A divergent canonical WNT-signaling pathway regulates microtubule dynamics: dishevelled signals locally to stabilize microtubules

L Ciani, O Krylova, MJ Smalley, TC Dale… - The Journal of cell …, 2004 - rupress.org
L Ciani, O Krylova, MJ Smalley, TC Dale, PC Salinas
The Journal of cell biology, 2004rupress.org
Dishevelled (DVL) is associated with axonal microtubules and regulates microtubule
stability through the inhibition of the serine/threonine kinase, glycogen synthase kinase 3β
(GSK-3β). In the canonical WNT pathway, the negative regulator Axin forms a complex with
β-catenin and GSK-3β, resulting in β-catenin degradation. Inhibition of GSK-3β by DVL
increases β-catenin stability and TCF transcriptional activation. Here, we show that Axin
associates with microtubules and unexpectedly stabilizes microtubules through DVL. In turn …
Dishevelled (DVL) is associated with axonal microtubules and regulates microtubule stability through the inhibition of the serine/threonine kinase, glycogen synthase kinase 3β (GSK-3β). In the canonical WNT pathway, the negative regulator Axin forms a complex with β-catenin and GSK-3β, resulting in β-catenin degradation. Inhibition of GSK-3β by DVL increases β-catenin stability and TCF transcriptional activation. Here, we show that Axin associates with microtubules and unexpectedly stabilizes microtubules through DVL. In turn, DVL stabilizes microtubules by inhibiting GSK-3β through a transcription- and β-catenin–independent pathway. More importantly, axonal microtubules are stabilized after DVL localizes to axons. Increased microtubule stability is correlated with a decrease in GSK-3β–mediated phosphorylation of MAP-1B. We propose a model in which Axin, through DVL, stabilizes microtubules by inhibiting a pool of GSK-3β, resulting in local changes in the phosphorylation of cellular targets. Our data indicate a bifurcation in the so-called canonical WNT-signaling pathway to regulate microtubule stability.
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