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J Biol Chem. 2012 Sep 7;287(37):31104-15. doi: 10.1074/jbc.M112.387498. Epub 2012 Jul 22.

Low-density lipoprotein receptor-related protein-1 (LRP1) mediates autophagy and apoptosis caused by Helicobacter pylori VacA.

Author information

1
Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.

Abstract

In Helicobacter pylori infection, vacuolating cytotoxin (VacA)-induced mitochondrial damage leading to apoptosis is believed to be a major cause of cell death. It has also been proposed that VacA-induced autophagy serves as a host mechanism to limit toxin-induced cellular damage. Apoptosis and autophagy are two dynamic and opposing processes that must be balanced to regulate cell death and survival. Here we identify the low-density lipoprotein receptor-related protein-1 (LRP1) as the VacA receptor for toxin-induced autophagy in the gastric epithelial cell line AZ-521, and show that VacA internalization through binding to LRP1 regulates the autophagic process including generation of LC3-II from LC3-I, which is involved in formation of autophagosomes and autolysosomes. Knockdown of LRP1 and Atg5 inhibited generation of LC3-II as well as cleavage of PARP, a marker of apoptosis, in response to VacA, whereas caspase inhibitor, benzyloxycarbonyl-VAD-fluoromethylketone (Z-VAD-fmk), and necroptosis inhibitor, Necrostatin-1, did not inhibit VacA-induced autophagy, suggesting that VacA-induced autophagy via LRP1 binding precedes apoptosis. Other VacA receptors such as RPTPα, RPTPβ, and fibronectin did not affect VacA-induced autophagy or apoptosis. Therefore, we propose that the cell surface receptor, LRP1, mediates VacA-induced autophagy and apoptosis.

PMID:
22822085
PMCID:
PMC3438942
DOI:
10.1074/jbc.M112.387498
[Indexed for MEDLINE]
Free PMC Article

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