Fig. 5.

HSF1 interacts with BMAL1 during UV-triggered clock synchronization. a, b NIH3T3 cells were stimulated with UV irradiation (10 J m⁻²) and sampled at 2 or 4 h after stimulation. Samples were immunoprecipitated with either the anti-BMAL1 or anti-HSF1 antibody and immunoblotted with an antibody against the target protein indicated in the figure. Representative images of four independent experiments (a, n = 4 for the IP-HSF1 experiment and n = 5 for the IP-BMAL1 experiment) are shown. See Supplementary Figure 15 for full-size blot images. Quantification of the band intensity of the coimmunoprecipitation assay (b). Values were normalized to the band intensity of β-actin from each corresponding sample and further normalized to the band intensity of the non-irradiated sample. c–e Wild-type and BMAL1−/− MEFs harboring the HSE-SLR reporter were exposed to UV stimulation. The temporal profiles of the reporter luminescence signal for the representative sample of each stimulation condition for wild-type (c) and BMAL1−/− MEFs (d). Quantification of the peak intensity for each profile. Values were normalized to that of the unstimulated sample (e). n = 3. f–h Wild-type and BMAL1−/− MEFs harboring the p53RE-Luc reporter were exposed to UV stimulation. The temporal profiles of the reporter luminescence signal for the representative sample of each stimulation condition for wild-type (f) and BMAL1−/− MEFs (g). Quantification of the peak intensity for each profile (h). Values were normalized to that of the unstimulated sample. n = 3. i Cell viability of wild-type, BMAL1−/−, HSF1−/−, and p53−/− MEFs 36 h after different levels of UV exposure. Cell viability was calculated from trypan blue staining. n = 3. For all data. *p < 0.05 and ns: not significant (p > 0.05), from a two-tailed t-test except for i. For i, *p < 0.05, two-tailed t-test for the comparison between non-irradiated and irradiated samples; ^†p < 0.05, two-tailed t-test for the comparison between wild-type MEFs and null mutants. Not significant (p > 0.05) unless indicated