Role of hTERT in TRF1 homeostasis.
A, TRF1 protein stability in ALT cells expressing hTERT. Stable cell lines, GM847/hTERT and GM847/vector, were used for the protein stability assay after transfection with myc-PinX1 or an empty vector. Proteins were detected by immunoblotting. B, quantification of the data represented in A. Error bars represent S.D. from three independent experiments. C, TRF1 protein stability in hTERT and PinX1 co-depleted cells. Protein stability assay was performed with HeLa cells transfected with siRNA against hTERT (hTERTi) and PinX1 (PinX1i). PinX1 and TRF1 proteins were detected by immunoblotting. hTERT status was detected by quantitative RT-PCR, and the hTERT amount normalized with GAPDH in controli-treated cells at 0-h point was defined as 100%. D, quantification of the data represented in C. TRF1 level was semiquantified using β-actin as a loading control, and relative TRF1 levels at time 0 were defined as 100%. Error bars indicate the S.D. from three independent experiments.