Department of Nephro-Urology, Nagoya City University Graduate School of Medical Sciences, Nagoya and Department of Urology, Fukushima Medical University School of Medicine (YK), Fukushima, Japan.
Department of Nephro-Urology, Nagoya City University Graduate School of Medical Sciences, Nagoya and Department of Urology, Fukushima Medical University School of Medicine (YK), Fukushima, Japan.
J Urol. 2014 May;191(5 Suppl):1564-72. doi: 10.1016/j.juro.2013.10.071. Epub 2014 Mar 26.
Gonocytes differentiate into spermatogonial stem cells, which make it possible to maintain spermatogenesis continuously throughout life. We previously reported attenuated spermatogonial stem cell activity in cryptorchid testes, which resulted in altered spermatogenesis and affected fertility. However, few groups have examined the differentiation process from gonocytes to spermatogonial stem cells. To clarify the underlying mechanisms comprehensively we performed microarray analysis to assess differential expression of transcripts between normal and undescended testes in juvenile rats.
Using microarray analysis we compared whole mRNA expression of normal and cryptorchid testes in a rat model. We subsequently validated differential expression of candidate genes by real-time reverse transcriptase-polymerase chain reaction and performed immunohistochemistry. We also investigated the methylation status of histone H3K4 in cryptorchid testes and the GC-1 spermatogonial cell line.
We detected 24 up-regulated and 39 down-regulated genes. Of these genes Kdm5a expression was significantly higher in undescended testes. Immunohistochemistry showed that Kdm5a was localized in the nuclei of gonocytes, spermatogonia and spermatocytes. H3K4me2/me3 expression levels were decreased in undescended testes at 9 days postpartum. Furthermore, Kdm5a over expression in GC-1 cells led to increased expression of Esr2, Neurog3, Pou5f1, Ret and Thy1.
Recent investigations revealed that not only genetic but also epigenetic regulation has a role in spermatogenesis. Kdm5a is likely involved in the transformation of gonocytes into spermatogonial stem cells by transcriptional regulation of specific genes via H3K4 histone modification. To our knowledge this is the first report of epigenetic analysis of germ cell differentiation during early spermatogenesis.
精原细胞分化为精原干细胞，这使得在整个生命周期中持续维持精子发生成为可能。我们之前报道过隐睾睾丸中精原干细胞活性减弱，导致精子发生改变并影响生育能力。然而，很少有研究小组研究从精原细胞到精原干细胞的分化过程。为了全面阐明潜在机制，我们使用微阵列分析评估了幼年大鼠正常和未降睾丸之间的全 mRNA 表达差异。
我们使用微阵列分析比较了正常和隐睾睾丸在大鼠模型中的全 mRNA 表达。随后，我们通过实时逆转录聚合酶链反应和免疫组织化学验证了候选基因的差异表达。我们还研究了隐睾睾丸和 GC-1 精原细胞系中组蛋白 H3K4 的甲基化状态。
我们检测到 24 个上调和 39 个下调基因。其中 Kdm5a 在未降睾丸中的表达明显更高。免疫组织化学显示 Kdm5a 定位于精原细胞、精母细胞和精细胞的核内。产后 9 天未降睾丸中的 H3K4me2/me3 表达水平降低。此外，GC-1 细胞中 Kdm5a 的过表达导致 Esr2、Neurog3、Pou5f1、Ret 和 Thy1 的表达增加。
最近的研究表明，不仅遗传调控，而且表观遗传调控在精子发生中也具有作用。Kdm5a 可能通过 H3K4 组蛋白修饰对特定基因的转录调控参与到精原细胞向精原干细胞的转化中。据我们所知，这是首次报道在早期精子发生过程中对生殖细胞分化进行表观遗传分析。
