Fig. 4: LARP3 plays a negative role in telomerase biogenesis.

a Western blots of cell extracts prepared from 293 T cells treated with either shRNA targeting LARP3 or transfected with an LARP3 plasmid. Endogenous tubulin served as a loading control. b, c Total RNA from 293 T cells treated with either shRNA targeting LARP3 (b) or transfected with an LARP3 plasmid (c) was subjected to qRT‒PCR for total hTR, 3′-extended hTR, GAPDH, ATP5β, and HPRT. Bar graph of the mean fold change in the hTR level relative to that of the control samples normalized to that of GAPDH, ATP5β, and HPRT. The mean values +/− SEMA were calculated from triplicate qRT‒PCR experiments of three biological replicates. Dots represent data points from individual experiments. The significance of changes between samples was calculated with a two-sided Student’s t test; *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.001. d Western blotting analysis of telomerase assembled on biotin-labelled hTR in the indicated extracts, followed by pulldown with streptavidin beads for the indicated times. e LARP3 was immunoprecipitated from cell extracts prepared from 293T cells either treated with shRNA targeting LARP3 or transfected with an LARP3 plasmid and subjected to a telomerase activity assay. f, g The in vitro 3′ end processing assay with ³²P-labelled hTR fragments was carried out in cell extracts prepared from 293T cells either treated with either shRNA targeting LARP3 (f) or transfected with an LARP3 plasmid (g) at 37 °C for the indicated times. RNA was resolved on a 6% polyacrylamide gel containing 8 M urea. Actin served as the loading control. The mean values +/− SD were calculated from triplicate experiments of three technical replicates. Dots represent data points from individual experiments. The significance was calculated with a two-sided Student’s t test; *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.001. Source data are provided as a Source data file.