Impaired SUMOylation of nuclear receptor LRH-1 promotes nonalcoholic fatty liver disease
Sokrates Stein, Vera Lemos, Pan Xu, Hadrien Demagny, Xu Wang, Dongryeol Ryu, Veronica Jimenez, Fatima Bosch, Thomas F. Lüscher, Maaike H. Oosterveer, Kristina Schoonjans
Sokrates Stein, Vera Lemos, Pan Xu, Hadrien Demagny, Xu Wang, Dongryeol Ryu, Veronica Jimenez, Fatima Bosch, Thomas F. Lüscher, Maaike H. Oosterveer, Kristina Schoonjans
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Research Article Hepatology Metabolism

Impaired SUMOylation of nuclear receptor LRH-1 promotes nonalcoholic fatty liver disease

Abstract

Hepatic steatosis is caused by metabolic imbalances that could be explained in part by an increase in de novo lipogenesis that results from increased sterol element binding protein 1 (SREBP-1) activity. The nuclear receptor liver receptor homolog 1 (LRH-1) is an important regulator of intermediary metabolism in the liver, but its role in regulating lipogenesis is not well understood. Here, we have assessed the contribution of LRH-1 SUMOylation to the development of nonalcoholic fatty liver disease (NAFLD). Mice expressing a SUMOylation-defective mutant of LRH-1 (LRH-1 K289R mice) developed NAFLD and early signs of nonalcoholic steatohepatitis (NASH) when challenged with a lipogenic, high-fat, high-sucrose diet. Moreover, we observed that the LRH-1 K289R mutation induced the expression of oxysterol binding protein-like 3 (OSBPL3), enhanced SREBP-1 processing, and promoted de novo lipogenesis. Mechanistically, we demonstrated that ectopic expression of OSBPL3 facilitates SREBP-1 processing in WT mice, while silencing hepatic Osbpl3 reverses the lipogenic phenotype of LRH-1 K289R mice. These findings suggest that compromised SUMOylation of LRH-1 promotes the development of NAFLD under lipogenic conditions through regulation of OSBPL3.

Authors

Sokrates Stein, Vera Lemos, Pan Xu, Hadrien Demagny, Xu Wang, Dongryeol Ryu, Veronica Jimenez, Fatima Bosch, Thomas F. Lüscher, Maaike H. Oosterveer, Kristina Schoonjans

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Figure 3

Osbpl3 silencing rescues the lipogenic phenotype of LRH-1 K289R mice.

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Osbpl3 silencing rescues the lipogenic phenotype of LRH-1 K289R mice. (...
(A) Immunoblots of OSBPL3, HSP90, precursor and cleaved SREBP-1, P62, and HDAC3 in hepatic lysates of fasted or refed WT plus Ad-GFP or refed WT plus Ad-OSBPL3 livers. (B–D) Hepatic mRNA expression of Osbpl3 (B), Srebf1 (C), and Fasn (D) in refed K289R and WT mice. WT, n = 3; K289R siScr or K289R siOsbpl3, n = 9 per genotype. (E) Immunoblots of OSBPL3, FASN, β-actin, precursor and cleaved SREBP-1, and PARP1 in hepatic lysates of refed K289R siScr or K289R siOsbpl3 livers. (F) Hepatic expression of OSBPL3, FASN, SCD1, and HSP90 in livers of ad libitum–fed WT, K289R siScr, and K289R siOsbpl3 mice. (G) Hepatic mRNA expression of genes involved in de novo lipogenesis in ad libitum–fed WT, K289R siScr, and K289R siOsbpl3 mice. n = 3 per genotype. (H) Quantification of hepatic triglycerides in hepatic lipid extracts from ad libitum–fed WT, K289R siScr, and K289R siOsbpl3 mice. n = 3 per genotype. (I and J) Hepatic mRNA expression of Osbpl3 (I) and Fasn (J) in 6-hour–refed WT, K289R, or K289R mirOsbpl3 mice. n = 3 per genotype. (K) Representative oil red O staining in liver cryosections from refed K289R mirScrambled or K289R mirOsbpl3 mice. Scale bars: 100 μm. Error bars represent mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 relative to K289R siScr, as determined by 1-way ANOVA with Bonferroni’s post-hoc test (B–D, G–J). WT, LRH-1 WT; K289R siOsbpl3, LRH-1 K289R mice injected with Osbpl3-siRNA complexes; K289R siScr, LRH-1 K289R mice injected with scrambled-siRNA complexes; K289R mirOsbpl3, LRH-1 K289R mice injected with AAV8 viral vectors containing an miRNA targeting Osbpl3.