CotH3 mediates fungal invasion of host cells during mucormycosis
Teclegiorgis Gebremariam, … , Michael R. Yeaman, Ashraf S. Ibrahim
Teclegiorgis Gebremariam, … , Michael R. Yeaman, Ashraf S. Ibrahim
Published December 20, 2013
Citation Information: J Clin Invest. 2014;124(1):237-250. https://doi.org/10.1172/JCI71349.
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Research Article

CotH3 mediates fungal invasion of host cells during mucormycosis

Abstract

Angioinvasion is a hallmark of mucormycosis. Previously, we identified endothelial cell glucose-regulated protein 78 (GRP78) as a receptor for Mucorales that mediates host cell invasion. Here we determined that spore coat protein homologs (CotH) of Mucorales act as fungal ligands for GRP78. CotH proteins were widely present in Mucorales and absent from noninvasive pathogens. Heterologous expression of CotH3 and CotH2 in Saccharomyces cerevisiae conferred the ability to invade host cells via binding to GRP78. Homology modeling and computational docking studies indicated structurally compatible interactions between GRP78 and both CotH3 and CotH2. A mutant of Rhizopus oryzae, the most common cause of mucormycosis, with reduced CotH expression was impaired for invading and damaging endothelial cells and CHO cells overexpressing GRP78. This strain also exhibited reduced virulence in a diabetic ketoacidotic (DKA) mouse model of mucormycosis. Treatment with anti-CotH Abs abolished the ability of R. oryzae to invade host cells and protected DKA mice from mucormycosis. The presence of CotH in Mucorales explained the specific susceptibility of DKA patients, who have increased GRP78 levels, to mucormycosis. Together, these data indicate that CotH3 and CotH2 function as invasins that interact with host cell GRP78 to mediate pathogenic host-cell interactions and identify CotH as a promising therapeutic target for mucormycosis.

Authors

Teclegiorgis Gebremariam, Mingfu Liu, Guanpingsheng Luo, Vincent Bruno, Quynh T. Phan, Alan J. Waring, John E. Edwards Jr., Scott G. Filler, Michael R. Yeaman, Ashraf S. Ibrahim

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Figure 2

S. cerevisiae cells heterologously expressing CotH2 or CotH3, but not CotH1, interact with host cells through GRP78.

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S. cerevisiae cells heterologously expressing CotH2 or CotH3, but not C...
(A) Endothelial cell surface proteins were labeled with NHS-biotin, then extracted with n-octyl-β-d-glucopyranoside in PBS-CM and protease inhibitors. Labeled proteins (250 mg) were incubated with 2 × 108S. cerevisiae cells, after which unbound proteins were removed by extensive rinsing with PBS-CM. The membrane proteins that remained bound to the organisms were eluted with 6 M urea, separated on 10% SDS-PAGE, and identified by immunoblotting with anti-GRP78 Ab. (B and C) Adherence and endocytosis (determined by differential fluorescence) assays were carried out using endothelial cells (B) or GRP78-overexpressing or parent CHO cells (C) split on 12-mm glass coverslips. HPF, high-power field. *P < 0.001 vs. empty plasmid or CotH1, **P < 0.001 vs. CotH1 and CotH2, Wilcoxon rank-sum test. n = 9 from 3 independent experiments. Data are median ± interquartile range.