State Key Laboratory of Plant Cell and Chromosome Engineering, CAS Center for Excellence in Molecular Plant Sciences, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
PLoS Genet. 2018 Feb 5;14(2):e1007218. doi: 10.1371/journal.pgen.1007218. eCollection 2018 Feb.
Organ size control is of particular importance for developmental biology and agriculture, but the mechanisms underlying organ size regulation remain elusive in plants. Meristemoids, which possess stem cell-like properties, have been recognized to play important roles in leaf growth. We have recently reported that the Arabidopsis F-box protein STERILE APETALA (SAP)/SUPPRESSOR OF DA1 (SOD3) promotes meristemoid proliferation and regulates organ size by influencing the stability of the transcriptional regulators PEAPODs (PPDs). Here we demonstrate that KIX8 and KIX9, which function as adaptors for the corepressor TOPLESS and PPD, are novel substrates of SAP. SAP interacts with KIX8/9 and modulates their protein stability. Further results show that SAP acts in a common pathway with KIX8/9 and PPD to control organ growth by regulating meristemoid cell proliferation. Thus, these findings reveal a molecular mechanism by which SAP targets the KIX-PPD repressor complex for degradation to regulate meristemoid cell proliferation and organ size.
器官大小的控制对发育生物学和农业具有特别重要的意义，但植物器官大小调节的机制仍不清楚。具有干细胞特性的分生细胞在叶片生长中发挥着重要作用。我们最近报道称，拟南芥 F-box 蛋白 STERILE APETALA (SAP)/SUPPRESSOR OF DA1 (SOD3) 通过影响转录调节因子 PEAPODs (PPDs) 的稳定性，促进分生细胞增殖并调节器官大小。在这里，我们证明 KIX8 和 KIX9 作为核心抑制因子 TOPLESS 和 PPD 的衔接子，是 SAP 的新型底物。SAP 与 KIX8/9 相互作用并调节其蛋白质稳定性。进一步的结果表明，SAP 通过调节分生细胞的增殖，与 KIX8/9 和 PPD 共同作用于一个途径来控制器官生长。因此，这些发现揭示了 SAP 将 KIX-PPD 抑制复合物作为降解目标，以调节分生细胞增殖和器官大小的分子机制。
