Regulation and function of Hsp70 in zebrafish embryos

热休克蛋白(HSPs)最初被鉴定为细胞在高温或有毒金属等环境应激下表达的蛋白质。随后，一些热休克蛋白被证明在正常的细胞内蛋白质折叠和靶向事件中也作为分子伴侣发挥重要作用，并在一些胚胎组织的发育过程中离散时期表达。HSP基因的表达在很大程度上是由一个称为热休克因子(HSFs)的小转录因子家族来调节的。我们已经证明，斑马鱼HSP70基因在非应激条件下从受精后28-38小时的正常胚胎晶状体形成的不同时间窗口中表达，它是正常晶状体形成所必需的，并且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，在接触有毒金属镉后，HSP70基因在斑马鱼幼体阶段强烈上调，这种应激诱导的上调是以组织特异性的方式发生的，在鱼类中重要的感觉细胞嗅神经元和侧线神经肥大中有强烈的表达。这项计划中的实验将旨在确定HSP70基因的结构性晶状体特异性表达和镉诱导的嗅神经元表达的调控机制，以及涉及的转录因子。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，特别是在减弱的类似凋亡的过程中，晶状体纤维细胞器被破坏以产生透明晶状体。这些实验将增进我们对单个基因如何在不同环境条件下以细胞特有的方式在完整、发育中的有机体的背景下协调表达的理解。这项研究计划的最终目标是生成一张全面的图片，将热休克基因的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.