Voisin P J, Pardue S, Morrison-Bogorad M
Department of Neurology, University of Texas Southwestern Medical Center at Dallas.
J Neurochem. 1995 Jan;64(1):109-20. doi: 10.1046/j.1471-4159.1995.64010109.x.
The beta 4 and beta 10 thymosins are G-actin binding proteins that exhibit complex patterns of expression during rat cerebellar development. Their expression in vivo is initially high in immature granule cells and diminishes as they migrate and differentiate, ceasing altogether by postnatal day 21. Thymosin beta 4 is present in a subset of glia throughout postnatal development, and its synthesis is also induced in maturing Bergmann glia. In contrast, thymosin beta 10 is only present at very low levels in a very small subpopulation of glia in the adult cerebellum. To study the factors differentially regulating expression of the beta-thymosins, we characterized their patterns of expression in primary cultures of rat cerebellum. Both beta-thymosins were initially expressed in granule cells, although expression, especially of thymosin beta 4, was truncated compared with the in vivo time course. As in vivo, thymosin beta 4 was synthesized at much higher levels in astrocytes and microglia in cultures from postnatal cerebellum than was thymosin beta 10. Unlike in vivo, the latter was expressed in glia cultured from fetal cerebellum. The similarities between the in vivo and in vitro expression of the beta-thymosins show that modulation of tissue culture conditions could be used to identify factors regulating beta-thymosin expression in vivo. The differences would identify regulatory mechanisms that are not evident from the in vivo studies alone.
β4和β10胸腺素是与G-肌动蛋白结合的蛋白质，在大鼠小脑发育过程中呈现出复杂的表达模式。它们在体内的表达最初在未成熟的颗粒细胞中较高，随着细胞迁移和分化而减少，在出生后第21天完全停止。胸腺素β4在出生后整个发育过程中存在于一部分神经胶质细胞中，其合成也在成熟的伯格曼神经胶质细胞中被诱导。相比之下，胸腺素β10在成年小脑的非常小的一部分神经胶质细胞亚群中仅以非常低的水平存在。为了研究差异调节β-胸腺素表达的因素，我们对它们在大鼠小脑原代培养物中的表达模式进行了表征。两种β-胸腺素最初都在颗粒细胞中表达，尽管与体内时间进程相比，尤其是胸腺素β4的表达被截断。与体内情况一样，出生后小脑培养物中的星形胶质细胞和小胶质细胞中胸腺素β4的合成水平比胸腺素β10高得多。与体内不同的是，后者在胎儿小脑培养的神经胶质细胞中表达。β-胸腺素在体内和体外表达的相似性表明，调节组织培养条件可用于识别体内调节β-胸腺素表达的因素。差异将识别仅从体内研究中不明显的调节机制。
