A maresin 1/RORα/12-lipoxygenase autoregulatory circuit prevents inflammation and progression of nonalcoholic steatohepatitis
Yong-Hyun Han, … , Bong-Jin Lee, Mi-Ock Lee
Yong-Hyun Han, … , Bong-Jin Lee, Mi-Ock Lee
Published March 11, 2019
Citation Information: J Clin Invest. 2019;129(4):1684-1698. https://doi.org/10.1172/JCI124219.
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Research Article Hepatology Inflammation Article has an altmetric score of 8

A maresin 1/RORα/12-lipoxygenase autoregulatory circuit prevents inflammation and progression of nonalcoholic steatohepatitis

Abstract

Retinoic acid–related orphan receptor α (RORα) is considered a key regulator of polarization in liver macrophages that is closely related to nonalcoholic steatohepatitis (NASH) pathogenesis. However, hepatic microenvironments that support the function of RORα as a polarity regulator were largely unknown. Here, we identified maresin 1 (MaR1), a docosahexaenoic acid (DHA) metabolite with a function of specialized proresolving mediator, as an endogenous ligand of RORα. MaR1 enhanced the expression and transcriptional activity of RORα and thereby increased the M2 polarity of liver macrophages. Administration of MaR1 protected mice from high-fat diet–induced NASH in a RORα-dependent manner. Surprisingly, RORα increased the level of MaR1 through transcriptional induction of 12-lipoxygenase (12-LOX), a key enzyme in MaR1 biosynthesis. Furthermore, we demonstrated that modulation of 12-LOX activity enhanced the protective function of DHA against NASH. Together, these results suggest that the MaR1/RORα/12-LOX autoregulatory circuit could offer potential therapeutic strategies for curing NASH.

Authors

Yong-Hyun Han, Kyong-Oh Shin, Ju-Yeon Kim, Daulat B. Khadka, Hyeon-Ji Kim, Yong-Moon Lee, Won-Jea Cho, Ji-Young Cha, Bong-Jin Lee, Mi-Ock Lee

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Figure 4

MaR1 is a novel ligand of RORα.

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MaR1 is a novel ligand of RORα. (A) BIAcore analysis for binding of MaR1...
(A) BIAcore analysis for binding of MaR1, RvD1, or cholesterol sulfate (CS) to RORα. The increasing concentrations of ligands were injected over immobilized GST-RORα-His proteins on the sensor chip and KD value was calculated by the BIAevaluation 3.1 software. (B) TR-FRET assay was performed using Lanthascreen RORα coactivator assay kit. The y axis represents the ratio of fluorescence intensity at 520 nm (signal) and at 495 nm (background). The x axis represents log scale of RvD1 (black line), MaR1 (red line), or CS (blue line) concentration. (C) Molecular surface model of RORα-MaR1 (magenta) complex (transparent view) obtained by docking that allows visualization of ligand bound to the internal ligand binding pocket. The figure was generated using Tripos Benchware 3D Explorer. (D) Docked model showing binding mode of MaR1 (magenta) and cholesterol sulfate (cyan) in the ligand binding pocket of RORα. The COOH group of MaR1 makes H-bond contacts with NH1-Arg370 and NH-Tyr290, and C7-OH of MaR1 with CO-Val364. (E) Raw 264.7 cells were transfected with the RORE-Luc reporter with the indicated point mutated Myc-RORα construct (left), or the Gal4-tk-Luc reporter with the indicated point mutated pM-RORα construct (right). The transfected cells were treated with 200 nM MaR1 for 24 hours and then luciferase activity was measured and normalized by β-galactosidase activity. *P < 0.05; #P < 0.05 (n = 3). The data represent mean ± SD. Data were analyzed by Mann–Whitney U test for simple comparisons or Kruskal-Wallis test for multiple groups. (F) A predicted model of interaction between MaR1 (ball & stick model; carbon atoms in yellow) and native RORα (amino acids of interest with meshed molecular surface and ball & stick model with carbon atoms in gray) (left). Introduction of bulky side chain by the point mutation of C288L would interfere optimal conformation of Arg370 (center). A330L would occupy space necessary for binding MaR1 (carbon atoms in yellow with meshed molecular surface) (right). The figures were generated using Tripos Benchware 3D Explorer.