Biosynthesis of fibronectin by human embryonal fibroblasts transformed by SV-40 virus

• Published in: Biokhimiia (Moscow, Russia) Vol. 51; no. 4; p. 596
• Main Authors: Belkin, V M, Volodarskaia, S M, Mazurov, V I
• Format: Journal Article
• Language: Russian
• Published: Russia (Federation) 01.04.1986
• Subjects: Cell Line; Cell Transformation, Viral; Cell-Free System; Electrophoresis, Polyacrylamide Gel; Embryo, Mammalian; Fibroblasts - metabolism; Fibroblasts - microbiology; Fibronectins - biosynthesis; Humans; Methionine - metabolism; Simian virus 40
• ISSN: 0320-9725

Fibronectin biosynthesis by human embryonic fibroblasts transformed with virus SV-40 was studied in intact cells and in a cell-free protein synthesizing system on free and membrane-bound polyribosomes isolated from these cells. It was found that fibronectin release from transformed fibroblasts into the culturing medium was decreased 4.5-fold, while its per cent content--2-fold. The amount of fibronectin precipitated by antibodies in the course of an immunoprecipitation reaction in transformed cells appeared to be somewhat higher than in normal cells, although when expressed on a per cent basis this content was decreased only 1.5-fold. However, the content of fibronectin monomer with Mr = 220 kD exceeded that in normal fibroblast cell material 1.6 times. Study on fibronectin biosynthesis in a cell-free system revealed that in transformed cells 45% of fibronectin is synthesized on free polyribosomes as compared to 13% in normal fibroblasts. It is assumed that the decreased fibronectin biosynthesis in human fibroblasts transformed with virus SV-40 results in spatial uncoupling of polyribosomes and membrane structures responsible for protein transport from the cell, as a result of which a significant part of fibronectin synthesized by transformed fibroblasts undergoes intracellular degradation.