Heat shock response in Chinese hamster (DHFR/sup -/) cells transfected with mouse DHFR and drosophila HSP70 genes

In order to understand the role of the M/sub r/ = 70,000 heat shock protein (hsp70) in mammalian cells in response to heat shock, the authors transfected CHO-DHFR/sup -/ cells with the recombinant vectors pSV2-DHFR (cell lines G and M) or with pSV2-DHFR-hsp70 (cell lines H and L). Both vectors express the DHFR gene, with the latter vector containing all the regulatory, coding and termination sequences for the gene coding for hsp70 from Drosophila melanogaster. The parental cell line (CHO-DHFR/sup -/) shows the induction of several hsps (including hsp70, hsp 68 and hsp110) after a 450C heat shock. Some transfected cell lines (M and L) showed a reduced level of hsp110 and failed to show any detectable hsp68 synthesis after a 450C heat shock. A non-tranfected, methotrexate-resistant CHO cell line that expresses high DHFR activity also fails to express or shows very reduced levels of hsp68 after a heat shock. The authors also tranfected cells (G and H) that do express hsp68 and hsp110 after a heat shock. They are currently investigating the effects of hsp68 and DHFR expression on growth and thermotolerance in these cell lines. The authors conclude that there are sequences present in the vector pSV2-DHFR (possibly the DHFR gene) that may be involved in hsp68 expression