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Aberrant lysine lactylation (Kla) is associated with various diseases which are caused by excessive glycolysis metabolism. However, the regulatory molecules and downstream protein targets of Kla remain largely unclear. Here, we observed a global Kla abundance profile in colorectal cancer (CRC) that negatively correlates with prognosis. Among lactylated proteins detected in CRC, lactylation of eEF1A2K408 resulted in boosted translation elongation and enhanced protein synthesis which contributed to tumorigenesis. By screening eEF1A2 interacting proteins, we identified that KAT8, a lysine acetyltransferase that acted as a pan-Kla writer, was responsible for installing Kla on many protein substrates involving in diverse biological processes. Deletion of KAT8 inhibited CRC tumor growth, especially in a high-lactic tumor microenvironment. Therefore, the KAT8-eEF1A2 Kla axis is utilized to meet increased translational requirements for oncogenic adaptation. As a lactyltransferase, KAT8 may represent a potential therapeutic target for CRC. [ABSTRACT FROM AUTHOR]

A rapid and sensitive bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS-MS) has been developed and validated to measure arbutin in rat plasma. Sample preparation of plasma after the addition of indapamide as internal standard (IS) involved solid-phase extraction (SPE) on C18 cartridges. Reversed-phase chromatography using acetonitrile and 0.5% formic acid solution (pH 2.56) was used for separation in a run time of 4.0 min. The analytes were detected in the negative ion mode using selective reaction monitoring (SRM) of the transitions at m/z 271.2→107.8 for arbutin and 364.3→189.0 for indapamide. The method has the following performance characteristics: a reliable response range of 7.5-5250.0 ng/mL with correlation coefficients (r) of >0.995. The lower limit of quantitation (LLOQ) was 7.5 ng/mL. The intra- and inter-day precision and accuracy of the quality control (QC) samples at low, medium and high concentration levels showed ≤8.79% relative standard deviation (RSD) and −1.15 to 1.49% relative error (RE). The method was successfully applied to a pharmacokinetic study to measure arbutin in rats after extracts of Vaccinium vitis-idaea was orally administered. [ABSTRACT FROM AUTHOR]

Hepatocytes in fatty livers are hypersensitive to apoptosis and undergo escalated apoptotic activity via death receptor–mediated pathways, particularly that of Fas-FasL, causing hepatic injury that can eventually proceed to cirrhosis and end-stage liver disease. Here we report that the hepatocyte growth factor receptor, Met, plays an important part in preventing Fas-mediated apoptosis of hepatocytes by sequestering Fas. We also show that Fas antagonism by Met is abrogated in human fatty liver disease (FLD). Through structure-function studies, we found that a YLGA amino-acid motif located near the extracellular N terminus of the Met α-subunit is necessary and sufficient to specifically bind the extracellular portion of Fas and to act as a potent FasL antagonist and inhibitor of Fas trimerization. Using mouse models of FLD, we show that synthetic YLGA peptide tempers hepatocyte apoptosis and liver damage and therefore has therapeutic potential. [ABSTRACT FROM AUTHOR]