Mitochondrial Lipid Kinase

描述（由申请人提供）：AGK与鞘氨醇（SPHK 1，2）和神经酰胺（CERK）激酶以及神经酰胺激酶样蛋白（CERKL）一起沿着，构成鞘脂激酶家族。AGK在这个家族的成员中是独特的，因为它是一种线粒体蛋白。我们发现，缺乏功能性AGK等位基因的小鼠在胚胎发育早期由于植入失败而死亡，这也不像SPHKs，CERK或CERKL，其中无效小鼠是可行的和可生育的。然而，AGK催化的磷酰基转移反应的脂质底物是不确定的。我们提出的研究计划将发现底物/产物，并在这样做时将定义一个脂质代谢途径，这对线粒体的生存至关重要。具体而言，我们将：（目的1）产生其中AGK表达显著不同的细胞培养物和组织的匹配对，并使用质谱来表征那些细胞和组织的脂质组，以便最终鉴定由AGK催化的反应，以及（目的2）通过确定AGK在线粒体中的亚细胞器位置来表征AGK功能，研究AGK缺陷细胞中的线粒体生理学，并使用AGK等位基因的条件性缺失来确定小鼠中细胞谱系的命运。我们在溶血磷脂化学生物学（包括鞘氨醇激酶）方面的丰富经验，加上线粒体生理学方面的专业知识，将使我们能够解决这个问题。至少，所提出的实验将揭示鞘脂代谢的一个新的分支。最重要的是，我们将定义一个新的途径，这是线粒体功能不可或缺的。 公共卫生相关性：许多严重的病理特征是身体的能量工厂缺陷，这些能量工厂是称为线粒体的细胞器。根据受线粒体疾病影响的器官系统，症状可能包括生长不良，肌肉无力，糖尿病，神经系统问题，如癫痫发作，呼吸系统疾病和痴呆症。在这个项目中，我们研究了一种名为AGK的蛋白质，它被认为与脂质代谢有关。AGK是一种线粒体蛋白，我们发现缺乏这种蛋白的小鼠在胚胎形成早期死亡，这表明AGK对包括人类在内的哺乳动物的发育至关重要。我们正在研究AGK，以了解受AGK影响的脂质途径的性质，以及为什么这种途径对线粒体存活如此重要。我们的目的是利用这些知识来提供更好的理解，诊断和最终治疗线粒体疾病。

DESCRIPTION (provided by applicant): AGK, along with the sphingosine (SPHK1, 2) and ceramide (CERK) kinases and the ceramide kinase like protein (CERKL), comprise the sphingolipid kinase family. AGK is unique among members of this family in that it is a mitochondrial protein. We discovered that mice lacking a functional AGK allele die early in embryogenesis due to failure to implant, which is also unlike SPHKs, CERK or CERKL where null mice are viable and fertile. However, the lipid substrate of phosphoryl transfer reaction catalyzed by AGK is uncertain. The research program we propose will discover that substrate/product and in doing so will define a lipid metabolic pathway that is most likely crucial to mitochondrial survival. Specifically, we will: (Aim 1) Generate matched pairs of cell cultures and tissues wherein AGK expression is markedly different and use mass spectrometry to characterize the lipidome of those cells and tissues so as to ultimately identify the reaction catalyzed by AGK and (Aim 2) characterize AGK function in mitochondria by determining its sub- organelle location, studying mitochondrial physiology in cells deficient in AGK and using conditional deletion of AGK alleles to determine the fate of cell lineages in the mouse. Our extensive experience studying lysophospholipid chemical biology including sphingosine kinases coupled with expertise in mitochondrial physiology will enable us to solve this problem. Minimally, the experiments proposed will reveal a new branch of sphingolipid metabolism. Maximally, we will define a new pathway that is integral to mitochondrial function. PUBLIC HEALTH RELEVANCE: A number of serious pathologies are characterized by defects in the body's energy factories, which are cell organelles named mitochondria. Depending on the organ system affected in mitochondrial diseases, symptoms might include poor growth, muscle weakness, diabetes, neurological problems such as seizures, respiratory disorders and dementia. In this project, we study a protein named AGK, which is thought to be involved in lipid metabolism. AGK is a mitochondrial protein and we discovered that mice lacking this protein die early in embryo formation, which indicates that AGK is essential for development in mammals including humans. We are researching AGK to learn the nature of the lipid pathway that is affected by AGK and why this pathway is so important to mitochondrial survival. Our intention is to use this knowledge to provide better understanding, diagnosis and, eventually, treatment of mitochondrial disease.