The E3 Ubiquitin Ligase SCFTIR1/AFB and Membrane Sterols Play Key Roles in Auxin Regulation of Endocytosis, Recycling, and Plasma Membrane Accumulation of the Auxin Efflux Transporter PIN2 in Arabidopsis thaliana
The E3 Ubiquitin Ligase SCFTIR1/AFB and Membrane Sterols Play Key Roles in Auxin Regulation of Endocytosis, Recycling, and Plasma Membrane Accumulation of the Auxin Efflux Transporter PIN2 in Arabidopsis thaliana
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DOI：
10.1105/tpc.108.061465
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发表时间：
2009-02-01
期刊：
影响因子：
11.6
通讯作者：
Chen, Rujin
中科院分区：
文献类型：
--
作者：
Pan, Jianwei;Fujioka, Shozo;Chen, Rujin
生长素外排转运蛋白PIN家族定位于极性质膜，在生长素梯度介导的发育过程中发挥重要作用。生长素抑制PIN 2内吞作用并促进其PM定位。然而，根本的机制仍然难以捉摸。在这里，我们发现生长素对PIN 2内吞的抑制作用在SCFTIR 1/AFB生长素信号转导突变体中受损。类似地，减少膜固醇损害了生长素对PIN 2内吞作用的抑制。气相色谱-质谱分析表明，膜甾醇显着减少SCFTIR 1/AFB突变体，支持膜甾醇和生长素信号之间的联系，调节PIN 2的内吞作用。我们表明，生长素促进PIN 2从内体到PM的再循环，并增加PM组分中的PIN 2稳态水平。此外，我们表明，生长素对PM中的PIN 2水平的积极作用通过抑制膜固醇或生长素信号传导而受损。与此一致，甾醇生物合成突变体fk-J79表现出明显的缺陷，在主根伸长和向重力反应。我们的数据共同表明，虽然有不同的过程参与特定的PM居民蛋白的内吞调节，SCFTIR 1/黄曲霉毒素B依赖的过程所需的生长素调节的内吞作用，回收，和PM积累的生长素外排转运蛋白PIN 2在拟南芥。
The PIN family of auxin efflux transporters exhibit polar plasma membrane (PM) localization and play a key role in auxin gradient-mediated developmental processes. Auxin inhibits PIN2 endocytosis and promotes its PM localization. However, the underlying mechanisms remain elusive. Here, we show that the inhibitory effect of auxin on PIN2 endocytosis was impaired in SCFTIR1/AFB auxin signaling mutants. Similarly, reducing membrane sterols impaired auxin inhibition of PIN2 endocytosis. Gas chromatography-mass spectrometry analyses indicate that membrane sterols were significantly reduced in SCFTIR1/AFB mutants, supporting a link between membrane sterols and auxin signaling in regulating PIN2 endocytosis. We show that auxin promoted PIN2 recycling from endosomes to the PM and increased PIN2 steady state levels in the PM fraction. Furthermore, we show that the positive effect of auxin on PIN2 levels in the PM was impaired by inhibiting membrane sterols or auxin signaling. Consistent with this, the sterol biosynthetic mutant fk-J79 exhibited pronounced defects in primary root elongation and gravitropic response. Our data collectively indicate that, although there are distinct processes involved in endocytic regulation of specific PM-resident proteins, the SCFTIR1/AFB-dependent processes are required for auxin regulation of endocytosis, recycling, and PM accumulation of the auxin efflux transporter PIN2 in Arabidopsis thaliana.