Yoshinaga K, Tanii I, Oh-oka T, Toshimori K
Department of Anatomy and Reproductive Cell Biology, Miyazaki Medical College, Kiyotake, Japan.
Cell Tissue Res. 2001 Feb;303(2):253-61. doi: 10.1007/s004410000308.
In this study, we examined the localization and characteristics of an intra-acrosomal protein, acrin2 (MC41), during guinea pig spermiogenesis and post-testicular sperm maturation in the epididymis, using the monoclonal antibody MC41. Immunoelectron microscopy demonstrated not only a specific domain localization of acrin2 in the apical segment of the guinea pig sperm acrosome, but also its dynamic behavior according to the spermatid differentiation and passage through the epididymis, as follows: acrin2 was exclusively localized in the membrane of the endoplasmic reticulum of early-stage spermatids but was not detectable in the developing acrosome until spermatids reached the maturation phase. In the final stage of spermiogenesis, acrin2 became localized in the outer acrosomal membrane (OAM)/matrix-associated materials both in the small region posterior to the dorsal matrix and along the ventral margin of the acrosomal apical segment. The acrosomal location of acrin2 in caput epididymidal sperm was almost identical to that observed in the final step spermatids, but during maturation it became progressively more restricted in area until on distal cauda epididymidal sperm it remained only in the dorsal region. In Western blot analysis, the MC41 antibody recognized a 165-kDa protein in the mature sperm extract. Furthermore, it was demonstrated that molecular weight reduction of the protein occurred during sperm passage through the epididymis. These findings indicate that acrin2 changes progressively in both distribution and size during development and maturation of the acrosome.
在本研究中，我们使用单克隆抗体MC41，检测了豚鼠精子发生过程中以及附睾中睾丸后精子成熟过程中一种顶体内蛋白acrin2（MC41）的定位和特征。免疫电子显微镜不仅显示了acrin2在豚鼠精子顶体顶端节段的特定区域定位，还显示了其根据精子细胞分化和通过附睾的过程而发生的动态变化，具体如下：acrin2仅定位于早期精子细胞内质网的膜上，但在精子细胞进入成熟阶段之前，在发育中的顶体中无法检测到。在精子发生的最后阶段，acrin2定位于顶体背侧基质后方的小区域以及顶体顶端节段腹侧边缘的顶体外膜（OAM）/基质相关物质中。附睾头精子中acrin2的顶体定位与在精子细胞最后阶段观察到的几乎相同，但在成熟过程中，其区域逐渐受到限制，直到在附睾尾远端精子中，它仅保留在背侧区域。在蛋白质印迹分析中，MC41抗体在成熟精子提取物中识别出一种165 kDa的蛋白质。此外，还证明了该蛋白质在精子通过附睾的过程中分子量降低。这些发现表明，acrin2在顶体发育和成熟过程中，其分布和大小都逐渐发生变化。
