Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Exploitation of Ministry of Education, Southwest Minzu University, Chengdu, Sichuan, 610041, PR China.
Key Laboratory for Animal Science of State Ethnic Affairs Commission, Southwest Minzu University, Chengdu, Sichuan, 610041, PR China.
Theriogenology. 2023 Oct 1;209:9-20. doi: 10.1016/j.theriogenology.2023.06.008. Epub 2023 Jun 16.
Lysine-specific histone demethylase 2 (Kdm2a) is a regulatory factor of histone modifications that participates in gametogenesis and embryonic development. The mis-regulation of Kdm2a can lead to aberrant gene expression, thereby contributing to abnormal cell proliferation, differentiation, apoptosis, and tumorigenesis. However, due to the potential confounding effects that are secondary to the loss of Kdm2a function from the soma in existing whole-animal mutants, the in vivo function of Kdm2a in spermatogenesis for male fertility remains unknown. Herein, we focus on exploring the spatiotemporal expression profile and biological functions of Kdm2a in the spermatogenesis and fertility of male mice. A testis-specific knockout Kdm2a model (Kdm2a cKO) was established by using the Stra8-Cre/loxP recombinase system to explore the roles of Kdm2a in male fertility. Our results showed that Kdm2a was ubiquitously expressed and dynamically distributed in multiple tissues and cell types in the testis of mice. Surprisingly, Kdm2a-deficient adult males were completely fertile and comparable with their control (Kdm2a) counterparts. Despite the significantly reduced total number of sperm and density of seminiferous tubules in Kdm2a cKO testis accompanied by the degeneration of spermatogenesis, the fertilization ability and embryonic developmental competence of the Kdm2a cKO were comparable with those of their control littermates, suggesting that Kdm2a disruption did not markedly affect male fertility, at least during younger ages. Furthermore, Kdm2a homozygous mutants exhibited a lower total number and motility of sperm than the control group and showed notably affected serum 17β-estradiol concentration. Interestingly, the transcriptome sequencing revealed that the loss of Kdm2a remarkably upregulated the expression level of Kdm2b. This effect, in turn, may induce compensative effects in the case of Kdm2a deficiency to maintain normal male reproduction. Together, our results reveal that Kdm2a shows spatiotemporal expression during testicular development and that its loss is insufficient to compromise the production of spermatozoa completely. The homologous Kdm2b gene might compensate for the loss of Kdm2a. Our work provides a novel Kdm2a cKO mouse allowing for the efficient deletion of Kdm2a in a testis-specific manner, and further investigated the biological function of Kdm2a and the compensatory effects of Kdm2b. Our study will advance our understanding of underlying mechanisms in spermatogenesis and male fertility.
赖氨酸特异性组蛋白去甲基化酶 2（Kdm2a）是一种参与配子发生和胚胎发育的组蛋白修饰的调节因子。Kdm2a 的失调会导致异常基因表达，从而导致异常细胞增殖、分化、凋亡和肿瘤发生。然而，由于现有整体动物突变体中由于体细胞中 Kdm2a 功能丧失而导致的潜在混杂效应，Kdm2a 在雄性生育力中的精子发生中的体内功能仍然未知。在此，我们专注于探索 Kdm2a 在雄性小鼠精子发生和生育力中的时空表达谱和生物学功能。使用 Stra8-Cre/loxP 重组酶系统建立了睾丸特异性敲除 Kdm2a 模型（Kdm2a cKO），以探索 Kdm2a 在雄性生育力中的作用。我们的结果表明，Kdm2a 在小鼠睾丸的多种组织和细胞类型中广泛表达，并具有动态分布。令人惊讶的是，缺乏 Kdm2a 的成年雄性完全具有生育能力，并且与它们的对照（Kdm2a）相比无差异。尽管 Kdm2a cKO 睾丸中的总精子数和生精小管密度显著减少，伴有精子发生退化，但 Kdm2a cKO 的受精能力和胚胎发育能力与它们的对照同窝仔相当，这表明 Kdm2a 的破坏并没有明显影响雄性生育力，至少在年轻时没有。此外，Kdm2a 纯合突变体的精子总数和活力低于对照组，并且血清 17β-雌二醇浓度明显受到影响。有趣的是，转录组测序表明，Kdm2a 的缺失显着上调了 Kdm2b 的表达水平。这种效应反过来可能会在 Kdm2a 缺乏的情况下诱导补偿作用，以维持正常的雄性生殖。总之，我们的结果表明，Kdm2a 在睾丸发育过程中表现出时空表达，其缺失不足以完全破坏精子的产生。同源的 Kdm2b 基因可能补偿了 Kdm2a 的缺失。我们的工作提供了一种新型的 Kdm2a cKO 小鼠，允许在睾丸特异性方式下有效地删除 Kdm2a，并进一步研究了 Kdm2a 的生物学功能和 Kdm2b 的补偿效应。我们的研究将促进对精子发生和雄性生育力的潜在机制的理解。
