Rho GTPases function as binary switches, cycling from GDP-bound """"""""off"""""""" states to GTP-bound """"""""on"""""""" states capable of engaging myriad effectors to coordinate a plethora of cellular responses that typically require changes in the cytoskeleton. For example, cellular responses that require Rho GTPases include: chemotaxis, differentiation and division, wound-healing, phagocytosis, axonal pathfinding, and polarized secretion. The cycling of guanine nucleotides bound to Rho GTPases is tightly controlled at several points. In particular, guanine nucleotide exchange factors (GEFs) directly bind Rho GTPases to accelerate the ejection of bound GDP and the loading of GTP. With approximately seventy members in humans, the Dbl-family of proteins represents the largest groups of GEFs for Rho GTPases. All Dbl-family members possess a characteristic Dbl homology (DH) domain necessary to engage Rho GTPases and catalyze exchange. A pleckstrin homology (PH) domain is found immediately C-terminal to the vast majority of DH domains. The nature of these associated PH domains is not fully understood, but in general, this tandem linkage serves to coordinate Rho GTPase activation with the binding of specific phosphoinositides to the DH-associated PH domains. Given the importance of Dbl-family GEFs in regulating the activation of Rho GTPases and the central role of these GTPases to numerous facets of cell biology, we are heavily invested in understanding the regulation of these exchange factors and their associated roles in controlling biological events. Accordingly, this application has three specific aims: 1. To define conserved mechanisms regulating the auto-inhibition of Dbl-family GEFs. 2. To define roles for a subset of Dbl-family GEFs in cancer and neuronal development. 3. To define general mechanisms underlying the cooperative functioning of DH/PH cassettes. Public Health Relevance: The dysregulated activation of Rho GTPases, often mediated by Dbl-family guanine nucleotide exchange factors (GEFs), is associated with numerous developmental, immunological, and proliferative diseases, including cancer. The proposed work is designed to illuminate conserved mechanisms regulating the activation of Rho GTPases by Dbl-family GEFs and to place this regulation within the context of models of cancer progression and neuronal development.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM062299-06
Application #
7585289
Study Section
Special Emphasis Panel (ZRG1-MIST-G (01))
Project Start
2001-06-01
Project End
2012-03-31
Budget Start
2009-04-01
Budget End
2010-03-31
Support Year
6
Fiscal Year
2009
Total Cost
$294,939
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Pharmacology
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Cherkis, Karen A; Temple, Brenda R S; Chung, Eui-Hwan et al. (2012) AvrRpm1 missense mutations weakly activate RPS2-mediated immune response in Arabidopsis thaliana. PLoS One 7:e42633
Huang, Weigang; Hicks, Stephanie N; Sondek, John et al. (2011) A fluorogenic, small molecule reporter for mammalian phospholipase C isozymes. ACS Chem Biol 6:223-8
Klein, Ryan R; Bourdon, David M; Costales, Chester L et al. (2011) Direct activation of human phospholipase C by its well known inhibitor u73122. J Biol Chem 286:12407-16
Hamel, Brant; Monaghan-Benson, Elizabeth; Rojas, Rafael J et al. (2011) SmgGDS is a guanine nucleotide exchange factor that specifically activates RhoA and RhoC. J Biol Chem 286:12141-8
Gresset, Aurelie; Hicks, Stephanie N; Harden, T Kendall et al. (2010) Mechanism of phosphorylation-induced activation of phospholipase C-gamma isozymes. J Biol Chem 285:35836-47
Waldo, Gary L; Ricks, Tiffany K; Hicks, Stephanie N et al. (2010) Kinetic scaffolding mediated by a phospholipase C-beta and Gq signaling complex. Science 330:974-80
Yohe, Marielle E; Rossman, Kent; Sondek, John (2008) Role of the C-terminal SH3 domain and N-terminal tyrosine phosphorylation in regulation of Tim and related Dbl-family proteins. Biochemistry 47:6827-39
Rojas, Rafael J; Yohe, Marielle E; Gershburg, Svetlana et al. (2007) Galphaq directly activates p63RhoGEF and Trio via a conserved extension of the Dbl homology-associated pleckstrin homology domain. J Biol Chem 282:29201-10
Chhatriwala, Mariya K; Betts, Laurie; Worthylake, David K et al. (2007) The DH and PH domains of Trio coordinately engage Rho GTPases for their efficient activation. J Mol Biol 368:1307-20
Yohe, Marielle E; Rossman, Kent L; Gardner, Olivia S et al. (2007) Auto-inhibition of the Dbl family protein Tim by an N-terminal helical motif. J Biol Chem 282:13813-23

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