Developmental Genetics of Secretory Vesicle Acidification During Caenorhabditis elegans Spermatogenesis
Developmental Genetics of Secretory Vesicle Acidification During Caenorhabditis elegans Spermatogenesis
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DOI：
10.1534/genetics.112.139618
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发表时间：
2012-06-01
期刊：
影响因子：
3.3
通讯作者：
L'Hernault, Steven W.
中科院分区：
文献类型：
--
作者：
Gleason, Elizabeth J.;Hartley, Paul D.;L'Hernault, Steven W.
分泌囊泡在精子发生过程中用于将蛋白质递送至细胞表面。在秀丽隐杆线虫中，分泌性膜细胞器 (MO) 与质膜融合，将精子细胞转化为具有受精能力的精子。我们发现，与哺乳动物精子的顶体囊泡一样，MO 在发育过程中也会经历酸化。用 V-ATP 酶抑制剂巴弗洛霉素处理精子细胞可阻断 MO 酸化和功能性精子的形成。有几种精子发生缺陷突变体会导致 MO 形态发生缺陷，其中包括 spe-5。我们确定位于 I 号染色体上的 spe-5 编码两个 V-ATPase B 旁系同源亚基之一。 spe-5 无效突变体是可行的，但不育，因为它形成停滞的多核精母细胞。 SPE-5 特异性单克隆抗体的免疫荧光显示，SPE-5 表达始于精母细胞，并存在于精子发生的所有后续阶段。大多数 SPE-5 在精子出芽期间被丢弃到残余体内，但少量保留在出芽的精子细胞中，作为离散点定位在 MO 中。另一个 V-ATPase B 亚基由位于 X 染色体上的 vha-12 编码。通常，spe-5 突变体在野生型 vha-12 背景下是自不育的。然而，含有由其自身启动子驱动的野生型vha-12的染色体外转基因允许spe-5突变雌雄同体产生后代，表明VHA-12至少可以部分替代SPE-5。其他研究表明，X 染色体在雄性种系中转录沉默，因此常染色体定位的 spe-5 基因的表达确保了精子发生过程中存在 V-ATPase B 亚基。
Secretory vesicles are used during spermatogenesis to deliver proteins to the cell surface. In Caenorhabditis elegans, secretory membranous organelles (MO) fuse with the plasma membrane to transform spermatids into fertilization-competent spermatozoa. We show that, like the acrosomal vesicle of mammalian sperm, MOs undergo acidification during development. Treatment of spermatids with the V-ATPase inhibitor bafilomycin blocks both MO acidification and formation of functional spermatozoa. There are several spermatogenesis-defective mutants that cause defects in MO morphogenesis, including spe-5. We determined that spe-5, which is on chromosome I, encodes one of two V-ATPase B paralogous subunits. The spe-5 null mutant is viable but sterile because it forms arrested, multi-nucleate spermatocytes. Immunofluorescence with a SPE-5-specific monoclonal antibody shows that SPE-5 expression begins in spermatocytes and is found in all subsequent stages of spermatogenesis. Most SPE-5 is discarded into the residual body during spermatid budding, but a small amount remains in budded spermatids where it localizes to MOs as a discrete dot. The other V-ATPase B subunit is encoded by vha-12, which is located on the X chromosome. Usually, spe-5 mutants are self-sterile in a wild-type vha-12 background. However, an extrachromosomal transgene containing wild-type vha-12 driven by its own promoter allows spe-5 mutant hermaphrodites to produce progeny, indicating that VHA-12 can at least partially substitute for SPE-5. Others have shown that the X chromosome is transcriptionally silent in the male germline, so expression of the autosomally located spe-5 gene ensures that a V-ATPase B subunit is present during spermatogenesis.