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Gastroenterology. 2008 Mar;134(3):756-67. doi: 10.1053/j.gastro.2007.12.008. Epub 2007 Dec 7.

Hypoxia-independent activation of HIF-1 by enterobacteriaceae and their siderophores.

Author information

1
Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Eberhard-Karls-Universität, Tübingen, Germany.

Abstract

BACKGROUND & AIMS:

Hypoxia inducible factor-1 (HIF-1) is the key transcriptional regulator during adaptation to hypoxia. Recent studies provide evidence for HIF-1 activation during bacterial infections. However, molecular details of how bacteria activate HIF-1 remain unclear. Here, we pursued the role of bacterial siderophores in HIF-1 activation during infection with Enterobacteriaceae.

METHODS:

In vivo, HIF-1 activation and HIF-1-dependent gene induction in Peyer's patches were analyzed after orogastric infection with Yersinia enterocolitica. The course of an orogastric Y enterocolitica infection was determined using mice with a deletion of HIF-1alpha in the intestine. In vitro, the mechanism of HIF-1 activation was analyzed in infections with Y enterocolitica, Salmonella enterica subsp enterica, and Enterobacter aerogenes.

RESULTS:

Infection of mice with Y enterocolitica led to functional activation of HIF-1 in Peyer's patches. Because mice with deletion of HIF-1alpha in the intestinal epithelium showed a significantly higher susceptibility to orogastric Y enterocolitica infections, bacterial HIF-1 activation appears to represent a host defense mechanism. Additional studies with Y enterocolitica, S enterica subsp enterica, or E aerogenes, and, moreover, application of their siderophores (yersiniabactin, salmochelin, aerobactin) caused a robust, dose-dependent HIF-1 response in human epithelia and endothelia, independent of cellular hypoxia. HIF-1 activation occurs most likely because of inhibition of prolylhydroxylase activity and is abolished upon infection with siderophore uptake deficient bacteria.

CONCLUSIONS:

Taken together, this study reveals what we believe to be a previously unrecognized role of bacterial siderophores for hypoxia-independent activation of HIF-1 during infection with human pathogenic bacteria.

PMID:
18325389
DOI:
10.1053/j.gastro.2007.12.008
[Indexed for MEDLINE]

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