Center for Translational Research and Molecular Biology of Cancer, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Wybrzeże Armii Krajowej 15, 44-101 Gliwice, Poland.
Reproduction. 2012 Jun;143(6):749-57. doi: 10.1530/REP-11-0270. Epub 2012 Apr 11.
The binding of capacitated spermatozoa to the egg's extracellular coat and induction of acrosome reaction are necessary for successful fertilization in mammals. Biogenesis of acrosome is complicated, and not all proteins involved in this process are known. In this study, we have cloned a novel mouse gene, Spaca7, that is expressed exclusively in the testes. During the postnatal development, transcripts of the gene could be detected at a very low level in 18-day-old mouse testes and at a higher level in 21-day-old mouse testes and later, which corresponds to an expansion of round spermatids. In the stably transfected PT67 cells, SPACA7 fused with EGFP was predominantly localized in the Golgi apparatus. In transgenic mouse testes, the fusion protein was found in acrosome (starting from the first stages of acrosome formation in late pachytene spermatocytes and finally in spermatozoa isolated from caput and cauda of epididymis). Confocal microscopy studies revealed an intra-acrosomal not membrane-bound localization of SPACA7/EGFP, which suggests that the protein can be released during acrosome reaction and involved in fertilization. Acrosomal localization of endogenous SPACA7 protein was also found in human spermatozoa.
顶体反应中获能精子与卵外被结合是哺乳动物受精成功的必要条件。顶体的生物发生过程很复杂，并非所有参与这一过程的蛋白质都已被认识。在这项研究中，我们克隆了一个新的小鼠基因 Spaca7，它只在睾丸中表达。在出生后的发育过程中，该基因的转录本在 18 日龄的小鼠睾丸中以非常低的水平被检测到，在 21 日龄的小鼠睾丸中以及以后的水平更高，这与圆形精子细胞的扩张相对应。在稳定转染的 PT67 细胞中，SPACA7 与 EGFP 融合主要定位于高尔基体。在转基因小鼠睾丸中，融合蛋白存在于顶体中（从粗线期精母细胞晚期顶体形成的最初阶段开始，最终存在于从附睾头部和尾部分离出来的精子中）。共聚焦显微镜研究显示 SPACA7/EGFP 的内部顶体而不是膜结合定位，这表明该蛋白可以在顶体反应中释放并参与受精。内源性 SPACA7 蛋白在人精子中也有顶体定位。
