CDK11 negatively regulates Wnt/β-catenin signaling in the endosomal compartment by affecting microtubule stability

摘要

Objectives:Improper activation of Wnt/β-catenin signaling has been implicated in human diseases.Beyond the well-studied glycogen synthase kinase 3p(GSK3p)and casein kinase 1(CK1),other kinases affecting Wnt/β-catenin signaling remain to be defined.Methods:To identify the kinases that modulate Wnt/β-catenin signaling,we applied a kinase small interfering RNA(siRNA)library screen approach.Luciferase assays,immunoblotting,and real-time polymerase chain reaction(PCR)were performed to confirm the regulation o f the Wnt/β-catenin signaling pathway by cyclin-dependent kinase 11(CDK11)and to investigate the underlying mechanism.Confocal immunofluorescence,coimmunoprecipitation(co-IP),and scratch wound assays were used to demonstrate colocalization,detect protein interactions,and explore the function of CDK11.Results:CDK11 was found to be a significant candidate kinase participating in the negative control of Wnt/P-catenin signaling.Down-regulation of CDK11 led to the accumulation of Wnt/β-catenin signaling receptor complexes,in a manner dependent on intact adenomatosis polyposis coli(APC)protein.Further analysis showed that CDK11 modulation of Wnt/P-catenin signaling engaged the endolysosomal machinery,and CDK11 knockdown enhanced the colocalization of Wnt/β-catenin signaling receptor complexes with early endosomes and decreased colocalization with lysosomes.Mechanistically,CDK11 was found to function in Wnt/β-catenin signaling by regulating microtubule stability.Depletion of CDK11 down-regulated acetyl-a-tubulin.Moreover,co-IP assays demonstrated that CDK11 interacts with the a-tubulin deacetylase SIRT2,whereas SIRT2 down-regulation in CDK11-depleted cells reversed the accumulation of Wnt/(3-catenin signaling receptor complexes.CDK11 was found to suppress cell migration through altered W nt/β-catenin signaling.Conclusions:CDK11 is a negative modulator of Wnt/β-catenin signaling that stabilizes microtubules,thus resulting in the dysregulation of receptor complex trafficking from early endosomes to lysosomes.