CPK28-NLP7 module integrates cold-induced Ca2+ signal and transcriptional reprogramming in Arabidopsis

背景回顾：Exposure to cold triggers a spike in cytosolic calcium (Ca2+) that often leads to transcriptional reprogramming in plants. 

提出问题：However, how this Ca2+ signal is perceived and relayed to the downstream cold signaling pathway remains unknown. 

主要发现：Here, we show that the CALCIUM-DEPENDENT PROTEIN KINASE 28 (CPK28) initiates a phosphorylation cascade to specify transcriptional reprogramming downstream of cold-induced Ca2+ signal. 

结果1-CPK28受低温诱导激活：Plasma membrane (PM)–localized CPK28 is activated rapidly upon cold shock within 10 seconds in a Ca2+-dependent manner.  

结果2-CPK28-NLP7-低温响应：CPK28 then phosphorylates and promotes the nuclear translocation of NIN-LIKE PROTEIN 7 (NLP7), a transcription factor that specifies the transcriptional reprogramming of cold-responsive gene sets in response to Ca2+, thereby positively regulating plant response to cold stress. 

结论：This study elucidates a previously unidentified mechanism by which the CPK28-NLP7 regulatory module integrates cold-evoked Ca2+ signal and transcriptome and thus uncovers a key strategy for the rapid perception and transduction of cold signals from the PM to the nucleus.

 摘 要 

暴露在低温下会诱导胞质钙离子出现峰值，这通常会导致植物中的转录重编程。然而，目前仍不清楚这种钙离子信号是如何被植物感知的，以及如何传递至下游低温信号转导途径。本文中，作者发现表明钙依赖蛋白激酶CPK28能够启始一个磷酸化级联，从而作用于低温诱导的钙离子信号下游的特定转录重编程。定位于质膜的CPK28蛋白在低温应激后的10秒内，就会以钙依赖性的方式迅速被激活。接着，CPK28会磷酸化NLP7蛋白，并促进该蛋白的核易位，而NLP7是一种转录因子，响应于钙离子信号作用于特定低温响应基因集的转录重编程，最终正调控植物对低温胁迫的响应。本文的研究阐明了一种先前未知的机制，即CPK28-NLP7调控模块整合受低温诱导的钙离子信号和转录组，从而揭示了植物感知低温信号后，将其从质膜到细胞核快速信号传递策略。

 杨淑华