Koshimizu U, Watanabe D, Sawada K, Nishimune Y
Research Institute for Microbial Diseases, Osaka University, Japan.
Biol Reprod. 1993 Nov;49(5):875-84. doi: 10.1095/biolreprod49.5.875.
A murine cell surface antigen exhibiting stage-specific expression during spermatogenesis was detected with two monoclonal antibodies (mAbs), designated BC7 and CA12. In mouse testis, these mAbs recognized a small population of cells located near the periphery of seminiferous tubules at stages XII and I-VI, and these spermatogenic cells were identified as zygotene and early pachytene spermatocytes. Expression of the antigens was transient and was not detected in germ cells at more advanced stages of spermatogenesis such as late pachytene spermatocytes and round spermatids. Immunoprecipitation and immunoblotting studies showed that both mAbs CA12 and BC7 reacted with the same antigenic molecule, which had an estimated molecular mass of 95 kDa. CA12/BC7 antigen, detected in plasma membrane fraction, was a glycoprotein with sialic acid residues and had affinity with WGA lectin. Furthermore, intraperitoneal injection of mAb BC7 caused an apparent spermatogenic disturbance in prepubertal mice. These results suggested that CA12/BC7 antigen, a novel cell surface glycoprotein, is an essential molecule that plays an important role during early meiotic prophase of spermatogenesis.
利用两种单克隆抗体（mAb），即BC7和CA12，检测到一种在精子发生过程中呈现阶段特异性表达的小鼠细胞表面抗原。在小鼠睾丸中，这些单克隆抗体识别位于生精小管外周附近的一小群细胞，这些细胞处于第XII阶段以及I-VI阶段，并且这些生精细胞被鉴定为偶线期和早粗线期精母细胞。抗原的表达是短暂的，在精子发生更后期阶段的生殖细胞如晚粗线期精母细胞和圆形精子细胞中未检测到。免疫沉淀和免疫印迹研究表明，单克隆抗体CA12和BC7均与同一抗原分子发生反应，该抗原分子的估计分子量为95 kDa。在质膜部分检测到的CA12/BC7抗原是一种带有唾液酸残基的糖蛋白，并且与麦胚凝集素（WGA）有亲和力。此外，腹腔注射单克隆抗体BC7会导致青春期前小鼠出现明显的生精障碍。这些结果表明，CA12/BC7抗原作为一种新型细胞表面糖蛋白，是在精子发生减数分裂前期早期发挥重要作用的必需分子。
