Rho family GTPases is ubiquitous molecular switches that control extraordinarily diverse cellular processes. They are activated by guanine nucleotide exchange factors (GEFs) that are roughly 5-fold more numerous than the GTPases themselves and integrate the many cellular inputs controlling GTPase function. GEFs and GTPases form complex networks that are constituted transiently and locally for specific purposes. Biochemical, genetic, molecular, and structural analyses have unraveled a great deal about these critically important pathways, but the most important functional property, their spatio-temporal regulation, can only be fully understood in the context of intact cells. This PPG brings together team members with diverse expertise to develop innovative technologies enabling the study of GEF/GTPase networks in vivo, computational tools to extract network architecture and signaling kinetics from imaging data, and in-depth knowledge of cell behaviors critically dependent on GEF/GTPase dynamics: (Project 1- Hahn) will deliver GEF biosensors based on designs addressing different GEF structural classes. In a collaborative effort with Sondek, expert in GEF structure, different biosensor designs will report GEF activation by specific upstream inputs, and activation of endogenous GEFs. (Project 2- Danuser) will develop the ability to simultaneously image and/or photomanipulate the activity of any pair of GEFs and GTPases, for high resolution studies of GEF/GTPase spatio-temporal coordination. New computational tools will combine data from different experiments to model large networks, and to extract network architecture and signaling kinetics from imaging data. These methods will be tested in studies of complex GEF-GTPase feedback interactions. (Project 3- Hall): This biologically focused project will extend our work to multicellular systems. We will focus on GEF activation in cell-cell junctions and cryptic lamellipodia, and identify GEFs regulating collective migration. (Project 4- Burridge) will address the role of GEF/GTPase netvvorks in mechanotransduction, exploring novel findings regarding the mechanical regulation of RhoA signaling at cell-matrix and cell-cell adhesions during initiation of protrusions, and in the nucleus.

Public Health Relevance

Little is known about how the cell uses networks of 'signaling proteins'for many purposes by controlling when and where they assemble. We will generate tools to address the dynamics of such networks in space and time within living cells, and study specific networks composed of GEFs and GTPases, ubiquitous proteins involved in many basic cell behaviors and diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
5P01GM103723-02
Application #
8744288
Study Section
Special Emphasis Panel (ZRG1-IMST-J (40))
Program Officer
Deatherage, James F
Project Start
2013-09-30
Project End
2018-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
2
Fiscal Year
2014
Total Cost
$1,101,950
Indirect Cost
$221,000
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
Tsygankov, Denis; Chu, Pei-Hsuan; Chen, Hsin et al. (2014) User-friendly tools for quantifying the dynamics of cellular morphology and intracellular protein clusters. Methods Cell Biol 123:409-27
Weitzman, Matthew; Hahn, Klaus M (2014) Optogenetic approaches to cell migration and beyond. Curr Opin Cell Biol 30:112-20