MAP3K1 functionally interacts with Axin1 in the canonical Wnt signalling pathway.

Journal article

A central point of regulation in the Wnt/beta-catenin signalling pathway is the formation of the beta-catenin destruction complex. Axin1, an essential negative regulator of Wnt signalling, serves as a scaffold within this complex and is critical for rapid turnover of beta-catenin. To examine the mechanism by which Wnt signalling disables the destruction complex, we used an immunoprecipitation-coupled proteomics approach to identify novel endogenous binding partners of Axin1. We found mitogen-activated protein kinase kinase kinase 1 (MAP3K1) as an Axin1 interactor in Ls174T colorectal cancer (CRC) cells. Importantly, confirmation of this interaction in HEK293T cells indicated that the Axin1-MAP3K1 interaction is induced and modulated by Wnt stimulation. siRNA depletion of MAP3K1 specifically abrogated TCF/LEF-driven transcription and Wnt3A-driven endogenous gene expression in both HEK293T as well as DLD-1 CRC. Expression of ubiquitin ligase mutants of MAP3K1 abrogated TCF/LEF transcription, whereas kinase mutants had no effect in TCF-driven activity, highlighting the essential role of the MAP3K1 E3 ubiquitin ligase activity in regulation of the Wnt/beta-catenin pathway. These results suggest that MAP3K1, previously reported as an Axin1 inter-actor in c-Jun NH(2)-terminal kinase pathway, is also involved in the canonical Wnt signalling pathway and positively regulates expression of Wnt target genes.

Authors: Sue Ng, S; Mahmoudi, T; Li, V; Hatzis, P; Boersema, P

• Publication status: Published
• Journal: Biological chemistry
• Volume: 391
• Issue: 2-3
• Pages: 171-180
• Publication date: 2010-01-01
• DOI: 10.1515/bc.2010.028
• EISSN: 1437-4315
• ISSN: 1431-6730
• Language: English
• Keywords: Signal Transduction; Axin Protein; Cell Line; beta Catenin; Transcription, Genetic; Reverse Transcriptase Polymerase Chain Reaction; Humans; Cell Line, Tumor; Amino Acid Sequence; Protein Binding; Immunoprecipitation; Wnt Proteins; Molecular Sequence Data; MAP Kinase Kinase Kinase 1; RNA, Small Interfering; Repressor Proteins; Mutagenesis, Site-Directed