Acute telomerase components depletion triggers oxidative stress as an early event previous to telomeric shortening
José Santiago Ibáñez-Cabellos,
Giselle Pérez-Machado,
Marta Seco-Cervera,
Ester Berenguer-Pascual,
José Luis García-Giménez,
Federico V. Pallardó
Affiliations
José Santiago Ibáñez-Cabellos
Center for Biomedical Network Research on Rare Diseases (CIBERER), Institute of Health Carlos III, Valencia, Spain; Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain; INCLIVA Biomedical Research Institute, Valencia, Spain
Giselle Pérez-Machado
Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain; INCLIVA Biomedical Research Institute, Valencia, Spain
Marta Seco-Cervera
Center for Biomedical Network Research on Rare Diseases (CIBERER), Institute of Health Carlos III, Valencia, Spain; Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain; INCLIVA Biomedical Research Institute, Valencia, Spain
Ester Berenguer-Pascual
Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
José Luis García-Giménez
Center for Biomedical Network Research on Rare Diseases (CIBERER), Institute of Health Carlos III, Valencia, Spain; Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain; INCLIVA Biomedical Research Institute, Valencia, Spain; Corresponding authors at: University of Valencia, Faculty of Medicine and Dentistry, Department of Physiology, Av/ Blasco Ibañez, 15, Valencia E46010, Spain.
Federico V. Pallardó
Center for Biomedical Network Research on Rare Diseases (CIBERER), Institute of Health Carlos III, Valencia, Spain; Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain; INCLIVA Biomedical Research Institute, Valencia, Spain; Corresponding authors at: University of Valencia, Faculty of Medicine and Dentistry, Department of Physiology, Av/ Blasco Ibañez, 15, Valencia E46010, Spain.
Loss of function of dyskerin (DKC1), NOP10 and TIN2 are responsible for different inheritance patterns of Dyskeratosis congenita (DC; ORPHA1775). They are key components of telomerase (DKC1 and NOP10) and shelterin (TIN2), and play an important role in telomere homeostasis. They participate in several fundamental cellular processes by contributing to Dyskeratosis congenita through mechanisms that are not fully understood. Presence of oxidative stress was postulated to result from telomerase ablation. However, the resulting disturbed redox status can promote telomere attrition by generating a vicious circle, which promotes cellular senescence. This fact prompted us to study if acute loss of DKC1, NOP10 and TINF2 can promote redox disequilibrium as an early event when telomere shortening has not yet taken place. We generated siRNA-mediated (DKC1, NOP10 and TINF2) cell lines by RNA interference, which was confirmed by mRNA and protein expression analyses. No telomere shortening occurred in any silenced cell line. Depletion of H/ACA ribonucleoproteins DKC1 and NOP10 diminished telomerase activity via TERC down-regulation, and produced alterations in pseudouridylation and ribosomal biogenesis. An increase in the GSSG/GSH ratio, carbonylated proteins and oxidized peroxiredoxin-6 was observed, in addition to MnSOD and TRX1 overexpression in the siRNA DC cells. Likewise, high PARylation levels and high PARP1 protein expression were detected. In contrast, the silenced TINF2 cells did not alter any evaluated oxidative stress marker. Altogether these findings lead us to conclude that loss of DKC1 and NOP10 functions induces oxidative stress in a telomere shortening independent manner. Keywords: Aging, Oxidative stress, Antioxidant, Telomeropathies, DNA damage
