主要发现: Here we found that, phytohormone auxin-induced, sterol-dependent nanoclustering of cell surface transmembrane receptor kinase 1 (TMK1) is critical for the formation of polarized domains at the plasma membrane (PM) during the morphogenesis of cotyledon pavement cells (PC) in Arabidopsis.

结果：Auxin-induced TMK1 nanoclustering stabilizes flotillin1-associated ordered nanodomains, which in turn promote the nanoclustering of ROP6 GTPase that acts downstream of TMK1 to regulate cortical microtubule organization. In turn, cortical microtubules further stabilize TMK1- and flotillin1-containing nanoclusters at the PM. 

结论：Hence, we propose a new paradigm for polarity formation: A diffusive signal triggers cell polarization by promoting cell surface receptor-mediated nanoclustering of signaling components and cytoskeleton-mediated positive feedback that reinforces these nanodomains into polarized domains.

细胞极性对于真核和原核生物的发育都是重中之重，然而细胞极性形成背后的机理却还不是很清楚。本文中，作者发现拟南芥中细胞表面跨膜受体激酶TMK1由植物激素生长素诱导、固醇依赖性的纳米聚集对于子叶铺板细胞形态建成中质膜上极性域的形成至关重要。生长素诱导的TMK1纳米聚集会稳定脂筏标记蛋白flotillin1相关的有序纳米域，从而促进ROP6 GTPase的纳米聚集，而ROP6 GTPase作用于TMK1的下游，调控皮质微管的组织。反过来，皮质微观会进一步稳定质膜上包含TMK1和flotillin1的纳米簇。因此，作者提出了一个细胞极性形成的新模式，即一个扩散信号诱导的细胞极性，该信号促进了由细胞表面受体介导的信号组分的纳米聚集，而后细胞骨架所介导的正向反馈进一步将纳米域增强为极性域。