Non-canonical functions of Telomerase Reverse Transcriptase – Impact on redox homeostasis

Telomerase consists of the catalytic subunit Telomerase Reverse Transcriptase (TERT) and the Telomerase RNA Component. Its canonical function is the prevention of telomere erosion. Over the last years it became evident that TERT is also present in tissues with low replicative potential. Important non-canonical functions of TERT are protection against apoptosis and maintenance of the cellular redox homeostasis in cancer as well as in somatic tissues. Intriguingly, TERT and reactive oxygen species (ROS) are interdependent on each other, with TERT being regulated by changes in the redox balance and itself controlling ROS levels in the cytosol and in the mitochondria. The latter is achieved because TERT is present in the mitochondria, where it protects mitochondrial DNA and maintains levels of anti-oxidative enzymes. Since numerous diseases are associated with oxidative stress, increasing the mitochondrial TERT level could be of therapeutic value. •Telomerase Reverse Transcriptase has non-canonical functions.•Telomerase Reverse Transcriptase is also present in mitochondria.•Localization of Telomerase Reverse Transcriptase depends on phosphorylation.•Telomerase Reverse Transcriptase and reactive oxygen species are interdependent.