Muñoz Alfonso, Mangano Silvina, González-García Mary Paz, Contreras Ramón, Sauer Michael, De Rybel Bert, Weijers Dolf, Sánchez-Serrano José Juan, Sanmartín Maite, Rojo Enrique
Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain.
Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands.
Plant Cell. 2017 Mar;29(3):575-588. doi: 10.1105/tpc.16.00791. Epub 2017 Feb 21.
The transcriptional regulator MINIYO (IYO) is essential and rate-limiting for initiating cell differentiation in Moreover, IYO moves from the cytosol into the nucleus in cells at the meristem periphery, possibly triggering their differentiation. However, the genetic mechanisms controlling IYO nuclear accumulation were unknown, and the evidence that increased nuclear IYO levels trigger differentiation remained correlative. Searching for IYO interactors, we identified RPAP2 IYO Mate (RIMA), a homolog of yeast and human proteins linked to nuclear import of selective cargo. Knockdown of causes delayed onset of cell differentiation, phenocopying the effects of knockdown at the transcriptomic and developmental levels. Moreover, differentiation is completely blocked when and activities are simultaneously reduced and is synergistically accelerated when and are concurrently overexpressed, confirming their functional interaction. Indeed, knockdown reduces the nuclear levels of IYO and prevents its prodifferentiation activity, supporting the conclusion that RIMA-dependent nuclear IYO accumulation triggers cell differentiation in Arabidopsis. Importantly, by analyzing the effect of the IYO/RIMA pathway on xylem pole pericycle cells, we provide compelling evidence reinforcing the view that the capacity for de novo organogenesis and regeneration from mature plant tissues can reside in stem cell reservoirs.
转录调节因子MINIYO（IYO）对于启动细胞分化至关重要且具有限速作用。此外，IYO在分生组织外围的细胞中从细胞质转移到细胞核，这可能触发它们的分化。然而，控制IYO核积累的遗传机制尚不清楚，并且核IYO水平升高触发分化的证据仍然只是相关性的。在寻找IYO相互作用蛋白时，我们鉴定出了RPAP2 IYO伴侣（RIMA），它是一种与选择性货物的核输入相关的酵母和人类蛋白质的同源物。敲低RIMA会导致细胞分化延迟开始，在转录组和发育水平上模拟敲低IYO的效果。此外，当RIMA和IYO的活性同时降低时，分化会完全受阻，而当RIMA和IYO同时过表达时，分化会协同加速，证实了它们的功能相互作用。实际上，敲低RIMA会降低IYO的核水平并阻止其促分化活性，支持了RIMA依赖性核IYO积累触发拟南芥细胞分化的结论。重要的是，通过分析IYO/RIMA途径对木质部极周细胞的影响，我们提供了令人信服的证据，强化了成熟植物组织从头进行器官发生和再生的能力可能存在于干细胞库中的观点。
