Marques P I, Fernandes S, Carvalho F, Barros A, Sousa M, Marques C J
Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.
I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
Andrology. 2017 May;5(3):451-459. doi: 10.1111/andr.12329. Epub 2017 Mar 10.
Imprinting errors have been described in spermatozoa from infertile patients with oligozoospermia and azoospermia. However, little is known about methylation of imprinted genes in other spermatogenic cells from azoospermic patients. Therefore, we aimed to evaluate the methylation status of single CpGs located in the differentially methylated regions (DMRs) of two imprinted genes, one paternally (H19) and one maternally (MEST) methylated, in primary spermatocytes of azoospermic patients presenting complete (MAc, n = 7) and incomplete (MAi, n = 8) maturation arrest, as well as in other spermatogenic cells from MAi patients that presented focus of complete spermatogenesis in some seminiferous tubules. We observed H19 imprinting errors in primary spermatocytes from one MAi patient and MEST imprinting errors in one MAi and two MAc patients. Additionally, H19 imprinting errors were observed in elongated spermatids/spermatozoa from one MAi patient. Nevertheless, no statistical differences were found for H19 and MEST global methylation levels (percentage of methylated and unmethylated CpGs, respectively) between patients with complete and incomplete MA and also between MA groups and a control group. These results provide further evidence that imprinting errors occur in spermatogenic cells from patients presenting impaired spermatogenesis, as we and others have previously described in ejaculated and testicular spermatozoa. As paternal imprinting errors can be transmitted to the embryo by the sperm cell, they can provide a possible explanation for poor embryo development and/or low pregnancy rates as correct expression of imprinted genes is crucial for embryo and placental development and function. Therefore, in cases with male factor infertility where unsuccessful in vitro fertilization (IVF) treatments are recurrent, analysis of imprinting marks in spermatozoa might be a useful diagnostic tool.
在少精子症和无精子症的不育患者的精子中已发现印记错误。然而，对于无精子症患者其他生精细胞中印迹基因的甲基化情况知之甚少。因此，我们旨在评估位于两个印记基因差异甲基化区域（DMR）中的单个CpG的甲基化状态，其中一个基因（H19）为父系甲基化，另一个基因（MEST）为母系甲基化，这些基因来自呈现完全（MAc，n = 7）和不完全（MAi，n = 8）成熟停滞的无精子症患者的初级精母细胞，以及来自MAi患者的其他生精细胞，这些患者的一些曲细精管中存在完全精子发生的灶区。我们在一名MAi患者的初级精母细胞中观察到H19印记错误，在一名MAi患者和两名MAc患者中观察到MEST印记错误。此外，在一名MAi患者的延长型精子细胞/精子中观察到H19印记错误。然而，在完全和不完全MA患者之间以及MA组与对照组之间，H19和MEST的整体甲基化水平（分别为甲基化和未甲基化CpG的百分比）没有发现统计学差异。这些结果提供了进一步的证据，证明印记错误发生在精子发生受损患者的生精细胞中，正如我们和其他人之前在射出精子和睾丸精子中所描述的那样。由于父系印记错误可通过精子细胞传递给胚胎，它们可能为胚胎发育不良和/或低妊娠率提供一种可能的解释，因为印记基因的正确表达对胚胎和胎盘的发育及功能至关重要。因此，在男性因素不育且体外受精（IVF）治疗反复失败的情况下，分析精子中的印记标记可能是一种有用的诊断工具。
