Rho GTPase Cdc42 对于人类 T 细胞的发育至关重要。
Rho GTPase Cdc42 is essential for human T-cell development.
机构信息
Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium.
出版信息
Haematologica. 2010 Mar;95(3):367-75. doi: 10.3324/haematol.2009.006890.
BACKGROUND
Rho GTPases are involved in the regulation of many cell functions, including some related to the actin cytoskeleton. Different Rho GTPases have been shown to be important for T-cell development in mice. However, their role in human T-cell development has not yet been explored.
DESIGN AND METHODS
We examined the expression and activation of Rho GTPases along different stages of T-cell development in the human thymus. Early stage human thymocytes were transduced with constitutively active and dominant negative mutants of different Rho GTPases to explore their role in human T-cell development, as analyzed in fetal thymus organ cultures. The use of these mutants as well as Rho GTPase-specific inhibitors allowed us to explore the role of GTPases in thymocyte migration.
RESULTS
We found that the expression of several Rho GTPases is differently regulated during successive stages of T-cell development in man, suggesting a specific role in human thymopoiesis. In chimeric fetal thymus organ culture, T-cell development was not or only mildly affected by expression of dominant negative Rac1 and Rac2, but was severely impaired in the presence of dominant negative Cdc42, associated with enhanced apoptosis and reduced proliferation. Kinetic analysis revealed that Cdc42 is necessary in human T-cell development both before and after expression of the pre-T-cell receptor. Using inhibitors and retrovirally transferred mutants of the aforementioned Rho GTPases, we showed that only Rac1 is necessary for migration of different thymocyte subsets, including the early CD34(+) fraction, towards stromal cell-derived factor-1 alpha. Constitutively active mutants of Rac1, Rac2 and Cdc42 all impaired migration towards stromal cell-derived factor-1 alpha and T-cell development to different degrees.
CONCLUSIONS
This is the first report on Rho GTPases in human T-cell development, showing the essential role of Cdc42. Our data suggest that enhanced apoptotic death and reduced proliferation rather than disturbed migration explains the decreased thymopoiesis induced by dominant negative Cdc42.
背景
Rho GTPases 参与许多细胞功能的调节，包括与肌动蛋白细胞骨架相关的一些功能。不同的 Rho GTPases 已被证明对小鼠 T 细胞的发育很重要。然而，它们在人类 T 细胞发育中的作用尚未被探索。
设计和方法
我们研究了 Rho GTPases 在人胸腺中 T 细胞发育的不同阶段的表达和激活。早期人胸腺细胞被转导以表达不同 Rho GTPases 的组成性激活和显性失活突变体，以在胎胸腺器官培养物中分析它们在人类 T 细胞发育中的作用。这些突变体的使用以及 Rho GTPase 特异性抑制剂的使用使我们能够探索 GTPases 在胸腺细胞迁移中的作用。
结果
我们发现，在人类 T 细胞发育的连续阶段，几种 Rho GTPases 的表达受到不同的调节，这表明它们在人类胸腺生成中具有特定的作用。在嵌合胎胸腺器官培养物中，表达显性失活 Rac1 和 Rac2 对 T 细胞发育没有影响或只有轻微影响，但在存在显性失活 Cdc42 的情况下，T 细胞发育严重受损，同时伴有凋亡增加和增殖减少。动力学分析表明，Cdc42 在人类 T 细胞发育中既在 pre-T 细胞受体表达之前又在之后都是必需的。使用上述 Rho GTPases 的抑制剂和逆转录病毒转移突变体，我们表明只有 Rac1 是不同胸腺细胞亚群（包括早期 CD34+ 部分）向基质细胞衍生因子-1α迁移所必需的。Rac1、Rac2 和 Cdc42 的组成性激活突变体都不同程度地损害了向基质细胞衍生因子-1α的迁移和 T 细胞发育。
结论
这是关于 Rho GTPases 在人类 T 细胞发育中的首次报道，表明 Cdc42 的重要作用。我们的数据表明，凋亡死亡增加和增殖减少而不是迁移受损解释了显性失活 Cdc42 诱导的胸腺生成减少。
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