La Salle Sophie, Oakes Christopher C, Neaga Oana R, Bourc'his Déborah, Bestor Timothy H, Trasler Jacquetta M
Department of Pharmacology & Therapeutics, McGill University and The Montreal Children's Hospital Research Institute, Montréal, QC H3H 1P3, Canada.
BMC Dev Biol. 2007 Sep 18;7:104. doi: 10.1186/1471-213X-7-104.
Formation of haploid spermatozoa capable of fertilization requires proper programming of epigenetic information. Exactly how DNMT3L (DNA methyltransferase 3-Like), a postulated regulator of DNA methyltransferase activity, contributes to DNA methylation pattern acquisition during gametogenesis remains unclear. Here we report on the role of DNMT3L in male germ cell development.
A developmental study covering the first 12 days following birth was conducted on a Dnmt3L mutant mouse model; lower germ cell numbers and delayed entry into meiosis were observed in Dnmt3L-/- males, pointing to a mitotic defect. A temporal expression study showed that expression of Dnmt3L is highest in prenatal gonocytes but is also detected and developmentally regulated during spermatogenesis. Using a restriction enzyme qPCR assay (qAMP), DNA methylation analyses were conducted on postnatal primitive type A spermatogonia lacking DNMT3L. Methylation levels along 61 sites across chromosomes 4 and X decreased significantly by approximately 50% compared to the levels observed in Dnmt3L+/+ germ cells, suggesting that many loci throughout the genome are marked for methylation by DNMT3L. More so, hypomethylation was more pronounced in regions of lower GC content than in regions of higher GC content.
Taken together, these data suggest that DNMT3L plays a more global role in genomic methylation patterning than previously believed.
能够受精的单倍体精子的形成需要对表观遗传信息进行适当编程。作为一种假定的DNA甲基转移酶活性调节剂，DNMT3L（DNA甲基转移酶3样蛋白）在配子发生过程中如何促成DNA甲基化模式的获得仍不清楚。在此，我们报告DNMT3L在雄性生殖细胞发育中的作用。
对Dnmt3L突变小鼠模型进行了一项涵盖出生后前12天的发育研究；在Dnmt3L - / - 雄性小鼠中观察到生殖细胞数量减少且减数分裂进入延迟，这表明存在有丝分裂缺陷。一项时间表达研究表明，DNMT3L的表达在产前生殖母细胞中最高，但在精子发生过程中也能检测到且受发育调控。使用限制性内切酶定量PCR分析（qAMP），对缺乏DNMT3L的出生后原始A型精原细胞进行了DNA甲基化分析。与在Dnmt3L + / + 生殖细胞中观察到的水平相比，4号染色体和X染色体上61个位点的甲基化水平显著降低了约50%，这表明基因组中的许多位点都由DNMT3L标记进行甲基化。更重要的是，低甲基化在GC含量较低的区域比在GC含量较高的区域更明显。
综上所述，这些数据表明DNMT3L在基因组甲基化模式形成中所起的作用比之前认为的更为广泛。
