Milton/Trak 1/2 Protein and the Transport of Mitochondria

该提案集中在细胞中线粒体的动态行为上。特别是，它检查了两个 通过不同的马达-适配器翻译后修饰来控制这种行为的途径 Milton/TRAK 1/2蛋白。线粒体的运动由两个基于微管的马达驱动， 驱动蛋白-1和动力蛋白，这些马达通过马达/适配器结合到线粒体表面 由Milton和Miro蛋白组成的复合物（也称为TRAK 1/2和RhoT 1/2）。第一 我们在这里研究的调节途径涉及酶O-GlcNAc转移酶（OGT）， 催化糖残基N-乙酰葡糖胺加到丝氨酸上的酶， 蛋白质上的苏氨酸残基。我们和其他人已经发现这种酶GlcNAylates米尔顿。我们 还发现OGT在神经元中的表达阻止了线粒体的运动， 直接通过其衬底Milton发生。因为OGT被认为是一种营养传感器， 当葡萄糖水平高时，OGT通路更活跃，我们假设OGT通路将停止， 线粒体在高细胞外葡萄糖的条件下，我们确实观察到， 当葡萄糖水平升高时，轴突中的运动通过该途径减少。我们建议 检查OGT停止线粒体的机制以及OGT和 Milton GlcNAc化用于线粒体在轴突中的分布。第二条调节途径 在这项授权中审查的也涉及线粒体/细胞骨架的相互作用及其 通过翻译后修饰来调节，在这种情况下，是Milton的磷酸化。通过 驱动线粒体和其他可能的锚定蛋白的马达，线粒体通常 与微管有着密切的关系。我们发现这种情况在划分上有很大不同 细胞当细胞进入有丝分裂时，微管被拆除并改革为纺锤体 设备.在有丝分裂过程中，线粒体被排除在细胞中含有 微管我们发现，milton在细胞周期中被磷酸化，可能是通过 cdk 1.我们将研究这种磷酸化对马达/适配器状态的意义 复合体及其对线粒体有丝分裂再分布的意义。

This proposal focuses on the dynamic behavior of mitochondria in cells. In particular, it examines two pathways that control that behavior via different posttranslational modifications of the motor-adaptor protein milton/TRAK1/2. The movement of mitochondria is driven by two microtubule-based motors, Kinesin-1 and Dynein, and these motors are bound to the mitochondrial surface by a motor/adaptor complex consisting of the proteins milton and Miro (also called TRAK1/2 and RhoT1/2). The first regulatory pathway we here investigate involves the enzyme O-GlcNAc Transferase (OGT), an enzyme that catalyzes the addition of the sugar residue N-Acetyl Glucosamine to serine and threonine residues on proteins. We and others have found that this enzyme GlcNAcylates milton. We also find that expression of OGT in neurons arrests the movement of the mitochondria and that this occurs directly through its substrate milton. Because OGT is thought to be a nutrient sensor that is more active when glucose levels are high, we hypothesized that the OGT pathway will stop mitochondria under conditions of high extracellular glucose and indeed we observe that mitochondrial movement is decreased in axons via this pathway when glucose levels are raised. We propose to examine the mechanism by which OGT halts mitochondria and also the significance of OGT and milton GlcNAcylation for the distribution of mitochondria in axons. The second regulatory pathway that is examined in this grant also concerns mitochondrial/cytoskeletal interactions and their regulation by a posttranslational modification, in this case phosphorylation of milton. Through the motors that move mitochondria and also additional likely anchoring proteins, mitochondria normally exist in a close relationship with microtubules. We find that this situation is very different in dividing cells. When a cell enters mitosis, the microtubules are dismantled and reform as the spindle apparatus. During mitosis, mitochondria are excluded from the regions of the cell that contain microtubules. We have found that milton becomes phosphorylated during the cell cycle, probably by cdk1. We will investigate the significance of this phosphorylation for the state of the motor/adaptor complex and its significance for the mitotic redistribution of mitochondria.