Our lab focuses on two synergistic areas: development of novel molecules to visualize and control protein activity in live cells and animals, and applying these tools to address basic questions re spatio-temporal control of signaling. Our biological studies center on the role of cytoskeletal and adhesion dynamics in signaling crosstalk, directed motility, and immune cell function. We are extending our cell biology studies to examine metastasis and macrophage motility in 3D models and in vivo.
While addressing specific molecules for our biological studies, we have produced generally applicable approaches to visualize and control signaling. These include new fluorescent biosensor designs to quantify conformational changes of endogenous proteins, and biosensors based on engineered protein scaffolds for otherwise inaccessible molecules. We are developing fluorescent dyes for single molecule microscopy of protein conformational changes in vivo. We are developing engineered domains that can be inserted into target proteins to control protein function using either light or small molecules. Other new methods selectively activate specific protein behaviors.
We greatly benefit from interactions with collaborators who focus on computational image analysis, modeling of signaling dynamics, and developing novel microscopes.
(Image: Activation of Rac1 (spot) leads to gradient of Pak activity; Yi Wu, Hahn lab)
Some specific directions (updated 7/2013):
GTPase networks. In several related projects that have been a major focus of our laboratory for years, we are studying GTPase signaling ‘circuits’ and how their transient construction at specific locations controls metastasis, platelet formation, and macrophage functions. New approaches are used to control specific protein activities, to understand the interactions of adhesion proteins, and to control and visualize multiple circuit ‘nodes’. New microscope techniques developed by our collaborators are helping us quantify signaling kinetics in individual cells with great accuracy for quantitative modeling and a deeper understanding of network architecture.
(Image: Biosensor fluctuation analysis reveals GEF/GTPase feedback loops. Hunter Elliot, Danuser lab, Harvard)
Zebrafish and engineered allosteric activation. We are working on new tools to examine and control signaling in zebrafish, transparent animals that serve as excellent microscopy models for human disease and development. The bulk of our work on engineered allosteric control of proteins occurs here, using small molecules that can be added to the medium to activate proteins or specific pathways. We are also examining unique biosensors designed for human diagnosis. These projects are being pursued with Anna Huttenlocher at U. Wisconsin, studying EMT and neutrophil infiltration of tumors.
Transendothelial migration. Cells signal through adhesion molecules on blood vessel walls, to pass through the vessels for immune surveillance, cancer metastasis and a host of other processes important in homeostasis and disease. Little is known about how adhesion molecules coordinate synchronized changes in the cytoskeletons of the blood vessel endothelial cells and the transmigrating cells. We are using our newly developed techniques for examining and controlling multiple molecules simultaneously to probe networks that guide transendothelial migration and other immune cell behaviors. Using 3D force microscopy developed by our collaborator, Richard Superfine, we are asking how forces experienced by migrating cells affect adhesion molecule signaling to Rho family GTPases.
(Image: Leucocytes induce cups in endothelial cells; Jaap Schroeder, Burridge Lab, UNC)
Thanks to our collaborators for their dedication and enthusiasm:
- Bergmeier Lab, UNC
- Betzig Lab, Janelia Research Institute
- Burridge Lab, UNC
- Leong Chew, Advanced Imaging Center, Janelia Research Institute
- Condeelis Lab, Albert Einstein College of Medicine
- Danuser Lab, UTSW
- Dokholyan Lab, UNC
- Elston Lab, UNC
- Ginsberg Lab, UCSD
- Gomez Lab, UNC
- Gratton Lab, NIH Laboratory for Fluorescence Dynamics, UC-Irvine
- Grinstein Lab, U. Toronto
- Hanein Lab, Burnham
- Huttenlocher Lab, U. Wisconsin
- Jacobson Lab, UNC
- Jirik Lab, U. Calgary
- Kasai Lab, U. Tokyo
- Keely Lab, U. Wisconsin
- Kubes Lab, U. Calgary
- Kuhlman Lab, UNC
- Kevin Eliceri at LOCI, U. Wisconsin
- Nain Lab, Va. Tech
- Rottapel Lab, U. Toronto
- Sondek Lab, UNC
- Superfine Lab, NIH Center for Computer Integrated Systems for Microscopy and Manipulation, UNC
- Tsygankov Lab, Georgia Tech and Emory
- Volkmann Lab, Burnham
Thanks to the following organizations, and to the taxpayers, for their support: