School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, Washington.
Dev Dyn. 2019 Jun;248(6):488-500. doi: 10.1002/dvdy.33. Epub 2019 Apr 19.
Male germ cells are unique because they express a substantial number of variants of the general DNA binding proteins, known as histones, yet the biological significance of these variants is still unknown. In the present study, we aimed to address the expression pattern of the testis-specific histone H2B variant (TH2B) and the testis-specific histone H2A variant (TH2A) within the neonatal mouse testis.
We demonstrate that TH2B and TH2A are present in a testis-enriched for undifferentiated spermatogonia. Co-localization studies with an undifferentiated marker, ZBTB16, revealed that TH2B and ZBTB16 co-localize in the neonatal testis. Upon the appearance of the primary spermatocytes, TH2B no longer co-localized with the ZBTB16 positive spermatogonia but were instead detected within the differentiating spermatogonia. This pattern of expression where TH2B and ZBTB16 no longer co-localize was maintained in the adult testis.
These findings are in contrast to previous studies, which demonstrated that TH2B and TH2A were found only in adult spermatocytes. Our data are in support of a switch in the expression of these variants following the first round of spermatogonial differentiation. These studies reinforce current understandings that spermatogonia within the neonatal mouse testis are inherently different from those residing within the adult testis.
男性生殖细胞是独特的，因为它们表达大量的一般 DNA 结合蛋白的变体，称为组蛋白，但这些变体的生物学意义仍然未知。在本研究中，我们旨在探讨睾丸特异性组蛋白 H2B 变体 (TH2B) 和睾丸特异性组蛋白 H2A 变体 (TH2A) 在新生小鼠睾丸中的表达模式。
我们证明 TH2B 和 TH2A 存在于富含未分化精原细胞的睾丸中。与未分化标志物 ZBTB16 的共定位研究表明，TH2B 和 ZBTB16 共定位在新生睾丸中。在初级精母细胞出现时，TH2B 不再与 ZBTB16 阳性精原细胞共定位，而是在分化的精原细胞中检测到。这种 TH2B 和 ZBTB16 不再共定位的表达模式在成年睾丸中得以维持。
这些发现与之前的研究相反，之前的研究表明 TH2B 和 TH2A 仅存在于成年精母细胞中。我们的数据支持这些变体在第一轮精原细胞分化后表达发生转换的观点。这些研究加强了当前的认识，即新生小鼠睾丸中的精原细胞与成年睾丸中的精原细胞本质上不同。
