Knockouts of , , or from cholesterol synthesis reveal pathways modulated by sterol intermediates.

Sterols from cholesterol synthesis are crucial for cholesterol production, but also have individual roles difficult to assess due to essentiality of cholesterol. We developed HepG2 cell models with knockouts (KOs) for three enzymes of cholesterol synthesis, each accumulating specific sterols. Surprisingly, KOs of , , and shared only 9% of differentially expressed genes. The most striking was the phenotype of KO with highly elevated lanosterol and 24,25-dihydrolanosterol, significant increase in G2+M phase and enhanced cancer and cell cycle pathways. Comparisons with mouse liver KO data suggest 24,25-dihydrolanosterol activates similar cell proliferation pathways, possibly via elevated LEF1 and WNT/NFKB signaling. In contrast, and KO cells with elevated lathosterol or desmosterol proliferated slowly, with downregulated E2F, mitosis, and enriched HNF1A. These findings demonstrate that increase of lanosterol and 24,25-dihydrolanosterol, but not other sterols, promotes cell proliferation in hepatocytes.