Regulation of small heat shock protein genes expression by heat shock factors transcriptome in Arabidopsis
Date Issued
2006
Date
2006
Author(s)
Lee, Tsung-Yuan
DOI
en-US
Abstract
Heat shock (HS) response is a general physiological reaction to both prokaryotic and eukaryotic cells when temperature is suddenly elevated. The heat shock proteins (HSPs) induced by HS act as molecular chaperones to protect cells from HS damages. In plants, small HSPs (sHSP) represent the most abundant and complexes HSPs. And heat shock factors (HSFs) are known to involve in the regulatory mechanism of sHSP expression under HS stress. In Arabidopsis and rice, there are 21 and 25 HSFs, which are divided into three classes, respectively. That may implicate a complicated regulation mechanism (regulome) in higher plants. Other than heat shock, the regulation of sHSPs expression is still not clear. In this study, we studied the relationship between the sHSPs and HSFs expression under various stresses and to speculate the function of individual HSF. To investigate the details of the sHSPs regulome, we set up a negative selection system to screen mutants that can not respond to the HS-like induction. RT-PCR was used to analyze the HSF transcriptome to clarify the regulation of sHSP genes expression. We determined that all of sHSP genes were induced when seedlings were challenged with HS, amino acid analog (azetidine, Aze) and arsenite. Some of sHSPs, in response to cadmium and sodium nitroprusside (SNP, a NO donor), did not affect the expression of sHSPs. However, expression of some HSFs was not interfered by treatments. HsfA2a and three class B HSFs were induced by HS, Aze, and heavy metals treatments. The expression of HsfA7b was hyper inducted under HS than by other chemical inducers. One HsfA6a T-DNA knock-out line was identified. Thermoacquisition and HS-induction sHSP genes expression were not interrupted in the hsfA6a-KO line. Using the Motifsampler program to analyze three azetidine up-regulation sHSP-CI genes promoter, a non HSE with the conserved element, “GCGTTCA”, was identified. In promoter::GUS assay, confirmation of this element may play an important role in the HS response. In this study, we set up the expression profile of sHSPs and HSFs under HS and chemical inducers. But the individual HSF knock-out lines and other mutants are necessary to used to clarify the regulation of sHSPs expression by HSFs.
Subjects
低分子量熱休克蛋白質
熱休克因子
阿拉伯芥
重金屬
胺基酸類似物
基因表現
small heat shock protein
heat shock factor
Arabidopsis
heavy metals
amino acid analogues
gene expression
Type
other
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