Figure 4. The effect of XHSF1 shRNAs on the HSR.

(A,B) Reporter gene analysis of (A) the effect of HSF1 shRNAs expressed from the human or Xenopus H1 promoter, and (B) the effect of different shRNAs expressed from the Xenopus H1 promoter, on the HSR. A6 cells were transfected with mixtures of an Hsp70-luciferase reporter, a CMV-β-galactosidase reporter and the indicated plasmids. Relative luciferase activities and -fold induction were determined as described in the legend to fig. 2C. The results are the average of three independent transfections (standard deviations are indicated by error bars). (B) Western blot analysis of Hsp90 levels in tadpoles carrying the indicated transgenes. Lysates were made from whole tadpoles before heat shock (C) or after a 1 h heat shock at 33°C followed by 6 h recovery at room temperature (HS). The lysates were subjected to SDS-PAGE and western blot analysis using anti-Hsp90 and anti-tubulin antibodies.