Inverted recruitment of autophagy proteins to the Plasmodium berghei parasitophorous vacuole membrane.

Jacqueline Schmuckli-Maurer,Volker Theo Heussler,Rahel Wacker,Vera Reber,Annina Bindschedler,Anthony Zakher,Gordon Langsley

doi:10.1371/journal.pone.0183797

Jacqueline Schmuckli-Maurer, Volker Theo Heussler + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0183797

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Journal: PloS one	Publication Date: Aug 25, 2017
Citations: 19	License type: CC BY 4.0

Affiliation: University of Bern

Abstract

Selective autophagy and related mechanisms can act as variable defense mechanisms against pathogens and can therefore be considered as intracellular immune responses. When in hepatocytes, Plasmodium parasites reside in a parasitophorous vacuole (PV) and the PV membrane (PVM) is the main contact site between host cell and parasite. Early in infection, the PVM is directly labeled with host cell autophagy proteins LC3B and p62 (nucleoporin 62). We investigated the recruitment of different selective autophagy receptors and could show that mainly p62 and NBR1 (neighbour of BRCA1 gene 1) and to a lesser extent NDP52 (nuclear dot protein 52) associate with the PVM. To investigate the recruitment of these receptors to the PVM in Plasmodium-infected cells, we generated LC3B knock out HeLa cells. In these cell lines, autophagosome formation and autophagic flux are not different to those in WT cells. Unexpectedly, p62 and NBR1 recruitment to the PVM was strongly impaired in LC3B-negative host cells, suggesting that LC3B recruits both receptors to the PVM of Plasmodium parasites. We also noticed that LC3B recruited ubiquitin to the PVM. This indicates that, in comparison to classical selective autophagy, in P. berghei-infected cells the order of membrane labeling with autophagy proteins appears to be inverted from canonical ubiquitin-receptor-LC3B recruitment to LC3B-receptor and possibly ubiquitin.

Highlights

Malaria is a devastating yet curable disease of global distribution, most prevalent in tropical and subtropical regions
In contrast to what has been shown for classical selective autophagy, we found that p62, neighbor of BRCA1 gene 1 (NBR1) and ubiquitin recruitment to the PV membrane (PVM) depends on the presence of LC3B
In all RFP-LC3B-transfected cells harboring a parasite, we observed a very strong PVM labeling with p62, suggesting that LC3B is responsible for the recruitment of p62 and not the other way around. These results provide strong evidence that LC3B plays a decisive role in recruiting the autophagy receptor p62 to the PVM in P. berghei-infected host cells

Summary

Introduction

Malaria is a devastating yet curable disease of global distribution, most prevalent in tropical and subtropical regions. We investigated selective autophagy events in Plasmodium-infected hepatocytes and showed that the PVM of Plasmodium liver stage parasites is rapidly and heavily labeled by the host cellderived autophagy marker protein LC3B, indicating that the host cell quickly recognises the invader [5,27]. This labeling is greatly reduced in later stages of normally developing parasites, suggesting that the parasite is able to escape from this host cell response in order to successfully establish infection and undergo replication [5]. In contrast to what has been shown for classical selective autophagy, we found that p62, NBR1 and ubiquitin recruitment to the PVM depends on the presence of LC3B

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