Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
VIB Center for Plant Systems Biology, Ghent, Belgium.
EMBO Rep. 2023 Sep 6;24(9):e54709. doi: 10.15252/embr.202254709. Epub 2023 Jul 17.
Endocytosis regulates the turnover of cell surface localized receptors, which are crucial for plants to rapidly respond to stimuli. The evolutionary ancient TPLATE complex (TPC) plays an essential role in endocytosis in Arabidopsis plants. Knockout or knockdown of single TPC subunits causes male sterility and seedling lethality phenotypes, complicating analysis of the roles of TPC during plant development. Partially functional alleles of TPC subunits however only cause mild developmental deviations. Here, we took advantage of the partially functional TPLATE allele, WDXM2, to investigate a role for TPC-dependent endocytosis in receptor-mediated signaling. We discovered that reduced TPC-dependent endocytosis confers a hypersensitivity to very low doses of CLAVATA3 peptide signaling. This hypersensitivity correlated with the abundance of the CLAVATA3 receptor protein kinase CLAVATA1 at the plasma membrane. Genetic and biochemical analysis as well as live-cell imaging revealed that TPC-dependent regulation of CLAVATA3-dependent internalization of CLAVATA1 from the plasma membrane is required for shoot stem cell homeostasis. Our findings provide evidence that TPC-mediated endocytosis and degradation of CLAVATA1 is a mechanism to dampen CLAVATA3-mediated signaling during plant development.
内吞作用调节细胞表面定位受体的周转，这对于植物快速响应刺激至关重要。进化上古老的 TPLATE 复合物（TPC）在拟南芥植物的内吞作用中发挥着重要作用。单个 TPC 亚基的敲除或敲低会导致雄性不育和幼苗致死表型，这使得分析 TPC 在植物发育过程中的作用变得复杂。然而，TPC 亚基的部分功能等位基因仅导致轻微的发育偏差。在这里，我们利用部分功能的 TPLATE 等位基因 WDXM2，研究 TPC 依赖性内吞作用在受体介导的信号转导中的作用。我们发现，TPC 依赖性内吞作用的减少赋予了对极低剂量 CLAVATA3 肽信号的超敏性。这种超敏性与质膜上 CLAVATA3 受体蛋白激酶 CLAVATA1 的丰度相关。遗传和生化分析以及活细胞成像表明，TPC 依赖性调节 CLAVATA3 从质膜内化 CLAVATA1 对于茎干细胞稳态是必需的。我们的研究结果提供了证据表明，TPC 介导的 CLAVATA1 的内吞作用和降解是在植物发育过程中减弱 CLAVATA3 介导的信号的一种机制。
