FIGURE 6.

Mortalin interacts with telomerase, leading to activation of its function. A, Western blotting of hTERT showing a higher level of hTERT expression in mot-N cells. B, telomere repeat amplification protocol assay showing activation of telomerase in mot-F and mot-N cells. U2OS (an alternative lengthening of telomeres cell line) and MRC5 cells transfected with hTERT were used as negative and positive controls, respectively. C, coimmunoprecipitation of mortalin and hTERT in which hTERT complexes were examined for the presence of mortalin. The latter was seen to coimmunoprecipitate with hTERT both in the whole cell lysates and the nuclear fractions of malignantly transformed cells. D, immunodepletion of hTERT by repeated immunoprecipitation (bottom panel, lanes 1–4) of hTERT from cell lysates revealed a decrease in mortalin both in mot-F and mot-N cells. Irrelevant IgG immunoprecipitation used as a control did not show a decrease in mortalin in serial immunodepletion rounds (top panel, lanes 1–4).