Towards an Understanding of Protein Homeostasis in Cold-adapted Antarctic Fish

了解适应寒冷的南极鱼类的蛋白质稳态

• 批准号: 0440799
• 负责人: Gretchen Hofmann
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0440799&HistoricalAwards=false
• 关键词: Towards; Understanding; Protein; Homeostasis; Cold

An unresolved question in the evolution of Antarctic fishes is how these organisms cope with cold-related protein damage and how the protein degradation machinery in Antarctic fish cells might be specially cold adapted to deal with elevated levels of protein misfolding at subzero temperatures. Investigators have found that the cold-adapted ectotherms are under unique selection pressures that may actually result in greater energetic costs of protein homeostasis rather than less. Given that the costs of protein synthesis are upwards of fifty percent in ectothermic organisms such as fish, exaggerated protein loss as a result of environmentally driven cold denaturation would have a significant impact on organismal performance. While cold denaturation of proteins and slow folding of proteins has been documented in some systems, very few studies have addressed how organisms in nature cope with extreme cold in terms of protein biogenesis. While the mechanism of cold denaturation is still not fully understood, temperatures at or near those encountered by Antarctic Notothenioids (icefish) have been shown to perturb protein structure (protein misfolding) for numerous proteins.Thus, despite living at temperatures that are ecological norms for the species, polar seawater temperatures may nevertheless be "stressful" for Antarctic organisms in terms of maintaining protein homeostasis. In order to test this hypothesis, a more direct measure of levels of misfolded proteins is required. Specifically, by examining the role of a major pathway for the degradation of misfolded and damaged proteins, the ubiquitin-proteasome pathway, research plan to determine whether cells in Antarctic fish are over-loaded with damaged proteins, presumably because there is a high degree of protein misfolding and because perhaps the proteasome pathway is suppressed at cold temperatures. Ubiquitin (Ub) conjugates are common indicator of protein damage within a cell. Preliminary data suggest that despite the "slow and cold" lifestyle of the Antarctic species, the levels of ubiquitinated proteins were as high as those measured in at least one of the temperate New Zealand species. The goals of this research are to: assess the relative amount of protein in Antarctic fish that has been tagged and targeted for degradation; to reveal whether Antarctic fish cells have elevated levels of protein degradation, as compared to New Zealand species, that could be related to extreme cold; to determine whether Antarctic cells are processing high levels of misfolded or other wise damaged proteins; and to examine how gene expression may have been altered in Antarctic fishes as an adaptation to near freezing temperatures. Broader impacts range from basic biology, through training of young scientists. Results from this study may highlight how Antarctic organisms may be models for studying cold denaturation of proteins in such as way as to benefit biomedical science.Additionally, these species may be models for studying cold denaturation of proteins in such as way as to benefit biomedical science.

南极鱼类进化中一个尚未解决的问题是这些生物如何科普与寒冷相关的蛋白质损伤，以及南极鱼类细胞中的蛋白质降解机制如何特别适应低温，以应对零度以下蛋白质错误折叠水平的升高。研究人员发现，适应寒冷的外温动物处于独特的选择压力之下，这实际上可能导致蛋白质稳态的能量消耗更大，而不是更少。考虑到蛋白质合成的成本在鱼类等外温生物中高达50%，环境驱动的冷变性导致的蛋白质损失将对生物体的性能产生重大影响。虽然蛋白质的冷变性和蛋白质的缓慢折叠已经在一些系统中被记录，但很少有研究涉及自然界中的生物如何在蛋白质生物合成方面科普极端寒冷。虽然冷变性的机制还没有完全弄清楚，南极南极银鱼所遇到的温度或附近的温度已经被证明会扰乱许多蛋白质的蛋白质结构（蛋白质错误折叠）。因此，尽管生活在该物种的生态标准温度下，极地海水温度仍然可能对南极生物维持蛋白质稳态产生“压力”。为了验证这一假设，需要更直接地测量错误折叠蛋白质的水平。具体而言，通过检查降解错误折叠和受损蛋白质的主要途径，即泛素-蛋白酶体途径的作用，研究计划确定南极鱼的细胞是否过载了受损蛋白质，这可能是因为存在高度的蛋白质错误折叠，也可能是因为蛋白酶体途径在低温下受到抑制。泛素（Ub）缀合物是细胞内蛋白质损伤的常见指示剂。初步数据表明，尽管南极物种的生活方式“缓慢而寒冷”，但泛素化蛋白质的水平与至少一种温带新西兰物种的水平一样高。 这项研究的目标是：评估南极鱼中被标记和作为降解目标的蛋白质的相对数量;揭示南极鱼细胞与新西兰鱼种相比是否有可能与极端寒冷有关的高水平蛋白质降解;确定南极鱼细胞是否正在处理高水平的错误折叠或其他损坏的蛋白质;并研究南极鱼类的基因表达如何改变以适应接近冰点的温度。更广泛的影响范围从基础生物学到年轻科学家的培训。本研究的结果可能会突出南极生物如何可能成为研究蛋白质冷变性的模式，从而有益于生物医学科学。此外，这些物种可能是研究蛋白质冷变性的模式，从而有益于生物医学科学。