Mitochondrial Lipid Kinase

描述(由申请人提供)：AGK与鞘氨醇(SPHK1，2)和神经酰胺(CERK)激酶以及神经酰胺激酶样蛋白(CERKL)一起组成鞘磷脂激酶家族。AGK在这个家族成员中是独一无二的，因为它是一种线粒体蛋白。我们发现，缺乏功能性AGK等位基因的小鼠由于植入失败而在胚胎发育早期死亡，这也不同于SPHKs、Cerk或CERKL，在这些地方，空小鼠是存活和可生育的。然而，AGK催化的磷酰化转移反应的脂质底物尚不确定。我们提出的研究计划将发现底物/产物，并在此过程中定义一条很可能对线粒体生存至关重要的脂代谢途径。具体地说，我们将：(1)建立AGK表达明显不同的细胞培养和组织的配对，并使用质谱学来表征这些细胞和组织的脂体，从而最终确定AGK催化的反应；(2)通过确定其亚细胞器位置，研究AGK缺乏细胞的线粒体生理学，并通过条件缺失AGK等位基因来确定细胞谱系的命运，来表征线粒体中AGK的功能。我们研究溶血磷脂化学生物学的丰富经验，包括鞘氨醇激酶，再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，拟议中的实验将揭示鞘磷脂代谢的一个新分支。最大限度地，我们将定义一条与线粒体功能不可或缺的新途径。

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.