Deletion of exons 3 and 4 in the mouse Nr1d1 gene worsens high-fat diet-induced hepatic steatosis.

Aims: To elucidate the role of nuclear receptor subfamily 1, group D, member 1 (Nr1d1) in hepatic lipid metabolism and pathogenesis of nonalcoholic fatty liver diseases, Nr1d1 gene mutant mice, in which the DNA-binding domain (exons 3 and 4) was deleted (Nr1d1 Δex3/4), were challenged with a high-fat diet (HFD), and the gene expression patterns that responded to this alteration were profiled.

Main Methods: The Nr1d1 Δex3/4 mice were fed an HFD for 12weeks. Liver tissues were examined by histology, and lipid droplets were detected by Oil-Red O staining. Serum biochemical analyses were performed to assess markers of liver injury. Microarray analysis was used to profile hepatic gene expression patterns. Functional annotation, upstream prediction, and gene coexpression prediction analyses were performed.

Key Findings: The Nr1d1 Δex3/4 mice showed enhanced hepatic steatosis after being challenged with an HFD, but not with a low-fat diet, indicating an interaction between diet and genotype for this phenotypic change. Gene expression profiling revealed that this interaction might involve neutrophil recruitment and the cyclic adenosine monophosphate metabolic pathway. A study of transcription factor binding site enrichment suggested that CCAAT/enhancer-binding protein alpha and hepatocyte nuclear factor 4 alpha were associated with this phenotypic change.

Significance: Loss of DNA binding of Nr1d1 was associated with a deterioration in hepatic steatosis. The interaction between the Nr1d1 Δex3/4 genotype with an HFD might mediate these phenotypic changes, probably through a nonclassical transcriptional function of Nr1d1.