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Am J Physiol Gastrointest Liver Physiol. 2018 Jun 1;314(6):G655-G667. doi: 10.1152/ajpgi.00326.2017. Epub 2018 Feb 15.

cGAS-mediated autophagy protects the liver from ischemia-reperfusion injury independently of STING.

Author information

1
Department of Hepatopancreatobiliary Surgery, The Third Xiangya Hospital, Central South University , Changsha, Hunan , China.
2
Department of Surgery, University of Pittsburgh , Pittsburgh, Pennsylvania.
3
Center for Biologic Imaging, University of Pittsburgh, Pennsylvania.
4
Pittsburgh Liver Research Center, University of Pittsburgh, Pennsylvania.

Abstract

Liver ischemia-reperfusion (I/R) injury occurs through induction of oxidative stress and release of damage-associated molecular patterns (DAMPs), including cytosolic DNA released from dysfunctional mitochondria or from the nucleus. Cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS) is a cytosolic DNA sensor known to trigger stimulator of interferon genes (STING) and downstream type 1 interferon (IFN-I) pathways, which are pivotal innate immune system responses to pathogen. However, little is known about the role of cGAS/STING in liver I/R injury. We subjected C57BL/6 (WT), cGAS knockout (cGAS-/-), and STING-deficient (STINGgt/gt) mice to warm liver I/R injury and that found cGAS-/- mice had significantly increased liver injury compared with WT or STINGgt/gt mice, suggesting a protective effect of cGAS independent of STING. Liver I/R upregulated cGAS in vivo and also in vitro in hepatocytes subjected to anoxia/reoxygenation (A/R). We confirmed a previously published finding that hepatocytes do not express STING under normoxic conditions or after A/R. Hepatocytes and liver from cGAS-/- mice had increased cell death and reduced induction of autophagy under hypoxic conditions as well as increased apoptosis. Protection could be restored in cGAS-/- hepatocytes by overexpression of cGAS or by pretreatment of mice with autophagy inducer rapamycin. Our findings indicate a novel protective role for cGAS in the regulation of autophagy during liver I/R injury that occurs independently of STING. NEW & NOTEWORTHY Our studies are the first to document the important role of cGAS in the acute setting of sterile injury induced by I/R. Specifically, we provide evidence that cGAS protects liver from I/R injury in a STING-independent manner.

KEYWORDS:

DAMPs; anoxia; apoptosis; cytosolic DNA sensing; hypoxia

PMID:
29446653
PMCID:
PMC6032062
DOI:
10.1152/ajpgi.00326.2017
[Indexed for MEDLINE]
Free PMC Article

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