Characteristics of the Nuclear Form of the Arabidopsis Transcription Factor AtbZIP60 during the Endoplasmic Reticulum Stress Response
Characteristics of the Nuclear Form of the Arabidopsis Transcription Factor AtbZIP60 during the Endoplasmic Reticulum Stress Response
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DOI：
10.1271/bbb.80779
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发表时间：
2009-04-01
影响因子：
1.6
通讯作者：
Koizumi, Nozomu
中科院分区：
文献类型：
--
作者：
Iwata, Yuji;Yoneda, Mari;Koizumi, Nozomu
真核细胞内质网（E-R）中未折叠蛋白的积累触发ER驻留分子伴侣的转录诱导以维持细胞内稳态，称为ER应激反应。以前，我们分离的AtbZIP 60，膜结合的转录因子参与拟南芥ER应激反应，其活性是由蛋白水解裂解控制。在这项研究中，我们的特点是积极的形式AtbZIP 60定位在细胞核中的ER应激反应。利用拟南芥原生质体的瞬时检测表明AtbZIP 60对BiP启动子的激活依赖于顺式元件植物未折叠蛋白应答元件（P-UPRE）和内质网应激应答元件（ERSE）。AtbZIP 60的转录激活活性主要位于AtbZIP 60的41-80位氨基酸区域。大小排阻色谱分析表明AtbZIP 60的核形式作为约260 kDa的蛋白复合物存在。在本研究的基础上，结合文献中描述的观察，讨论了AthZIP 60在细胞核中作用的可能机制。
Accumulation of unfolded proteins in the endoplasmic reticulum (E-R) of eukaryotic cells triggers the transcriptional induction of ER-resident molecular chaperones to maintain cellular homeostasis, termed the ER stress response. Previously we isolated AtbZIP60, a membrane-bound transcription factor involved in the Arabidopsis ER stress response whose activity is controlled by proteolytic cleavage. In this study we characterized the active form of AtbZIP60 localized in the nucleus during the ER stress response. Transient assay using Arabidopsis protoplasts revealed that activation of BiP promoters by AtbZIP60 is dependent on the cis-elements plant-unfolded protein response element (P-UPRE) and ER stress response element (ERSE). Transcriptional activation activity of AtbZIP60 was mainly located in the region for amino acids 41-80 of AtbZIP60. Size exclusion chromatography analysis showed that the nuclear form of AtbZIP60 exists as a protein complex of approximately 260kDa. On the basis of the present study combined with observations described in the literature, possible mechanisms of AthZIP60's action in the nucleus are discussed.