Loss of Hilnc prevents diet-induced hepatic steatosis through binding of IGF2BP2

The Hedgehog (Hh) signalling pathway plays a critical role in regulating liver lipid metabolism and related diseases. However, the underlying mechanisms are poorly understood. Here, we show that the Hh signalling pathway induces a previously undefined long non-coding RNA (Hilnc, Hedgehog signalling-induced long non-coding RNA), which controls hepatic lipid metabolism. Mutation of the Gli-binding sites in the Hilnc promoter region (HilncBM/BM) decreases the expression of Hilnc in vitro and in vivo. HilncBM/BM and Hilnc-knockout mice are resistant to diet-induced obesity and hepatic steatosis through attenuation of the peroxisome proliferator-activated receptor signalling pathway, as Hilnc directly interacts with IGF2BP2 to enhance Pparγ mRNA stability. Furthermore, we identify a potential functional human homologue of Hilnc, h-Hilnc, which has a similar function in regulating cellular lipid metabolism. These findings uncover a critical role of the Hh-Hilnc–IGF2BP2 signalling axis in lipid metabolism and suggest a potential therapeutic target for the treatment of diet-induced hepatic steatosis. Regulation of lipid metabolism by Hedgehog signalling is found to be mediated by a long non-coding RNA, named Hilnc, which can enhance Pparγ mRNA stability via the mRNA-binding protein IGF2BP2, and thereby affect obesity and liver steatosis.