DDX1 Crotonylation Mediates ACOX1 Alternative Splicing through HNRNPK to Increase Peroxisomal Oxidative Damage

Peroxisomes are essential organelles that maintain cellular redox homeostasis. Although alternatively spliced variants of certain peroxisome-related genes have been identified, the regulatory mechanisms governing alternative splicing (AS) and its functional impact on peroxisomal redox homeostasis remain poorly understood. Here, we demonstrate that glucose starvation (GS) induces crotonylation of DEAD-box helicase 1 (DDX1), which is regulated by the crotonyltransferase general control non-repressed protein 5 (GCN5) and the decrotonylase histone deacetylase 1 (HDAC1). DDX1 crotonylation at the lysine 490 residue enhances its interaction with heterogeneous nuclear ribonucleoprotein K (HNRNPK), which mediates mutually exclusive AS of acyl-CoA oxidase 1 (ACOX1). The AS of ACOX1, driven by DDX1 crotonylation and HNRNPK, promotes the generation of peroxisomal ROS, thereby enhancing oxidative damage and ultimately suppressing colorectal cancer (CRC) cell proliferation. Our findings uncover a novel mechanism by which DDX1 crotonylation regulates the AS of peroxisome-related genes and mediates peroxisomal redox homeostasis. This discovery bridges a critical gap in our understanding of how posttranslational modifications (PTMs) of DEAD/DEXD box RNA helicases modulate gene AS and identifies a potential therapeutic target for colorectal cancer.