SPAG6/SPINK2蛋白复合物在小鼠精子顶体形成中的作用初探

The role of SPAG6/SPINK2 protein complex in the formation of sperm acrosome in mice

目的:初步探讨精子相关抗原6(SPAG6)在小鼠精子发生过程中顶体形成阶段的表达及其调控作用。方法:采用Western印迹检测出生后小鼠睾丸发育不同阶段(第8、12、16、20、24、28、30、35天)中SPAG6的表达;免疫荧光观察SPAG6在生精细胞中的定位;分别构建SPAG6和SPINK2蛋白表达质粒,以AH109和CHO细胞为对象,采用酵母双杂交及细胞内共定位实验检测SPAG6与SPINK2蛋白间相互作用;免疫荧光检测SPINK2在SPAG6基因敲除(KO)小鼠的睾丸生精细胞中的表达与定位。结果:小鼠出生后第16～28天,SPAG6表达显著升高,且定位于圆形精子细胞的顶体;酵母双杂交实验显示SPAG6/SPINK2组能在选择性培养基(SD/-Leu/-Trp/-His)中生长;CHO细胞共转染SPAG6和SPINK2表达质粒时,SPAG6与SPINK2共定位在细胞核周围;SPAG6 KO小鼠睾丸生精细胞中未检测到SPINK2表达及定位于精子顶体。结论:SPAG6与SPINK2形成蛋白复合体,并可能通过调控SPINK2的稳定表达参与精子顶体形成。

Objective: To explore the expression and regulatory function of sperm-associated antigen 6(SPAG6) in the formation of the sperm acrosome in mice. Methods: The expression of SPAG6 during the first wave of spermatogenesis on postnatal days(PN) 8, 12, 16, 20, 24, 28, 30 and 35 was examined by Western blot and the localization of SPAG6 in the testicular germ cells was determined by immunofluorescence. The expression plasmids of SPAG6 and serine protease inhibitor Kazal-type 2(SPINK2) were constructed, the interaction between SPAG6 and SPINK2 in the AH109 and CHO cells examined by yeast two-hybrid and co-localization assays, and the expression and localization of SPINK2 in the testicular germ cells of the SPAG6-knockout(SPAG6 KO) mice detected by immunofluorescence. Results: SPAG6 was highly expressed between PN 16 and 28 and localized in the acrosome of the round spermatids. Yeast two-hybrid assay showed the growth of SPAG6 and SPINK2 in the selective culture medium SD/-Leu/-Trp/-His, and the transfection of the CHO cells revealed the co-localization of SPAG6 and SPINK2 around the nuclei. The expression and acrosomal localization of SPINK2 were not found in the testicular germ cells of the SPAG6-KO mice. Conclusion: SPAG6 interacts with SPINK2 and probably participates in the formation of the sperm acrosome by stabilizing the expression of SPINK2 during spermatogenesis.