Busso D, Cohen D J, Hayashi M, Kasahara M, Cuasnicú P S
Instituto de Biología y Medicina Experimental (IBYME), Buenos Aires (1428), Argentina.
Mol Hum Reprod. 2005 Apr;11(4):299-305. doi: 10.1093/molehr/gah156. Epub 2005 Feb 25.
Testicular protein Tpx-1, also known as CRISP-2, is a cysteine-rich secretory protein specifically expressed in the male reproductive tract. Since the information available on the human protein is limited to the identification and expression of its gene, in this work we have studied the presence and localization of human Tpx-1 (TPX1) in sperm, its fate after capacitation and acrosome reaction (AR), and its possible involvement in gamete interaction. Indirect immunofluorescence studies revealed the absence of significant staining in live or fixed non-permeabilized sperm, in contrast to a clear labelling in the acrosomal region of permeabilized sperm. These results, together with complementary evidence from protein extraction procedures strongly support that TPX1 would be mainly an intra-acrosomal protein in fresh sperm. After in vitro capacitation and ionophore-induced AR, TPX1 remained associated with the equatorial segment of the acrosome. The lack of differences in the electrophoretic mobility of TPX1 before and after capacitation and AR indicates that the protein would not undergo proteolytical modifications during these processes. The possible involvement of TPX1 in gamete interaction was evaluated by the hamster oocyte penetration test. The presence of anti-TPX1 during gamete co-incubation produced a significant and dose-dependent inhibition in the percentage of penetrated zona-free hamster oocytes without affecting sperm motility, the AR or sperm binding to the oolema. Together, these results indicate that human TPX1 would be a component of the sperm acrosome that remains associated with sperm after capacitation and AR, and is relevant for sperm-oocyte interaction.
睾丸蛋白Tpx-1，也称为CRISP-2，是一种富含半胱氨酸的分泌蛋白，在雄性生殖道中特异性表达。由于关于该人类蛋白的现有信息仅限于其基因的鉴定和表达，因此在本研究中，我们研究了人类Tpx-1（TPX1）在精子中的存在和定位、获能和顶体反应（AR）后的命运，以及它在配子相互作用中的可能作用。间接免疫荧光研究显示，活的或固定的未通透精子中没有明显的染色，而通透精子的顶体区域有明显的标记。这些结果，连同蛋白质提取程序的补充证据，有力地支持了TPX1在新鲜精子中主要是一种顶体内蛋白的观点。在体外获能和离子载体诱导的AR后，TPX1仍与顶体的赤道段相关联。获能和AR前后TPX1的电泳迁移率没有差异，这表明该蛋白在这些过程中不会发生蛋白水解修饰。通过仓鼠卵母细胞穿透试验评估了TPX1在配子相互作用中的可能作用。配子共孵育期间抗TPX1的存在对未带透明带的仓鼠卵母细胞穿透率产生了显著的剂量依赖性抑制，而不影响精子活力、AR或精子与卵膜的结合。总之，这些结果表明，人类TPX1是精子顶体的一个组成部分，在获能和AR后仍与精子相关联，并且与精卵相互作用有关。
