Keith Burridge, Ph.D.

Burridge
kburridg@med.unc.edu
Lab Webpage

Lab Personnel

Burridge Crenshaw 2 Burridge Lessey 2
Burridge Marjoram 2 Burridge Sharek 2 Burridge Tolbert 2
Burridge Wittchen 2

Professor

  • B.A., Cambridge, 1971
  • Ph.D., Cambridge, 1975
  • Postdoc, Cold Spring Harbor, 1975-77

Funding Sources

  • National Institutes of Health

Research Interests

Key words: Rho GTPases, GEFs and GAPs, focal adhesions, adherens junctions, mechanotransduction, leukocyte/endothelial cell interactions, tumor cell invasion.

We have a longstanding interest in cell adhesion and the regulation of Rho GTPases. The Rho GTPases regulate many aspects of cell behavior including cytoskeletal organization, cell migration, adhesion, vesicle trafficking, progress through the cell cycle, gene expression and differentiation. Many signaling pathways converge to regulate Rho GTPase activity. These proteins are active when they have GTP bound and become inactive when this is hydrolyzed to GDP. Activation of Rho proteins is promoted by guanine nucleotide exchange factors (GEFs) that catalyze GDP for GTP exchange, whereas inactivation is regulated by GTPase activating proteins (GAPs) that stimulate the intrinsic GTPase activity of the Rho proteins. Additionally, Rho guanine nucleotide dissociation inhibitor (Rho GDI) extracts Rho proteins from cell membranes and sequesters the GTPases in the inactive state within the cytoplasm. We are studying the regulation of GEFs, GAPs and GDI and how these regulatory components interact.

Cell adhesion either to the extracellular matrix (ECM) or to other cells affects the activities of multiple Rho proteins (RhoA, Rac1, Cdc42 and RhoG), sometimes depressing the activity of one Rho protein while elevating the activity of another, and thereby affecting cell behavior. We are investigating the pathways by which engagement of adhesion molecules regulates the activities of Rho proteins. Cell adhesion molecules provide attachment for the cytoskeleton and transmit forces from outside the cell to the cytoskeleton and forces generated within the cytoskeleton to the extracellular environment. In recent work, collaborating with Richard Superfine’s lab in Physics and Astronomy, we have used magnetic beads coated with adhesion molecule ligands or with antibodies in combination with magnets to generate force on specific adhesion molecules. Along with other labs, we have shown that tension on integrins activates RhoA and have identified two RhoA GEFs that are responsible. We have dissected the signaling pathways that lead to activation of these GEFs and surprisingly find that they are distinct.

Burridge Image

We are interested in how leukocytes interact with endothelial cells and then migrate across the endothelium during inflammation. We have shown that engagement of the endothelial adhesion molecule ICAM-1 by leukocytes activates several Rho GTPases within endothelial cells. In turn, these affect the integrity of endothelial junctions. Specifically, we have shown that Rac1 activation leads to the generation of reactive oxygen species and that these elevate tyrosine phosphorylation of several junctional proteins. The phosphorylation of the cytoplasmic domain of VE-cadherin results in decreased binding of β-catenin and p120-catenin, both of which will decrease junctional integrity. We are investigating whether metastasizing tumor cells use similar signaling pathways to weaken endothelial junctions to pass through the endothelium. In addition to Rho GTPases regulating endothelial junctions, we have shown that the Rap1 GTPase also regulates endothelial junctions. Rap1 is another GTPase but more closely related to Ras rather than Rho. How Rap1 activation enhances the barrier function of endothelial cells is being pursued.

While much is known about the role of tyrosine kinases in many different signaling pathways, much less is known about the protein tyrosine phosphatases (PTPs) that oppose them. PTPs are a complex family of proteins, some of which are transmembrane proteins that interact with extracellular ligands including matrix proteins. Although PTPs often antagonize tyrosine kinases, they can also activate kinases and so their effects on signaling pathways are complex and often unexpected. Several transmembrane PTPs are concentrated in endothelial and epithelial cell-cell junctions where they likely regulate junctional integrity. It is interesting that some transmembrane PTPs reveal altered levels of expression in various cancers. We are investigating the role of specific transmembrane PTPs that are up-regulated in invasive breast cancer cells.

Burridge Image 2

Selected Publications

  • Chrzanowska-Wodnicka, M. and Burridge, K. Rho-stimulated contractility drives the formation of stress fibers and focal adhesions. J. Cell Biol. 133:1403-1415 (1996).
  • Noren, NK, Niessen, CM, Gumbiner, BM, and Burridge, K. Cadherin engagement regulates Rho family GTPases. J. Biol. Chem.276: 33305-33308 (2001).
  • Ridley, AJ, Schwartz, MA, Burridge, K, Firtel, RA, Ginsberg, MH, Borisy, G, Parsons, JT and Horwitz, AR.  Cell migration: Integrating signals from front to back. Science 302: 1704-1709 (2003)
  • Burridge, K and Wennerberg, K. Rho and Rac take center stage.  Cell 116: 167-179 (2004)
  • Garcia-Mata, R, Wennerberg, K, Arthur, WT, Noren, NK, Ellerbroek, SM, Burridge, K. Analysis of activated GAPs and GEFs in cell lysates. Methods in Enzymol. 406: 425-37 (2006)
  • Allingham, MJ, van Buul, JD, Burridge, K. ICAM1-mediated, Src and Pyk2 dependent VE-cadherin tyrosine phosphorylation is required for leukocyte transendothelial migration. J. Immunol. 179: 4053-64 (2007)
  • van Buul, JD, Allingham, MJ, Samson, T, Meller, J, Boulter, E, Garcia-Mata, R, Burridge, K. RhoG regulates endothelial apical cup assembly downstream from ICAM1 engagement and is involved in leukocyte transendothelial migration. J. Cell Biol. 178: 1279-93 (2007) PMCID: PMC2064659
  • Dubash, A, Wennerberg, K, Garcia-Mata, R, Menold, MM, Arthur, WT, Burridge, K. A novel role for Lsc/p115 RhoGEF and LARG in regulating RhoA activity downstream of adhesion to fibronectin. J. Cell Sci. 120: 3989-98 (2007)
  • Monaghan-Benson E, Burridge, K. The regulation of VEGF-induced microvascular permeability requires Rac and ROS. J. Biol. Chem. 284: 25602-11 (2009) PMCID: PMC2757962
  • Samson T, Welch C, Monaghan-Benson E, Hahn KM, Burridge K. Endogenous RhoG is rapidly activated after EGF stimulation by multiple GEFs. Mol. Biol. Cell 21(9):1629-42 (2010) PMID: 20237158. PMCID: PMC2861620
  • Boulter, E, Garcia-Mata, R, Guilluy, C, Dubash, A, Rossi, G, Brennwald, PJ, Burridge, K. Regulation of RhoGTPase crosstalk, degradation and activity by RhoGDI1. Nat. Cell Biol. 12(5):477-83 (2010). PMID: 20400958. PMCID: PMC2866742
  • Hamel B, Monaghan-Benson E, Rojas RJ, Temple BR, Marston DJ, Burridge K, Sondek J.  SmgGDS is a guanine nucleotide exchange factor that specifically activates RhoA and RhoC. J Biol Chem. 286 (14):12141-8 (2011) PMCID: PMC3069418
  • Guilluy, C, Swaminathan, V, Garcia-Mata, R, O’Brien, ET, Superfine and Burridge, K. The Rho GEFs LARG and GEF-H1 regulate the mechanical response to force on integrins. Nat. Cell Biol. 13(6):724-9 (2011). PMID:21572419. PMCID: 3107386
  • Garcia-Mata, R, Boulter, E, Burridge, K. The invisible hand: Regulation of Rho GTPases by RhoGDIs. Nature Reviews Molecular Cell Biology. 12 (8):493-504 (2011). PMID:21779026 PMCID: PMC3260518
  • Guilluy, C, Garcia-Mata, R, and Burridge, K.  Rho protein crosstalk: another social network? Trends in Cell Biology. 21(12):718-26 (2011). PMID:21924908 PMCID: PMC3221770
  • Lessey EC, Guilluy C, Burridge K. From mechanical force to RhoA activation. Biochemistry 51, 7420−7432 (2012). PMID: 22931484