Abstract：
Spermatogenesis is tightly controlled at transcriptional, post-transcriptional, and epigenetic levels by various regulators, including miRNAs. This study deals with the identification of miRNAs critical to the three important stages of germ cell development (spermatocytes, round spermatids, and mature sperm) during spermatogenesis. We used high-throughput transcriptome sequencing to identify the differentially expressed miRNAs in the pachytene spermatocytes, round spermatids, and mature sperm of rat. We identified 1843 miRNAs that were differentially expressed across the three stages of germ cell development. These miRNAs were further categorized into three classes according to their pattern of expression during spermatogenesis: class 1 - miRNAs found exclusively in one stage and absent in the other two stages; class 2 - miRNAs found in any two stages but absent in the third stage; class 3 - miRNAs expressed in all the three stages. Six hundred forty-six miRNAs were found to be specific to one developmental stage, 443 miRNAs were found to be common across any two stages, and 754 miRNAs were common to all the three stages. Target prediction for ten most abundant miRNAs specific to each category identified miRNA regulators of mitosis, meiosis, and cell differentiation. The expression of each miRNA is specific to a particular developmental stage, which is required to maintain a significant repertoire of target mRNAs in the respective stage. Thus, this study provided valuable data that can be used in the future to identify the miRNAs involved in spermatogenic arrest at a particular stage of the germ cell development.
摘要：
精子发生在转录上受到严格控制，转录后，和各种调节因子的表观遗传水平，包括miRNA。本研究涉及对生殖细胞发育的三个重要阶段（精母细胞，圆形精子细胞，和成熟的精子）在精子发生过程中。我们使用高通量转录组测序来鉴定粗线精母细胞中差异表达的miRNAs，圆形精子细胞，和成熟的大鼠精子。我们鉴定了在生殖细胞发育的三个阶段差异表达的1843个miRNA。根据精子发生过程中的表达模式，这些miRNA进一步分为三类：1类-仅在一个阶段中发现而在其他两个阶段中不存在的miRNA；2类-在任何两个阶段中发现但在第三阶段中不存在的miRNA；3类-在所有三个阶段中表达的miRNA。发现有六百四十六种miRNAs特异于一个发育阶段，发现443个miRNA在任何两个阶段都是常见的，754个miRNAs在所有三个阶段都是常见的。对10个最丰富的miRNA特异性的每个类别的目标预测鉴定有丝分裂的miRNA调节因子，减数分裂,和细胞分化。每个miRNA的表达对特定的发育阶段具有特异性，这对于在相应阶段中维持靶mRNA的显著库是必需的。因此，这项研究提供了有价值的数据，可用于将来鉴定在生殖细胞发育的特定阶段参与生精停滞的miRNAs。
