Center for Animal Transgenesis and Germ Cell Research, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Mol Reprod Dev. 2010 Apr;77(4):348-52. doi: 10.1002/mrd.21153.
Mammalian spermatogonial stem cells reside on the basement membrane of the seminiferous tubules. The mechanisms responsible for maintenance of spermatogonia at the basement membrane are unclear. Since acetylated alpha-tubulin (Ac-alpha-Tu) is a component of long-lived, stable microtubules and deacetylation of alpha-tubulin enhances cell motility, we hypothesized that acetylation of alpha-tubulin might be associated with positioning of spermatogonia at the basement membrane. The expression pattern of Ac-alpha-Tu at different stages of testis development was characterized by immunohistochemistry for Ac-alpha-Tu and spermatogonia-specific proteins (PGP 9.5, DAZL). In immature pig testes, Ac-alpha-Tu was present exclusively in gonocytes at 1 week of age, and in a subset of spermatogonia at 10 weeks of age. At this age, spermatogonia are migrating toward the tubule periphery and Ac-alpha-Tu appeared polarized toward the basement membrane. In adult pig testes, Ac-alpha-Tu was detected in few single or paired spermatogonia at the basement membrane as well as in spermatids and spermatozoa. Only undifferentiated (DAZL-), proliferating (determined by BrdU incorporation) spermatogonia expressed high levels of Ac-alpha-Tu. Comparison with the expression pattern of beta-tubulin and tyrosinated alpha-tubulin confirmed that only Ac-alpha-Tu is specific to germ cells. The unique pattern of Ac-alpha-Tu in undifferentiated germ cells during postnatal development suggests that posttranslational modifications of microtubules may play an important role in recruiting and anchoring spermatogonia at the basement membrane. Mol. Reprod. Dev. 77: 348-352, 2010. (c) 2009 Wiley-Liss, Inc.
哺乳动物精原干细胞位于生精小管的基膜上。负责维持精原细胞在基膜上的机制尚不清楚。由于乙酰化α-微管蛋白（Ac-α-Tu）是长寿命、稳定微管的组成部分，并且α-微管蛋白去乙酰化增强细胞迁移能力，因此我们假设α-微管蛋白的乙酰化可能与精原细胞在基膜上的定位有关。通过免疫组织化学方法检测 Ac-α-Tu 和精原细胞特异性蛋白（PGP9.5、DAZL），研究了 Ac-α-Tu 在睾丸发育不同阶段的表达模式。在未成熟的猪睾丸中，1 周龄时 Ac-α-Tu 仅存在于性母细胞中，而在 10 周龄时存在于部分精原细胞中。此时，精原细胞向小管周围迁移，Ac-α-Tu 似乎向基膜极化。在成年猪睾丸中，在基膜上的少数单个或成对精原细胞以及精细胞和精子中检测到 Ac-α-Tu。只有未分化（DAZL-）、增殖（通过 BrdU 掺入确定）的精原细胞表达高水平的 Ac-α-Tu。与β-微管和酪氨酸化α-微管的表达模式比较证实，只有 Ac-α-Tu 是生殖细胞特异性的。Ac-α-Tu 在出生后发育过程中未分化的生殖细胞中的独特表达模式表明，微管的翻译后修饰可能在招募和锚定精原细胞在基膜上发挥重要作用。 Mol.Reprod.Dev.77:348-352,2010.（c）2009 Wiley-Liss, Inc.
