Epididymosomes Transfer Epididymal Sperm Binding Protein 1 (ELSPBP1) to Dead Spermatozoa During Epididymal Transit in Bovine
Epididymosomes Transfer Epididymal Sperm Binding Protein 1 (ELSPBP1) to Dead Spermatozoa During Epididymal Transit in Bovine
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DOI：
10.1095/biolreprod.112.100990
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发表时间：
2012-10-01
影响因子：
3.6
通讯作者：
Sullivan, Robert
中科院分区：
文献类型：
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作者：
D'Amours, Olivier;Frenette, Gilles;Sullivan, Robert
以前，我们发现，附睾精子结合蛋白1（ELSPBP 1）的特点精子已经死亡，在牛射精前。在这项研究中，我们调查了ELSPBP 1在公牛生殖道的存在，以及它的收购精子在附睾运输。如通过实时RT-PCR评估的，ELSPBP 1在附睾头和附睾体中高度表达，但在睾丸和附睾尾中以较低的表达水平存在。免疫组化显示相同的表达模式。然而，组织匀浆上的蛋白质印迹显示出一些差异，因为发现ELSPBP 1在沿着附睾的所有部位的浓度相当。这种差异是由于附睾液中存在ELSPBP 1。在附睾头和尾部液中，ELSPBP 1与附睾体相关，附睾体是由附睾上皮细胞分泌的小膜泡，并参与蛋白质向精子的转移。通过免疫细胞计数法评估，ELSPBP 1被发现在附睾头的死亡精子的一个子集，但被发现在附睾尾的所有死亡精子。为了评估精子获得ELSPBP 1，在各种条件下将附睾头精子与附睾尾精子体孵育。ELSPBP 1的免疫细胞计数法检测显示，只有精子已经死亡的孵化前接受ELSPBP 1的附睾体转移。这种感受性通过在孵育培养基中存在锌而增强。精子亚群的这种特异性表明，一个潜在的机制参与，ELSPBP 1可能是一个标签，用于识别死亡的精子在附睾运输。
Previously, we showed that epididymal sperm binding protein 1 (ELSPBP1) characterizes spermatozoa already dead before ejaculation in bovine. In this study, we investigated the presence of ELSPBP1 in bull genital tract as well as its acquisition by spermatozoa during epididymal transit. As assessed by real-time RT-PCR, ELSPBP1 was highly expressed in the caput and the corpus epididymis but was present in lower expression levels in the testis and the cauda epididymis. Immunohistochemistry revealed the same expression pattern. However, Western blot on tissue homogenates showed some discrepancies, as ELSPBP1 was found in a comparable concentration all along the epididymis. This difference was due to the presence of ELSPBP1 in the epididymal fluid. In both caput and cauda epididymal fluid, ELSPBP1 was associated with the epididymosomes, small membranous vesicles secreted by epithelial cells of the epididymis and implicated in the transfer of proteins to spermatozoa. As assessed by immunocytometry, ELSPBP1 was found on a subset of dead spermatozoa in caput epididymis but was found on all dead spermatozoa in cauda epididymis. To assess ELSPBP1 acquisition by spermatozoa, caput epididymal spermatozoa were incubated with cauda epididymosomes under various conditions. ELSPBP1 detection by immunocytometry assay revealed that only spermatozoa already dead before incubation were receptive to ELSPBP1 transfer by epididymosomes. This receptivity was enhanced by the presence of zinc in the incubation medium. This specificity for a sperm subpopulation suggests that an underlying mechanism is involved and that ELSPBP1 could be a tag for the recognition of dead spermatozoa during epididymal transit.