Regulation of protein synthesis in HeLa cells: Translation at elevated temperatures

Abstract

When HeLa cells are incubated at 42 °C, the rate of amino acid incorporation decreases, and extensive polyribosome disaggregation occurs. An early function in translation is shown to be rate limiting at the elevated temperature and is the cause of polyribosome disaggregation. Further incubation at 42 °C results in a partial recovery in the number of functioning ribosomes and the rate of amino acid incorporation. This recovery is shown to be dependent upon RNA synthesis but not protein synthesis. A response of cells to a prolonged incubation at 42 °C appears to be the production of a species of RNA which promotes the association of ribosomes with messenger RNA. This factor may be produced in response to reduced protein synthesis. Inhibition of protein synthesis at normal temperature with actidione results in an effect similar to that caused by prolonged incubation at 42 °C. An RNA factor is produced which appears to promote the association of ribosomes with messenger RNA. The kinetics of production and decay of the factor induced by actidione pretreatment indicate an approximate half-life of one hour.