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G?12 overexpression induced by miR-16 dysregulation contributes to liver fibrosis by promoting autophagy in hepatic stellate cells.


ABSTRACT: BACKGROUND & AIMS:Hepatic stellate cells (HSCs) have a role in liver fibrosis. Guanine nucleotide-binding ?-subunit 12 (G?12) converges signals from G-protein-coupled receptors whose ligand levels are elevated in the environment during liver fibrosis; however, information is lacking on the effect of G?12 on HSC trans-differentiation. This study investigated the expression of G?12 in HSCs and the molecular basis of the effects of its expression on liver fibrosis. METHODS:G?12 expression was assessed by immunostaining, and immunoblot analyses of mouse fibrotic liver tissues and primary HSCs. The role of G?12 in liver fibrosis was estimated using a toxicant injury mouse model with G?12 gene knockout and/or HSC-specific G?12 delivery using lentiviral vectors, in addition to primary HSCs and LX-2 cells using microRNA (miR) inhibitors, overexpression vectors, or adenoviruses. miR-16, G?12, and LC3 were also examined in samples from patients with fibrosis. RESULTS:G?12 was overexpressed in activated HSCs and fibrotic liver, and was colocalised with desmin. In a carbon tetrachloride-induced fibrosis mouse model, G?12 ablation prevented increases in fibrosis and liver injury. This effect was attenuated by HSC-specific lentiviral delivery of G?12. Moreover, G?12 activation promoted autophagy accompanying c-Jun N-terminal kinase-dependent ATG12-5 conjugation. In addition, miR-16 was found to be a direct inhibitor of the de novo synthesis of G?12. Modulations of miR-16 altered autophagy in HSCs. In a fibrosis animal model or patients with severe fibrosis, miR-16 levels were lower than in their corresponding controls. Consistently, cirrhotic patient liver tissues showed G?12 and LC3 upregulation in desmin-positive areas. CONCLUSIONS:miR-16 dysregulation in HSCs results in G?12 overexpression, which activates HSCs by facilitating autophagy through ATG12-5 formation. This suggests that G?12 and its regulatory molecules could serve as targets for the amelioration of liver fibrosis. LAY SUMMARY:Guanine nucleotide-binding ?-subunit 12 (G?12) is upregulated in activated hepatic stellate cells (HSCs) as a consequence of the dysregulation of a specific microRNA that is abundant in HSCs, facilitating the progression of liver fibrosis. This event is mediated by c-Jun N-terminal kinase-dependent ATG12-5 formation and the promotion of autophagy. We suggest that G?12 and its associated regulators could serve as new targets in HSCs for the treatment of liver fibrosis.

SUBMITTER: Kim KM 

PROVIDER: S-EPMC5818314 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Gα<sub>12</sub> overexpression induced by miR-16 dysregulation contributes to liver fibrosis by promoting autophagy in hepatic stellate cells.

Kim Kyu Min KM   Han Chang Yeob CY   Kim Ji Young JY   Cho Sam Seok SS   Kim Yun Seok YS   Koo Ja Hyun JH   Lee Jung Min JM   Lim Sung Chul SC   Kang Keon Wook KW   Kim Jae-Sung JS   Hwang Se Jin SJ   Ki Sung Hwan SH   Kim Sang Geon SG  

Journal of hepatology 20180102 3


<h4>Background & aims</h4>Hepatic stellate cells (HSCs) have a role in liver fibrosis. Guanine nucleotide-binding α-subunit 12 (Gα<sub>12</sub>) converges signals from G-protein-coupled receptors whose ligand levels are elevated in the environment during liver fibrosis; however, information is lacking on the effect of Gα<sub>12</sub> on HSC trans-differentiation. This study investigated the expression of Gα<sub>12</sub> in HSCs and the molecular basis of the effects of its expression on liver fi  ...[more]

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