An energy-sensitive pathway of cold-induced metabolic remodeling in threespine stickleback

新陈代谢的调整是必要的，以满足运动、温度波动和癌症等疾病引起的能量需求的变化。新陈代谢变化的最显著的例子之一发生在鱼对温度的反应中。由于鱼类是变温动物，它们的体温与其所处的环境相当，一些鱼类的体温可能会发生高达15-20摄氏度的昼夜或季节性变化，这需要调整新陈代谢来维持活动和游泳表现。尽管一些鱼类对温度的代谢重塑已经有了很好的记录，但人们对其如何调节知之甚少。虽然鱼类和哺乳动物之间的调节途径的某些组成部分是相似的，但其他部分则不同，这为扩大对代谢如何被调节的理解提供了机会。本项目将确定三刺鱼体内温度诱导代谢变化的信号通路。刺鱼是这些研究的理想选择，因为它们生活在温度变化的环境中，而且它们的基因组已经被测序，与其他物种相比，分子生物学研究更容易处理。高中生、本科生和研究生将参与这项研究，获得生理学、生物化学和分子生物学方面的培训。阿拉斯加本地高中学生将通过独立学习参与阿拉斯加农村高中荣誉学院，这是阿拉斯加大学费尔班克斯分校为期六周的大学预科课程。这项研究的结果将更好地理解新陈代谢是如何被调节的，这是一个对所有生物体的健康至关重要的过程。本项目研究了三刺棘鱼（Gasterosteus aculeatus）表型可塑性的机制，特别是sirtuins （NAD+依赖的去乙酰化酶）在驱动代谢重组以响应温度的作用。该假设将被验证，sirtuins激活c-MYC，一种有效的细胞生长和代谢调节剂，不同组织之间染色质堆积的差异将影响c-MYC的结合，导致组织特异性代谢重塑，这反映在有氧代谢范围内有机体水平的热补偿程度上。棘鱼将适应三种温度（5、12或20摄氏度）10周。关键代谢酶的最大活性、渗透细胞的线粒体呼吸速率、有氧代谢范围、腺苷酸、sirtuins和c-MYC的水平将在肝脏、糖酵解和氧化肌肉中被量化。然后在12℃的动物体内控制sirtuins的水平，并对这些参数以及选定的线粒体基因的表达进行量化。c-MYC的基因靶点将通过染色质免疫沉淀结合高通量测序（ChIP-Seq）进行鉴定，c-MYC启动子和报告基因构建将用于评估c-MYC DNA在体内热驯化过程中的结合活性。该项目将确定细胞水平上的代谢变化如何促进整个生物体的代谢重塑，并确定驱动组织特异性代谢重塑的信号级联的组成部分，从而建立对跨越分子、细胞和生物体水平的代谢重塑的综合理解。更广泛的影响包括研究生培训和阿拉斯加本地高中生参加为期六周的夏季大学预科课程的研究机会。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Adjustments in metabolism are necessary to meet changing energetic demands that result from processes such as exercise, temperature fluctuations, and diseases such as cancer. One of the most striking examples of alterations in metabolism occurs in fish in response to temperature. Because fish are ectotherms, with body temperatures equivalent to their environment, some species may experience body temperature changes as great as 15-20oC diurnally or seasonally, requiring adjustments in metabolism to maintain activity and swimming performance. Although metabolic remodeling in response to temperature has been well documented in several fish species, little is known about how it is regulated. While some components of the regulatory pathway are similar between fish and mammals, others differ, providing an opportunity to expand understanding of how metabolism is regulated. This project will identify the signaling pathway involved in temperature-induced changes in metabolism in the threespine stickleback fish. Stickleback are ideal for these studies because they inhabit thermally variable environments and their genome has been sequenced, making molecular biological studies more tractable compared to other species. High-school, undergraduate, and graduate students will participate in this research, obtaining training in physiology, biochemistry, and molecular biology. Native Alaskan high school students will be involved through independent studies as part of the Rural Alaskan High School Honors Institute, a six-week college preparatory program at the University of Alaska, Fairbanks. Results from this research will provide a better understanding of how metabolism is regulated, a process essential to the health of all organisms.This project investigates mechanisms of phenotypic plasticity, specifically the role of sirtuins, NAD+-dependent deacetylases, in driving metabolic reorganization in response to temperature in the threespine stickleback, Gasterosteus aculeatus. The hypothesis will be tested that sirtuins activate c-MYC, a potent regulator of cell growth and metabolism, and that differences in chromatin packing among different tissues will affect c-MYC binding, resulting in tissue-specific metabolic remodeling that is reflected in the degree of thermal compensation at the organismal level in aerobic metabolic scope. Stickleback will be acclimated to three temperatures (5, 12, or 20oC) for 10 weeks. Maximal activities of key metabolic enzymes, mitochondrial respiration rates in permeabilized cells, aerobic metabolic scope, and levels of adenylates, sirtuins, and c-MYC will be quantified in liver and glycolytic and oxidative muscles. Levels of sirtuins will then be manipulated in vivo in animals at 12oC and these parameters quantified, along with the expression of select mitochondrial genes. Gene targets of c-MYC will be identified using chromatin immunoprecipitation coupled with high throughput sequencing (ChIP-Seq), and a c-MYC promoter and reporter construct will be used to assess c-MYC DNA binding activity in vivo during thermal acclimation. This project will determine how changes in metabolism at the cellular level contribute to whole-organismal metabolic remodeling and identify components of the signaling cascade driving tissue-specific metabolic remodeling, creating an integrated understanding of metabolic remodeling that spans molecular, cellular and organismal levels. Broader impacts include graduate student training and research opportunities for Native Alaskan high-school students participating in a six-week summer college preparatory program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.