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

氧气与其他分子结合，产生能量，为许多生物化学过程提供动力。没有氧气，人类就无法生存。然而，在通过用氧气“燃烧”营养物质来产生能量的过程中，某些“流氓”氧分子，称为活性氧（ROS），作为不可避免的副产品被创造出来。超氧化物歧化酶（SOD）是人体最强大的天然抗氧化酶之一，负责消除所有自由基中最危险的自由基：高活性超氧化物自由基。 所有人体细胞产生超氧化物歧化酶来中和这些超氧化物自由基。已经一致地表明，肌肉活动由于增加的耗氧量而导致ROS产生的强烈增加。 研究人员将测试一种称为肌细胞增强因子-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，MEF 2和SOD在肌肉组织中的机制之间的联系将被评估。 该项目将提供最先进的技术技能，许多本科生谁将参与许多部分的实验。 霍华德大学是一所文化多样、研究密集型的历史黑人学院和大学（HBCU），约97%的入学者是非洲裔美国人，因此，该项目将为代表性不足的少数民族提供丰富的培训机会。肌肉功能取决于高水平的氧消耗和伴随的高水平的有毒活性氧（ROS）通量，这些活性氧是氧代谢的副产品。锰超氧化物歧化酶（或SOD 2）参与线粒体防御活性氧（ROS）。SOD 2功能丧失导致新生儿死亡。SOD 2在肌肉中的功能比在其他组织中更关键，这与肌肉线粒体的高水平氧消耗和多产ROS产生一致。 所以，不受限制的ROS产生是线粒体的危险。肌细胞增强因子-2（Myocyte Enhancing Factor-2，MEF-2）作为一种转录因子，在肌肉的特化和分化过程中起着重要作用。MEF-2继续在成体肌肉中表达，在成体昆虫中没有归因于MEF-2的其他功能。在果蝇中，SOD 2的表达依赖于MEF-2转录因子的存在。 该提议的中心假设是MEF-2通过SOD 2调节线粒体应激反应在成人肌肉生理学中发挥新的持续作用。这三个具体目标是确定：1）MEF-2和SOD 2在成年肌肉中的机械联系，2）MEF-2/SOD 2相互作用对氧化应激反应和线粒体完整性的影响，以及3）MEF-2/SOD 2相互作用在整个生物体水平上对肌肉生物学的广泛生物学意义。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代表性不足的少数民族本科生和研究生，他们将获得基本和翻译应用的新技能。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.