Tankyrase1/2 inhibition reveals that PARylation is regulating aerobic activities in hepatocytes and HepG2 cells

XAV-939 is an anti-oncogenic small molecule that potently inhibits tankyrase1/2 (TNKS1/2), thereby blocking protein poly ADP-ribosylation (PARylation) of pleiotropic protein targets. In the present study, XAV-939 was used to explore its potential for improving human-derived liver models in vitro. Epithelial-to-mesenchymal transitioning indeed seemed to be reduced in XAV-939 treated primary human hepatocytes and HepG2 cells, while nutritional homeostasis, mitochondrial function, and CYP450-mediated biotransformation capacities were enhanced. Subsequently, CRISPR/Cas9 was utilised to generate tankyrase1 and/or tankyrase2 knockout HepG2 cells, which elucidated PARylation as master regulator for aerobic-dependent respiration. Novel (in)direct TNKS1/2-mediated PARylation targets were identified, using targeted proteomics and MS-coupled anti-PAR co-immunoprecipitation. In conclusion, XAV-939 can be applied to improve state-of-the art hepatic models in vitro in terms of metabolism and aerobic respiration. This work sheds light on a new mechanistic framework by linking PARylation to respiration and metabolism, thereby broadening the current understanding that underlies these vital processes.