Cloning and developmental analysis of murid spermatid-specific thioredoxin-2 (SPTRX-2), a novel sperm fibrous sheath protein and autoantigen
Cloning and developmental analysis of murid spermatid-specific thioredoxin-2 (SPTRX-2), a novel sperm fibrous sheath protein and autoantigen
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DOI：
10.1074/jbc.m305475200
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发表时间：
2003-11-07
影响因子：
4.8
通讯作者：
Oko, R
中科院分区：
文献类型：
--
作者：
Miranda-Vizuete, A;Tsang, K;Oko, R
硫氧还蛋白是一个不断增长的蛋白质家族，通过氧化还原介导的反应参与不同的细胞过程。本文报道小鼠Sptrx-2基因的克隆、发育表达和定位。小鼠和大鼠SPTRX-2蛋白在硫氧还蛋白和NDP激酶结构域中与其人类直系同源物显示出高度同源性，并且编码基因位于同线位置。北方印迹和原位杂交证实了小鼠Sptrx-2 mRNA的睾丸特异性表达，主要在圆形精子细胞中。对大鼠精子发生19个步骤的免疫组织化学分析表明，SPTRX-2表达在第15-18步精子细胞的胞质叶中变得突出，并在精子形成前的第19步中减少。然而，在精子细胞尾部，SPTRX-2的免疫反应性增加，从第15至19步，并仅限于主片。通过免疫金电子显微镜，SPTRX-2首先在第14-15步精子细胞中被检测到分散在整个轴丝的细胞质中，但在第16步开始被并入纤维鞘（FS）中。在步骤17-18期间，在组装的FS的肋和柱上增加标签。在第19步达到峰值，并保留在附睾精子的FS中。从精子中分离的FS的免疫印迹证实，SPTRX-2是一个不可分割的组成部分的FS和输精管结扎大鼠的梗阻后自身抗原。我们的数据表明，SPTRX-2纳入FS落后于FS组装，这表明它是需要在精子尾部成熟的睾丸和/或附睾，FS蛋白发生广泛的二硫键结合的最后阶段。
Thioredoxins compose a growing family of proteins that participate in different cellular processes via redox-mediated reactions. We report here the cloning, developmental expression, and location of murid Sptrx-2. Mouse and rat SPTRX-2 proteins display a high homology to their human ortholog in the thioredoxin and NDP kinase domains, and the coding genes are located at syntenic positions. Northern blotting and in situ hybridization confirmed the testis-specific expression of murine Sptrx-2 mRNA, mostly in round spermatids. Immunohistochemical analysis of the 19 steps of rat spermiogenesis showed that SPTRX-2 expression becomes prominent in the cytoplasmic lobe of step 15-18 spermatids and diminishes in step 19 just before spermiation. However, in the spermatid tail, SPTRX-2 immunoreactivity increased from step 15 to 19 and was confined to the principal piece. By immunogold electron microscopy, SPTRX-2 was first detected scattered throughout the cytoplasm of the axoneme in step 14-15 spermatids, but began to be incorporated by step 16 into the fibrous sheath (FS). During steps 17-18, the labeling increased over the ribs and columns of the assembled FS. It peaked in step 19 and remained in the FS of epididymal spermatozoa. Immunoblots of isolated FS obtained from spermatozoa confirmed that SPTRX-2 is an integral component of the FS and a post-obstruction autoantigen in vasectomized rats. Our data indicate that SPTRX-2 incorporation into the FS lags well behind FS assembly, suggesting it is required during the final stages of sperm tail maturation in the testis and/or epididymis, where extensive disulfide bonding of FS proteins occurs.