热激转录因子HSFA1d参与植物内质网胁迫应答

Heat Shock Transcription Factor HSFA1d is Involved in ER Stress Response in Arabidopsis

环境胁迫是全球范围内影响植物正常生长发育的重要因素之一.研究植物的抗逆机制,运用生物技术提高作物的抗逆性,不仅具有重要的科学意义,也对农业生产具有重要的促进作用.内质网是蛋白合成和加工的重要场所,当环境胁迫引起内质网中错误折叠蛋白积累时,就会引起一个保守的未折叠蛋白应答(UPR)机制,帮助细胞达到一个新的平衡状态.热激转录因子HSFA1s在植物细胞质热激反应过程中起着重要的作用.本研究证明,拟南芥HSFA1d的表达受内质网胁迫的诱导,过表达HSFA1d的转基因植株对内质网胁迫诱导剂衣霉素(TM)具有一定程度的抗性.统计显示,在TM板上生长的转基因植株出真叶率明显提高.亚细胞定位显示,HSFA1d在正常条件下定位于细胞质中,当受到内质网胁迫时,HSFA1d从细胞质转移到细胞核中.HSFA1d可以调控UPR下游基因的表达.这些结果表明,经典的热激反应相关热激转录因子HSFA1d也参与了植物的内质网未折叠蛋白应答过程.

Environmental stresses induce the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum（ER）, which elicits a well-conserved response known as the unfolded protein response（UPR） in plants. Heat shock transcription factors known as HSFA1s play important roles in the heat shock response when misfolded proteins accumulate in the cytosol, but their roles in the UPR have not been reported. In the current study, Arabidopsis HSFA1d was found to be up-regulated by ER stress during the UPR, and over-expression of HSFA1d up-regulated UPR downstream genes and increased plant tolerance to the ER stress inducer tunicamycin. The cytosol-nucleus re-localization of HSFA1d was also induced by ER stress. These results demonstrate that the heat shock transcription factor HSFA1d regulates not only the heat shock response but also the UPR in Arabidopsis plants.