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Nature Cell Biology 3, 628–636 (1 July 2001) | doi:10.1038/35083016

PAR-1 is a Dishevelled-associated kinase and a positive regulator of Wnt signalling

Tian-Qiang Sun , Bingwei Lu , Jia-Jia Feng , Christoph Reinhard , Yuh Nung Jan , Wendy J. Fantl & Lewis T. Williams

Wnt signalling regulates β-catenin-dependent developmental processes through the Dishevelled protein (Dsh). Dsh regulates two distinct pathways, one mediated by β-catenin and the other by Jun kinase (JNK). We have purified a Dsh-associated kinase from Drosophila that encodes a homologue of Caenorhabditis elegans PAR-1, a known determinant of polarity during asymmetric cell divisions. Treating cells with Wnt increases endogenous PAR-1 activity coincident with Dsh phosphorylation. PAR-1 potentiates Wnt activation of the β-catenin pathway but blocks the JNK pathway. Suppressing endogenous PAR-1 function inhibits Wnt signalling through β-catenin in mammalian cells, and Xenopus and Drosophila embryos. PAR-1 seems to be a positive regulator of the β-catenin pathway and an inhibitor of the JNK pathway. These findings show that PAR-1, a regulator of polarity, is also a modulator of Wnt–β-catenin signalling, indicating a link between two important developmental pathways.