减数分裂后, 圆形精子细胞经过一系列变态过程最终发育为成熟精子。期间, 精子细胞质逐渐丢失, 其染色质组蛋白逐渐经过渡蛋白替换为鱼精蛋白, 染色质被致密包装并高度浓缩。很多学者认为, 精子转录活性被关闭, 不存在RNA。但近些年却在精子中检测到了种类繁多的转录本, 包括精子染色质重新包装所需蛋白的转录本及一些小分子RNA等。由于精子核内组蛋白没有完全被鱼精蛋白替换, 且染色质上包含一些核酸活性敏感位点, 推测精子存在一定的转录活性, 并通过激素和表观遗传修饰等调控转录。精子中的这些RNA一部分是精子形成过程中残留下来的, 另一部分是精子细胞适时表达的。深入研究精子形成中的基因转录表达, 可增进对精子形成与成熟遗传本质的理解, 为高效利用雄性配子进行生殖控制提供理论依据。文章综述了近年来精子形成期基因转录表达的研究进展, 并提出了未来的研究方向。
After meiosis, round spermatid develops into mature sperm through metamorphosis. During this stage, most cytoplasm in the germ cell is gradually lost. The histones associated with chromatin are replaced by transition proteins and eventually transformed into protamines. Thus, the spermatid chromatin is stringently packaged and highly concentrated. It was thought that the transcription activity of spermatid is lost and RNAs are absent in spermatid. Nevertheless, many types of transcripts are detected in recent years, including the transcripts needed during chromatin repackaged and some small RNAs, etc. Because histones in the nuclear are not replaced entirely, and there are some active sites on the chromatin, we conjectured that spermatid has some transcription activity, and this activity is regulated by hormone and epigenetic modification. These RNAs may be the residues in the spermatogenesis, or timely expressed during spermiogenesis. A deep study on gene transcription in spermiogenesis will help understand the genetic characteristics and provide the theoretic basis for reproductive control using male gamete. This article reviewed recent advances in spermiogenesis at gene transcription level and proposed the future research directions.
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