Perfringolysin O-Induced Plasma Membrane Pores Trigger Actomyosin Remodeling and Endoplasmic Reticulum Redistribution.

Cláudia Brito,Sandra Sousa,James R Sellers,Francisco S Mesquita,Christopher K E Bleck,Didier Cabanes

doi:10.3390/toxins11070419

Abstract

Clostridium perfringens produces an arsenal of toxins that act together to cause severe infections in humans and livestock animals. Perfringolysin O (PFO) is a cholesterol-dependent pore-forming toxin encoded in the chromosome of virtually all C. perfringens strains and acts in synergy with other toxins to determine the outcome of the infection. However, its individual contribution to the disease is poorly understood. Here, we intoxicated human epithelial and endothelial cells with purified PFO to evaluate the host cytoskeletal responses to PFO-induced damage. We found that, at sub-lytic concentrations, PFO induces a profound reorganization of the actomyosin cytoskeleton culminating into the assembly of well-defined cortical actomyosin structures at sites of plasma membrane (PM) remodeling. The assembly of such structures occurs concomitantly with the loss of the PM integrity and requires pore-formation, calcium influx, and myosin II activity. The recovery from the PM damage occurs simultaneously with the disassembly of cortical structures. PFO also targets the endoplasmic reticulum (ER) by inducing its disruption and vacuolation. ER-enriched vacuoles were detected at the cell cortex within the PFO-induced actomyosin structures. These cellular events suggest the targeting of the endothelium integrity at early stages of C. perfringens infection, in which secreted PFO is at sub-lytic concentrations.

Highlights

Clostridium perfringens is an anaerobic gram-positive bacterium often found as a natural resident of the intestine of humans and animals [1,2]
Perfringolysin O (PFO) has been extensively studied and became the structural archetype of pore-forming toxin (PFT) belonging to the cholesterol-dependent cytolysin (CDCs) family [8,9], which comprises a variety of PFTs such as listeriolysin O (LLO), produced by Listeria monocytogenes or pneumolysin (PLY), produced by Streptococcus pneumoniae
At sub-lytic concentrations, PFO induces a profound reorganization of the actomyosin cytoskeleton culminating in the assembly of cortical actomyosin structures at sites of plasma membrane (PM) blebbing in both HeLa and HUVEC cells

Summary

Introduction

Clostridium perfringens is an anaerobic gram-positive bacterium often found as a natural resident of the intestine of humans and animals [1,2]. Toxins 2019, 11, 419 undergoes rapid proliferation and causes severe systemic and enteric diseases such as gas gangrene (myonecrosis), gastroenteritis, and enterocolitis [3,4]. The pathogenicity of C. perfringens is largely attributed to its ability to produce an arsenal of toxins [5]. While many of its toxins are encoded in extra-chromosomal plasmids, the gene encoding the pore-forming toxin (PFT), perfringolysin O (PFO) [6], is located in the chromosome of the majority of C. perfringens strains [7]. PFO is secreted by C. perfringens as a water-soluble monomer that upon binding to the host plasma membrane (PM)

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