Regulation and function of Hsp70 in zebrafish embryos

热休克蛋白（hsps）最初被确定为细胞暴露于环境应激（如高温或有毒金属）后表达的蛋白质。一些热休克蛋白随后也被证明在正常的细胞内蛋白折叠和靶向事件中作为分子伴侣发挥重要作用，并在许多胚胎组织发育的离散时期表达。热休克蛋白基因的表达在很大程度上是由一个被称为热休克因子（hsf）的转录因子小家族调节的。我们已经证明，在非应激条件下，斑马鱼hsp70基因在受精后28-38小时（hpf）正常胚胎晶状体形成的不同时间窗口中表达，这是正常晶状体形成所必需的，晶状体特异性表达需要热休克因子1 （HSF1）的活性。我们还发现hsp70基因在暴露于有毒金属镉后，在斑马鱼的幼虫期强烈上调，并且这种应激诱导的上调以组织特异性的方式发生，在嗅觉神经元和侧线神经突中强烈表达，这两个细胞都是鱼的重要感觉细胞。本实验将旨在确定组成晶状体特异性表达和镉诱导的hsp70基因的嗅觉神经元表达的调控机制，以及所涉及的转录因子。其他实验将进一步研究hsp70基因产物在晶状体形成中的作用，特别是在晶状体纤维细胞器被破坏以产生透明晶状体的衰减凋亡样过程中。这些实验将促进我们对单个基因的表达如何在不同环境条件下以细胞特异性方式协调的理解，在完整的，发育的生物体的背景下。本研究计划的最终目标是生成一个综合的图像，将热休克基因表达和功能整合到发育中的胚胎的发育和生理中。

Heat shock proteins (hsps) were originally identified as proteins expressed following exposure of cells to environmental stress such as elevated temperature or toxic metals. Several hsps were subsequently shown to also play important roles as molecular chaperones in normal intracellular protein folding and targeting events, and to be expressed during discrete periods during the development of a number of embryonic tissues. Hsp gene expression is regulated in large part by a small family of transcription factors known as heat shock factors (HSFs). We have shown that the zebrafish hsp70 gene is expressed during a distinct temporal window of normal embryonic lens formation from 28-38 hours post fertilization (hpf) under non-stress conditions, that it is required for normal lens formation, and that lens-specific expression requires the activity of heat shock factor 1 (HSF1). We have also found that the hsp70 gene is strongly upregulated in larval stage zebrafish following exposure to the toxic metal cadmium, and that this stress-induced upregulation occurs in a tissue-specific manner with strong expression in the olfactory neurons and lateral line neuromasts, both important sensory cells in fish. Experiments in this proposal will be aimed at defining the mechanisms by which constitutive lens-specific expression and cadmium-induced olfactory neuron expression of the hsp70 gene are regulated, and the transcription factors involved. Other experiments will further examine the role of the hsp70 gene product in lens formation, particularly in the attenuated apoptotic-like process by which lens fibre organelles are destroyed in order to produce a transparent lens. These experiments will advance our understanding of how expression of a single gene is co-ordinated in a cell-specific manner under different environmental conditions in the context of the intact, developing organism. The end goal of this research program is to generate a comprehensive picture that integrates heat shock gene expression and function into the development and physiology of the developing embryo.