Amith

Could one liver enzyme have far more biological roles than its traditional place in the urea cycle suggests? #GUTRecentAdvancesInBasicScience paper by Chen et al. presents “CPS1: a multipurpose mitochondrial enzyme, bile protein, acute liver injury biomarker, and cytokine” via bit.ly/4AdXdIO This review examines the expanding biology of carbamoyl phosphate synthetase 1 (CPS1), a highly abundant mitochondrial enzyme best known for catalysing the first step of the hepatic urea cycle. CPS1 is also physiologically secreted into bile and can enter the circulation following hepatocyte injury. Its abundance, selective release and short serum half-life make it a potentially valuable biomarker of acute liver injury, particularly acute liver failure associated with acetaminophen toxicity. The review also highlights an unexpected non-enzymatic role for CPS1 as an immune modulator. Following its release into the circulation, CPS1 can be taken up by monocytes and promote differentiation towards anti-inflammatory cells that home to and protect the injured liver. Beyond liver injury, CPS1 is increasingly implicated in cancer, where altered expression can influence metabolic reprogramming and the tumour microenvironment. The work illustrates how a protein traditionally viewed through the lens of hepatic nitrogen metabolism is emerging as a multifunctional molecule linking metabolism, bile biology, liver injury, immunity and cancer. #AcuteLiverInjury #CPS1