Nygård Skalman Lars, Holst Mikkel R, Larsson Elin, Lundmark Richard
Integrative Medical Biology, Umeå University, 901 87 Umeå, Sweden.
Medical Biochemistry and Biophysics, Laboratory for Molecular Infection Medicine Sweden, Umeå University, 901 87 Umeå, Sweden.
Biol Open. 2018 Oct 22;7(10):bio035287. doi: 10.1242/bio.035287.
Endocytic mechanisms have been suggested to be important for plasma membrane repair in response to pore-forming toxins such as listeriolysin O (LLO), which form membrane pores that disrupt cellular homeostasis. Yet, little is known about the specific role of distinct endocytic machineries in this process. Here, we have addressed the importance of key endocytic pathways and developed reporter systems for real-time imaging of the endocytic response to LLO pore formation. We found that loss of clathrin-independent endocytic pathways negatively influenced the efficiency of membrane repair. However, we did not detect any increased activity of these pathways, or co-localisation with the toxin or markers of membrane repair, suggesting that they were not directly involved in removal of LLO pores from the plasma membrane. In fact, markers of clathrin-independent carriers (CLICs) were rapidly disassembled in the acute phase of membrane damage due to Ca influx, followed by a reassembly about 2 min after pore formation. We propose that these endocytic mechanisms might influence membrane repair by regulating the plasma membrane composition and tension, but not via direct internalisation of LLO pores.
内吞机制被认为对于响应诸如李斯特菌溶血素O（LLO）等形成孔道的毒素时的质膜修复很重要，这些毒素会形成破坏细胞内稳态的膜孔。然而，对于不同内吞机制在这个过程中的具体作用知之甚少。在这里，我们探讨了关键内吞途径的重要性，并开发了报告系统用于实时成像内吞对LLO孔形成的反应。我们发现，不依赖网格蛋白的内吞途径的缺失对膜修复效率有负面影响。然而，我们没有检测到这些途径的任何活性增加，也没有检测到它们与毒素或膜修复标记物的共定位，这表明它们不直接参与从质膜上去除LLO孔。事实上，不依赖网格蛋白载体（CLICs）的标记物在由于钙内流导致的膜损伤急性期迅速解体，随后在孔形成后约2分钟重新组装。我们提出，这些内吞机制可能通过调节质膜组成和张力来影响膜修复，而不是通过LLO孔的直接内化。
