Transfection of a Temperature Sensitive V-MOS Oncogene in Chinese Hamster Ovary Cells
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The viral mos oncogene derived from the Moloney murine sarcoma virus, is capable of forming cancerous tumors in suitable animal tissues. The Chinese hamster ovary cell line has been used to study v-mos protein kinase activity in vitro. One significant effect of v-mos transfection into Chinese hamster ovary cells is the increased presence of a 25 kilodalton phosphoprotein. The object of this study was to use a temperature sensitive cell line to induce the activity of the v-mos gene and correlate the phosphorylation of the 25 kilodalton protein with v-mos expression. A temperature sensitive v-mos gene was used to study v-mos expression and the phosphorylation of the 25 kilodalton phosphoprotein. By using a temperature sensitive gene, the expression of the v-mos oncogene could be suppressed and then reinstated. The temperature sensitive 159 neo (ts159neo) plasmid was transfected into both the wild type and a mutant (10248) cell line deficient in cyclic AMP-dependent protein kinase activity. The morphology, growth rates, and 8-bromo-cyclic AMP sensitivity were determined for each of the clones at both the permissive (32°C) and nonpermissive (39°C) temperatures for v-mos expression. One and two dimensional gel electrophoresis procedures were used to determine the presence of the 25 kilodalton phosphoprotein at both temperatures. One clone (10248 3D1) was found to be temperature sensitive in the phosphorylation of the 25 kilodalton protein. These results suggest that the v-mos oncogene may be acting directly to phosphorylate the 25 kilodalton protein.