Korhonen Hanna Maria, Yadav Ram Prakash, Da Ros Matteo, Chalmel Frédéric, Zimmermann Céline, Toppari Jorma, Nef Serge, Kotaja Noora
Institute of Biomedicine, Department of Physiology, University of Turku, Turku, Finland.
Inserm U1085-Irset, Université de Rennes 1, Rennes, France.
Biol Reprod. 2015 Dec;93(6):139. doi: 10.1095/biolreprod.115.131938. Epub 2015 Oct 28.
The endonuclease DICER that processes micro-RNAs and small interfering RNAs is essential for normal spermatogenesis and male fertility. We previously showed that the deletion of Dicer1 gene in postnatal spermatogonia in mice using Ngn3 promoter-driven Cre expression caused severe defects in the morphogenesis of haploid spermatid to mature spermatozoon, including problems in cell polarization and nuclear elongation. In this study, we further analyzed the same mouse model and revealed that absence of functional DICER in differentiating male germ cells induces disorganization of the cell-cell junctions in the seminiferous epithelium. We detected discontinuous and irregular apical ectoplasmic specializations between elongating spermatids and Sertoli cells. The defective anchoring of spermatids to Sertoli cells caused a premature release of spermatids into the lumen. Our findings may help also explain the abnormal elongation process of remaining spermatids because these junctions and the correct positioning of germ cells in the epithelium are critically important for the progression of spermiogenesis. Interestingly, cell adhesion-related genes were generally upregulated in Dicer1 knockout germ cells. Claudin 5 ( Cldn5 ) was among the most upregulated genes and we show that the polarized localization of CLAUDIN5 in the apical ectoplasmic specializations was lost in Dicer1 knockout spermatids. Our results suggest that DICER-dependent pathways control the formation and organization of cell-cell junctions in the seminiferous epithelium via the regulation of cell adhesion-related genes.
加工微小RNA和小干扰RNA的核酸内切酶DICER对于正常精子发生和男性生育能力至关重要。我们之前表明，利用Ngn3启动子驱动的Cre表达在小鼠出生后的精原细胞中删除Dicer1基因，会导致单倍体精子细胞向成熟精子的形态发生出现严重缺陷，包括细胞极化和细胞核伸长方面的问题。在本研究中，我们进一步分析了同一小鼠模型，发现分化中的雄性生殖细胞中缺乏功能性DICER会导致生精上皮中细胞间连接的紊乱。我们检测到伸长中的精子细胞与支持细胞之间的顶端胞质特化是不连续且不规则的。精子细胞与支持细胞的锚定缺陷导致精子细胞过早释放到管腔中。我们的发现可能也有助于解释剩余精子细胞异常的伸长过程，因为这些连接以及生殖细胞在上皮中的正确定位对于精子形成的进展至关重要。有趣的是，细胞黏附相关基因在Dicer1基因敲除的生殖细胞中通常会上调。Claudin 5（Cldn5）是上调最为明显的基因之一，我们发现Dicer1基因敲除的精子细胞中，顶端胞质特化中CLAUDIN5的极化定位消失了。我们的结果表明，DICER依赖的途径通过调节细胞黏附相关基因来控制生精上皮中细胞间连接的形成和组织。
