Our lab develops novel molecules that report and control protein behavior in vivo. We strive to develop broadly applicable approaches, but this is driven by addressing specific questions about immune cell function and spatio-temporal control of signaling. In technique development, our focus is on protein engineering and novel dyes, used to manipulate signaling networks using light or small molecules, or to build proteins that report their signaling behavior in vivo. In our biological studies, we focus on dynamic cellular processes where spatio-temporal control of signaling is critical, and where communication occurs across many scales in living cells. The techniques we develop enable us to study how information flow through signaling networks is controlled by restricted localization of protein activities, and by precise control of kinetics. We are designing molecules for novel microscopes that will greatly enhance the resolution of these studies.
(Image: Activation of Rac1 (spot) leads to gradient of Pak activity; Yi Wu, Hahn lab)
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’ simultaneously. 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 allostric 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 within larger networks. We are also examining unique biosensors designed for use in animals, and ultimately human diagnosis. These projects are being pursued together 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 the adhesion molecules coordinate synchronized changes in the cytoskeletons of the blood vessel endothelial cells and the transmigrating cells. We are using single particle tracking, together with our newly developed techniques for examining multiple biosensors simultaneously, to probe the signaling that guides transendothelial migration. Using 3D force microscopy developed by our collaborator, Richard Superfine, we are asking how forces experienced by migrating tumor 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, help and enthusiasm:
- Betzig Lab, Janelia Research Institute
- Burridge Lab, UNC
- Chew, Advanced Imaging Center, Janelia Research Institute
- Condeelis Lab, Albert Einstein College of Medicine
- Danuser Lab, Harvard
- Dokholyan Lab, UNC
- Elston Lab, UNC
- Ginsberg Lab, UCSD
- Gomez Lab, UNC
- Gratton Lab, NIH Laboratory for Fluorescence Dynamics, UC-Irvine
- Hall Lab, Sloan-Kettering Institute
- 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
- LOCI at U. Wisconsin, Kevin Elicieri, Director
- Nain Lab, Va. Tech
- Sondek Lab, UNC
- Superfine Lab, NIH Center for Computer Integrated Systems for Microscopy and Manipulation, UNC
- Volkmann Lab, Burnham
Thanks to the following organizations, and to the US and NC taxpayers, for their support: