Epididymosomes convey different repertoires of miRNAs throughout the epididymis. Bos taurus

Epididymosomes are small membrane vesicles (50-500nm) secreted by epididymal epithelial cells and involved in post-testicular sperm maturation. While their role in protein transfer to the sperm membrane is well acknowledged, we unveil here their capacity to vehicle microRNAs (miRNAs), which are potent regulators of post-transcriptional gene expression. Using a global microarray approach, we showed that epididymosomes providing from two discrete bovine epididymal regions (caput and cauda) possess distinct miRNA signatures. In addition, we established that miRNA repertoires contained in epididymosomes differ from those of their parent epithelial cells, suggesting that miRNA populations released from the cells may be selectively sorted. Binding of DilC12-labeled epididymosomes to primary cultured epididymal cells was measured by flow cytometry and indicated that epididymosomes from the median caput and their miRNA content may be incorporated into distal caput epithelial cells. Overall, these findings reveal that distinct miRNA repertoires are released into the intraluminal fluid in a region-specific manner and could be involved in a novel mechanism of intercellular communication throughout the epididymis via epididymosomes. Overall design: We determined the miRNA profiles of epididymosomes isolated by perfusion from caput and cauda regions of the epididymis and compared it with the miRNA content of epididymal epithelial cells from the same regions.

附睾小体（Epididymosomes）是由附睾上皮细胞分泌的小型膜囊泡（直径50~500nm），参与睾丸后精子成熟过程。尽管其向精子膜转运蛋白的功能已得到广泛认可，但本研究首次揭示了其携带微小RNA（miRNAs）的能力——后者是一类强效的转录后基因表达调控因子。
本研究采用全基因组微阵列分析技术，证实源自牛附睾两个离散区域（头段与尾段）的附睾小体具有截然不同的miRNA表达谱。此外，本研究发现附睾小体所含的miRNA谱库与其亲本上皮细胞的miRNA谱库存在显著差异，这提示细胞释放的miRNA群体可能经过选择性分选。
本研究通过流式细胞术检测了DilC12标记的附睾小体与原代培养附睾上皮细胞的结合情况，结果显示，附睾头段中部的附睾小体及其所含miRNA可被整合至头段远端的上皮细胞中。
综上，本研究结果表明，不同区域的附睾小体可通过区域特异性的方式将独特的miRNA谱库释放至管腔内液中；这一过程可能介导了附睾内一种新型的细胞间通讯机制。
实验设计概述：本研究对通过灌注法从附睾头段与尾段分离得到的附睾小体的miRNA谱进行了检测，并将其与对应区域附睾上皮细胞的miRNA含量进行了对比分析。