Protein tyrosine phosphatase receptor kappa regulates glycolysis, de novo lipogenesis and promotes hepatocyte metabolic reprogramming in obesity

Metabolic dysfunction within the liver is a major cause of human disease worldwide. Fat accumulation, de novo lipogenesis, and glycolysis are key drivers of hepatocyte reprogramming and the consequent metabolic dysfunction-associated steatotic liver disease (MASLD). The underpinning molecular mechanisms affected by steatosis and inflammation in the obese states remain unknown. Here we report that obesity leads to dysregulated expression of protein-tyrosine phosphatases (PTPs) in the liver. Protein Tyrosine Phosphatase Receptor Kappa (PTPRK) expression was increased in hepatocytes during steatosis and inflammation in humans and mice, and positively correlates with PPARγ-induced lipogenic signalling. Supporting this, PTPRK knockout mice displayed reduced fat accumulation in adipose tissue and liver after exposure to an obesogenic diet. Phosphoproteomic analysis in primary hepatocytes and hepatic metabolomics identified specific phosphotyrosine residues in fructose-1,6 bisphosphatase-1 and glycolysis regulation as targets of PTPRK. The changes in glycolysis and de novo lipogenesis revealed PTPRK was a driving force for metabolic reprogramming in hepatocytes. Moreover, hepatoma cell lines showed reduced colony-forming ability after PTPRK silencing in vitro, and PTPRK knockout mice developed smaller tumours after diethylnitrosamine-induced hepatocarcinogenesis in vivo. Through computational modelling, we identified selective PTPRK inhibitors. These compounds decreased glycolytic rates in hepatoma cell lines, PPARγ expression in primary hepatocytes and steatosis in obese mice. In conclusion, our study defines a novel mechanism for the development of MASLD, revealing a key role of PTPRK on hepatic glycolysis regulation with implications in lipid metabolism, and liver tumour development. We propose PTPRK as a potential target for metabolic liver dysfunction, and the identified inhibitors may represent promising candidates for therapy in obesity-associated liver diseases.