Telomerase Reverse Transcriptase (TERT) has, besides its task in telomere-preservation, also non-telomeric functions. It is well accepted that TERT is present in the nucleus as well as in the mitochondria of post-mitotic cells and that it has protective functions in both organelles. Under certain conditions, it is exported from the nucleus with a concomitant increase in the mitochondria. Up to now it is unclear, if the same TERT molecules that leave the nucleus enter the mitochondria. Combining the unique expertises and methods of the biophysicist Valentin Borshchevskiy from the Moscow Institute of Physics and Technology (MIPT) and us will allow for the first time to follow existing TERT molecules in single cells, also under conditions relevant for cellular senescence, aging and age-related diseases. One aim of this project is to track already existing TERT molecules fused to the photoconvertible Dendra2 protein, which after irradiation changes its fluorescence properties and can thereby be distinguished from newly synthesized molecules, in living cells. The above-described increase in mitochondrial TERT suggests that this protein affects intra-mitochondrial processes at various levels. Since TERT, the Mitochondrial Transcription Factor A and Manganese Superoxide Dismutase can associate with mitochondrial DNA, we will investigate their interaction by Förster Resonance Energy Transfer, Single Molecule Localization Microscopy and immunoprecipitation. Finally, we will treat cardiomyocytes and cardiac fibroblasts with stimuli relevant for cellular senescence, aging and age-related diseases and follow TERT travel by life cell imaging and biochemical approaches. On the functional side, we will measure respiration, apoptosis, hypertrophy, senescence and myofibroblast differentiation potential. This project will for the first time shed light on the dynamic distribution of existing TERT molecules and its cellular consequences in senescence, aging and age-related diseases.
- Spannbrucker, T., Ale-Agha, N., Goy, C., Dyballa-Rukes, N., Jakobs, P., Jander, K., Altschmied, J., Unfried, K., and Haendeler, J. (2019) Induction of a senescent like phenotype and loss of gap junctional intercellular communication by carbon nanoparticle exposure of lung epithelial cells. Exp Gerontol 117, 106-112.
- Czypiorski P*, Altschmied J*, Rabanter LL, Goy C, Jakob S, Haendeler J. Outfielders playing in the infield: functions of aging-associated "nuclear" proteins in the mitochondria. Curr Mol Med. 2014;14:1247-1251. (*equal contribution)
- Büchner N, Ale-Agha N, Jakob S, Sydlik U, Kunze K, Unfried K, Altschmied J, Haendeler J. Unhealthy diet and ultrafine carbon black particles induce senescence and disease associated phenotypic changes. Exp Gerontol. 2013;48:8-16.
- Haendeler J#, Dröse S, Büchner N, Jakob S, Altschmied J, Goy C, Spyridopoulos I, Zeiher AM, Brandt U, Dimmeler S. Mitochondrial telomerase reverse transcriptase binds to and protects mitochondrial DNA and function from damage. Arterioscler Thromb Vasc Biol. 2009;29:929-935. (#first and corresponding author)
- Haendeler J, Hoffmann J, Diehl JF, Vasa M, Spyridopoulos I, Zeiher AM, Dimmeler S. Antioxidants inhibit nuclear export of telomerase reverse transcriptase and delay replicative senescence of endothelial cells. Circ Res. 2004;94:768-775.
- Haendeler J, Hoffmann J, Brandes RP, Zeiher AM, Dimmeler S. Hydrogen peroxide triggers nuclear export of telomerase reverse transcriptase via Src kinase family-dependent phosphorylation of tyrosine 707. Mol Cell Biol. 2003;23:4598-4610.