From genetics to epigenetics to unravel the etiology of adolescent idiopathic scoliosis.

Scoliosis is defined as the three-dimensional (3D) structural deformity of the spine with a radiological lateral Cobb angle (a measure of spinal curvature) of ≥10° that can be caused by congenital, developmental or degenerative problems. However, those cases whose etiology is still unknown, and affect healthy children and adolescents during growth, are the commonest form of spinal deformity, known as adolescent idiopathic scoliosis (AIS). In AIS management, early diagnosis and the accurate prediction of curve progression are most important because they can decrease negative long-term effects of AIS treatment, such as unnecessary bracing, frequent exposure to radiation, as well as saving the high costs of AIS treatment. Despite efforts made to identify a method or technique capable of predicting AIS progression, this challenge still remains unresolved. Genetics and epigenetics, and the application of machine learning and artificial intelligence technologies, open up new avenues to not only clarify AIS etiology, but to also identify potential biomarkers that can substantially improve the clinical management of these patients. This review presents the most relevant biomarkers to help explain the etiopathogenesis of AIS and provide new potential biomarkers to be validated in large clinical trials so they can be finally implemented into clinical settings.

Oxidative Stress and the Epigenetics of Cell Senescence: Insights from Progeroid Syndromes.

BACKGROUND: Cell senescence constitutes a critical process to respond to a variety of insults and adverse circumstances. Senescence involves the detention of DNA replication and cell proliferation, and hence, genetic programs associated with DNA damage response, chromosome stability, chromatin rearrangement, epigenetic reprogramming, and cell cycle are tightly linked to the senescent phenotype. Although senescence increases with age, the real implication of senescence regulation in the progress of aging in humans is largely discussed. In this context, reactive oxygen species (ROS) accumulation has also been postulated to play a critical role in cell homeostasis, aging processes, and control of proliferation. METHODS: The previous years have produced a high increase in data that refine our understanding of the role of ROS, and their relationship with epigenetic events, in determining cellular fate. RESULTS: The accumulating evidence regarding the epigenetic regulation of ROS-mediated processes provides promising tools to deepen in our comprehension of the process of senescence, and to develop novel therapeutic strategies. In this review, we aim to provide an overview of the relationships between oxidative stress and cell senescence. CONCLUSION: We provide information about the role of epigenetic regulation in senescence and aging, collecting recent data from some examples of progeroid syndromes in which cell senescence, oxidative stress and epigenetic mechanisms are severely impaired. Finally, a collection of data is presented regarding current pharmacological approaches that either target or use oxidative stress-related factors or epigenetic regulators as strategies for disease treatment.

Acute telomerase components depletion triggers oxidative stress as an early event previous to telomeric shortening.

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.

Cellular Responses in Human Dental Pulp Stem Cells Treated with Three Endodontic Materials.

Human dental pulp stem cells (HDPSCs) are of special relevance in future regenerative dental therapies. Characterizing cytotoxicity and genotoxicity produced by endodontic materials is required to evaluate the potential for regeneration of injured tissues in future strategies combining regenerative and root canal therapies. This study explores the cytotoxicity and genotoxicity mediated by oxidative stress of three endodontic materials that are widely used on HDPSCs: a mineral trioxide aggregate (MTA-Angelus white), an epoxy resin sealant (AH-Plus cement), and an MTA-based cement sealer (MTA-Fillapex). Cell viability and cell death rate were assessed by flow cytometry. Oxidative stress was measured by OxyBlot. Levels of antioxidant enzymes were evaluated by Western blot. Genotoxicity was studied by quantifying the expression levels of DNA damage sensors such as ATM and RAD53 genes and DNA damage repair sensors such as RAD51 and PARP-1. Results indicate that AH-Plus increased apoptosis, oxidative stress, and genotoxicity markers in HDPSCs. MTA-Fillapex was the most cytotoxic oxidative stress inductor and genotoxic material for HDPSCs at longer times in preincubated cell culture medium, and MTA-Angelus was less cytotoxic and genotoxic than AH-Plus and MTA-Fillapex at all times assayed.