Human Smooth-Muscle Myosin Light Chain-2 Gene Expression Is Repressed in Ras Transformed Fibroblast Cells

Kumar, C. C., Chang, C. (January 1992) Human Smooth-Muscle Myosin Light Chain-2 Gene Expression Is Repressed in Ras Transformed Fibroblast Cells. Cell Growth & Differentiation, 3 (1). pp. 1-10. ISSN 1044-9523

Abstract

We have previously characterized human smooth muscle myosin light chain (MLC) -2 isoform by complementary DNA cloning and have shown that this isoform is expressed in a number of nonmuscle cells such as fibroblast cells. In this report, we show that when human osteosarcoma derived clonal cells (TE 85 clone F-5) (HOS), which are immortalized and nontumorigenic, undergo transformation following infection by Kirsten murine sarcoma virus (K-HOS) or by a chemical carcinogen [N-methyl-N-nitro-N-nitrosoguanidine (MNNG-HOS)], the smooth muscle MLC-2 mRNA is repressed. Revertants of transformed K-HOS cells (K-HOS312H) show normal levels of smooth muscle MLC-2 mRNA. Transformation of HOS cells by Ha-ras oncogene sequences, either by retroviral infection or by transfection followed by selection for tumorigenic cells in nude mice, results in complete repression of smooth muscle MLC-2 mRNA level. Treatment of HOS cells with tumor promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, results in repression of smooth muscle MLC-2 mRNA. Smooth muscle MLC-2 mRNA level is repressed in many, but not all, transformed cell lines, suggesting that it is not an indirect consequence of transformation but is specific to the agent that brings about transformation. HOS cells synthesize three MLC-2 protein species resolved by the two-dimensional gel electrophoretic system. The identity of the smooth muscle MLC-2 isoform was established by coelectrophoresis of the in vitro synthesized MLC-2 protein corresponding to the cloned complementary DNA in the two-dimensional gel system along with total [S-35]methionine labeled HOS cell proteins. Quantitative analysis of MLC-2 isoforms in different HOS cells indicates that the synthesis of smooth muscle MLC-2 isoform is specifically repressed to an undetectable level in ras transformed and MNNG transformed cells and also following treatment with 12-O-tetradecanoylphorbol-13-acetate.

Item Type:	Paper
Uncontrolled Keywords:	MURINE SARCOMA-VIRUS HUMAN OSTEOSARCOMA CELLS CHEMICAL CARCINOGEN CELLULAR ONCOGENES EMBRYO FIBROBLASTS TUMOR PROMOTERS PROTEINS TROPOMYOSIN CULTURE GROWTH
Subjects:	organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > myosin bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > G protein > Ras
CSHL Authors:	Chang, Cecile
Communities:	CSHL labs
Depositing User:	Matt Covey
Date:	January 1992
Date Deposited:	01 Oct 2015 14:10
Last Modified:	01 Oct 2015 14:10
Related URLs:	Publisher
URI:	https://repository.cshl.edu/id/eprint/31783

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