Abstract

We study the role of a biomimetic actin network during the application of electric pulses that induce electroporation or electropermeabilization, using giant unilamellar vesicles (GUVs) as a model system. The actin cortex, a subjacently attached interconnected network of actin filaments, regulates the shape and mechanical properties of the plasma membrane of mammalian cells, and is a major factor influencing the mechanical response of the cell to external physical cues. We demonstrate that the presence of an actin shell inhibits the formation of macropores in the electroporated GUVs. Additionally, experiments on the uptake of dye molecules after electroporation show that the actin network slows down the resealing process of the permeabilized membrane. We further analyze the stability of the actin network inside the GUVs exposed to high electric pulses. We find disruption of the actin layer that is likely due to the electrophoretic forces acting on the actin filaments during the permeabilization of the GUVs. Our findings on the GUVs containing a biomimetic network provide a step towards understanding the discrepancies between the electroporation mechanism of a living cell and its simplified model of the empty GUV.

Highlights

  • The plasma membrane is a selective barrier that separates the intracellular environment from the cell exterior and regulates the influx and efflux of differently sized molecules

  • It has been shown that actin depolymerization in Chinese hamster ovary (CHO) cells and human erythrocytes leads to acceleration of the post-pulse membrane resealing, while it does not considerably affect the initial steps in the permeabilization process[11,12]

  • We focus on the role of a biomimetic actin network in the electroporation of the membrane in order to understand the discrepancy between the electropermeabilization of simplified model membranes and the plasma membrane

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Summary

Introduction

The plasma membrane is a selective barrier that separates the intracellular environment from the cell exterior and regulates the influx and efflux of differently sized molecules. The actin cortex plays an essential role in electroporation, referred to as electropermeabilization, of cells This is a membrane permeabilization technique used for the delivery of a wide variety of molecules ranging from small molecules, such as drugs, to large molecules, such as DNA, into the cell. It has been shown that cells can remain permeabilized from minutes up to hours after pulsation[4,5,6] This long resealing process is considerably slower than that observed for bare lipid bilayers (less than one second)[7,8,9]. It has been shown that actin depolymerization in Chinese hamster ovary (CHO) cells and human erythrocytes leads to acceleration of the post-pulse membrane resealing, while it does not considerably affect the initial steps in the permeabilization process[11,12]. Some biological processes like apoptosis and necrosis can be triggered by nanosecond pulses[19,21], which could involve the pulse-mediated disruption of the actin cytoskeleton[15,22]

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