Xu Faqing, Yu Yongqiang, Guan Bin, Xu Tongda, Xu Zhihong, Xue Hongwei
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Horticulture and Metabolic Biology Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
Cell Rep. 2025 Aug 26;44(8):116056. doi: 10.1016/j.celrep.2025.116056. Epub 2025 Jul 24.
Auxin regulates various aspects of plant growth and development by modulating the transcription of target genes through the degradation of auxin/indole-3-acetic acid (Aux/IAA) repressors via the 26S proteasome. Proteasome regulator 1 (PTRE1), a positive regulator of proteasome activity, has been implicated in auxin-mediated proteasome suppression; however, the mechanism by which auxin modulates PTRE1 function remains unclear. Here, we demonstrate that auxin promotes the interaction between germin-like protein 1 (GLP1) and PTRE1, facilitating PTRE1 retention at the plasma membrane. The relocation of PTRE1 results in reduced nuclear 26S proteasome activity, and thus the attenuated Aux/IAA degradation and altered Aux/IAA homeostasis, ultimately resulting in suppressed auxin-mediated transcriptional regulation. Our findings uncover a previously uncharacterized regulatory axis in auxin signaling that controls Aux/IAA protein stability, functioning alongside the TIR1- and TRANSMEMBRANE KINASE 1 (TMK1)-mediated pathways, and highlight the coordination of auxin signaling from the cell surface to the nucleus via auxin-induced PTRE1 relocation, which fine-tunes Aux/IAA protein homeostasis and auxin responses.
生长素通过26S蛋白酶体降解生长素/吲哚-3-乙酸（Aux/IAA）阻遏物来调节靶基因的转录，从而调控植物生长发育的各个方面。蛋白酶体调节因子1（PTRE1）作为蛋白酶体活性的正调控因子，参与了生长素介导的蛋白酶体抑制作用；然而，生长素调节PTRE1功能的机制仍不清楚。在此，我们证明生长素促进萌发素样蛋白1（GLP1）与PTRE1之间的相互作用，促使PTRE1保留在质膜上。PTRE1的重新定位导致细胞核内26S蛋白酶体活性降低，进而使Aux/IAA降解减弱，Aux/IAA稳态改变，最终导致生长素介导的转录调控受到抑制。我们的研究结果揭示了生长素信号传导中一个以前未被表征的调控轴，该调控轴控制Aux/IAA蛋白稳定性，与TIR1和跨膜激酶1（TMK1）介导的途径协同发挥作用，并强调了通过生长素诱导的PTRE1重新定位实现从细胞表面到细胞核的生长素信号传导协调，从而微调Aux/IAA蛋白稳态和生长素反应。
