Plasma membrane damage caused by listeriolysin O is not repaired through endocytosis of the membrane pore

Lars Nygård Skalman; Mikkel R Holst; Elin Larsson; Richard Lundmark

doi:10.1242/bio.035287

Plasma membrane damage caused by listeriolysin O is not repaired through endocytosis of the membrane pore

Biol Open. 2018 Oct 22;7(10):bio035287. doi: 10.1242/bio.035287.

Authors

Lars Nygård Skalman^{1

2}, Mikkel R Holst¹, Elin Larsson², Richard Lundmark^{3

2}

Affiliations

¹ Integrative Medical Biology, Umeå University, 901 87 Umeå, Sweden.
² Medical Biochemistry and Biophysics, Laboratory for Molecular Infection Medicine Sweden, Umeå University, 901 87 Umeå, Sweden.
³ Integrative Medical Biology, Umeå University, 901 87 Umeå, Sweden richard.lundmark@umu.se.

Abstract

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 Ca²⁺ 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.

Keywords: Clathrin-independent endocytosis; CLIC; Caveolae; Clathrin-mediated endocytosis; LLO; Listeriolysin; Membrane damage; Membrane pore; Repair.