Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.

Intracellular pathogens include all viruses, many bacteria and parasites capable of invading and surviving within host cells. Key to survival is the subversion of host cell pathways by the pathogen for the purpose of propagation and evading the immune system. The intracellular bacterium Shigella fle...

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Main Authors: Allon Weiner, Nora Mellouk, Noelia Lopez-Montero, Yuen-Yan Chang, Célia Souque, Christine Schmitt, Jost Enninga
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2016-05-01
Series:PLoS Pathogens
Online Access:https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1005602&type=printable
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author Allon Weiner
Nora Mellouk
Noelia Lopez-Montero
Yuen-Yan Chang
Célia Souque
Christine Schmitt
Jost Enninga
author_facet Allon Weiner
Nora Mellouk
Noelia Lopez-Montero
Yuen-Yan Chang
Célia Souque
Christine Schmitt
Jost Enninga
author_sort Allon Weiner
collection DOAJ
description Intracellular pathogens include all viruses, many bacteria and parasites capable of invading and surviving within host cells. Key to survival is the subversion of host cell pathways by the pathogen for the purpose of propagation and evading the immune system. The intracellular bacterium Shigella flexneri, the causative agent of bacillary dysentery, invades host cells in a vacuole that is subsequently ruptured to allow growth of the pathogen within the host cytoplasm. S. flexneri invasion has been classically described as a macropinocytosis-like process, however the underlying details and the role of macropinosomes in the intracellular bacterial lifestyle have remained elusive. We applied dynamic imaging and advanced large volume correlative light electron microscopy (CLEM) to study the highly transient events of S. flexneri's early invasion into host epithelial cells and elucidate some of its fundamental features. First, we demonstrate a clear distinction between two compartments formed during the first step of invasion: the bacterial containing vacuole and surrounding macropinosomes, often considered identical. Next, we report a functional link between macropinosomes and the process of vacuolar rupture, demonstrating that rupture timing is dependent on the availability of macropinosomes as well as the activity of the small GTPase Rab11 recruited directly to macropinosomes. We go on to reveal that the bacterial containing vacuole and macropinosomes come into direct contact at the onset of vacuolar rupture. Finally, we demonstrate that S. flexneri does not subvert pre-existing host endocytic vesicles during the invasion steps leading to vacuolar rupture, and propose that macropinosomes are the major compartment involved in these events. These results provide the basis for a new model of the early steps of S. flexneri epithelial cell invasion, establishing a different view of the enigmatic process of cytoplasmic access by invasive bacterial pathogens.
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spelling doaj-art-ffcbe349c1fd45a58116ae1d081f392a2025-08-20T03:12:47ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742016-05-01125e100560210.1371/journal.ppat.1005602Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.Allon WeinerNora MelloukNoelia Lopez-MonteroYuen-Yan ChangCélia SouqueChristine SchmittJost EnningaIntracellular pathogens include all viruses, many bacteria and parasites capable of invading and surviving within host cells. Key to survival is the subversion of host cell pathways by the pathogen for the purpose of propagation and evading the immune system. The intracellular bacterium Shigella flexneri, the causative agent of bacillary dysentery, invades host cells in a vacuole that is subsequently ruptured to allow growth of the pathogen within the host cytoplasm. S. flexneri invasion has been classically described as a macropinocytosis-like process, however the underlying details and the role of macropinosomes in the intracellular bacterial lifestyle have remained elusive. We applied dynamic imaging and advanced large volume correlative light electron microscopy (CLEM) to study the highly transient events of S. flexneri's early invasion into host epithelial cells and elucidate some of its fundamental features. First, we demonstrate a clear distinction between two compartments formed during the first step of invasion: the bacterial containing vacuole and surrounding macropinosomes, often considered identical. Next, we report a functional link between macropinosomes and the process of vacuolar rupture, demonstrating that rupture timing is dependent on the availability of macropinosomes as well as the activity of the small GTPase Rab11 recruited directly to macropinosomes. We go on to reveal that the bacterial containing vacuole and macropinosomes come into direct contact at the onset of vacuolar rupture. Finally, we demonstrate that S. flexneri does not subvert pre-existing host endocytic vesicles during the invasion steps leading to vacuolar rupture, and propose that macropinosomes are the major compartment involved in these events. These results provide the basis for a new model of the early steps of S. flexneri epithelial cell invasion, establishing a different view of the enigmatic process of cytoplasmic access by invasive bacterial pathogens.https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1005602&type=printable
spellingShingle Allon Weiner
Nora Mellouk
Noelia Lopez-Montero
Yuen-Yan Chang
Célia Souque
Christine Schmitt
Jost Enninga
Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
PLoS Pathogens
title Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
title_full Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
title_fullStr Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
title_full_unstemmed Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
title_short Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells.
title_sort macropinosomes are key players in early shigella invasion and vacuolar escape in epithelial cells
url https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1005602&type=printable
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