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

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.

Suppression of ITPKB degradation by Trim25 confers TMZ resistance in glioblastoma through ROS homeostasis

Temozolomide(TMZ)represents a standard-of-care chemotherapeutic agent in glioblastoma(GBM).However,the development of drug resistance constitutes a significant hurdle in the treatment of malignant glioma.Although specific innovative approaches,such as immunotherapy,have shown favorable clinical outcomes,the inherent invasiveness of most gliomas continues to make them challenging to treat.Consequently,there is an urgent need to identify effective therapeutic targets for gliomas to overcome chemoresistance and facilitate drug development.This investigation used mass spectrometry to examine the proteomic profiles of six pairs of GBM patients who underwent standard-of-care treatment and surgery for both primary and recurrent tumors.A total of 648 proteins exhibiting significant differential expression were identified.Gene Set Enrichment Analysis(GSEA)unveiled notable alterations in pathways related to METABOLISM_OF_LIPIDS and BIOLOGICAL_OXIDATIONS between the primary and recurrent groups.Validation through glioma tissue arrays and the Xiangya cohort confirmed substantial upregulation of inositol 1,4,5-triphosphate(IP3)kinase B(ITPKB)in the recurrence group,correlating with poor survival in glioma patients.In TMZ-resistant cells,the depletion of ITPKB led to an increase in reactive oxygen species(ROS)related to NADPH oxidase(NOX)activity and restored cell sensitivity to TMz.Mechanistically,the decreased phosphorylation of the E3 ligase Trim25 at the S100 position in recurrent GBM samples accounted for the weakened ITPKB ubiquitination.This,in turn,elevated ITPKB stability and impaired ROS production.Furthermore,ITPKB depletion or the ITPKB inhibitor GNF362 effectively overcome TMZ chemoresistance in a glioma xenograft mouse model.These findings reveal a novel mechanism underlying TMZ resistance and propose ITPKB as a promising therapeutic target forTMZ-resistant GBM.

Engineering an enthesis-like graft for rotator cuff repair:An approach to fabricate highly biomimetic scaffold capable of zone-specifically releasing stem cell differentiation inducers

Rotator cuff(RC)attaches to humerus across a triphasic yet continuous tissue zones(bone-fibrocartilage-tendon),termed“enthesis”.Regrettably,rapid and functional enthesis regeneration is challenging after RC tear.The existing grafts bioengineered for RC repair are insufficient,as they were engineered by a scaffold that did not mimic normal enthesis in morphology,composition,and tensile property,meanwhile cannot simultaneously stimulate the formation of bone-fibrocartilage-tendon tissues.Herein,an optimized decellularization approach based on a vacuum aspiration device(VAD)was developed to fabricate a book-shaped decellularized enthesis matrix(O-BDEM).Then,three recombinant growth factors(CBP-GFs)capable of binding collagen were synthesized by fusing a collagen-binding peptide(CBP)into the N-terminal of BMP-2,TGF-β3,or GDF-7,and zone-specifically tethered to the collagen of O-BDEM to fabricate a novel scaffold(CBP-GFs/O-BDEM)satisfying the above-mentioned requirements.After ensuring the low immunogenicity of CBP-GFs/O-BDEM by a novel single-cell mass cytometry in a mouse model,we interleaved urine-derived stem cell-sheets into this CBP-GFs/O-BDEM to bioengineer an enthesis-like graft.Its high-performance on regenerating enthesis was determined in a canine model.These findings indicate this CBP-GFs/O-BDEM may be an excellent scaffold for constructing enthesis-like graft to patch large/massive RC tears,and provide breakthroughs in fabricating graded interfacial tissue.