Development of a cellular model with mutations in the ERCC2/XPD (TTD) and ADH5 genes, contributing to the understanding of the genotoxic effects of formaldehydes.

• Grant number: 25/07480-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Carlos Frederico Martins Menck
• Grantee: Mylena Bevilcqua Nogueira
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/19435-3 - The role of DNA damage and mitochondrial function in vascular, immune and neurological ageing (DNA MoVINg), AP.TEM

Abstract

The DNA molecule is susceptible to various damages induced by exogenous and endogenous sources within the organism. In this context, to maintain genomic stability, DNA repair mechanisms, such as the nucleotide excision repair (NER) mechanism, act by removing these lesions. The NER pathway removes bulky lesions in the DNA molecule through two sub-pathways: transcription-coupled repair (TCR) and global genome repair (GGR), which converge after the recruitment of the TFIIH complex. The first is related to the repair in differentiated cells and thus plays a more significant role in removing DNA lesions in somatic cells. Dysfunction of the NER pathway due to mutations in genes encoding proteins involved in repair can lead to dysfunctions in the organism, giving rise to genetic diseases such as trichothiodystrophy (TTD). TTD is associated with mutations in the XPD helicase, which is part of the TFIIH complex and functions in unwinding the DNA helix during lesion repair. Patients with TTD exhibit symptoms such as brittle hair (due to sulfur deficiency), UV light sensitivity, and development impairment, which results in short stature, intellectual disability, low fertility and other systems of premature aging. The accumulation of bulky lesions in the DNA molecule that block transcription has been linked to the development of neurological problems in TTD. However, the source of endogenous DNA damage remains uncertain, with a possible candidate being formaldehyde (FA), an endogenous product of the cellular metabolism. Interestingly, FA has been associated with bulky DNA damage that causes transcription blockage, and thus, these lesions may be repaired by TCR. Additionally, the cell has other FA detoxification mechanisms, including the enzyme aldehyde dehydrogenase 5 (ADH5). Thus, based on preliminary results obtained by our group, this study aims to construct a model of TTD cells knockout cells for the ADH5 gene, by editing with CRISPR-Cas9.