CELL and I³ Research Group, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
J Cell Sci. 2011 Aug 1;124(Pt 15):2611-21. doi: 10.1242/jcs.089532. Epub 2011 Jul 12.
The gap junction protein connexin43 (Cx43) is widely expressed in mammalian cells and forms intercellular channels for the transfer of small molecules between adjacent cells, as well as hemichannels that mediate bidirectional transport of molecules between the cell and the surrounding environment. Cx43 regulates cell adhesion and migration in neurons and glioma cells, and we now show that Cx43 influences BCR-, LFA-1- and CXCL12-mediated activation of the Rap1 GTPase. Using shRNA knockdown of Cx43 in WEHI 231 cells, we show that Cx43 is required for sustained Rap1 activation and BCR-mediated spreading. To determine the domains of Cx43 that are important for this effect, Cx43-null J558 μm3 B cells (which express a wild-type IgM BCR) were transfected with wild-type Cx43-GFP or a C-terminal-truncated Cx43 (Cx43ΔT-GFP). Expression of wild-type Cx43-GFP, but not Cx43ΔT-GFP, was sufficient to restore sustained, BCR-mediated Rap1 activation and cell spreading. Cx43, and specifically the C-terminal domain, was also important for LFA-1- and CXCL12-mediated Rap1 activation, spreading and adhesion to an endothelial cell monolayer. These data show that Cx43 has an important and previously unreported role in B-cell processes that are essential to normal B-cell development and immune responses.
间隙连接蛋白 connexin43（Cx43）广泛表达于哺乳动物细胞中，形成细胞间小分子在相邻细胞间传递的通道，以及连接细胞和周围环境的半通道，介导分子的双向转运。Cx43 调节神经元和神经胶质瘤细胞的细胞黏附和迁移，我们现在表明 Cx43 影响 BCR、LFA-1 和 CXCL12 介导的 Rap1 GTP 酶的激活。使用 shRNA 敲低 WEHI 231 细胞中的 Cx43，我们表明 Cx43 是持续 Rap1 激活和 BCR 介导的扩展所必需的。为了确定对这种效应重要的 Cx43 结构域，用野生型 Cx43-GFP 或 C 端截断的 Cx43（Cx43ΔT-GFP）转染表达野生型 IgM BCR 的 Cx43 缺失 J558 μm3 B 细胞。野生型 Cx43-GFP 的表达，但不是 Cx43ΔT-GFP 的表达，足以恢复持续的 BCR 介导的 Rap1 激活和细胞扩展。Cx43，特别是 C 端结构域，对于 LFA-1 和 CXCL12 介导的 Rap1 激活、扩展和与内皮细胞单层的黏附也是重要的。这些数据表明 Cx43 在 B 细胞过程中具有重要的和以前未报道的作用，这些作用对正常 B 细胞发育和免疫反应至关重要。
