Host Cell P-glycoprotein Is Essential for Cholesterol Uptake and Replication of Toxoplasma gondii

Iveta Bottova,Adrian B Hehl,Saša Štefanić,Gemma Fabriàs,Josefina Casas,Elisabeth Schraner,Jean Pieters,Sabrina Sonda

doi:10.1074/jbc.m809420200

Abstract

P-glycoprotein (P-gp) is a membrane-bound efflux pump that actively exports a wide range of compounds from the cell and is associated with the phenomenon of multidrug resistance. However, the role of P-gp in normal physiological processes remains elusive. Using P-gp-deficient fibroblasts, we showed that P-gp was critical for the replication of the intracellular parasite Toxoplasma gondii but was not involved in invasion of host cells by the parasite. Importantly, we found that the protein participated in the transport of host-derived cholesterol to the intracellular parasite. T. gondii replication in P-gp-deficient host cells not only resulted in reduced cholesterol content in the parasite but also altered its sphingolipid metabolism. In addition, we found that different levels of P-gp expression modified the cholesterol metabolism in uninfected fibroblasts. Collectively our findings reveal a key and previously undocumented role of P-gp in host-parasite interaction and suggest a physiological role for P-gp in cholesterol trafficking in mammalian cells.

Highlights

P-glycoprotein (P-gp, ABCB1, MDR1)2 is one of the most intensively studied members of the ABC transporter superfamily
P-gp-complemented host cells generated a higher T. gondii burden than that found in wild type (WT) cells
To further confirm that P-gp activity confers a replication advantage for the parasite, we used WT 3T3 fibroblasts transfected to overexpress P-gp as host cells [12]

Summary

Introduction

P-glycoprotein (P-gp, ABCB1, MDR1) is one of the most intensively studied members of the ABC transporter superfamily. The possibility that physiological levels of host P-gp play a role in host-pathogen interaction, other than mediating drug resistance, has not been investigated so far We addressed this question using Toxoplasma gondii as a model pathogenic parasite. We analyzed DKO cells complemented with the human P-gp homologue (DKO/ P-gp) [10], which restored P-gp functionality to DKO cells and allowed P-gp expression levels higher than those found in WT cells (supplemental Fig. S1) In this way, our model did not depend on either drug-selected P-gp-overexpressing cells, which may acquire adaptation mechanisms different from P-gp overexpression during the development of the MDR phenotype, or P-gp inhibitors, several of which are known to have side effects on host metabolism

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