Two Functional Forms of ACRBP/sp32 Are Produced by Pre-mRNA Alternative Splicing in the Mouse
Two Functional Forms of ACRBP/sp32 Are Produced by Pre-mRNA Alternative Splicing in the Mouse
复制标题
DOI：
10.1095/biolreprod.112.107425
复制
发表时间：
2013-04-01
影响因子：
3.6
通讯作者：
Baba, Tadashi
中科院分区：
文献类型：
--
作者：
Kanemori, Yoshinori;Ryu, Jin-Hyeob;Baba, Tadashi
ACRBP/sp32是精子丝氨酸蛋白酶ACR前体（前ACR）和中间形式的特异性结合蛋白。在这项研究中，我们研究了小鼠ACRBP在生精细胞和附睾精子中的表达模式、定位和可能的作用。与其他哺乳动物的Acrbp不同，在小鼠中，通过选择性剪接Acrbp可产生两种形式的Acrbp mrna——野生型Acrbp- w和变体Acrbp- v5 mrna。ACRBP-W在粗线精母细胞和单倍体精母细胞中合成，并通过去除n端一半立即加工成成熟蛋白ACRBP-C。保留内含子5剪接变体mRNA产生ACRBP的主要形式，ACRBP- v5，存在于粗线精细胞和圆形精细胞中，但不存在于细长精细胞中。在早期圆形精子顶体颗粒中，ACRBP-W和ACRBP-V5均与前acr共定位，而精子顶体中仅含有ACRBP-C。谷胱甘肽s -转移酶下拉实验显示，ACRBP-V5和ACRBP-C具有不同的结构域，能够结合前acr c端区域的两个片段。此外，ACRBP-C的存在显著加速了前acr的自激活。这些结果表明，ACRBP-V5和ACRBP-C可能分别参与精子发生过程中ACR前体转运/包装到顶体颗粒中，以及顶体胞吐过程中促进ACR从顶体释放。
ACRBP/sp32 is a binding protein specific for the precursor (pro-ACR) and intermediate forms of sperm serine protease ACR. In this study, we examined the expression pattern, localization, and possible role of mouse ACRBP in spermatogenic cells and epididymal sperm. Unlike other mammalian ACRBPs, two forms of Acrbp mRNA-wild-type Acrbp-W and variant Acrbp-V5 mRNAs-were generated by alternative splicing of Acrbp in the mouse. ACRBP-W was synthesized in pachytene spermatocytes and haploid spermatids and immediately processed into a mature protein, ACRBP-C, by removal of the N-terminal half. The intron 5-retaining splice variant mRNA produced a predominant form of ACRBP, ACRBP-V5, that was present in pachytene spermatocytes and round spermatids, but was absent in elongating spermatids. ACRBP-W and ACRBP-V5 were both colocalized with pro-ACR in the acrosomal granules of early round spermatids, whereas the sperm acrosome contained only ACRBP-C. Glutathione S-transferase pull-down assays revealed that ACRBP-V5 and ACRBP-C possess a different domain capable of binding each of two segments in the C-terminal region of pro-ACR. Moreover, autoactivation of pro-ACR was remarkably accelerated by the presence of ACRBP-C. These results suggest that ACRBP-V5 and ACRBP-C may function in the transport/packaging of pro-ACR into acrosomal granules during spermiogenesis and in the promotion of ACR release from the acrosome during acrosomal exocytosis, respectively.