Departments of Pharmacology and Therapeutics, McGill University, Montréal, Quebec, Canada.
Biol Reprod. 2011 Dec;85(6):1269-78. doi: 10.1095/biolreprod.111.094219. Epub 2011 Aug 24.
The present trend of increasing paternal age is accompanied by concerns for the development of complex multigene diseases (e.g., autism and schizophrenia) in progeny. Recent studies have established strong correlations between male age, increased oxidative stress, decreased sperm quality, and structural aberrations of chromatin and DNA in spermatozoa. We tested the hypothesis that increasing age would result in altered gene expression relating to oxidative stress and DNA damage/repair in germ cells. To test this hypothesis, pachytene spermatocytes and round spermatids were isolated from Brown Norway (BN) rats at 4 (young) and 18 (aged) mo of age. Microarray analysis was used to compare gene expression between the groups. The probe sets with significantly altered expression were linked to DNA damage/repair and oxidative stress in pachytene spermatocytes but not in round spermatids. Further analysis of pachytene spermatocytes demonstrated that genes involved in the base excision repair (BER) and nucleotide excision repair (NER) pathways were specifically altered. Quantitative RT-PCR confirmed that NER genes were upregulated (>1.5-fold), whereas BER genes were downregulated (>1.5-fold). At the protein level the members of the BER pathway were also altered by up to 2.3-fold; levels of NER proteins remained unchanged. Furthermore, there was an increase in 8-oxo-2'-deoxyguanosine (8-oxodG) immunoreactivity in testes from aged males and in the number of spermatozoa positive for 8-oxodG. In conclusion, aging is associated with differential regulation of DNA repair pathways with a decrease in the BER pathway leading to deficient repair of 8-oxo-dG lesions in germ cells and spermatozoa.
目前，父亲年龄增加的趋势伴随着对后代复杂多基因疾病（如自闭症和精神分裂症）发展的担忧。最近的研究已经确立了男性年龄、氧化应激增加、精子质量下降以及精子染色质和 DNA 结构异常之间的强相关性。我们测试了这样一个假设，即年龄的增加会导致与生殖细胞中氧化应激和 DNA 损伤/修复相关的基因表达发生改变。为了验证这一假设，我们从 4 个月（年轻）和 18 个月（年老）的 BN 大鼠中分离出粗线期精母细胞和圆形精子细胞。使用微阵列分析比较两组之间的基因表达。具有显著改变表达的探针集与粗线期精母细胞中的 DNA 损伤/修复和氧化应激有关，但与圆形精子细胞无关。对粗线期精母细胞的进一步分析表明，参与碱基切除修复（BER）和核苷酸切除修复（NER）途径的基因发生了特异性改变。定量 RT-PCR 证实 NER 基因上调（>1.5 倍），而 BER 基因下调（>1.5 倍）。在蛋白质水平上，BER 途径的成员也被改变了高达 2.3 倍；NER 蛋白水平保持不变。此外，衰老雄性睾丸中的 8-oxo-2'-脱氧鸟苷（8-oxodG）免疫反应性增加，并且具有 8-oxodG 的精子数量增加。总之，衰老与 DNA 修复途径的差异调节有关，BER 途径的减少导致生殖细胞和精子中 8-oxo-dG 损伤的修复不足。
