Mitochondrial inorganic polyphosphate (polyP) as a key regulator of mammalian mitochondrial physiology

线粒体是细胞中产生绝大多数细胞能量的部分。从细菌的运动到哺乳动物的心跳，每一种生物功能都需要这种能量。在哺乳动物细胞中，当压力存在时，线粒体功能失调，能量产生失调，最终导致细胞死亡。虽然这一连串的有害影响是众所周知的，但在哺乳动物中，导致线粒体功能障碍并最终在应激条件下失效的确切机制尚不完全清楚。无机聚磷酸盐（polyP）可能在这些机制中起重要作用。PolyP的结构类似于细胞能量的主要分子ATP。多项研究表明，线粒体含有大量的polyP，这种化合物调节线粒体产生ATP的主要过程。本项目将开展实验，以更好地了解polyP在正常和应激条件下对线粒体的调节作用，以及这些作用背后的分子机制。这些发现将进一步了解许多植物和动物线粒体健康和能量产生受损的基本情况。此外，该项目将采用多种方法来增加培训和扩大研究队伍，包括为来自该地区资源不足社区的本科生提供在我们实验室进行有偿研究的机会。应激诱导的线粒体功能障碍，包括生物能量失调，在所有真核生物中都有广泛的研究。然而，在应激条件下导致哺乳动物线粒体功能障碍和最终衰竭的机制尚不完全清楚。无机聚磷酸盐（polyP）是一种进化上保守的聚合物，存在于每一种被研究生物的每一个组织中。它是由正磷酸盐链形成的，这些正磷酸盐链通过高能量的磷酸酐键连接在一起，类似于ATP中的键。这种分子结构，以及其在哺乳动物线粒体中的高浓度，使息肉蛋白成为哺乳动物生物能量调节的完美候选者。事实上，许多研究人员已经证明了息肉蛋白在线粒体和线粒体外水平上对能量产生的调节作用。然而，息肉蛋白在生物能量学中的调节作用的确切分子机制仍然知之甚少。在这里，这些机制将被探索，使用野生型哺乳动物细胞和线粒体息肉（MitoPPX）酶耗尽的细胞。这些细胞将在控制和压力条件下使用。具体来说，抗氧化系统失调会引起应激。该研究项目的长期目标是增加线粒体生物学的知识，并有助于扩大研究人员的参与。这将通过在本研究中纳入来自该地区资源不足社区的本科生，以及为这些学生提供在毕业前共同撰写科学评论的机会来实现。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。

Mitochondria are the part of the cells where the vast majority of cell energy is produced. This energy is needed for every organismal function, from the movement of bacteria to the heartbeats of mammals. In mammalian cells, when stress is present, mitochondria become dysfunctional, the production of energy is dysregulated and, eventually, cells can die. While this chain of deleterious effects is well known, the exact mechanisms that drive mitochondria to dysfunction and, eventually, to fail under stress conditions are not yet fully understood in mammals. Inorganic polyphosphate (polyP) could play an important role in these mechanisms. PolyP has a structure which is similar to that of ATP, the main molecule of cellular energy. Multiple studies have shown that mitochondria contain large amounts of polyP and that this compound regulates the main mitochondrial process of producing ATP. This project will carry out experiments to better understand the regulatory effects of polyP on mitochondria in normal conditions and under stress, as well as the molecular mechanisms that underly these effects. These findings will further basic understanding of many plant and animal conditions where mitochondria health and generation of energy are impaired. In addition, this project will use multiple methods to increase training and to expand the research workforce, including providing undergraduate students from underresourced communities in the area with paid research opportunities in our laboratory. Stress-induced mitochondrial dysfunction, including dysregulated bioenergetics, has been broadly described in all eukaryotic organisms where it has been investigated. However, the mechanisms that drive mammalian mitochondria to dysfunction and eventual failure under stress conditions are not yet fully understood. Inorganic polyphosphate (polyP) is an evolutionarily well conserved polymer that is present in every tissue from every studied organism. It is formed by chains of orthophosphates that are linked together by highly energetic phosphoanhydride bonds, similar to those found in ATP. This molecular structure, along with its high concentration in mammalian mitochondria, makes polyP a perfect candidate to contribute to the regulation of mammalian bioenergetics. In fact, multiple researchers have demonstrated a regulatory role for polyP in energy production at both the mitochondrial and extra-mitochondrial levels. However, the exact molecular mechanisms that underly this regulatory role of polyP in bioenergetics remain poorly known. Here, these mechanisms will be explored, using both wild-type mammalian cells and cells enzymatically depleted of mitochondrial polyP (MitoPPX). These cells will be used under both control and stress conditions. Specifically, stress will be induced by dysregulating the antioxidant system. The long-term goal of this research project is to increase knowledge of mitochondrial biology, as well as to contribute to broadening participation of the research workforce. This will be accomplished through inclusion of undergraduate students from underresourced communities in the area in this research, as well as by providing these students with the opportunity to co-author a scientific review before graduation.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.