Regulation of Mitochondrial Fission/Fusion by PP2A and PKA in Neurons

神经元中 PP2A 和 PKA 对线粒体裂变/融合的调节

• 批准号: 7426845
• 负责人: STEFAN STRACK
• 金额: $ 15万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7426845
• 关键词: A kinase anchoring protein; Address; Affect; Apoptosis; Behavioral; Biolistics; Biological Assay; Brain; Brain Injuries; Buffers; Calcium; Cell Death; Chromosome Pairing; Condition; Cultured Cells; Cyclic AMP-Dependent Protein Kinases; Data; Dendritic Spines; Development; Dynamin; Enzymes; Equilibrium; Figs - dietary; Free Radicals; Functional disorder; Galactosidase; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Holoenzymes; Homeostasis; Hydrolysis; Hypoglycemia; Hypoglycemic Agents; Hypoxia; In Vitro; Inherited; Injury; Ischemia; Knockout Mice; Label; Lead; Link; Localized; Mediating; Metabolic; Mitochondria; Modeling; Molecular Target; Monoclonal Antibodies; Morphology; Mus; Mutagenesis; Mutate; Mutation; Natural regeneration; Nervous System Trauma; Neurodegenerative Disorders; Neurons; Organelles; Outer Mitochondrial Membrane; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiology; Predisposition; Process; Protein Kinase; Proteins; Proteomics; RNA Splicing; Rattus; Regulation; Reporter; Research Personnel; Resistance; Role; Shapes; Side; Signal Transduction; Spinocerebellar Ataxias; Stable Isotope Labeling; Structure; Surface; Synapses; System; Transfection; Transient Cerebral Ischemia; follow-up; in vivo; inhibitor/antagonist; mitochondrial dysfunction; mossy fiber; nervous system disorder; neuron loss; neuronal survival; neuropathology; novel; programs; protein phosphatase 2A regulatory subunit 65 kDa; response; stroke therapy; synaptic function; synaptogenesis; tandem mass spectrometry; trafficking

DESCRIPTION (provided by applicant): Mitochondria provide energy, buffer calcium, and sequester cell death-inducing molecules, and mitochondrial dysfunction is implicated in various neuropathologies. Especially in neurons, mitochondria are highly dynamic organelles that constantly move, divide, and fuse. This proposal investigates the regulation of mitochondrial fission and fusion in neurons, which are antagonistic processes carried out by large GTPases similar to dynamin. Mutations in two of these enzymes, Opal and Mfn2, are responsible for hereditary neurological diseases. While a proper balance of mitochondrial fusion and fragmentation is clearly important for neuronal survival, some fragmentation is necessary for axonal and dendritic transport of mitochondria, and consequently for the development and function of synapses. We have found that shape changes of mitochondria are controlled by an opposing protein kinase and phosphatase that are localized to the outer mitochondrial membrane via specific targeting/regulatory subunits. On the phosphatase side, Bp2 is a neuron-specific, postnatally induced protein phosphatase 2A (PP2A) regulatory subunit mutated in spinocerebellar ataxia type 12. The alternatively spliced N terminus of Bp2 mediates translocation of the PP2A holoenzyme to the mitochondrial surface, where PP2A accelerates cell death, apparently by fragmenting mitochondria. The kinase opposing PP2A/Bp2's effect on mitochondrial morphology and survival is cAMP-dependent protein kinase (PKA) anchored to the OMM via A kinase anchoring protein (AKAP)121. Aim 1 investigates the mechanism by which outer-mitochondrial PP2A and PKA control neuronal survival. In Aim 2, we will identify the relevant substrates and phosphorylation sites among mitochondrial fission/fusion enzymes. Aim 3 addresses the role of PP2A/PKA-dependent mitochondrial restructuring in the delivery of mitochondria to and development of dendritic spines. Finally, Aim 4 characterizes PP2A/Bp2 knockout mice in terms of mitochondria and synapse morphology and resistance to ischemic injury. These studies will advance our understanding of how shape transitions of mitochondria are regulated, and how this affects vulnerability of neurons and the establishment of functional connections between them. Our studies may ultimately lead to better therapies for stroke and neurodegenerative disorders.

描述（由申请人提供）：线粒体提供能量、缓冲钙和隔离细胞死亡诱导分子，线粒体功能障碍与各种神经病理学有关。尤其是在神经元中，线粒体是高度动态的细胞器，不断移动、分裂和融合。该提案研究了神经元中线粒体裂变和融合的调节，这是由类似于动力的大型 GTP 酶执行的拮抗过程。其中两种酶 Opal 和 Mfn2 的突变是遗传性神经系统疾病的原因。虽然线粒体融合和断裂的适当平衡对于神经元的生存显然很重要，但一些断裂对于线粒体的轴突和树突运输以及突触的发育和功能是必要的。我们发现线粒体的形状变化是由相反的蛋白激酶和磷酸酶控制的，这些蛋白激酶和磷酸酶通过特定的靶向/调节亚基定位于线粒体外膜。在磷酸酶方面，Bp2 是一种神经元特异性、出生后诱导的蛋白磷酸酶 2A (PP2A) 调节亚基，在 12 型脊髓小脑共济失调中发生突变。Bp2 的选择性剪接 N 末端介导 PP2A 全酶易位至线粒体表面，在线粒体表面，PP2A 加速细胞死亡，显然是由于线粒体断裂造成的。对抗 PP2A/Bp2 对线粒体形态和存活的影响的激酶是 cAMP 依赖性蛋白激酶 (PKA)，通过 A 激酶锚定蛋白 (AKAP)121 锚定到 OMM。目标 1 研究线粒体外 PP2A 和 PKA 控制神经元存活的机制。在目标 2 中，我们将鉴定线粒体裂变/融合酶中的相关底物和磷酸化位点。目标 3 探讨 PP2A/PKA 依赖性线粒体重组在线粒体递送和树突棘发育中的作用。最后，Aim 4 在线粒体和突触形态以及​​对缺血性损伤的抵抗力方面表征了 PP2A/Bp2 敲除小鼠。这些研究将增进我们对线粒体形状转变如何调节，以及这如何影响神经元的脆弱性以及它们之间功能连接的建立的理解。我们的研究最终可能会带来更好的中风和神经退行性疾病治疗方法。