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Am J Respir Cell Mol Biol. 2009 Oct;41(4):385-96. doi: 10.1165/rcmb.2008-0302OC. Epub 2009 Jan 23.

IL-6 protects against hyperoxia-induced mitochondrial damage via Bcl-2-induced Bak interactions with mitofusins.

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1
Pulmonary Critical Care Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Bulfinch 148, Boston, MA 02114, USA. abwaxman@partners.org.

Abstract

Overexpression of IL-6 markedly diminishes hyperoxic lung injury, hyperoxia-induced cell death, and DNA fragmentation, and enhances Bcl-2 expression. We hypothesized that changes in the interactions between Bcl-2 family members play an important role in the IL-6-mediated protective response to oxidative stress. Consistent with this hypothesis, we found that IL-6 induced Bcl-2 expression, both in vivo and in vitro, disrupted interactions between proapoptotic and antiapoptotic factors, and suppressed H(2)O(2)-induced loss of mitochondrial membrane potential in vitro. In addition, IL-6 overexpression in mice protects against hyperoxia-induced lung mitochondrial damage. The overexpression of Bcl-2 in vivo prolonged the survival of mice exposed to hyperoxia and inhibited alveolar capillary protein leakage. In addition, apoptosis-associated DNA fragmentation was substantially reduced in these animals. This IL-6-mediated protection was lost when Bcl-2 was silenced, demonstrating that Bcl-2 is an essential mediator of IL-6 cytoprotection. Finally, Bcl-2 blocked the dissociation of Bak from mitofusin protein (Mfn) 2, and inhibited the interaction between Bak and Mfn1. Taken together, our results suggest that IL-6 induces Bcl-2 expression to perform cytoprotective functions in response to oxygen toxicity, and that this effect is mediated by alterations in the interactions between Bak and Mfns.

PMID:
19168699
PMCID:
PMC2746985
DOI:
10.1165/rcmb.2008-0302OC
[Indexed for MEDLINE]
Free PMC Article

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