博文
Development：组蛋白变体H3.15促进拟南芥愈伤形成
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The atypical histone variant H3.15 promotes callus formation in Arabidopsis thaliana
第一作者：An Yan
第一单位：新加坡南洋理工大学
通讯作者：Zhong Chen
Abstract
背景回顾：Plants are capable of regenerating new organs after mechanical injury.
研究基础：The regeneration process involves genome-wide reprogramming of transcription, which usually requires dynamic changes in the chromatin landscape.
主要发现：We show that the histone 3 variant, HISTONE THREE RELATED 15 (H3.15), plays an important role in cell fate reprogramming during plant regeneration in Arabidopsis.
试验结果：H3.15 expression is rapidly induced upon wounding. Ectopic overexpression of H3.15 promotes cell proliferation to form a larger callus at the wound site, while htr15 mutation compromises callus formation. H3.15 is distinguished from other Arabidopsis histones by the absence of the lysine residue 27 that is trimethylated by the POLYCOMB REPRESSIVE COMPLEX 2 (PRC2) in constitutively expressed H3 variants. Overexpression of H3.15 promotes the removal of the transcriptional repressive mark H3K27me3 from chromatin, which results in transcriptional derepression of downstream genes such as WUSCHEL RELATED HOMEOBOX11 (WOX11).
结论：Our results reveal a new mechanism for a release from PRC2-mediated gene repression through H3.15 deposition into chromatin, which is involved in reprogramming cell fate to produce pluripotent callus cells.
摘 要
植物在受到机械损伤后，能够再生新的器官。植物的再生过程涉及到了全基因组范围的转重编程，而这通常需要染色质全景的动态变化。本文中，作者发现拟南芥组蛋白3的变体H3.15在植物再生过程中的细胞命运重编程方面发挥了重要作用。在植物受到损伤后，H3.15的表达被快速诱导。异位过表达H3.15能够促进细胞增殖，在创伤口形成大块的愈伤，而htr15突变体则在愈伤形成方面有所欠缺。H3.15区别于拟南芥中其它组蛋白的特征是其缺失了一个27号位赖氨酸残基，而在组成型表达的H3变体上对应的位点会被PRC2所三甲基化。过表达H3.15能够促进染色质上转录抑制标记H3K27me3的移除，从而解除WOX11等下游基因的转录抑制。本文的结果揭示了一个新的分子机制，该机制通过染色质上H3.15的沉积，解除PRC2介导的基因抑制，从而参与细胞命运的重编程，最终产生具有全能性的愈伤细胞。
Proposed model of the role of the H3.15 pathway in plant regeneration.
doi: 10.1242/dev.184895
Journal: Development
First Published: May 21, 2020
p.s. 往期相关研究：
https://blog.sciencenet.cn/blog-3158122-1236038.html
上一篇：PNAS：拟南芥DELLA蛋白的非经典降解途径
下一篇：Nature Communications：山羊草胚胎发生早期根组织程序性消除B套染色体
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