Hypoxia inducible factor-1 alpha induction by tumour necrosis factor-alpha, but not by toll-like receptor agonists, modulates cellular respiration in cultured human hepatocytes

Regueira, Tomas; Lepper, Philipp M; Brandt, Sebastian; Ochs, Matthias; Vuda, Madhusudanarao; Takala, Jukka; Jakob, Stephan M; Djafarzadeh, Siamak (2009). Hypoxia inducible factor-1 alpha induction by tumour necrosis factor-alpha, but not by toll-like receptor agonists, modulates cellular respiration in cultured human hepatocytes. Liver international, 29(10), pp. 1582-92. Oxford: Blackwell Munksgaard 10.1111/j.1478-3231.2009.02109.x

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BACKGROUND/AIMS: Genes encoding for some of the mitochondrial proteins are under the control of the transcriptional factor hypoxia inducible factor-1 alpha (HIF-1 alpha), which can accumulate under normoxic conditions in inflammatory states. The aim of this study was to evaluate the effects of cobalt chloride (CoCl(2), a hypoxia mimicking agent), tumour necrosis factor-alpha (TNF-alpha) and toll-like receptor (TLR) -2, -3 and -4 agonists on HIF-1 alpha accumulation, and further on HIF-1 alpha-mediated modulation of mitochondrial respiration in cultured human hepatocytes. METHODS: The human hepatoma cell line HepG2 was used in this study. Cells were treated with CoCl(2), TNF-alpha and TLR-2, -3 and -4 agonists. HIF-1 alpha was determined by Western blotting and mitochondrial respiration in stimulated cells by high-resolution respirometry. RESULTS: CoCl(2), TNF-alpha and TLR agonists induced the expression of HIF-1 alpha in a time-dependent fashion. TNF-alpha and CoCl(2), but not TLR agonists, induced a reduction in complex I-, II- and IV-dependent mitochondrial oxygen consumption. TNF-alpha-associated reduction of cellular oxygen consumption was abolished through inhibition of HIF-1 alpha activity by chetomin (CTM). Pretreatment with cyclosporine A prevented CoCl(2)-induced reduction of complex I- and II-dependent mitochondrial oxygen consumption and TNF-alpha-induced reduction of complex-I-dependent respiration, implicating the involvement of the mitochondrial permeability transition pore openings. TNF-alpha and TLR-2, -3 and -4 agonists induced the expression of vascular endothelial growth factor, which was partially abolished by the blockage of HIF-1 alpha with CTM. CONCLUSIONS: The data suggest that HIF-1 alpha modulates mitochondrial respiration during CoCl(2) and TNF-alpha stimulation, whereas it has no effect when induced with TLR-2, -3 and -4 agonists.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Intensive Care, Emergency Medicine and Anaesthesiology (DINA) > Clinic of Intensive Care
UniBE Contributor:	Regueira, Tomas Emilio, Lepper, Philipp, Vuda, Madhusudanarao, Takala, Jukka, Jakob, Stephan, Djafarzadeh, Siamak
ISSN:	1478-3223
Publisher:	Blackwell Munksgaard
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 15:13
Last Modified:	05 Dec 2022 14:22
Publisher DOI:	10.1111/j.1478-3231.2009.02109.x
PubMed ID:	19744167
Web of Science ID:	000270429000020
URI:	https://boris.unibe.ch/id/eprint/32223 (FactScience: 197232)