Perturbed liver gene zonation in a mouse model of non-alcoholic steatohepatitis
Liver zonation characterizes the separation of metabolic pathways along the lobules and is required for optimal hepatic function. Wnt signaling is a master regulator of spatial liver zonation. A perivenous-periportal Wnt activity gradient orchestrates metabolic zonation by activating genes in perivenous hepatocytes, while suppressing genes in their periportal counterparts. The understanding of liver gene zonation and zonation regulators in disease was limited. Non-alcoholic steatohepatitis (NASH) is a chronic liver disease characterized by fat accumulation, inflammation, and fibrosis. Here, we investigated the perturbation of liver gene zonation in a mouse NASH model by combination of spatial transcriptomics, bulk RNAseq and in situ hybridization. Wnt target genes represented a major subset of genes showing altered spatial expression in the NASH liver. The altered Wnt target gene expression level and zonation spatial pattern were in line with the upregulation of Wnt regulators and the augmentation of Wnt signaling. Particularly, we found that the Wnt activator Rspo3 expression was restricted to the perivenous zone in control livers, whereas expanded to the periportal zone in NASH livers. AAV8-mediated RSPO3 overexpression in controls resulted in a zonation change, and further amplified the disturbed zonation of Wnt target genes in NASH, but had no impacts on steatosis, inflammation and fibrosis. In summary, our study demonstrated the alteration of Wnt signaling in a mouse NASH model, leading to perturbed liver zonation. Overall design: Age matched adult (7-10 months old) male C57BL/6 mice (The Jackson Laboratory) were housed in a controlled environment (12-hour light/dark cycle, 22±1 °C, 60-70% humidity). 3 Mice were fed ad libitum with standard chow (Purina Laboratory, Rodent diet 5001, LabDiet) and 4 mice are fed on  CDAA-HFD diets (Diet A16092201i containing 45% fat and 28% fructose in calorie, and 1% cholesterol, 0.1% methionine with no choline, Research Diets) inducing NASH for 8-12 weeks. Two sections from each mouse were used for 10X Visium platform library preparation and sequencing.