n nnnEndoreduplication involves a doubling of chromosomal DNA withoutcorresponding cell division. In plants, many cell types transitfrom the mitotic cycle to the endoreduplication cycle or endocycle,and this transition is often coupled with the initiation ofcell expansion and differentiation. Although a number of cellcycle regulators implicated in endocycle onset have been identified,it is still largely unknown how this transition is developmentallyregulated at the whole organ level. Here, we report that a nuclear-localizedSUMO E3 ligase, HIGH PLOIDY2 (HPY2), functions as a repressorof endocycle onset in Arabidopsis thaliana meristems. Loss ofHPY2 results in a premature transition from the mitotic cycleto the endocycle, leading to severe dwarfism with defectivemeristems. HPY2 possesses an SP-RING domain characteristic ofMMS21-type SUMO E3 ligases, and we show that the conserved residueswithin this domain are required for the in vivo and in vitrofunction of HPY2. HPY2 is predominantly expressed in proliferatingcells of root meristems and it functions downstream of meristempatterning transcription factors PLETHORA1 (PLT1) and PLT2.These results establish that HPY2-mediated sumoylation modulatesthe cell cycle progression and meristem development in the PLT-dependentsignaling pathway.展开▼
机译：ABSTRACTn n
n TOP n <字体颜色= 464c53>抽象 n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n n nnn内源重复涉及无 cor的染色体DNA的加倍反应细胞分裂。在植物中，许多细胞类型 从有丝分裂周期过渡到核内复制周期或内周期， ，并且这种转变通常与 细胞的启动有关扩张和分化。尽管已经鉴定出许多与内循环发作有关的细胞 周期调节因子，但 仍然很大程度上未知这种过渡如何整体上受发育调控。器官水平。在这里，我们报道了一个核定位的 SUMO E3连接酶，HIGH PLOIDY2（HPY2），在拟南芥中起内源性阻遏物 的作用。分生组织。 HPY2的丢失导致从有丝分裂周期 到内周期的过早过渡，导致严重的侏儒症和缺陷的 分生组织。 HPY2具有 MMS21型SUMO E3连接酶的SP-RING结构域，我们证明该结构域内的保守残基对于体内和体外都是必需的。 HPY2的SUP> 功能。 HPY2主要在增殖的根分生组织的 细胞中表达，并在分生组织 下游的模式转录因子PLETHORA1（PLT1）和PLT2中起作用。 HPY2介导的SUMO化作用在依赖PLT的 信号通路中调节 细胞周期进程和分生组织发育。展开▼
RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan;
RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan;
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan;
Department of Cell and Developmental Biology, John Innes Centre, Norwich, NR4 7UH, United Kingdom;
RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan;
RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan;
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, 630-0101, Japan;
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, 630-0101, Japan;
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, 630-0101, Japan;
RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan|Department of Cell and Developmental Biology, John Innes Centre, Norwich, NR4 7UH, United Kingdom;
