2,3 cAMP in Traumatic Brain Injury

2,3 cAMP 在创伤性脑损伤中的作用

• 批准号: 9100931
• 负责人: EDWIN Kerry JACKSON
• 金额: $ 33.69万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9100931
• 关键词: 2' -adenylic acid; Adenosine; Age; Alkaline Phosphatase; Astrocytes; Biochemical; Biochemistry; Brain; Brain Injuries; Cells; Cyclic AMP; Cyclic Nucleotides; Development; Enzymes; Evolution; Goals; Health; Human; Hypoxia; Injury; Isomerism; Knockout Mice; Left; Mechanics; Mediating; Metabolic stress; Metabolism; Microglia; Mitochondria; Myelin; Myelin Proteins; Neurologic; Neurons; Neuroprotective Agents; Neurosciences; Neurotoxins; Oligodendroglia; Outcome; P-Glycoproteins; Pathway interactions; Permeability; Play; Process; Production; Public Health; Purines; Reaction; Research Personnel; Rodent; Second Messenger Systems; System; Testing; Tissues; Toxin; Traumatic Brain Injury; axonal degeneration; body system; cell type; central nervous system injury; design; extracellular; improved outcome; in vivo; mRNA Transcript Degradation; mitochondrial permeability transition pore; neurotoxic; new therapeutic target; novel; novel strategies; novel therapeutics; phosphoric diester hydrolase; research study; response to injury; second messenger; tandem mass spectrometry

DESCRIPTION (provided by applicant): The term "cAMP" usually refers to the second messenger 3',5'-cyclic adenosine monophosphate. We serendipitously discovered that organ systems can produce (from mRNA degradation) and export to the extracellular compartment a positional isomer of 3',5'-cAMP, namely 2',3'-cAMP. We showed that organ systems convert extracellular 2',3'-cAMP to 2'-AMP + 3'-AMP and can metabolize 2'-AMP and 3'-AMP to adenosine. We refer to this pathway as the "2',3'-cAMP-adenosine pathway." We also showed that extracellular 2',3'-cAMP increases greatly post-traumatic brain injury (TBI) in brain in rodents and humans; and that when the pathway is impaired, TBI outcomes worsen in rodents. Intracellular 2',3'-cAMP opens mitochondrial permeability transition pores while extracellular adenosine is neuroprotective. Thus the "2',3'- cAMP-adenosine pathway" may be important in TBI because it eliminates an intracellular neurotoxin (export of 2',3'-cAMP) and generates an extracellular neuroprotectant (conversion of 2',3'-cAMP to adenosine). We also identified the enigmatic myelin protein 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) to be the major enzyme that metabolizes extracellular 2',3'-cAMP to 2'-AMP (a key step toward conversion into adenosine). KO mice lacking CNPase produce less extracellular adenosine post-TBI, are more susceptible to injury and develop axonal degeneration with age despite no gross myelin abnormalities. Hypothesis: the "2',3'-cAMP- adenosine pathway" is an endogenous cytoprotective mechanism after TBI. We will elucidate which CNS cell types produce 2',3'-cAMP, what kinds of injury trigger 2',3'-cAMP production, how 2',3'-cAMP is transported out of cells, how downstream AMPs are converted to adenosine, and if manipulating the 2',3'-cAMP-adenosine pathway alters secondary damage. Specific Aim 1: To determine which CNS cell types produce 2',3'-cAMP after injury. Because in vivo TBI increases extracellular 2',3'-cAMP, it is important to determine which CNS cells produce 2',3'-cAMP and whether the effect is injury-type dependent. Aim 1 will determine if metabolic stress, hypoxia or mechanical injury enhances 2',3'-cAMP production by astrocytes, microglia, neurons or oligodendrocytes. Specific Aim 2: To determine whether Multidrug Resistance Protein 4 (MRP4) mediates egress of 2',3'-cAMP. Because 2',3'-cAMP is an intracellular toxin, it is critical to elucidate how 2',3'-cAMP is extrude from CNS cells. Aim 2 will test the hypothesis that MRP4 exports 2',3'-cAMP. Specific Aim 3: To determine if Tissue Alkaline Phosphatase (TAP) participates in the extracellular metabolism of 2'-AMP and 3'- AMP (downstream metabolites of 2',3'-cAMP) to adenosine. Because extracellular adenosine is neuroprotective it is essential to understand how extracellular 2'-AMP and 3'-AMP are converted to extracellular adenosine. Specific Aim 4: To test the hypothesis that the 2',3'-cAMP-adenosine pathway is an endogenous protective mechanism post-TBI. Aim 4 will further test the hypothesis that the 2',3'-cAMP- adenosine pathway is cytoprotective by determining the effect of inhibiting or augmenting it on TBI outcomes.

描述（由申请人提供）：术语“cAMP”通常指第二信使3',5'-环单磷酸腺苷。我们偶然发现器官系统可以（通过 mRNA 降解）产生 3',5'-cAMP 的位置异构体并将其输出到细胞外区室，即 2',3'-cAMP。我们表明，器官系统将细胞外 2',3'-cAMP 转化为 2'-AMP + 3'-AMP，并且可以将 2'-AMP 和 3'-AMP 代谢为腺苷。我们将该途径称为“2',3'-cAMP-腺苷途径”。我们还表明，细胞外 2',3'-cAMP 会大大增加啮齿动物和人类大脑中的创伤后脑损伤 (TBI)；当该通路受损时，啮齿动物的 TBI 结局会恶化。细胞内 2',3'-cAMP 打开线粒体通透性转换孔，而细胞外腺苷具有神经保护作用。因此，“2',3'- cAMP-腺苷途径”在 TBI 中可能很重要，因为它消除细胞内神经毒素（2',3'-cAMP 的输出）并产生细胞外神经保护剂（2',3'- 的转化） cAMP 至腺苷）。我们还鉴定出神秘的髓磷脂蛋白 2',3'-环核苷酸 3'-磷酸二酯酶 (CNPase) 是将细胞外 2',3'-cAMP 代谢为 2'-AMP 的主要酶（这是转化为 2'-AMP 的关键一步）腺苷）。缺乏 CNPase 的 KO 小鼠在 TBI 后产生的细胞外腺苷较少，更容易受到损伤，并且随着年龄的增长，尽管没有明显的髓磷脂异常，但会出现轴突变性。假设：“2',3'-cAMP-腺苷途径”是TBI后的内源性细胞保护机制。我们将阐明哪些 CNS 细胞类型产生 2',3'-cAMP、哪种损伤会触发 2',3'-cAMP 产生、2',3'-cAMP 如何转运出细胞、下游 AMP 如何转化为腺苷，如果操纵 2',3'-cAMP-腺苷途径会改变继发性损伤。具体目标 1：确定哪些 CNS 细胞类型在损伤后产生 2',3'-cAMP。由于体内 TBI 会增加细胞外 2',3'-cAMP，因此确定哪些 CNS 细胞产生 2',3'-cAMP 以及该效应是否依赖于损伤类型非常重要。目标 1 将确定代谢应激、缺氧或机械损伤是否会增强星形胶质细胞、小胶质细胞、神经元或少突胶质细胞产生 2',3'-cAMP。具体目标 2：确定多药耐药蛋白 4 (MRP4) 是否介导 2',3'-cAMP 的流出。由于 2',3'-cAMP 是一种细胞内毒素，因此阐明 2',3'-cAMP 如何从 CNS 细胞中挤出至关重要。目标 2 将检验 MRP4 输出 2',3'-cAMP 的假设。具体目标 3：确定组织碱性磷酸酶 (TAP) 是否参与 2'-AMP 和 3'-AMP（2',3'-cAMP 的下游代谢物）到腺苷的细胞外代谢。由于细胞外腺苷具有神经保护作用，因此了解细胞外 2'-AMP 和 3'-AMP 如何转化为细胞外腺苷至关重要。具体目标 4：检验 2',3'-cAMP-腺苷途径是 TBI 后内源性保护机制的假设。目标 4 将通过确定抑制或增强 2',3'-cAMP-腺苷途径对 TBI 结果的影响，进一步检验 2',3'-cAMP-腺苷途径具有细胞保护作用的假设。