PDF(Pubmed)
Abstract：
Connexins (Cxs) are transmembrane proteins that assemble into gap junction channels (GJCs) and hemichannels (HCs). Previous researches support the involvement of Rho GTPases and actin microfilaments in the trafficking of Cxs, formation of GJCs plaques, and regulation of channel activity. Nonetheless, it remains uncertain whether distinct types of Cxs HCs and GJCs respond differently to Rho GTPases or changes in actin polymerization/depolymerization dynamics. Our investigation revealed that inhibiting RhoA, a small GTPase that controls actin polymerization, or disrupting actin microfilaments with cytochalasin B (Cyto-B), resulted in reduced GJCs plaque size at appositional membranes and increased transport of HCs to non-appositional plasma membrane regions. Notably, these effects were consistent across different Cx types, since Cx26 and Cx43 exhibited similar responses, despite having distinct trafficking routes to the plasma membrane. Functional assessments showed that RhoA inhibition and actin depolymerization decreased the activity of Cx43 GJCs while significantly increasing HC activity. However, the functional status of GJCs and HCs composed of Cx26 remained unaffected. These results support the hypothesis that RhoA, through its control of the actin cytoskeleton, facilitates the transport of HCs to appositional cell membranes for GJCs formation while simultaneously limiting the positioning of free HCs at non-appositional cell membranes, independently of Cx type. This dynamic regulation promotes intercellular communications and reduces non-selective plasma membrane permeability through a Cx-type dependent mechanism, whereby the activity of Cx43 HCs and GJCs are differentially affected but Cx26 channels remain unchanged.
摘要：
连接蛋白(Cxs)是组装成间隙连接通道(GJC)和半通道(HC)的跨膜蛋白。以前的研究支持RhoGTP酶和肌动蛋白微丝参与Cxs的贩运，GJCs斑块的形成，和渠道活动的调节。尽管如此，不同类型的CxsHCs和GJCs对RhoGTP酶的反应是否不同或肌动蛋白聚合/解聚动力学的变化仍不确定。我们的调查显示抑制RhoA，一种控制肌动蛋白聚合的小GTP酶，或用细胞松弛素B（Cyto-B）破坏肌动蛋白微丝，导致在并置膜处的GJCs斑块大小减小，并增加了HC向非并置质膜区域的转运。值得注意的是,这些影响在不同的Cx类型中是一致的，由于Cx26和Cx43表现出相似的反应，尽管有不同的运输途径到质膜。功能评估显示RhoA抑制和肌动蛋白解聚降低Cx43GJCs的活性,同时显著增加HC活性。然而,GJCs和由Cx26组成的HCs的功能状态未受影响.这些结果支持RhoA，通过它对肌动蛋白细胞骨架的控制，促进HCs运输到并置细胞膜以形成GJCs，同时限制游离HCs在非并置细胞膜上的定位，独立于Cx类型。这种动态调节通过Cx型依赖机制促进细胞间通讯并降低非选择性质膜通透性。其中Cx43HC和GJCs的活性受到差异影响，但Cx26通道保持不变。
