Studies of gene expression regulated by membrane bound transcription factors in plants

2014 Fiscal Year Final Research Report

• Project/Area Number: 23380206
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied molecular and cellular biology
• Research Institution: Osaka Prefecture University
• Principal Investigator: KOIZUMI Nozomu 大阪府立大学, 生命環境科学研究科(系), 教授 (20252835)
• Co-Investigator(Renkei-kenkyūsha): SHIMADA Yukihisa 横浜市立大学, 木原生物学研究所, 教授 (30300875)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: 小胞体ストレス / 転写因子 / シロイヌナズナ / 細胞質スプライシング

Outline of Final Research Achievements

We tried to clarify the activation mechanism of two membrane-bound transcription factors of Arabidopsis, bZIP60 and bZIP28; both of them are involved in the ER stress response. We also tried to identify the substrate of cytoplasmic splicing catalyzed by IRE1, a sensor molecule of the ER stress response. Transcriptomes analysis using microarray and, IRE1 and bZIP60 knockouts indicated that bZIP60 locates in downstream of IRE1 signaling. Taken together additional biochemical experiments, we concluded that newly synthesized bZIP60 protein loses its transmembrane domain due to the frame shift caused by cytoplasmic splicing and then translocates to the nucleus where it activates the expression of the ER stress related genes. This finding answered two of our questions, activation mechanism of bZIP60 and target of IRE1. Another membrane bound transcription factor bZIP28 was found not to be regulated by a protease S1P, even though it has been considered to regulate the activation of bZIP28.

Free Research Field

植物細胞分子生物学