Hormone perception and signaling pathways have a fundamental regulatory function in the physiological processes of plants. Cytokinins, a class of plant hormones, regulate cell division and meristem maintenance. The cytokinin signaling pathway is well established in the model plant Arabidopsisthaliana. Several negative feedback mechanisms, tightly controlling cytokinin signaling output, have been described previously. In this study, we identified a new feedback mechanism executed through alternative splicing of the cytokinin receptor AHK4/CRE1. A novel splicing variant named CRE1int7 results from seventh intron retention, introducing a premature termination codon in the transcript. We showed that CRE1int7 is translated in planta into a truncated receptor lacking the C-terminal receiver domain essential for signal transduction. CRE1int7 can bind cytokinin but cannot activate the downstream cascade. We present a novel negative feedback mechanism of the cytokinin signaling pathway, facilitated by a decoy receptor that can inactivate canonical cytokinin receptors via dimerization and compete with them for ligand binding. Ensuring proper plant growth and development requires precise control of the cytokinin signaling pathway at several levels. CRE1int7 represents a so-far unknown mechanism for fine-tuning the cytokinin signaling pathway in Arabidopsis.

中文翻译：

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来自选择性剪接的诱饵受体可微调拟南芥中的细胞分裂素信号传导


激素感知和信号通路在植物的生理过程中具有基本的调节功能。细胞分裂素是一类植物激素，可调节细胞分裂和分生组织维持。细胞分裂素信号通路在模式植物拟南芥中已建立。前面已经描述了几种严格控制细胞分裂素信号输出的负反馈机制。在这项研究中，我们确定了一种新的反馈机制，通过细胞分裂素受体 AHK4/CRE1 的选择性剪接来执行。一种名为 CRE1int7 的新型剪接变体来自第七个内含子保留，在转录本中引入了一个过早终止密码子。我们发现 CRE1int7 在植物中被翻译成截短受体，缺乏信号转导所必需的 C 端接收器结构域。CRE1int7 可以结合细胞分裂素，但不能激活下游级联反应。我们提出了一种新的细胞分裂素信号通路的负反馈机制，由诱饵受体促进，该诱饵受体可以通过二聚化灭活经典细胞分裂素受体并与它们竞争配体结合。确保植物的正常生长和发育需要在多个水平上精确控制细胞分裂素信号通路。CRE1int7 代表了迄今为止未知的微调拟南芥中细胞分裂素信号通路的机制。