FIGURE 2.

TLP prolongs the duration of p53 activation upon UV irradiation. A, shTLP-expressing HCT116 cells were exposed to the indicated doses of UV light and incubated for 36 h. Amounts of indicated transcripts were determined for each gene by RT-qPCR (mean ± S.D.). B, left, HCT116 cells expressing shTLP were exposed to 50 J/m² of UV light and harvested every 4 h. p53, Lys-382-acetylated p53 (Ac-382), MDM2, and p21 in whole cell lysates were detected. Right, p53, p21, and TLP proteins shown in the upper figures of panel B were quantified (means ± S.E.). *, p < 0.05; **, p < 0.01 (p53 and p21, Welch's t test; TLP, Tukey's honestly significant difference test). C, shTLP-expressing HCT116 cells were exposed to UV light and harvested every 8 h. Transcripts were determined by RT-qPCR (mean ± S.E.). D, TLP-depleted HCT116 cells were exposed to UV light and harvested every 16 h. Then chromatin-bound p53 was immunoprecipitated with anti-p53 antibody, and the sequences of the p21, PUMA, and MDM2 promoters were determined by qPCR (mean ± S.E.). E, HCT116 cells were transfected with the FH-TLP expression vector and exposed to UV light for 36 h. Chromatin-bound TLP was immunoprecipitated with anti-FLAG antibody, and the sequences of the p21, PUMA, and MDM2 promoters were determined by qPCR (mean ± S.E.).