Molecular Mechanisms of Cell Adhesion

点击翻译按钮获取中文摘要

Program Summary This Maximizing Investigators’ Research Award (MIRA) proposal is directly relevant to the long-range plans of the National Institute of General Medical Sciences (NIGMS). Our laboratory received continuous NIGMS funding since 2004 that allowed us to make substantial advances in our understanding of the mechanisms of the dynamic contacts between neighboring cells (adherens junctions), as well as between cells and the extracellular matrix (focal adhesions structures). These cell junctions, in addition of holding animal cells together, communicate signals and control the stress placed upon cells. Over the past 16 years, we contributed important mechanistic discoveries towards an understanding of · how the cell-cell junctions connect cells in tissues to regulate tissue homeostasis that are crucial to provide the tissue barrier of epithelia, as well as cell migration and proliferation; and · how cell junctions initiate and maintain cell adhesion while regulating the organization of the underlying actin cytoskeleton by establishing a center for cell signaling and gene transcript regulation. Such processes are highly dynamic and tightly regulated. Our laboratory focused on defining the activation mechanisms of key regulators of these cell junctions that we studied biochemically and in live cells. Our discoveries were accelerated by our development of new techniques that overcame significant structural biology hurdles that stalled the field and that are applicable to many other structural biology studies. We discovered how talin activates vinculin, two ubiquitously expressed, actin-binding proteins, to stabilizes focal adhesions and thereby suppressing cell migration. Our high-resolution vinculin crystal structures, that we confirmed biochemically and in live cells, showed the auto-inhibitory intramolecular interactions that inactivate vinculin and thereby prevent vinculin from binding to the actin cytoskeleton. On the other hand, our high-resolution crystal structures of a-catenin, a crucial mediator of intercellular adhesions, revealed the mechanistic roles that its quaternary structures play in cell-cell adhesion and in the formation of the dynamic link to the actin cytoskeleton. Significantly, our discoveries led to mechano- transduction studies of cell-cell and cell-matrix junctions on how cells sense and transmit forces. More recently, we discovered how lipid binding to vinculin, to its cardiac isoform metavinculin, and to talin regulates focal adhesion turnover. This knowledge and expertise are the foundation for further discoveries that will additionally focus on the understudied role that the plasma membrane plays in cell adhesion. In the long run, we hope to gain a complete understanding of cell adhesion by attaining a near atomic structure of a “synthetic” cell junction. The regulation and dysregulation of cell junctions are fundamental to many biological processes such as development and cancer, and our proposed studies have therefore both basic and potentially translational significance.