Regulation and function of Hsp70 in zebrafish embryos

热休克蛋白最初被认为是细胞暴露于环境胁迫（如高温或有毒金属）后表达的蛋白质。 随后发现，几种hsps也作为分子伴侣在正常细胞内蛋白质折叠和靶向事件中发挥重要作用，并在许多胚胎组织发育过程中的不连续时期表达。 热休克蛋白基因的表达在很大程度上是由一个小家族的转录因子被称为热休克因子（HSFs）。 我们已经表明，斑马鱼hsp 70基因表达在一个独特的时间窗口正常胚胎透镜形成28-38小时后受精（hpf）在非应激条件下，它是所需的正常透镜形成，和透镜特异性表达需要热休克因子1（HSF 1）的活性。 我们还发现，热休克蛋白70基因强烈上调，在幼虫期斑马鱼暴露于有毒金属镉，这种压力诱导的上调发生在组织特异性的方式与强烈表达的嗅觉神经元和侧线神经瘤，在鱼的重要感觉细胞。 在这个建议中的实验将旨在定义的机制，通过它的组成性晶状体特异性表达和镉诱导的嗅觉神经元表达的热休克蛋白70基因的调节，和参与的转录因子。 其他实验将进一步研究hsp 70基因产物在透镜形成中的作用，特别是在衰减的类晶状体形成过程中，通过该过程破坏透镜纤维细胞器以产生透明的透镜。 这些实验将推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在完整的发育生物体中协调的理解。 这项研究计划的最终目标是产生一个全面的图片，将热休克基因的表达和功能整合到发育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.