Abstract

Telomerase contributes to cell proliferation and survival through both telomere-dependent and telomere-independent mechanisms. In this report, we discovered that endoplasmic reticulum (ER) stress transiently activates the catalytic components of telomerase (TERT) expression in human cancer cell lines and murine primary neural cells. Importantly, we show that depletion of hTERT sensitizes cells to undergo apoptosis under ER stress, whereas increased hTERT expression reduces ER stress-induced cell death independent of catalytically active enzyme or DNA damage signaling. Our findings establish a functional link between ER stress and telomerase, both of which have important implications in the pathologies associated with aging and cancer.

Highlights

  • Telomerase contributes to cell proliferation and survival through both telomere-dependent and telomere-independent mechanisms

  • Human telomerase is a ribonucleoprotein enzyme complex that is minimally composed of a RNA component and the telomerase reverse transcriptase

  • The expression of hTERT was increased in MCF7 cells under different endoplasmic reticulum (ER) stress conditions (Fig. S1B). As another proof that hTERT protein levels are increased under ER stress, we showed that the telomerase enzymatic activity in vitro was increased (Figs 1C and S1C)

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Summary

Introduction

Telomerase contributes to cell proliferation and survival through both telomere-dependent and telomere-independent mechanisms. We sought to investigate the expression and function of telomerase in ER stress responses. In HeLa and MCF7 cells, treatment with thapsigargin (Tg) or ionomycin (In) induced ER stress responses characterized by increased specific expression of Bip, IRE1a, CHOP, and XBP-1 (Fig. 1A). We found that hTERT protein and hTERT mRNA expression was up-regulated 1 h after the Tg or In treatment, which decreased 8 h post-treatment (Figs 1A,B and S1A).

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