SOX9 adenovirus

The transcription factor sex-determining region Y-associated high-mobility group box gene 9 (SOX9) plays a crucial role in organ development. Although SOX9 has been shown to be involved in the regulation of lipid metabolism in vitro, its specific role in metabolic dysfunction-associated steatohepatitis (MASH) remains unclear. Here, the researchers established a MASH model using mice fed a methionine and choline-deficient (MCD) diet or a high-fat, high-fructose diet. The study showed that SOX9 expression was significantly increased in hepatocytes of MASH mice. Hepatocyte-specific SOX9 deletion exacerbated MCD-induced MASH, while SOX9 overexpression alleviated high-fat, high-fructose-induced MASH. Lipidomics and RNA sequencing analyses showed that SOX9 suppressed the expression of genes related to lipid metabolism, inflammation, and fibrosis in MCD-fed mice. In addition, SOX9 deletion inhibited AMPK pathway activation, while SOX9 overexpression enhanced the pathway activation. Notably, the use of an AMPK inhibitor abrogated the protective effect of SOX9 overexpression, leading to increased lipid accumulation in HepG2 cells. These results highlight SOX9 as a promising therapeutic target for the treatment of MASH.

To further evaluate the expression of SOX9 in hepatocytes during the progression of MASH, researchers performed immunohistochemical staining of liver tissues from patients with normal livers and MASH, control mice, and MASH mice induced by MCD or HFF (Figure 1A and B). These results confirmed that SOX9 expression was increased in hepatocytes in both MASH patients and mice, suggesting that SOX9 may play a role in hepatocyte lipid metabolism. Next, the effect of SOX9 on hepatocyte lipotoxicity was examined. adenovirus (Ad)-SOX9 or Ad-GFP was transduced into HepG2 cells, followed by oral treatment (Figure 1C). Quantitative real-time PCR showed that SOX9 overexpression significantly reduced the mRNA levels of genes involved in de novo lipogenesis (DNL) (fatty acid synthase, sterol regulatory element binding protein 1, and acetyl-CoA carboxylase 1) and lipid transport genes (fatty acid binding protein 1 and cluster of differentiation 36) in HepG2 and AML12 cells (Figure 1D). Nile red staining further showed that SOX9 overexpression significantly reduced PO-induced lipid accumulation in HepG2 cells (Figure 1E). To complement these results, researchers designed two siRNAs targeting SOX9 (siSOX9-1 and siSOX9-2) to knock down SOX9 expression (Figure 1F). SOX9 knockdown led to increased expression of genes related to DNL and lipid transport (Figure 1G) and exacerbated PO-induced lipid accumulation (Figure 1H). Together, these results suggest that SOX9 inhibits lipid accumulation caused by lipotoxicity.

Figure 1. SOX9 suppresses lipid accumulation in HepG2 cells. (Deng J, et al., 2024)