Department of Reproduction and Development, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
J Cell Sci. 2010 Feb 1;123(Pt 3):331-9. doi: 10.1242/jcs.059949. Epub 2010 Jan 5.
The cytoplasmic chromatoid body (CB) organizes mRNA metabolism and small regulatory RNA pathways, in relation to haploid gene expression, in mammalian round spermatids. However, little is known about functions and fate of the CB at later steps of spermatogenesis, when elongating spermatids undergo chromatin compaction and transcriptional silencing. In mouse elongating spermatids, we detected accumulation of the testis-specific serine/threonine kinases TSSK1 and TSSK2, and the substrate TSKS, in a ring-shaped structure around the base of the flagellum and in a cytoplasmic satellite, both corresponding to structures described to originate from the CB. At later steps of spermatid differentiation, the ring is found at the caudal end of the newly formed mitochondrial sheath. Targeted deletion of the tandemly arranged genes Tssk1 and Tssk2 in mouse resulted in male infertility, with loss of the CB-derived ring structure, and with elongating spermatids possessing a collapsed mitochondrial sheath. These results reveal TSSK1- and TSSK2-dependent functions of a transformed CB in post-meiotic cytodifferentiation of spermatids.
细胞质色素体（CB）组织 mRNA 代谢和小调控 RNA 途径，与单倍体基因表达有关，在哺乳动物圆形精母细胞中。然而，对于 CB 在精子发生的后期步骤中的功能和命运知之甚少，此时伸长的精子经历染色质浓缩和转录沉默。在小鼠伸长的精子中，我们检测到睾丸特异性丝氨酸/苏氨酸激酶 TSSK1 和 TSSK2 及其底物 TSKS 在鞭毛基部的环状结构和细胞质卫星中的积累，这两种结构都与源自 CB 的结构相对应。在精子分化的后期阶段，该环位于新形成的线粒体鞘的尾部。在小鼠中靶向缺失串联排列的基因 Tssk1 和 Tssk2 导致男性不育，失去了源自 CB 的环状结构，并且伸长的精子具有塌陷的线粒体鞘。这些结果揭示了 TSSK1 和 TSSK2 依赖性转化 CB 在精子后减数细胞分化中的作用。
