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bioRxiv · 10.1101/734665

Auxin-induced nanoclustering of membrane signaling complexes underlies cell polarity establishment in Arabidopsis

Pan, X.·Fang, L.·Liu, J.·Senay-Aras, B.·Lin, W.·Zheng, S.·Zhang, T.·Manor, U.·Chen, W.·Yang, Z.
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Abstract

Cell polarity is fundamental to the development of both eukaryotic and prokaryotic organisms, yet the mechanism of its establishment remains poorly understood. Here we show that signal-activated nanoclustering of membrane proteins and a cytoskeleton-based feedback loop provide an important mechanism for the establishment of cell polarity. The phytohormone auxin promoted sterol-dependent nanoclustering of cell surface transmembrane receptor-like kinase 1 (TMK1) to initiate cell polarity during the morphogenesis of Arabidopsis puzzle piece-shaped leaf pavement cells (PC). Auxin-triggered nanoclustering of TMK1 stabilized flotillin-associated ordered nanodomains, which were essential for auxin-mediated formation of ROP6 GTPase nanoclusters that act downstream TMK1 to promote cortical microtubule ordering. Mathematical modeling further demonstrated the essential role of this auxin-mediated stabilization of TMK1 and ROP6 nanoclusters, and predicted the additional requirement of ROP6-dependent cortical microtubules for further stabilization of TMK1-sterol nanodomains and the polarization of PC. This prediction was experimentally validated by genetic and biochemical data. Our studies reveal a new paradigm for polarity establishment: A diffusive signal triggers cell polarization by activating cell surface receptor-mediated lateral segregation of signaling components and a cytoskeleton-mediated positive feedback loop of nanodomain stabilization.\n\nHighlightsO_LISterols are required for cell polarity in Arabidopsis leaf epidermal cells\nC_LIO_LIAuxin promotes lipid ordering and polar distribution of ordered lipid nanodomains at the plasma membrane (PM)\nC_LIO_LIAuxin stabilizes sterol-dependent nanoclustering of transmembrane kinase (TMK1), a PM auxin signal transducer\nC_LIO_LIAuxin-induced TMK1 nanoclustering is required but insufficient for cell polarization\nC_LIO_LIMicrotubule-based feedback stabilization of the auxin-induced TMK1 nanodomains can generate cell polarity\nC_LI

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Pan, X., Fang, L., Liu, J., Senay-Aras, B., Lin, W., Zheng, S., Zhang, T., Manor, U., Chen, W., Yang, Z.. 2019-08-13. Auxin-induced nanoclustering of membrane signaling complexes underlies cell polarity establishment in Arabidopsis. https://doi.org/10.1101/734665

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