A somatic permeability barrier around the germline is essential for Drosophila spermatogenesis
A somatic permeability barrier around the germline is essential for Drosophila spermatogenesis
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DOI：
10.1242/dev.114967
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发表时间：
2015-01-15
期刊：
影响因子：
4.6
通讯作者：
Tanentzapf, Guy
中科院分区：
文献类型：
--
作者：
Fairchild, Michael J.;Smendziuk, Christopher M.;Tanentzapf, Guy
索马和生殖细胞之间的相互作用对配子发生是必不可少的。在果蝇睾丸中，分化中的生殖细胞被两个体细胞包裹，在整个精子发生过程中，体细胞围绕着生殖细胞。山雀（chic），Profilin的果蝇直系同源物，介导体细胞-生殖系相互作用。索马中Chic的敲低导致不育和由于有缺陷的包囊而严重破坏的精子发生。为了进一步研究这一缺陷，我们开发了一种渗透性测定来分析生殖系是否被索马从周围环境中隔离。我们发现，生殖细胞包裹的索马，本身是不足以形成一个渗透性屏障，但这样的障碍逐渐发展在早期精子发生。因此，生殖系干细胞、成角细胞和早期精原细胞不是与外界环境隔离的。然而，到了精母细胞晚期，索马形成了一个渗透屏障。此外，我们发现，伴随着渗透性屏障的形成，分隔连接标记物在索马中表达，并定位于连接生殖系周围的两个体细胞的连接部位。重要的是，隔膜连接组件的敲除也破坏了渗透性屏障。最后，我们表明，当渗透性屏障受到损害时，种系分化被延迟。我们认为，在精子发生过程中，生殖细胞周围的通透性屏障通过塑造发生在索马和生殖细胞之间的信号传导事件发挥重要的调节作用。
Interactions between the soma and germline are essential for gametogenesis. In the Drosophila testis, differentiating germ cells are encapsulated by two somatic cells that surround the germline throughout spermatogenesis. chickadee (chic), the fly ortholog of Profilin, mediates soma-germline interactions. Knockdown of Chic in the soma results in sterility and severely disrupted spermatogenesis due to defective encapsulation. To study this defect further, we developed a permeability assay to analyze whether the germline is isolated from the surrounding environment by the soma. We find that germline encapsulation by the soma is, by itself, insufficient for the formation of a permeability barrier, but that such a barrier gradually develops during early spermatogenesis. Thus, germline stem cells, gonialblasts and early spermatogonia are not isolated from the outside environment. By late spermatocyte stages, however, a permeability barrier is formed by the soma. Furthermore, we find that, concomitant with formation of the permeability barrier, septate junction markers are expressed in the soma and localize to junctional sites connecting the two somatic cells that surround the germline. Importantly, knockdown of septate junction components also disrupts the permeability barrier. Finally, we show that germline differentiation is delayed when the permeability barrier is compromised. We propose that the permeability barrier around the germline serves an important regulatory function during spermatogenesis by shaping the signaling events that take place between the soma and the germline.