Effect of temperature on normal and SV40-transformed human fibroblasts

The effect of a temperature shift from low (36 degrees C) to high (40 degrees C) temperature on human fibroblasts (IMR90) at various population doubling levels and IMR90 cells transformed by SV40 virus infection at a population doubling level of 30 (SV40/IMR90) was examined. Both IMR90 and SV40/IMR90 cells showed a decrease in cell saturation density at confluency, whereas an increase in population doubling time and protein content was noted when the cells were shifted up to 40 degrees C from 36 degrees C. The modification of IMR90 chromosomal proteins by arginyl-tRNA transferase was increased by the temperature shift, whereas NH2-terminal arginylation of SV40/IMR90 chromatin was not altered. Similarly, no appreciable change in 2-deoxyglucose uptake was noted with SV40/IMR90 cells at either temperature, although 2-deoxyglucose uptake by IMR90 cells was increased by the temperature shift. Additionally, the rate of 2-deoxyglucose uptake showed no difference between IMR90 and SV40/IMR90 cells. The above results support previous findings that environmental alterations, such as temperature shift can cause acceleration of cellular senescence. These findings also imply that cellular senescence remains fixed when viral transformation occurs and is rendered refractory to further age-associated alterations.