   Confocal fluorescence microscopy of actin filaments in NIH 3T3 fibroblasts visualized by expression of tropomyosin 2 tagged with green fluorescent protein (GFP-TM2). Image overlay of the green label (GFP-TM2) and the red label (actin filaments revealed by phaloidin conjugated to Texas Red). The overlap between the two labels appears as yellow. |
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David Helfman Professor Ph.D., Emory University, 1981 Cytoskeleton; transformation; signal transduction; gene regulation email helfman@cshl.edu, phone (516) 367-8838, fax (516) 367-8815
Our laboratory studies the expression, structure, and function of cytoskeletal components in normal and transformed cells. We are interested in how specific actin assemblies are organized and regulated and how alterations in actin filament assembly contribute to aberrant cell growth. Actin filaments play an important role in cell movements, muscle contraction, cell division, intracellular transport, and regulation of cell shape and adhesion. Eukaryotic cells contain three major filamentous systems involved in cytoskeletal structure: actin filaments, intermediate filaments, and microtubules. Each of these filamentous systems contains several different protein components, although different cell types and tissues express specific protein isoforms that make up these structures. Within a given cell type, such as a fibroblast, distinct actin structures are organized (e.g., contractile ring, stress fibers, filopodia, and lamellopodia). These distinct actin assemblies appear to form by the combination of different structural components. We are studying dynamic and stable macromolecular assemblies that are characteristic of specific cell types (e.g., stress fibers, contractile ring, and filopodia in fibroblasts or sarcomeres in skeletal muscle) to determine which components are required for the assembly and regulation of specific structures. We are also investigating how the assembly of different cytoskeletal structures is regulated by extracellular signals, and how cellular contractility contributes to signaling cascades that lead to focal adhesion formation and regulation of adhesion-dependent signaling. Selected PublicationsHelfman, D.M., E.T. Levy, C. Berthier, M. Shtutman, D. Riveline, I. Grosheva, A. Lachish-Zalait, M. Elbaum, and A.D. Bershadsky. 1999. Caldesmon inhibits nonmuscle cell contractility and interferes with the formation of focal adhesions. Mol. Biol. Cell 10: 3097–3112. Pawlak, G. and D.M. Helfman. 2001. Cytoskeletal changes in cell transformation
and tumorigenesis. Curr. Opin. Genet. Dev. 11: 41–47. |
