MAMMALIAN SPERMATOGENESIS--HISTONES/DNA REORGANIZATION

哺乳动物精子发生的特征是进行性的 当鱼精蛋白取代细胞表面的组蛋白时， DNA. 一个转录和翻译的小鼠H2 b新基因 特别是在减数分裂后的圆形精子细胞中， 其含有极疏水的羧基末端， 这表明它可能与核膜相互作用。 的 本建议中的实验旨在检查：1） 这些信号在限制转录方面很重要， 将该基因翻译到特定的生精群体， 也就是说，圆形精子细胞; 2）这种蛋白质可能的作用 在染色质重组中。 精子细胞特异性 H2 b基因可以识别在人类免疫系统中起关键作用的序列元件。 限制其表达。 与大多数其他组蛋白mRNA不同， 转录物是聚腺苷酸化的。 由于精子发生在两周后， 在小鼠的一周时间内，多聚腺苷酸化在 稳定这些转录本将通过生成 用含有该基因的构建体转化的体细胞系 有和没有其多聚腺苷酸化信号序列。 抗血清 针对独特的羧基末端区域产生的信号将识别 这种蛋白质。 特别是，它在单倍体中的定位 细胞核和它的命运作为精子发生的进行将被检查。 蛋白质在染色质组织中的功能将是 通过其在转化细胞系中的产生及其 在转基因小鼠中过量生产。 由于在精子中经常观察到核异常， 遗传不育小鼠，缺乏特定基因的表达 可能会阻碍正常的染色质凝聚和随后的精子 发展 染色质的重组可能允许 精子发生过程中特定DNA序列的定位。 这 区室化对于转录调控可能是重要的。 在精子发生的后期和精子发生的早期阶段， 胚胎发育。

Mammalian spermatogenesis is characterized by the progressive condensation of chromatin as protamines replace histones on the DNA. A novel mouse H2b gene which is transcribed and translated specifically in post-meiotic round spermatids codes for a protein which contains an extremely hydrophobic carboxyl-terminus, suggesting that it may interact with the nuclear membrane. The experiments in this proposal are designed to examine: 1) the signals that are important in restricting the transcription and translation of this gene to a particular spermatogenic population, i.e., round spermatids; and, 2) the possible role this protein has in chromatin reorganization. Analysis of the spermatid-specific H2b gene may identify sequence elements that are critical in restricting its expression. Unlike most other histone mRNAs, this transcript is polyadenylated. As spermiogenesis occurs over a two week period in the mouse, the possible role of polyadenylation in stabilizing these transcripts will be examined by generating transformed somatic cell lines with constructs containing the gene with and without its polyadenylation signal sequence. An antiserum raised against the unique carboxyl-terminal region will identify this protein. In particular, its localization within the haploid nucleus and its fate as spermiogenesis proceeds will be examined. The function of the protein in chromatin organization will be assessed by its production in transformed cell lines and its overproduction in transgenic mice. As nuclear abnormalities frequently are observed in sperm of genetically sterile mice, the lack of expression of specific genes may hinder normal chromatin condensation and subsequent sperm development. Reorganization of the chromatin may permit localization of specific DNA sequences during spermiogenesis. This compartmentalization may be important for transcriptional regulation both late in spermatogenesis and in the early stages of embryonic development.