Adhesion of cells to extracellular matrices is a fundamental characteristic of allmulticellular organisms. Adhesion provides not only structural links between theintracellular cytoskeleton and the extracellular environment, but also provides sites ofsignal transduction that affect many aspects of cell behavior. This grant is aimed atunderstanding how signals from cell-matrix adhesions regulate members of the Rhofamily of GTPases, which are themselves key regulators of the cytoskeleton and manyintracellular processes. The goal of the first aim is to determine how adhesion to theextracellular matrix protein fibronectin stimulates RhoA. Having recently identifiedguanine nucleotide exchange factors, such as Lsc, that are involved in this process, weaim to determine the signaling pathways that lead to their activation. Our finding thatadhesion stimulates Lsc tyrosine phosphorylation and promotes Lsc binding to vinculinsuggests possible mechanisms of regulation and will be investigated further. We will alsoexamine how mechanical tension and substrate rigidity/pliability regulate RhoA activity.Here we have found that some but not all of the same exchange factors are involved.We will investigate the signaling pathways downstream from mechanical tension thatlead to exchange factor activation. In the second aim, we will follow up the discovery thatreactive oxygen species can activate Rho proteins by transient oxidation of cysteinesulfhydryls without involvement of exchange factors. Using redox-resistant mutants ofRho GTPases, we will determine the role of Rho protein activation by cysteine oxidationin events such as adhesion and in response to growth factor stimulation. In the finalaim, we will focus on the Rho GTPase sequestering protein RhoGDI, which we haverecently found contributes to crosstalk between different Rho family members.Competitive interactions of Rho proteins for binding to RhoGDI will be explored. We willinvestigate how Rho proteins are released from RhoGDI in response to adhesion anddetermine the pathways that lead to their degradation following displacement fromRhoGDI. Finally, we will explore the role of RhoGDI in mediating the trafficking of Rhoproteins from their sites of postranslational modification to their sites of action at theplasma membrane.

Public Health Relevance

The adhesive interactions of cells determine whether they will grow, die, migrate or stay in their current location. Our work aims to understand the signals that cells receive from their adhesions and how these signals regulate the Rho family of proteins that affect cell behavior. Deciphering adhesion-mediated signaling should increase our understanding of the role that adhesion plays in various diseases.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Intercellular Interactions (ICI)
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Gindhart, Joseph G
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University of North Carolina Chapel Hill
Schools of Medicine
Chapel Hill
United States
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Schaefer, Antje; van Duijn, Trynette J; Majolee, Jisca et al. (2017) Endothelial CD2AP Binds the Receptor ICAM-1 To Control Mechanosignaling, Leukocyte Adhesion, and the Route of Leukocyte Diapedesis In Vitro. J Immunol 198:4823-4836
Thompson, Peter M; Ramachandran, Srinivas; Case, Lindsay B et al. (2017) A Structural Model for Vinculin Insertion into PIP2-Containing Membranes and the Effect of Insertion on Vinculin Activation and Localization. Structure 25:264-275
Burridge, Keith (2017) Focal adhesions: a personal perspective on a half century of progress. FEBS J 284:3355-3361
Lawson, Campbell D; Fan, Cheng; Mitin, Natalia et al. (2016) Rho GTPase Transcriptome Analysis Reveals Oncogenic Roles for Rho GTPase-Activating Proteins in Basal-like Breast Cancers. Cancer Res 76:3826-37
Graham, David M; Burridge, Keith (2016) Mechanotransduction and nuclear function. Curr Opin Cell Biol 40:98-105
Morillon 2nd, Y Maurice; Lessey-Morillon, Elizabeth Chase; Clark, Matthew et al. (2016) Antibody Binding to CD4 Induces Rac GTPase Activation and Alters T Cell Migration. J Immunol 197:3504-3511
Marjoram, R J; Guilluy, C; Burridge, K (2016) Using magnets and magnetic beads to dissect signaling pathways activated by mechanical tension applied to cells. Methods 94:19-26
Uzer, Gunes; Thompson, William R; Sen, Buer et al. (2015) Cell Mechanosensitivity to Extremely Low-Magnitude Signals Is Enabled by a LINCed Nucleus. Stem Cells 33:2063-76
Scott, David W; Tolbert, Caitlin E; Graham, David M et al. (2015) N-glycosylation controls the function of junctional adhesion molecule-A. Mol Biol Cell 26:3205-14
Guilluy, Christophe; Burridge, Keith (2015) Nuclear mechanotransduction: forcing the nucleus to respond. Nucleus 6:19-22

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