Cornwall G A, Hann S R
Department of Cell Biology and Biochemistry, Texas Tech University Health Science Center, Lubbock 79430, USA.
Mol Reprod Dev. 1995 May;41(1):37-46. doi: 10.1002/mrd.1080410107.
In previous studies we identified an epididymal gene that exhibits homology to the cystatin family of cysteine protease inhibitors. The expression of this gene, termed CRES (cystatin-related epididymal and spermatogenic), was shown to be highly restricted to the proximal caput epididymal epithelium with less expression in the testis and no expression in the 24 other tissues examined. In this report, studies were carried out to examine CRES gene expression in the testis as well as to characterize the CRES protein in the testis and epididymis. In situ hybridization experiments revealed that within the testis CRES gene expression is stage-specific during spermatogenesis and is exclusively expressed by the round spermatids of Stages VII-VIII and the early elongating spermatids of Stages IX and X. Immunohistochemical studies demonstrated that CRES protein was transiently expressed in both the testis and epididymis. Within the testis the protein was localized to the elongating spermatids, whereas within the epididymis CRES protein was exclusively synthesized by the proximal caput epithelium and then secreted into the lumen. Surprisingly, the secreted CRES protein had completely disappeared from the epididymal lumen by the distal caput epididymidis. Western blot analysis of testicular and epididymal proteins showed that the CRES antibody specifically recognized a predominant 19 kDa CRES protein and a less abundant 14 kDa form. These observations suggest that the CRES protein performs a specialized role during sperm development and maturation.
在先前的研究中，我们鉴定出一个与半胱氨酸蛋白酶抑制剂胱抑素家族具有同源性的附睾基因。该基因被命名为CRES（与胱抑素相关的附睾和生精基因），其表达高度局限于附睾头近端上皮，在睾丸中的表达较少，在其他24种检测组织中无表达。在本报告中，我们进行了研究以检测睾丸中CRES基因的表达，并对睾丸和附睾中的CRES蛋白进行表征。原位杂交实验表明，在睾丸内，CRES基因的表达在精子发生过程中具有阶段特异性，仅由VII - VIII期的圆形精子细胞以及IX和X期的早期伸长精子细胞表达。免疫组织化学研究表明，CRES蛋白在睾丸和附睾中均有短暂表达。在睾丸内，该蛋白定位于伸长的精子细胞，而在附睾内，CRES蛋白仅由附睾头近端上皮合成，然后分泌到管腔中。令人惊讶的是，分泌的CRES蛋白在附睾头远端时已从附睾管腔中完全消失。对睾丸和附睾蛋白的蛋白质印迹分析表明，CRES抗体特异性识别一种主要的19 kDa CRES蛋白和一种含量较少的14 kDa形式。这些观察结果表明，CRES蛋白在精子发育和成熟过程中发挥着特殊作用。
