol.Cell 11:49-58.
  • Tadokoro,S., Shattil,S.J., Eto,K., Tai,V., Liddington,R.C., de Pereda,J.M., Ginsberg,M.H., and Calderwood,D.A. 2003. Talin binding to integrin tails: a final common step in integrin activation. Science 302:103-106.
  • Ulmer,T.S., Calderwood,D.A., Ginsberg,M.H., and Campbell,I.D. 2003. Domain-Specific Interactions of Talin with the Membrane-Proximal Region of the Integrin beta3 Subunit. Biochemistry 42:8307-8312.
  • Calderwood,D.A., Tai,V., Di Paolo,G., De Camilli,P., and Ginsberg,M.H. 2004. Competition for Talin results in trans-dominant inhibition of integrin activation. J Biol Chem. 279:28889-28895.
  • de Pereda,J.M., Wegener,K., Santelli,E., Bate,N., Ginsberg,M.H., Critchley,D.R., Campbell,I.D., and Liddington,R.C. 2004. Structural bases for phosphatidylinositol phosphate kinase type I-gamma binding to talin at focal adhesions. J Biol Chem. 280:8381-8386.
  • Kloeker,S., Major,M.B., Calderwood,D.A., Ginsberg,M.H., Jones,D.A., and Beckerle,M.C. 2004. The Kindler syndrome protein is regulated by TGFbeta and involved in integrin-mediated adhesion. J Biol Chem. 279:6824-6833.
  • Arias-Salgado,E.G., Lizano,S., Shattil,S.J., and Ginsberg,M.H. 2005. Specification of the direction of adhesive signaling by the integrin beta cytoplasmic domain. J Biol Chem. 280:29699-29707.
  • Partridge,A.W., Liu,S., Kim,S., Bowie,J.U., and Ginsberg,M.H. 2005. Transmembrane domain helix packing stabilizes integrin alpha IIbbeta 3 in the low affinity state. J Biol Chem. 280:7294-7300.
  • Ratnikov,B., Ptak,C., Han,J., Shabanowitz,J., Hunt,D.F., and Ginsberg,M.H. 2005. Talin phosphorylation sites mapped by mass spectrometry. J Cell Sci 118:4921-4923.

Suppressors of Integrin Activation

  • Formstecher,E., Ramos,J.W., Fauquet,J., Calderwood,D.A., Hsieh,J.-C., Canton,B., Nguyen,X., Barnier,J.-V., Camonis,J., Ginsberg,M.H. et al. 2001. PEA-15 Mediates Cytoplasmic Sequestration of ERK MAP Kinase. Developmental Cell 1:239-250.
  • Baker,S.E., Lorenzen,J.A., Miller,S.W., Bunch,T.A., Jannuzi,A.L., Ginsberg,M.H., Perkins,L.A., and Brower,D.L. 2002. Genetic Interaction Between Integrins and moleskin, a Gene Encoding a Drosophila Homolog of Importin-7. Genetics 162:285-296.
  • Hansen,M., Rusyn,E.V., Hughes,P.E., Ginsberg,M.H., Cox,A.D., and Willumsen,B.M. 2002. R-Ras C-terminal sequences are sufficient to confer R-Ras specificity to H-Ras. Oncogene 21:4448-4461.
  • Hill,J.M., Vaidyanathan,V., Ramos,J.W., Ginsberg,M.H., and Werner,M.H. 2002. Recognition of ERK MAP kinase by PEA-15 reveals a common docking site within the death domain and death effector domain. EMBO J. 21:6494-6504.
  • Hughes,P.E., Oertli,B., Hansen,M., Chou,F.L., Willumsen,B.M., and Ginsberg,M.H. 2002. Suppression of Integrin Activation by Activated Ras or Raf Does Not Correlate with Bulk Activation of ERK MAP Kinase. Mol.Biol.Cell 13:2256-2265.
  • Chou,F.L., Hill,J.M., Hsieh,J.C., Pouyssegur,J., Brunet,A., Glading,A., Uberall,F., Ramos,J.W., Werner,M.H., and Ginsberg,M.H. 2003. PEA-15 binding to ERK1/2 MAP kinases is required for its modulation of integrin activation. J Biol Chem. 278:52587-52597.
  • Krueger,J., Chou,F.L., Glading,A., Schaefer,E., and Ginsberg,M.H. 2005. Phosphorylation of Phosphoprotein Enriched in Astrocytes (PEA15) Regulates ERK-dependent Transcription and Cell Proliferation. Mol.Biol Cell 16:3552-3561.
  • Bartholomeusz,C., Itamochi,H., Nitta,M., Saya,H., Ginsberg,M.H., and Ueno,N.T. 2006. Antitumor effect of E1A in ovarian cancer by cytoplasmic sequestration of activated ERK by PEA15. Oncogene 25:79-90.

CD98hc (4F2 Antigen, SLC3A2) in Adhesive Signaling

  • Fenczik,C.A., Zent,R., Dellos,M., Calderwood,D.A., Satriano,J., Kelly,C., and Ginsberg,M.H. 2001. Distinct domains of CD98hc regulate integrins and amino acid transport. J.Biol.Chem. 276:8746-8752.
  • Feral,C.C., Nishiya,N., Fenczik,C.A., Stuhlmann,H., Slepak,M., and Ginsberg,M.H. 2004. CD98hc (SLC3A2) mediates integrin signaling. Proc.Natl.Acad.Sci U.S.A 102:355-360.
  • Henderson,N.C., Collis,E.A., Mackinnon,A.C., Simpson,K.J., Haslett,C., Zent,R., Ginsberg,M., and Sethi,T. 2004. CD98hc (SLC3A2) interaction with beta 1 integrins is required for cellular transformation. J Biol Chem. 279:54731-54741.

Reviews

  • Liddington,R.C. and Ginsberg,M.H. 2002. Integrin activation takes shape. J.Cell Biol. 158:833-839.
  • Ramos,J.W. and Ginsberg,M. 2002. Expression Cloning Strategies for the Idenfication of Adhesion Molecules. In Methods in Cell-Matrix Adheson. J.C.Adams, editor. Academic Press, San Diego. 209-221.
  • Rose,D.M., Han,J., and Ginsberg,M.H. 2002. alpha4 integrins and the immune response. Immunol.Rev. 186:118-124.
  • Schwartz,M.A. and Ginsberg,M.H. 2002. Networks and crosstalk: integrin signalling spreads. Nat.Cell Biol. 4:E65-E68.
  • Calderwood,D.A. and Ginsberg,M.H. 2003. Talin forges the links between integrins and actin. Nat.Cell Biol 5:694-697.
  • Kinbara,K., Goldfinger,L.E., Hansen,M., Chou,F.L., and Ginsberg,M.H. 2003. Ras GTPases: integrins' friends or foes? Nat.Rev.Mol.Cell Biol 4:767-776.
  • Ridley,A.J., Schwartz,M.A., Burridge,K., Firtel,R.A., Ginsberg,M.H., Borisy,G., Parsons,J.T., and Horwitz,A.R. 2003. Cell migration: integrating signals from front to back. Science 302:1704-1709.
  • Campbell,I.D. and Ginsberg,M.H. 2004. The talin-tail interaction places integrin activation on FERM ground. TIBS 29:429-435.
  • Nakamoto,T., Kain,K.H., and Ginsberg,M.H. 2004. Neurobiology: New connections between integrins and axon guidance. Curr.Biol 14:R121-R123.
  • Ginsberg,M.H., Partridge,A., and Shattil,S.J. 2005. Integrin regulation. Curr.Opin.Cell Biol.
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