The Arabidopsis SWI2/SNF2 chromatin Remodeler BRAHMA regulates polycomb function during vegetative development and directly activates the flowering repressor gene SVP.
The Arabidopsis SWI2/SNF2 chromatin Remodeler BRAHMA regulates polycomb function during vegetative development and directly activates the flowering repressor gene SVP.
复制标题
DOI：
10.1371/journal.pgen.1004944
复制
发表时间：
2015-01
期刊：
影响因子：
4.5
通讯作者：
Cui Y
中科院分区：
文献类型：
--
作者：
Li C;Chen C;Gao L;Yang S;Nguyen V;Shi X;Siminovitch K;Kohalmi SE;Huang S;Wu K;Chen X;Cui Y
染色质重构体Brahma(BRM)是一种在苍蝇和哺乳动物中拮抗Polycomb Group(PcG)蛋白功能的三胸基团(TrxG)蛋白。最近的研究也暗示了拟南芥BRM的这种作用，但这种拮抗作用的分子机制尚不清楚。为了了解BRM和PcG在植物发育过程中的相互作用，我们利用染色质免疫沉淀和下一代测序(CHIP-SEQ)对BRM突变幼苗中的三甲基化组蛋白H3赖氨酸27(H3K27me3)进行了全基因组分析。在BRM突变体中观察到数百个基因的H3K27me3沉积增加，这种增加可以通过去除H3K27甲基转移酶卷叶(CLF)或摆动(SWN)而部分抑制。芯片实验表明，BRM直接与基因的一个子集结合，并阻止这些基因座上PcG蛋白的不适当关联和/或活性。综上所述，这些结果表明BRM在植物发育过程中限制PcG的不适当活性方面发挥了至关重要的作用。关键的开花抑制基因短营养阶段(SVP)就是这样一个BRM靶标。在BRM突变体中，SVP的PcG占有率升高伴随着该基因座H3K27me3水平的急剧增加和SVP表达的降低。此外，我们的功能获得和功能丧失的遗传证据证实，BRM通过直接激活SVP表达来控制开花时间。这项工作揭示了BRM和PcG之间的全基因组功能相互作用，并为这些蛋白质在植物生长和发育中的影响提供了新的见解。在开花植物中，从营养生长到开花的适当过渡对它们的繁殖成功至关重要，必须加以精确控制。多个基因已被证明对环境和内源线索的反应调节花的过渡。其中包括短营养阶段(SVP)，它是拟南芥中的一个关键的开花抑制基因。SVP在营养生长期高表达以促进生长，但SVP维持高表达的机制尚不清楚。在这里，我们报告了一项全基因组研究，以检查BRM染色质重构体和PcG蛋白之间的功能相互作用，PcG蛋白催化组蛋白H3(H3K27me3)上赖氨酸27的三甲基化，组蛋白标记通常与转录抑制基因相关。我们认为BRM是SVP的直接上游激活剂。BRM通过抑制PcG蛋白的结合和活性来保持SVP基因上H3K27me3的低水平。因此，我们的工作确定了一个以前未知的开花时间调控机制，并展示了全基因组方法在解剖控制植物发育的调控网络方面的力量。
The chromatin remodeler BRAHMA (BRM) is a Trithorax Group (TrxG) protein that antagonizes the functions of Polycomb Group (PcG) proteins in fly and mammals. Recent studies also implicate such a role for Arabidopsis (Arabidopsis thaliana) BRM but the molecular mechanisms underlying the antagonism are unclear. To understand the interplay between BRM and PcG during plant development, we performed a genome-wide analysis of trimethylated histone H3 lysine 27 (H3K27me3) in brm mutant seedlings by chromatin immunoprecipitation followed by next generation sequencing (ChIP-seq). Increased H3K27me3 deposition at several hundred genes was observed in brm mutants and this increase was partially supressed by removal of the H3K27 methyltransferase CURLY LEAF (CLF) or SWINGER (SWN). ChIP experiments demonstrated that BRM directly binds to a subset of the genes and prevents the inappropriate association and/or activity of PcG proteins at these loci. Together, these results indicate a crucial role of BRM in restricting the inappropriate activity of PcG during plant development. The key flowering repressor gene SHORT VEGETATIVE PHASE (SVP) is such a BRM target. In brm mutants, elevated PcG occupancy at SVP accompanies a dramatic increase in H3K27me3 levels at this locus and a concomitant reduction of SVP expression. Further, our gain- and loss-of-function genetic evidence establishes that BRM controls flowering time by directly activating SVP expression. This work reveals a genome-wide functional interplay between BRM and PcG and provides new insights into the impacts of these proteins in plant growth and development. In flowering plants, the proper transition from vegetative growth to flowering is critical for their reproductive success and must be controlled precisely. Multiple genes have been shown to regulate the floral transition in response to environmental and endogenous cues. Among them is SHORT VEGETATIVE PHASE (SVP), a key flowering repressor gene in Arabidopsis. SVP is highly expressed during the vegetative phase to promote growth, but the mechanism by which the high expression level of SVP is maintained remains unknown. Here, we report a genome-wide study to examine the functional interplay between the BRM chromatin remodeler and the PcG proteins that catalyze trimethylation of lysine 27 on histone H3 (H3K27me3), a histone mark normally associated with transcriptionally repressed genes. We identify BRM as a direct upstream activator of SVP. BRM acts to keep the levels of H3K27me3 low at the SVP locus by inhibiting the binding and activities of the PcG proteins. Thus, our work identifies a previously unknown mechanism in regulation of flowering time and demonstrates the power of genome-wide approaches in dissecting regulatory networks controlling plant development.
登录
查看更多内容
影响因子：
4.5
作者：
Bouyer D;Roudier F;Heese M;Andersen ED;Gey D;Nowack MK;Goodrich J;Renou JP;Grini PE;Colot V;Schnittger A
通讯作者：
Schnittger A
影响因子：
4.6
作者：
Chanvivattana, Y;Bishopp, A;Goodrich, J
通讯作者：
Goodrich, J
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF
影响因子：
11.6
作者：
Han, Soon-Ki;Sang, Yi;Wagner, Doris
通讯作者：
Wagner, Doris
影响因子：
9.2
作者：
Alvarez-Venegas, R;Pien, S;Avramova, Z
通讯作者：
Avramova, Z