Department of Microbiology & Immunology and the Life Sciences Institute, University of British Columbia , Vancouver, BC, Canada.
Small GTPases. 2020 Nov;11(6):402-412. doi: 10.1080/21541248.2018.1441626. Epub 2018 Mar 8.
When B lymphocytes encounter antigen-bearing surfaces, B-cell receptor (BCR) signaling initiates remodeling of the F-actin network and reorientation of the microtubule-organizing center (MTOC) towards the antigen contact site. We have previously shown that the Rap1 GTPase, an evolutionarily conserved regulator of cell polarity, is essential for these processes and that Rap1-regulated actin remodeling is required for MTOC polarization. The role of Rap2 proteins in establishing cell polarity is not well understood. We now show that depleting Rap2c, the only Rap2 isoform expressed in the A20 B-cell line, impairs BCR-induced MTOC reorientation as well as the actin remodeling that supports MTOC polarization. Thus Rap1 and Rap2 proteins may have similar but non-redundant functions in coupling the BCR to MTOC polarization.
当 B 淋巴细胞遇到带有抗原的表面时，B 细胞受体 (BCR) 信号会启动 F-肌动蛋白网络的重塑，并将微管组织中心 (MTOC) 重新定向到抗原接触部位。我们之前已经表明，Rap1 GTPase 是一种进化上保守的细胞极性调节剂，对于这些过程至关重要，并且 Rap1 调节的肌动蛋白重塑对于 MTOC 极化是必需的。Rap2 蛋白在建立细胞极性中的作用尚不清楚。我们现在表明，耗尽仅在 A20 B 细胞系中表达的 Rap2c，会损害 BCR 诱导的 MTOC 重新定向以及支持 MTOC 极化的肌动蛋白重塑。因此，Rap1 和 Rap2 蛋白在将 BCR 与 MTOC 极化偶联方面可能具有相似但非冗余的功能。
