Conservation of IRE1-Regulated bZIP74 mRNA Unconventional Splicing in Rice (Oryza sativa L.) Involved in ER Stress Responses
Conservation of IRE1-Regulated bZIP74 mRNA Unconventional Splicing in Rice (Oryza sativa L.) Involved in ER Stress Responses
复制标题
水稻 (Oryza sativa L.) 中 IRE1 调节的 bZIP74 mRNA 非常规剪接的保守性参与了 ER 应激反应。
DOI：
10.1093/mp/ssr115
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发表时间：
2012-03-01
期刊：
影响因子：
27.5
通讯作者：
Liu, Jian-Xiang
中科院分区：
文献类型：
--
作者：
Lu, Sun-Jie;Yang, Zheng-Ting;Liu, Jian-Xiang
内质网(ER)中的蛋白质折叠是植物细胞中的一个基本过程，容易受到许多环境胁迫的影响。当未折叠或错误折叠的蛋白质聚集在内质网时，保守的未折叠蛋白应答(UPR)被启动，通过增强蛋白质折叠能力和/或加速内质网相关蛋白的降解来缓解内质网应激。在这里，我们报道了单子叶植物水稻中重要的内质网逆境调节因子OsbZIP74(也称为OsbZIP50)的激活机制的保守性。在正常情况下，OsbZIP74mRNA编码一个碱性亮氨酸拉链转录因子，推测具有跨膜结构域。经衣霉素和DTT等内质网应激诱导剂处理后，OsbZIP74基因保守的双茎环结构被剪接掉。此后，产生的新的OsbZIP74 mRNA产生定位于核的OsbZIP74蛋白，消除疏水性区域。激活形式的OsbZIP74在酵母细胞和拟南芥叶片原生质体中都具有转录激活活性。在OsIRE1基因敲除的水稻植株中，OsbZIP74剪接的诱导受到抑制，这表明OsIRE1参与了OsbZIP74的剪接。我们还证明了OsbZIP74非常规剪接与热胁迫和水杨酸有关，水杨酸是一种重要的植物激素，在系统获得对病原菌或寄生虫的抗性。
Protein folding in the endoplasmic reticulum (ER) is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response (UPR) is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 (also known as OsbZIP50), an important ER stress regulator in monocot plant rice (Oryza sativa L.). Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock-down rice plants, indicating the involvement of OsIRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.