Coffield V McNeil, Helms Whitney S, Jiang Qi, Su Lishan
Lineberger Comprehensive Cancer Center, Dept. of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7295, USA.
J Exp Med. 2004 Nov 15;200(10):1315-24. doi: 10.1084/jem.20040944. Epub 2004 Nov 8.
G protein signaling via the Galpha12 family (Galpha12 and Galpha13) has not been well studied in T cells. To investigate whether Galpha12 and Galpha13 are involved in thymopoiesis, we expressed the regulator of G protein signaling domain of p115RhoGEF to inhibit Galpha12 and Galpha13 during thymopoiesis. Fetal thymus organ cultures seeded with p115DeltaDH-expressing progenitor cells showed impaired thymopoiesis with a block at the CD4-CD8-CD44-CD25+ (DN3) stage. Using Galpha13 or Galpha12 minigenes, we demonstrated that Galpha13, but not Galpha12, is required for thymopoiesis. T progenitor cells expressing p115DeltaDH showed reduced proliferation and increased cell death. T cell receptor stimulation of the fetal thymus organ cultures did not rescue the block. Overexpression of the antiapoptotic gene Bcl2 rescued the defect in DN3 cells and partially rescued T cell development. Therefore, Galpha13-mediated signaling is necessary in early thymocyte proliferation and survival.
G蛋白通过Gα12家族（Gα12和Gα13）进行的信号传导在T细胞中尚未得到充分研究。为了研究Gα12和Gα13是否参与胸腺生成，我们在胸腺生成过程中表达p115RhoGEF的G蛋白信号调节剂结构域以抑制Gα12和Gα13。接种表达p115DeltaDH的祖细胞的胎胸腺器官培养物显示胸腺生成受损，在CD4-CD8-CD44-CD25+（DN3）阶段出现阻滞。使用Gα13或Gα12小基因，我们证明胸腺生成需要Gα13而不是Gα12。表达p115DeltaDH的T祖细胞显示增殖减少和细胞死亡增加。胎胸腺器官培养物的T细胞受体刺激不能挽救这种阻滞。抗凋亡基因Bcl2的过表达挽救了DN3细胞中的缺陷并部分挽救了T细胞发育。因此，Gα13介导的信号传导在早期胸腺细胞增殖和存活中是必需的。
