In:
Science Signaling, American Association for the Advancement of Science (AAAS), Vol. 10, No. 491 ( 2017-08-08)
Abstract:
Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of diseases that ranges in severity from hepatic steatosis to steatohepatitis, the latter of which is a major predisposing factor for liver cirrhosis and cancer. Toll-like receptor (TLR) signaling, which is critical for innate immunity, is generally believed to aggravate disease progression by inducing inflammation. Unexpectedly, we found that deficiency in TIR domain–containing adaptor-inducing interferon-β (TRIF), a cytosolic adaptor that transduces some TLR signals, worsened hepatic steatosis induced by a high-fat diet (HFD) and that such exacerbation was independent of myeloid cells. The aggravated steatosis in Trif −/− mice was due to the increased hepatocyte transcription of the gene encoding stearoyl–coenzyme A (CoA) desaturase 1 (SCD1), the rate-limiting enzyme for lipogenesis. Activation of the TRIF pathway by polyinosinic:polycytidylic acid [poly(I:C)] suppressed the increase in SCD1 abundance induced by palmitic acid or an HFD and subsequently prevented lipid accumulation in hepatocytes. Interferon regulatory factor 3 (IRF3), a transcriptional regulator downstream of TRIF, acted as a transcriptional suppressor by directly binding to the Scd1 promoter. These results suggest an unconventional metabolic function for TLR/TRIF signaling that should be taken into consideration when seeking to pharmacologically inhibit this pathway.
Type of Medium:
Online Resource
ISSN:
1945-0877
,
1937-9145
DOI:
10.1126/scisignal.aal3336
Language:
English
Publisher:
American Association for the Advancement of Science (AAAS)
Publication Date:
2017
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