title: Sunlight damage to cellular DNA: Focus on oxidatively generated lesions.
abstract: The routine and often unavoidable exposure to solar ultraviolet (UV) radiation makes it one of the most significant environmental DNA-damaging agents to which humans are exposed. Sunlight, specifically UVB and UVA, triggers various types of DNA damage. Although sunlight, mainly UVB, is necessary for the production of vitamin D, which is necessary for human health, DNA damage may have several deleterious consequences, such as cell death, mutagenesis, photoaging and cancer. UVA and UVB photons can be directly absorbed not only by DNA, which results in lesions, but also by the chromophores that are present in skin cells. This process leads to the formation of reactive oxygen species, which may indirectly cause DNA damage. Despite many decades of investigation, the discrimination among the consequences of these different types of lesions is not clear. However, human cells have complex systems to avoid the deleterious effects of the reactive species produced by sunlight. These systems include antioxidants, that protect DNA, and mechanisms of DNA damage repair and tolerance. Genetic defects in these mechanisms that have clear harmful effects in the exposed skin are found in several human syndromes. The best known of these is xeroderma pigmentosum (XP), whose patients are defective in the nucleotide excision repair (NER) and translesion synthesis (TLS) pathways. These patients are mainly affected due to UV-induced pyrimidine dimers, but there is growing evidence that XP cells are also defective in the protection against other types of lesions, including oxidized DNA bases. This raises a question regarding the relative roles of the various forms of sunlight-induced DNA damage on skin carcinogenesis and photoaging. Therefore, knowledge of what occurs in XP patients may still bring important contributions to the understanding of the biological impact of sunlight-induced deleterious effects on the skin cells.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97110-970 Santa Maria, RS, Brazil. Electronic address: schuchap@gmail.com.
authors.forename: André Passaglia
authors.initials: AP
authors.lastname: Schuch
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-000 São Paulo, SP, Brazil. Electronic address: nacestari@hotmail.com.
authors.forename: Natália Cestari
authors.initials: NC
authors.lastname: Moreno
authors.affiliation: Departamento de Nutrição, Centro Universitário Franciscano, 97010-032 Santa Maria, RS, Brazil. Electronic address: natielen@yahoo.com.br.
authors.forename: Natielen Jacques
authors.initials: NJ
authors.lastname: Schuch
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-000 São Paulo, SP, Brazil. Electronic address: cfmmenck@usp.br.
authors.forename: Carlos Frederico Martins
authors.initials: CFM
authors.lastname: Menck
authors.affiliation: Núcleo de Pesquisa em Ciências Biológicas & Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, 35400-000 Ouro Preto, MG, Brazil. Electronic address: carriao.camila@gmail.com.
authors.forename: Camila Carrião Machado
authors.initials: CCM
authors.lastname: Garcia
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D063646:Carcinogenesis; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D006801:Humans; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011740:Pyrimidine Dimers / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism; D012867:Skin / Q000473:pathology*; D015595:Skin Aging; D013472:Sunlight / Q000009:adverse effects; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000473:pathology*
chemical_list: D000975:Antioxidants; D011740:Pyrimidine Dimers; D017382:Reactive Oxygen Species; D004247:DNA
keywords: DNA lesions; DNA repair; Photoaging; Skin cancer; Ultraviolet radiation