Swindell William R, Huebner Marianne, Weber Andreas P
Department of Statistics and Probability, Michigan State University, East Lansing, MI 48824, USA.
BMC Genomics. 2007 May 22;8:125. doi: 10.1186/1471-2164-8-125.
The heat shock response of Arabidopsis thaliana is dependent upon a complex regulatory network involving twenty-one known transcription factors and four heat shock protein families. It is known that heat shock proteins (Hsps) and transcription factors (Hsfs) are involved in cellular response to various forms of stress besides heat. However, the role of Hsps and Hsfs under cold and non-thermal stress conditions is not well understood, and it is unclear which types of stress interact least and most strongly with Hsp and Hsf response pathways. To address this issue, we have analyzed transcriptional response profiles of Arabidopsis Hsfs and Hsps to a range of abiotic and biotic stress treatments (heat, cold, osmotic stress, salt, drought, genotoxic stress, ultraviolet light, oxidative stress, wounding, and pathogen infection) in both above and below-ground plant tissues.
All stress treatments interact with Hsf and Hsp response pathways to varying extents, suggesting considerable cross-talk between heat and non-heat stress regulatory networks. In general, Hsf and Hsp expression was strongly induced by heat, cold, salt, and osmotic stress, while other types of stress exhibited family or tissue-specific response patterns. With respect to the Hsp20 protein family, for instance, large expression responses occurred under all types of stress, with striking similarity among expression response profiles. Several genes belonging to the Hsp20, Hsp70 and Hsp100 families were specifically upregulated twelve hours after wounding in root tissue, and exhibited a parallel expression response pattern during recovery from heat stress. Among all Hsf and Hsp families, large expression responses occurred under ultraviolet-B light stress in aerial tissue (shoots) but not subterranean tissue (roots).
Our findings show that Hsf and Hsp family member genes represent an interaction point between multiple stress response pathways, and therefore warrant functional analysis under conditions apart from heat shock treatment. In addition, our analysis revealed several family and tissue-specific heat shock gene expression patterns that have not been previously described. These results have implications regarding the molecular basis of cross-tolerance in plant species, and raise new questions to be pursued in future experimental studies of the Arabidopsis heat shock response network.
拟南芥的热激反应依赖于一个复杂的调控网络，该网络涉及21个已知的转录因子和4个热激蛋白家族。已知热激蛋白（Hsps）和转录因子（Hsfs）除了参与细胞对热的反应外，还参与细胞对各种形式胁迫的反应。然而，Hsps和Hsfs在低温和非热胁迫条件下的作用尚未得到充分了解，并且不清楚哪些类型的胁迫与Hsp和Hsf反应途径的相互作用最弱和最强。为了解决这个问题，我们分析了拟南芥Hsfs和Hsps在地上和地下植物组织中对一系列非生物和生物胁迫处理（热、冷、渗透胁迫、盐、干旱、遗传毒性胁迫、紫外线、氧化胁迫、创伤和病原体感染）的转录反应谱。
所有胁迫处理都与Hsf和Hsp反应途径在不同程度上相互作用，这表明热胁迫和非热胁迫调控网络之间存在相当多的相互作用。一般来说，Hsf和Hsp的表达受到热、冷、盐和渗透胁迫的强烈诱导，而其他类型的胁迫则表现出家族或组织特异性的反应模式。例如，对于Hsp20蛋白家族，在所有类型的胁迫下都发生了大量的表达反应，表达反应谱之间具有显著的相似性。属于Hsp20、Hsp70和Hsp100家族的几个基因在根组织受伤12小时后被特异性上调，并且在从热胁迫恢复过程中表现出平行的表达反应模式。在所有Hsf和Hsp家族中，地上组织（茎）在紫外线B光胁迫下发生了大量的表达反应，而地下组织（根）则没有。
我们的研究结果表明，Hsf和Hsp家族成员基因代表了多个胁迫反应途径之间的一个相互作用点，因此值得在热激处理以外的条件下进行功能分析。此外，我们的分析揭示了几种以前未描述过的家族和组织特异性热激基因表达模式。这些结果对植物物种交叉耐受性的分子基础具有启示意义，并提出了在拟南芥热激反应网络未来的实验研究中有待探讨的新问题。
