Regulation and Function of Intermediate Filaments in Cell Mechanics

The overall hypothesis of this Program Project Grant is that the unique mechanical properties of cytoskeletal vimentin intermediate filaments (VIF) play a key role in regulating the micromechanical properties of cells; in modulating these properties as the cells respond to changes in their external environment; and in regulating cell motility and cytoskeletal crosstalk. The principal investigators are all leaders in the field of cell biology and cell mechanics. The overall project is multi-disciplinary and brings together cell biologists, physicists, engineers and computer scientists to work closely together as a collaborative research team focused on understanding the structure and function of VIF. In Project #1, Dr. Goldman, Northwestern University, will determine the structural interactions among VIF, microtubules (MT) and actin microfilaments (MF) using high resolution microscopic techniques; determine the role of the assembly and disassembly of VIF in wound healing and motility assays; and determine the role of vimentin phosphorylation in cellular signal transduction. In Project #2, Dr. Gelfand, Northwestern University will determine the dynamic mechanisms regulating VIF-MT interactions; determine the mechanisms responsible for the dynamic interactions between VIF and MF; determine how VIF modulate the transport and distribution of membrane-bound organelles. In Project #3, Dr. Danuser, UTSW Dallas, will examine mechanisms by which VIF control microtubule organization and cell polarity; investigate mechanisms by which vimentin controls cell traction; and examine mechanisms by which VIF respond to cell-external guidance cues. In Project #4, Dr. Weitz, Harvard University, will determine the properties of reconstituted networks of VIF as well as composite networks supplemented with VIF, MF and myosin motors; study the micromechanical properties of VIF networks in living cells; and study the mechanical properties of both reconstituted networks and cells in 3D settings. In Project #5, Dr. Janmey, University of Pennsylvania, will determine the mechanisms that regulate force-dependent VIF assembly in cells; study the mechanics of VIF networks under compression in vitro; and determine how VIF regulate the response of cells and tissues to compression loading. Interactions among members of all projects and data sharing will allow for integration of physical characterizations made by different groups using methods unique to their labs that cover a wide range of time and length scales. These data will help interpret and possibly redesign biochemical and imaging studies of the biological function of VIFs to control cell structure, mechanics and motility. These efforts will be further tied together by the Cell and Tissue Core, under the guidance of Dr. Ridge, Northwestern University, will support all PIs by generating the required purified proteins and tissue and cell type-specific vimentin knockout animals; by isolating primary cells from various tissues of these animals; and by analyzing gene expression patterns of Wt and the various mutant animals.