Parental metabolic syndrome epigenetically reprograms offspring hepatic lipid metabolism in mice
Dario F. De Jesus, … , Jussi Pihlajamäki, Rohit N. Kulkarni
Dario F. De Jesus, … , Jussi Pihlajamäki, Rohit N. Kulkarni
Published April 6, 2020
Citation Information: J Clin Invest. 2020;130(5):2391-2407. https://doi.org/10.1172/JCI127502.
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Research Article Development Hepatology

Parental metabolic syndrome epigenetically reprograms offspring hepatic lipid metabolism in mice

Abstract

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Although gene-environment interactions have been implicated in the etiology of several disorders, the impact of paternal and/or maternal metabolic syndrome on the clinical phenotypes of offspring and the underlying genetic and epigenetic contributors of NAFLD have not been fully explored. To this end, we used the liver-specific insulin receptor knockout (LIRKO) mouse, a unique nondietary model manifesting 3 hallmarks that confer high risk for the development of NAFLD: hyperglycemia, insulin resistance, and dyslipidemia. We report that parental metabolic syndrome epigenetically reprograms members of the TGF-β pathway, including neuronal regeneration–related protein (NREP) and growth differentiation factor 15 (GDF15). NREP and GDF15 modulate the expression of several genes involved in the regulation of hepatic lipid metabolism. In particular, NREP downregulation increases the protein abundance of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and ATP-citrate lyase (ACLY) in a TGF-β receptor/PI3K/protein kinase B–dependent manner, to regulate hepatic acetyl-CoA and cholesterol synthesis. Reduced hepatic expression of NREP in patients with NAFLD and substantial correlations between low serum NREP levels and the presence of steatosis and nonalcoholic steatohepatitis highlight the clinical translational relevance of our findings in the context of recent preclinical trials implicating ACLY in NAFLD progression.

Authors

Dario F. De Jesus, Kazuki Orime, Dorota Kaminska, Tomohiko Kimura, Giorgio Basile, Chih-Hao Wang, Larissa Haertle, Renzo Riemens, Natalie K. Brown, Jiang Hu, Ville Männistö, Amélia M. Silva, Ercument Dirice, Yu-Hua Tseng, Thomas Haaf, Jussi Pihlajamäki, Rohit N. Kulkarni

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Figure 5

NREP is downregulated by palmitate-induced steatosis in HepG2, and NREP regulates hepatic lipid metabolism.

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NREP is downregulated by palmitate-induced steatosis in HepG2, and NREP ...
(A) NREP protein levels in HepG2 cells treated with BSA or palmitate for 24 hours (n = 3 independent experiments). (B) Quantification of NREP protein levels. (C) NREP knockdown (KD) in HepG2 cells at protein levels (n = 3). (D) Representative oil red staining in HepG2 cells with NREP KD challenged with palmitate for 24 hours (n = 3 independent experiments; original magnification, ×400; scale bar: 50 μm). (E and F) Triglyceride (E) and cholesterol (F) content quantification in HepG2 cell lysates after stimulation for 24 hours with 500 μM palmitate (n = 3 independent experiments). (G and H) RNA sequencing selected enriched pathway analyses of upregulated (G) and downregulated genes (H) in HepG2 cells with NREP KD compared with scramble (n = 3 per group). (I) Heatmap representation of differently expressed genes involved in cholesterol biosynthesis, AKT signaling, apoptosis, fibrosis, and cell cycle. (J) Basal signaling analyses in lysates from HepG2 cells treated with scramble (left) or NREP KD (right) (n = 3 independent experiments). (K) Protein levels of indicated proteins in HepG2-scramble and NREP KD treated with BSA or palmitate for 24 hours in the presence of AKT inhibitor (MK-2206) or DMSO (n = 2 independent experiments). Significance was determined by 2-tailed unpaired t test in B, and 1-way ANOVA with Holm-Šidák multiple-comparisons test in E and F. **P < 0.01; ***P < 0.001. Data are expressed as means ± SEM.