Project Details
Projekt
Dissection of telomere-independent functions of nuclear and mitochondrial Telomerase Reverse Transcriptase ex vivo and in vivo
Subject Area
Cardiac and Vascular Surgery
Biogerontology and Geriatric Medicine
Biogerontology and Geriatric Medicine
Term
from 2012 to 2017
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 226386019
The enzyme telomerase plays a central role in aging processes. An essential component of the holoenzyme is its catalytic subunit telomerase reverse transcriptase (TERT). Besides its role in telomere maintenance it has additional non-telomeric functions also outside the nucleus. We could show that under physiological conditions TERT is found in the nucleus and the mitochondria and that nuclear as well as mitochondrial TERT convey protection against apoptosis. In addition, TERT is essential for the activity of the respiratory chain, which could result from its binding to mitochondrial DNA and protecting it from damaging exogenous influences. Furthermore, TERT seems to be involved in reducing cellular reactive oxygen species (ROS), which are known to increase during aging. In model systems for the influence of physical activity on aging processes we could show that TERT can suppress senescence in a telomere-independent fashion. A drawback of all previous analyses is the expression of TERT in nearly all cell-types and the use of completely TERT-deficient animals and tissues, which makes it impossible to differentiate between the functions of TERT in the nucleus and in the mitochondria. The goal of the projected studies is to discriminate for the first time between nuclear and mitochondrial functions of TERT ex vivo and in vivo. For this purpose we will on one hand equip primary cells from the cardiovascular system of TERT-deficient animals or cell lines derived from these with transgenes encoding TERT fusion proteins, which are exclusively transported to the nucleus or the mitochondria. These cells will be subjected to stimuli, which are known as cardiovascular risk factors, to determine the influence of TERT in the different cellular compartments on mitochondrial function and ROS production as well as on the protection against apoptosis and senescence. For in vivo studies we generated transgenic mice ubiquitously expressing the same TERT fusion proteins. We will backcross them onto a TERT-deficient genetic background to obtain animals containing TERT exclusively in the nucleus or the mitochondria. To be able to study telomere-independent TERT functions, we have devised a breeding strategy to avoid aging phenomena evoked by telomere erosion. A comprehensive phenotyping on the whole animal and organ level in comparison with wildtype and TERT-deficient littermates will show which functions mitochondrial and nuclear TERT have in aging processes. In addition, we will study regeneration processes compromised with age and the influence of organelle-specific TERT on the positive, "anti-aging" effects of physical exercise. Overall, the projected studies will for the first time uncover unknown facets of telomere-independent TERT functions in the nucleus and mitochondria.
DFG Programme
Research Grants
