Spatial transcriptomics unravels palmitoylation and zonation-dependent gene regulation by AEG-1 in mouse liver.

ABSTRACT

Obesity-induced metabolic dysfunction-associated steatohepatitis (MASH) leads to hepatocellular carcinoma (HCC). Astrocyte-elevated gene-1/Metadherin (AEG-1/MTDH) plays a key role in promoting MASH and HCC. AEG-1 is palmitoylated at residue cysteine 75 (Cys75) and a knock-in mouse representing mutated Cys75 to serine (AEG-1-C75S) showed activation of MASH- and HCC-promoting gene signature when compared to wild-type littermates (AEG-1-WT). The liver consists of three zones, periportal, mid-lobular, and pericentral, and zone-specific dysregulated gene expression impairs metabolic homeostasis in the liver, contributing to MASH and HCC. Here, to elucidate how palmitoylation influences AEG-1-mediated gene regulation in regard to hepatic zonation, we performed spatial transcriptomics (ST) in the livers of AEG-1-WT and AEG-1-C75S littermates. ST identified six different clusters in livers and using zone- and cell-type-specific markers we attributed specific zones and cell types to specific clusters. Ingenuity Pathway Analysis (IPA) of differentially expressed genes in each cluster unraveled activation of pro-inflammatory and MASH- and HCC-promoting pathways, mainly in periportal and pericentral hepatocytes, in AEG-1-C75S liver compared to AEG-1-WT. Interestingly, in AEG-1-C75S liver, the mid-lobular zone exhibited widespread inhibition of xenobiotic metabolism pathways and inhibition of PXR/RXR and LXR/RXR activation, versus AEG-1-WT. In conclusion, AEG-1-C75S mutant exhibited zone-specific differential gene expression, which might contribute to metabolic dysfunction and dysregulated drug metabolism leading to MASH and HCC.