Kim Y J, Hwang I, Tres L L, Kierszenbaum A L, Chae C B
Department of Biochemistry, University of North Carolina, Chapel Hill 27514.
Dev Biol. 1987 Nov;124(1):23-34. doi: 10.1016/0012-1606(87)90455-6.
We have cloned cDNA of a testis-specific histone, TH2B (a variant of H2B), and rat somatic H2B gene to investigate regulation of testis-specific histone genes during rat spermatogenesis. The amino acid sequences deduced from DNA sequences show extensive sequence divergence in the N-terminal third of the two histones. The rest is highly conserved. One cysteine residue was found in TH2B. No cysteine is present in somatic histones except in H3 histone. We investigated the expression of TH2B and H2B genes using the regions of sequence divergence as hybridization probes. The TH2B gene is expressed only in the testis, and the expression of this gene is detected 14 days after birth, reaching a maximum at Day 20. The level of H2B mRNA shows a reciprocal pattern. This contrasting pattern can be explained by the gradually changing proportion of spermatogonia and spermatocytes with testicular maturation. In situ cytohybridization studies show that H2B gene is expressed primarily in proliferating spermatogonia and preleptotene spermatocytes, whereas TH2B gene is expressed exclusively in pachytene spermatocytes which first appear in testis about 14 days after birth. H2B and TH2B genes appear to be ideal markers for the study of proliferation and differentiation events in spermatogenesis and their regulatory mechanisms.
我们克隆了一种睾丸特异性组蛋白TH2B（H2B的一种变体）的cDNA以及大鼠体细胞H2B基因，以研究大鼠精子发生过程中睾丸特异性组蛋白基因的调控。从DNA序列推导的氨基酸序列显示，这两种组蛋白在N端三分之一区域存在广泛的序列差异。其余部分高度保守。在TH2B中发现了一个半胱氨酸残基。除了H3组蛋白外，体细胞组蛋白中不存在半胱氨酸。我们使用序列差异区域作为杂交探针，研究了TH2B和H2B基因的表达。TH2B基因仅在睾丸中表达，该基因在出生后14天被检测到表达，在第20天达到最大值。H2B mRNA水平呈现相反的模式。这种相反的模式可以通过随着睾丸成熟，精原细胞和精母细胞比例的逐渐变化来解释。原位细胞杂交研究表明，H2B基因主要在增殖的精原细胞和前细线期精母细胞中表达，而TH2B基因仅在粗线期精母细胞中表达，粗线期精母细胞在出生后约14天首次出现在睾丸中。H2B和TH2B基因似乎是研究精子发生过程中的增殖和分化事件及其调控机制的理想标记。
