Hwang I, Chae C B
Department of Biochemistry, University of North Carolina, Chapel Hill 27599-7260.
Mol Cell Biol. 1989 Mar;9(3):1005-13. doi: 10.1128/mcb.9.3.1005-1013.1989.
The testis-specific H2B histone (TH2B) gene is expressed in pachytene spermatocytes during meiotic prophase I in the absence of any significant DNA synthesis. Unlike somatic histones, synthesis of testis-specific histones is not affected by inhibitors of DNA synthesis. A genomic rat TH2B gene was cloned by using a DNA fragment derived from TH2B cDNA as a probe. Expression of the cloned TH2B was investigated by gene transfer experiments. From these studies, we found that the 5' upstream region of the cloned TH2B gene contained S-phase-specific transcription elements which regulated expression of a reporter gene in an S-phase-specific manner. The S-phase-regulatory element was found to be located in two regions containing CCAAT elements between -153 and -110 base pairs (bp) and an octamer element (ATTTGCAT) between -109 and -84 bp. The two regions were required for a maximal stimulation of transcription of the cloned TH2B gene in S phase. On the other hand, only the octamer element was reported be important for the S-phase-specific transcription of human H2B gene. Since the synthesis of the TH2B histone is independent of DNA synthesis and specific for pachytene spermatocytes in vivo, the presence of the S-phase-specific transcription regulatory elements in the TH2B gene is surprising.
睾丸特异性H2B组蛋白（TH2B）基因在减数分裂前期I的粗线期精母细胞中表达，此时不存在任何显著的DNA合成。与体细胞组蛋白不同，睾丸特异性组蛋白的合成不受DNA合成抑制剂的影响。通过使用源自TH2B cDNA的DNA片段作为探针克隆了大鼠基因组TH2B基因。通过基因转移实验研究了克隆的TH2B的表达。从这些研究中，我们发现克隆的TH2B基因的5'上游区域包含S期特异性转录元件，这些元件以S期特异性方式调节报告基因的表达。发现S期调节元件位于两个区域，一个区域在-153至-110碱基对（bp）之间包含CCAAT元件，另一个区域在-109至-84 bp之间包含一个八聚体元件（ATTTGCAT）。这两个区域是在S期最大程度刺激克隆的TH2B基因转录所必需的。另一方面，据报道只有八聚体元件对人H2B基因的S期特异性转录很重要。由于TH2B组蛋白的合成独立于DNA合成且在体内对粗线期精母细胞具有特异性，因此TH2B基因中存在S期特异性转录调节元件令人惊讶。
