Liver fibrosis is the excessive accumulation of
extracellular matrix proteins that occurs in chronic
liver disease. Ubiquitination is a post-translational modification that is crucial for a plethora of physiological processes. Even though the
ubiquitin system has been implicated in several human diseases, the role of ubiquitination in
liver fibrosis remains poorly understood. Here, multi-omics approaches were used to address this. Untargeted metabolomics showed that
carbon tetrachloride (CCl4)-induced
liver fibrosis promotes changes in the hepatic metabolome, specifically in
glycerophospholipids and
sphingolipids. Gene ontology analysis of public deposited gene array-based data and validation in our mouse model showed that the biological process "
protein polyubiquitination" is enriched after CCl4-induced
liver fibrosis. Finally, by using transgenic mice expressing biotinylated
ubiquitin (bioUb mice), the ubiquitinated
proteome was isolated and characterized by mass spectrometry in order to unravel the hepatic ubiquitinated
proteome fingerprint in CCl4-induced
liver fibrosis. Under these conditions, ubiquitination appears to be involved in the regulation of cell death and survival, cell function, lipid metabolism, and DNA repair. Finally, ubiquitination of
proliferating cell nuclear antigen (
PCNA) is induced during CCl4-induced
liver fibrosis and associated with the DNA damage response (DDR). Overall, hepatic ubiquitome profiling can highlight new therapeutic targets for the clinical management of
liver fibrosis.