JASMONATE ZIM-DOMAIN (JAZ) transcriptional repressors are key regulators of jasmonate (JA) signaling in plants. At the resting stage, the C-terminal Jas motifs of JAZ proteins bind the transcription factor MYC2 to repress JA signaling. Upon hormone elicitation, the Jas motif binds the hormone receptor CORONATINE INSENSITIVE1, which mediates proteasomal degradation of JAZs and thereby allowing the Mediator subunit MED25 to activate MYC2. Subsequently, plants desensitize JA signaling by feedback generation of dominant JAZ splice variants that repress MYC2. Here we report the mechanistic function of Arabidopsis (Arabidopsis thaliana) MED25 in regulating the alternative splicing of JAZ genes through recruiting the splicing factors PRE-mRNA-PROCESSING PROTEIN 39a (PRP39a) and PRP40a. We demonstrate that JA-induced generation of JAZ splice variants depends on MED25 and that MED25 recruits PRP39a and PRP40a to promote the full splicing of JAZ genes. Therefore, MED25 forms a module with PRP39a and PRP40a to prevent excessive desensitization of JA signaling mediated by JAZ splice variants.

中文翻译：

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介体亚基 MED25 将 JAZ 基因的选择性剪接与茉莉酸信号传导的微调结合起来。

JASMONATE ZIM-DOMAIN (JAZ) 转录抑制因子是植物中茉莉酸 (JA) 信号传导的关键调节因子。在静止阶段，JAZ 蛋白的 C 端 Jas 基序结合转录因子 MYC2 以抑制 JA 信号传导。激素诱导后，Jas 基序与激素受体 CORONATINE INSENSITIVE1 结合，介导 JAZ 的蛋白酶体降解，从而允许介质亚基 MED25 激活 MYC2。随后，植物通过反馈产生抑制 MYC2 的显性 JAZ 剪接变体来使 JA 信号脱敏。在这里，我们报告了拟南芥（Arabidopsis thaliana）MED25通过招募剪接因子前mRNA加工蛋白39a（PRP39a）和PRP40a来调节JAZ基因的选择性剪接的机制功能。我们证明 JA 诱导的 JAZ 剪接变体的生成取决于 MED25，并且 MED25 招募 PRP39a 和 PRP40a 来促进 JAZ 基因的完全剪接。因此，MED25 与 PRP39a 和 PRP40a 形成模块，以防止 JAZ 剪接变体介导的 JA 信号过度脱敏。