Excellence in Research: Involvement of MEF-2 transcription factor in mitochondrial stress response through SOD2

氧与其他分子结合，产生能量，为许多生化过程提供动力。没有氧气，人类就无法生存。然而，在用氧气“燃烧”营养物质来产生能量的过程中，作为不可避免的副产品，会产生某些“无赖”的氧分子，称为“活性氧种”(ROS)。人体内最强大的天然抗氧化酶之一是超氧化物歧化酶(SOD)，它负责解除所有自由基中最危险的自由基的武装：高活性的超氧自由基。所有的人类细胞都会产生超氧化物歧化酶来中和这些超氧自由基。一直以来的研究表明，由于氧气消耗的增加，肌肉活动会导致ROS产量的显著增加。研究人员将测试一种名为肌细胞增强因子-2(MEF-2)的肌肉特异性蛋白质调节肌肉组织中SOD表达的假设。使用各种分子和细胞生物学程序，将评估肌肉组织中MEF2和SOD之间的机制联系。该项目将为许多本科生提供最先进的技术技能，他们将参与实验的许多部分。霍华德大学是一所文化多元、研究密集的历史黑人学院和大学(HBCU)，大约97%的注册学生是非裔美国人，因此，该项目将为代表不足的少数族裔提供丰富的培训机会。肌肉功能依赖于高水平的耗氧量和伴随而来的氧代谢副产物有毒活性氧簇(ROS)的高水平通量。锰超氧化物歧化酶(或SOD2)参与线粒体对活性氧(ROS)的防御。SOD2功能丧失会导致新生儿死亡。Sod2的功能在肌肉中比在其他组织中更关键，这与肌肉线粒体的高耗氧量和大量ROS的产生是一致的。因此，不受限制的ROS产生是线粒体的危险。作为一种转录因子，肌细胞增强因子-2(MEF-2)在所有肌肉类型的指定和随后的分化中起着至关重要的作用。MEF-2在成虫肌肉中继续表达，在成虫中没有其他功能。在果蝇中，SOD2的表达依赖于MEF-2转录因子的存在。这一建议的中心假设是，MEF-2通过SOD2调节线粒体应激反应，在成人肌肉生理学中发挥着新的、持续的作用。这三个具体目标是：1)成年肌肉中MEF-2和SOD2之间的机制联系；2)MEF-2/SOD2相互作用对氧化应激反应和线粒体完整性的影响；3)MEF-2/SOD2相互作用在整个有机体水平上对肌肉生物学的广泛生物学意义。这项拟议的研究将有助于理解肌肉中的氧化损伤，特别是在线粒体生物学的背景下。研究培训机会将提供给许多不被充分代表的少数族裔本科生和研究生，他们将获得基本和翻译应用方面的新技能。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Oxygen, in combination with other molecules, generates energy that powers many biochemical processes. Without oxygen, humans could not exist. However, in the process of generating energy by "burning" nutrients with oxygen, certain "rogue" oxygen molecules, known as reactive oxygen species (ROS), are created as inevitable byproducts. One of the body's most powerful natural antioxidant enzymes is superoxide dismutase (SOD), which is responsible for disarming the most dangerous free radicals of all: the highly reactive superoxide radicals. All human cells produce superoxide dismutase to neutralize these superoxide radicals. It has been shown consistently that muscle activity leads to a strong increase in ROS production due to increased oxygen consumption. The investigator will test the hypothesis that a muscle specific protein, called Myocyte Enhancing Factor-2 (MEF-2), regulates SOD expression in the muscle tissue. Using a variety of molecular and cell biological procedures, the mechanistic link between MEF2 and SOD in muscle tissue will be evaluated. The project will provide state of the art technical skills to many undergraduate students who will be involved in many parts of the experiments. Howard University, a culturally diverse, research-intensive Historically Black College and University (HBCU) has approximately 97% of enrollees who are African Americans, therefore, the project will provide rich training opportunities for underrepresented minorities. Muscle function depends on high-level oxygen consumption and the concomitant high-level flux of toxic reactive oxygen species (ROS) that are generated as by-products of oxygen metabolism. Manganese superoxide dismutase (or SOD2) is engaged in the mitochondrial defense against reactive oxygen species (ROS). Loss of SOD2 function causes neonatal lethality. SOD2 function is more critical in muscles than in other tissues, which is consistent with the high level of oxygen consumption and prolific ROS generation by muscle mitochondria. So, unfettered ROS production is a mitochondrial hazard. As a transcription factor, Myocyte Enhancing Factor-2 (MEF-2) plays a critical role in the specification and subsequent differentiation of all muscle types. MEF-2 continues to be expressed in adult muscles with no other function attributed to MEF-2 in adult insects. In Drosophila, SOD2 expression is dependent on the presence of MEF-2 transcription factor. The central hypothesis of this proposal is that MEF-2 plays a novel, continuing role in adult muscle physiology by modulating mitochondrial stress response through SOD2. The three specific objectives are to determine: 1) the mechanistic connection between MEF-2 and SOD2 in adult muscle, 2) the influence of the MEF-2/SOD2 interaction on oxidative stress response and mitochondrial integrity, and 3) the broad biological significance of the MEF-2/SOD2 interaction on muscle biology at the whole organism level. The proposed study will contribute to the understanding of oxidative damage in muscle specifically in context to the biology of mitochondria. Research training opportunities will be provided to many underrepresented minority undergraduate and graduate students, who will acquire new skills with basic and translational applications.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.