Institute for Biogenesis Research, John A. Burns School of Medicine, University of Hawaii at Manoa, 1960 East-West Road, Honolulu, HI 96822, USA.
Mol Hum Reprod. 2010 Jan;16(1):30-6. doi: 10.1093/molehr/gap080. Epub 2009 Sep 11.
Understanding how DNA is packaged in the mammalian sperm cell has important implications for human infertility as well as for the cell biology. Recent advances in the study of mammalian sperm chromatin structure and function have altered our perception of this highly condensed, inert chromatin. Sperm DNA is packaged very tightly to protect the DNA during the transit that occurs before fertilization. However, this condensation cannot sacrifice chromosomal elements that are essential for the embryo to access the correct sequences of the paternal genome for proper initiation of the embryonic developmental program. The primary levels of the sperm chromatin structure can be divided into three main categories: the large majority of DNA is packaged by protamines, a smaller amount (2-15%) retains histone-bound chromatin and the DNA is attached to the nuclear matrix at roughly 50 kb intervals. Current data suggest that the latter two structural elements are transferred to the paternal pronucleus after fertilization where they have important functional roles. The nuclear matrix organization is essential for DNA replication, and the histone-bound chromatin identifies genes that are important for embryonic development. These data support the emerging view of the sperm genome as providing, in addition to the paternal DNA sequence, a structural framework that includes molecular regulatory factors that are required for proper embryonic development.
了解 DNA 如何在哺乳动物精子细胞中包装，对人类不育以及细胞生物学都有重要意义。近年来，对哺乳动物精子染色质结构和功能的研究进展改变了我们对这种高度浓缩、惰性染色质的认识。精子 DNA 被非常紧密地包装，以在受精前发生的转运过程中保护 DNA。然而，这种浓缩不能牺牲对胚胎至关重要的染色体元件，以便胚胎能够访问父本基因组的正确序列，从而正确启动胚胎发育程序。精子染色质结构的主要水平可以分为三大类：绝大多数 DNA 由鱼精蛋白包装，一小部分（2-15%）保留组蛋白结合的染色质，DNA 以大约 50kb 的间隔附着在核基质上。目前的数据表明，后两种结构元件在受精后被转移到父本原核中，它们在那里具有重要的功能作用。核基质的组织对于 DNA 复制是必不可少的，而组蛋白结合的染色质则鉴定了对胚胎发育很重要的基因。这些数据支持了精子基因组的新兴观点，即除了父本 DNA 序列外，它还提供了一个结构框架，其中包括胚胎发育所必需的分子调节因子。
