G-quadruplexes (G4) are highly stable tetra-stranded secondary DNA structures known to mediate gene regulation. These structures are resolved by DNA helicases and are believed to be a causal factor in the phenotype of premature ageing disorders following mutations in DNA helicase genes. The relevance of G4 structures in ageing may be further implicated by their dynamic relationship with DNA modification mechanisms. When DNA methylation and oxidation occur at the vicinity of G4 elements, they can affect the stability of G4 structures which may in turn mediate gene expression resulting in deleterious effects on genome integrity. Therefore, the influence of nutritional deficiencies or excess on oxidation and methylation mechanisms may be contributing factors affecting the stability of G4 structures and their balance in the human genome. We propose that dietary nutrients such as folate and antioxidants may play a beneficial role in reducing G4-induced DNA damage through changes in G4 structure stability. The current knowledge advocates the importance of resolving G4 structures by DNA helicases for sustained genome integrity, and the existence of stability changes in G4 structures when associated with DNA methylation and oxidation modifications.

中文翻译：

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G-四链体：营养的可能的表观遗传学靶标。

G-四链体（G4）是高度稳定的四链二级DNA结构，已知可介导基因调控。这些结构被DNA解旋酶解析，并且被认为是DNA解旋酶基因突变后的早衰症表型的原因。G4结构与衰老的相关性可能进一步与G4结构与DNA修饰机制的动态关系有关。当DNA甲基化和氧化发生在G4元件附近时，它们会影响G4结构的稳定性，进而可能介导基因表达，从而对基因组完整性造成有害影响。因此，营养不足或营养过剩对氧化和甲基化机制的影响可能是影响G4结构的稳定性及其在人类基因组中的平衡的因素。我们建议饮食营养素，例如叶酸和抗氧化剂，可能通过改变G4结构稳定性而在减少G4诱导的DNA损伤中发挥有益作用。当前的知识主张通过DNA解旋酶解析G4结构对于持续的基因组完整性的重要性，并且当与DNA甲基化和氧化修饰相关时，G4结构中存在稳定性变化。