Forced expression of tropomyosin 2 or 3 in v-Ki-ras-transformed fibroblasts results in distinct phenotypic effects

Gimona, M., Kazzaz, J. A., Helfman, D. M. (1996) Forced expression of tropomyosin 2 or 3 in v-Ki-ras-transformed fibroblasts results in distinct phenotypic effects. Proceedings of the National Academy of Sciences, 93 (18). pp. 9618-23. ISSN 0027-8424 (Print)



Transformation of cells in tissue culture results in a variety of cellular changes including alterations in cell growth, adhesiveness, motility, morphology, and organization of the cytoskeleton. Morphological and cytoskeletal changes are perhaps the most readily apparent features of transformed cells. Although a number of studies have documented a decrease in the expression of specific tropomyosin (TM) isoforms in transformed cells, it remains to be determined if the suppression of TM synthesis is essential in the establishment and maintenance of the transformed pheno-type. To address the roles of different TM isoforms in transformed cells we have examined the effects of expressing specific TM isoforms in transformed cells using a Kirsten virus-transformed cell line (ATCC NRK1569) as a model system. In contrast to normal fibroblasts, the NRK 1569 cells contain reduced levels of TM-1 and undetectable levels of TM-2 and TM-3. These cells have a rounded morphology and are devoid of stress fibers. Employing expression plasmids for TM-2 and TM-3, stable cell lines were established from the NRK 1569 cells that express these isoforms individually. We demonstrate that expression of TM-2 or TM-3 leads to increased cell spreading accompanied by the formation of identifiable microfilament bundles, as well as significant restoration of well-defined vinculin-containing focal adhesion plaques, although expression of each isoform exhibited distinct properties. In addition, cells expressing TM-2, but not TM-3, exhibited contact-inhibited cell growth and a requirement for serum.

Item Type: Paper
Uncontrolled Keywords: Actins/metabolism Animals Cell Adhesion Cell Division Cell Line, Transformed Cell Transformation, Neoplastic Cytoskeleton/metabolism Fibroblasts/metabolism Fluorescent Antibody Technique, Indirect Genes, ras Microscopy, Phase-Contrast Phenotype Rats Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. Tropomyosin/biosynthesis/ physiology
Subjects: organs, tissues, organelles, cell types and functions > cell types and functions > cell functions
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > myosin
CSHL Authors:
Communities: CSHL labs > Helfman lab
Depositing User: Matt Covey
Date Deposited: 22 May 2014 18:44
Last Modified: 22 May 2014 18:44
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