2020年5月5日, 美國密西根大學的John Schiefelbein 在Plant Cell 在線發表了題為Molecular Basis for a Cell Fate Switch in Response to Impaired Ribosome Biogenesis in the Arabidopsis Root Epidermis 的研究論文。文章研究揭示了核糖體生物發生缺陷和逆境條件觸發的轉錄調控途徑,會導致根表皮細胞命運轉換的分子基礎。
與此文章同時上線的還有一篇IN BRIEF 文章:Twist of fate - ribosomal stress reprograms root hair pattering. 該文章就核糖體逆境對根毛細胞命運的重編程作了相關的討論。
擬南芥根表皮由根毛細胞和非根毛細胞組成,且具有位置依賴性的模式。這種細胞模式的基礎是一個轉錄因子網絡,這個網絡的中心複合物是MYB-bHLH-WD40,其包含的組分有WER (WEREWOLF), GL3/EGL3 (GLABRA 3/ENHANCER OF GLABRA 3)和 TTG1 (TRANSPARENT TESTA GLABRA 1)。
本研究使用遺傳增強子篩選鑑定到了核糖體生物發生因子(RBF)基因PUMILIO 23 (APUM23)的突變體apum23-4,該突變體導致潛在的根毛細胞轉換為非根毛細胞的命運。研究發現,這種細胞命運的轉換依賴於MYB23。MYB23是一種MYB蛋白,由WER靶基因編碼,並且與WER存在功能冗餘。在apum23-4突變體中,MYB23表現出不依賴於WER的異位表達,而是需要ANAC082,ANAC082是近來發現的核糖體應激響應的介質。作者還檢查了其他的產生異位非根毛細胞的RBF突變體,並確定這種細胞命運轉換通常與核糖體生物發生缺陷有關。此外,鞭毛肽flg22還觸發了ANAC082-MYB23-GL2途徑。
綜上所述,核糖體缺陷的根表皮細胞命運會發生轉換,本研究為此提供了分子解釋。更廣泛地說,本研究闡明了逆境條件和植物細胞命運控制之間的一種新的調控聯繫。
野生型植物和核糖體缺陷植物根表皮細胞命運調控的工作模式
附:
ABSTRACT
The Arabidopsis (Arabidopsis thaliana) root epidermis consists of a position-dependent pattern of root-hair cells and non-hair cells. Underlying this cell-type patterning is a network of transcription factors including a central MYB-bHLH-WD40 complex containing WEREWOLF (WER), GLABRA 3/ENHANCER OF GLABRA 3 (GL3/EGL3), and TRANSPARENT TESTA GLABRA 1 (TTG1). In this study, we used a genetic enhancer screen to identify apum23-4, a mutant allele of the ribosome biogenesis factor (RBF) gene PUMILIO 23 (APUM23), which caused prospective root-hair cells to instead adopt the non-hair cell fate. We discovered that this cell fate switch relied on MYB23, a MYB protein encoded by a WER target gene and acting redundantly with WER. In the apum23-4 mutant, MYB23 exhibited ectopic expression that was WER-independent and instead required ANAC082, a recently identified ribosomal stress response mediator. We examined additional RBF mutants that produced ectopic non-hair cells and determined that this cell fate switch is generally linked to defects in ribosome biogenesis. Further, the flagellin peptide flg22 triggers the ANAC082-MYB23-GL2 pathway. Taken together, our study provides a molecular explanation for root epidermal cell fate switch in response to ribosomal defects and, more generally, it demonstrates a novel regulatory connection between stress conditions and cell fate control in plants.
文章連結:http://www.plantcell.org/content/early/2020/05/05/tpc.19.00773
IN BRIEF 文章連結:http://www.plantcell.org/content/early/2020/05/05/tpc.20.00313
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