ABSTRACT
Objective To characterize the effects of TPP1 knockdown on Pot1a and Pot1b localization at telomeres and on the telomere end protection.Methods Knockdown of endogenous TPP1 in mouse embryonic fibroblasts(MEFs) with the retrovirus vector encoding shRNA targeting TPP1,IF/PNA-FISH was performed to determine the localization of Pot1a and Pot1b at telomeres,and TdT-FITC was applied to characterize the effects on the function of telomere end protection,cellular senescence was analyzed by SA-beta gal staining,and phosphorylated p53ser18 and p21 were examined by Western blotting.Results Pot1a and Pot1b were unable to localize at telomeres in about 65% of MEFs with TPP1 knockdown,while that was found in less than 5% of MEFs without TPP1 knockdown(t=10.96,P