Carnos1, or carnosine synthase 1, is an enzyme that catalyzes the synthesis of carnosine, a histidine-containing dipeptide with antiproliferative activity in cancer [1]. It is involved in multiple biological processes and pathways, such as being present in oligodendrocytes and contributing to the regulation of oxidative stress, and may also play a role in the regulation of arginine metabolism [2,3,5].

Gene knockout models have provided significant insights into Carns1 function. In Carns1-KO mice, there are lower numbers of mature oligodendrocytes, increased lipid peroxidation, and behavioral changes, suggesting that Carns1-synthesized histidine dipeptides protect oligodendrocytes from oxidative stress [3]. In the context of multiple sclerosis, Carns1 expression is diminished in demyelinated lesions, and Carns1-KO mice display exaggerated neuroinflammation and clinical symptoms, indicating that loss of Carns1 can aggravate disease progression [2]. In a CARNS1 -/- rat model, cardiac muscle contractile function is significantly impaired, showing that histidine-containing dipeptides synthesized by CARNS1 are key regulators of excitation-contraction coupling in cardiac muscle [4].

In summary, Carns1 is crucial for the synthesis of histidine-containing dipeptides that protect oligodendrocytes from oxidative stress, maintain normal cardiac muscle function, and may impact disease processes such as multiple sclerosis. Gene knockout models, like Carns1-KO mice and CARNS1 -/- rats, have been instrumental in revealing these functions, providing valuable insights into the role of Carns1 in various biological processes and disease conditions.