Iron in Mitochondrial Physiology and Disease

描述(申请人提供)：很大一部分细胞铁代谢发生在线粒体中，包括铁输入、铁-硫簇组装和血红素生物合成。一些血红素和铁硫团被安装到呼吸复合体中，而另一些则被输出到细胞质和其他细胞室。整个系统都受到严格监管。在这个项目中，将从系统生物学的角度研究线粒体中的铁成分和铁相关的过程，以获得对健康和疾病状态的新陈代谢的新见解。从酵母和人类细胞中分离和完整的线粒体将进行穆斯堡尔谱、电子顺磁共振、电子吸收光谱和电感耦合等离子体发射质谱分析，以评估细胞器的铁组。这种生物物理方法将被用来研究从不同条件(发酵和呼吸；缺铁和富铁)和不同遗传菌株中分离的野生型酵母细胞的线粒体。被研究的酵母菌株(Yah1p、Atm1p、MRs3p/4p和Mtm1p缺失)已知会影响铁的代谢，通常是通过使铁在线粒体中积累来实现的。在人类中也有类似的情况，同源蛋白的缺陷会导致铁的积累。将对累积的铁进行表征，并研究其反应性。用于线粒体中铁的低分子量单核非血红素复合体将通过层析分离，然后通过质谱学和核磁共振谱进行鉴定。这些络合物的代谢功能也将被研究。来自人类HL60细胞的线粒体的铁组将与酵母的线粒体进行比较，差异将从铁线粒体的生化和生理学角度进行解释。该项目意义重大，因为将探索与疾病相关的铁在线粒体中积累的机制，并将分离和鉴定用于细胞运输的铁复合体。这种知识可以更好地控制铁进入和流出细胞器。这些铁复合体还可能在产生活性氧物种(ROS)方面发挥作用，ROS被认为是细胞损伤和衰老的某些方面的原因。与公众健康相关：铁在细胞过程中极其重要；它以血红素基团和铁-硫簇的形式被发现。摄入的铁被打包，然后被送到线粒体--一个细胞器，在那里它被转化成这些形式。包装材料的结构将被确定；这种结构可能会“告诉”铁在细胞内的位置。将开发一种方法来检测从酵母和人类细胞中分离出来的线粒体中所有不同形式的铁。在某些遗传状态下，铁聚集并可能导致疾病；这种聚集的铁将被描述为试图消除它。

DESCRIPTION (provided by applicant): A significant portion of cellular iron metabolism occurs in the mitochondria, including iron import, iron-sulfur cluster assembly and heme biosynthesis. Some heme and iron-sulfur clusters are installed into respiratory complexes, while others are exported to the cytosol and other cellular compartments. The entire system is tightly regulated. In this project, iron components and iron-related processes in mitochondria will be investigated from a systems-biology perspective to gain new insights into the metabolism of healthy and diseased states. Isolated and intact mitochondria from yeast and human cells will be subjected to M"ssbauer spectroscopy, electron paramagnetic resonance, electronic absorption spectroscopy and inductively coupled plasma emission mass spectrometry to evaluate the "iron-ome" of the organelle. This biophysical approach will be used to study mitochondria isolated from wild-type yeast cells grown under different conditions (fermenting vs. respiring; Fe deficient vs. Fe replete) and from different genetic strains. The yeast strains to be investigated (depleted in Yah1p, Atm1p, Mrs3p/4p, and Mtm1p) are known to affect iron metabolism, generally by causing iron to accumulate in the mitochondria. There are analogous situations in humans, in which defects in homologous proteins result in iron accumulation. The accumulated iron will be characterized and its reactivity investigated. Low molecular weight mononuclear nonheme complexes that are used in "trafficking" iron in the mitochondria will be isolated by chromatography, and then identified by mass spectrometry and NMR spectroscopy. The metabolic function of these complexes will also be investigated. The iron-ome of mitochondria from human HL60 cells will be compared to that of yeast mitochondria and differences will be interpreted in terms of iron mitochondrial biochemistry and physiology. The project is significant because the mechanism of disease-related Fe accumulation in mitochondria will be explored and iron complexes that are used in cellular trafficking will be isolated and identified. Such knowledge may allow better control of iron trafficking into and out of the organelle. These iron complexes may also play a role in generating reactive oxygen species (ROS) which are thought to be responsible for some aspects of cellular damage and aging. PUBLIC HEALTH RELEVANCE: Iron is exceedingly important in cellular processes; it is found as heme groups and iron-sulfur clusters. Ingested iron is packaged and then sent to the mitochondria, a cellular organelle, where it is converted into these forms. The structure of the packaging material will be determined; this structure probably "tells" the iron where to go within the cell. Methods will be developed to detect all of the different forms of iron in mitochondria isolated from yeast and human cells. In some genetic states, iron aggregates and can cause disease; this aggregated iron will be characterized in an attempt to eliminate it.