Lipid hydroxylation in glial cell signaling and myelination

神经胶质细胞信号传导和髓鞘形成中的脂质羟基化

• 批准号: 8046317
• 负责人: HIROKO HAMA
• 金额: $ 28.17万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8046317
• 关键词: Adult; Affect; Alleles; Anabolism; Animal Model; Axon; Binding; Biochemical; Biochemistry; Biological Assay; Brain; Carbohydrates; Carrier Proteins; Cell Cycle; Cell Cycle Regulation; Cell Differentiation process; Cell Surface Receptors; Cells; Ceramides; Characteristics; Complex; Cuprizone; Cyclic AMP; Cyclin-Dependent Kinases; Data; Demyelinating Diseases; Demyelinations; Development; Disease; Dose; Electron Transport; Employee Strikes; Enzymes; Family; Fatty Acids; Feedback; Foundations; Galactolipids; Galactose; Galactosylceramides; Genes; Genetic Recombination; Goals; Head; Health; Human; Hydrogen Bonding; Hydroxylation; In Vitro; Integrins; Knockout Mice; Knowledge; Lead; Length; Lipids; Maintenance; Mass Fragmentography; Mediating; Membrane; Membrane Microdomains; Mixed Function Oxygenases; Modeling; Molecular; Molecular Conformation; Molecular Genetics; Morphology; Multiple Sclerosis; Mus; Myelin; Nature; Neural Conduction; Neuraxis; Neuregulin Receptor; Neurilemmoma; Neurodegenerative Disorders; Neuroglia; Oligodendroglia; Pathway interactions; Peripheral Nervous System; Physiological; Play; Positioning Attribute; Protein Isoforms; Proteins; RNA Interference; Regulation; Role; Schwann Cells; Signal Transduction; Signaling Molecule; Solid; Stimulus; Structure; Substrate Specificity; Sulfoglycosphingolipids; Surface; Tamoxifen; Testing; Therapeutic Agents; Time; Tissues; Transcriptional Activation; Transcriptional Regulation; Transgenic Mice; Up-Regulation; Vertebrates; Withdrawal; base; brain tissue; cell motility; cofactor; dihydroceramide synthase; effective therapy; fatty acid elongases; hydroxyl group; in vivo; insight; long chain fatty acid; membrane model; mouse model; myelination; novel; oncoprotein p21; protein expression; response; role model; transcription factor

DESCRIPTION (provided by applicant): In higher vertebrates, nerve conduction is greatly facilitated by myelin, a lipid-rich membrane that wraps around the axon. A number of devastating demyelinating diseases threat human health, and few effective treatments exist. To develop better treatment for these diseases, we must understand the mechanisms involved in myelination. Myelin is a specialized structure with distinct lipid and protein constituents. Galactosylceramide (GalCer) and sulfatide make up approximately 30% of total myelin lipids, and more than half of these galactolipids contain fatty acid with a hydroxyl group at the C2 position (2-OH galactolipids). No other mammalian tissues contain such high concentrations of 2-OH fatty acids, suggesting that 2-OH galactolipids may play a crucial role in creating the special characteristics of myelin. Despite the extraordinary abundance of 2-OH galactolipids in myelin, there is surprisingly little understanding of the basic biochemistry and physiological role of 2-OH galactolipids. The overall goal of this study is to elucidate the pathway for myelin 2-OH lipids and their roles in myelination, myelin function, and cell signaling. A recently identified fatty acid 2-hydroxylase, FA2H, provides the precursor for the synthesis of myelin 2- OH galactolipids in oligodendrocytes and Schwann cells. FA2H and other enzymes are responsible for the increase in 2-OH very-long-chain (>C20) fatty acid contents in galactolipids during myelination. The first aim of this project is to establish the biosynthetic pathway involved in the unique lipid compositions of myelin galactolipids. Extensive biochemical analyses of FA2H will be performed to determine its physiological substrate, cofactors, and potential feedback mechanisms. Isoforms of fatty acid elongases and dihydroceramide synthases will be identified by a molecular genetic approach. More recently, it was found that reduced FA2H expression via RNAi significantly enhanced motility of D6P2T cells. Cellular 2-OH also partially blocked the upregulation of cyclin-dependent kinase inhibitors, p21 and p27, in response to a stimulus for differentiation. These observations indicate that 2-OH lipids are not only major structural components of myelin, but also function as signaling molecules to modulate cell differentiation and motility. In the second aim, the mechanism of action of 2-OH lipids in cell differentiation and motility will be determined. Transcriptional regulation for p21 and p27 will be investigated to determine the target protein modulated by 2-OH lipids, and the molecular identity of 2-OH lipid species with signaling function will be determined. The third aim is to determine the role of 2-OH galactolipids in myelin function and remyelination in adult brain. The cuprizone- induced demyelination/remyelination will be used to show FA2H is involved in remyelination. Subsequently, newly available conditional FA2H-knockout mice will be used to inactivate FA2H in adult brain. This model will be used to investigate myelin morphology, function, and remyelination in the absence of 2-OH lipids. PUBLIC HEALTH RELEVANCE To develop better treatment for devastating demyelinating diseases, we must understand the mechanisms involved in myelination. This project seeks to unravel the complex pathways for the synthesis of myelin lipids and their roles in myelin maintenance and function, as well as in cell signaling that controls proper myelination. Results obtained from this study will aid in developing better therapeutic agents for neurodegenerative diseases, such as multiple sclerosis.

描述（由申请人提供）：在高等脊椎动物中，髓鞘（一种包裹轴突的富含脂质的膜）极大地促进了神经传导。许多毁灭性的脱髓鞘疾病威胁着人类健康，并且几乎没有有效的治疗方法。为了更好地治疗这些疾病，我们必须了解髓鞘形成的机制。髓鞘是一种特殊的结构，具有不同的脂质和蛋白质成分。半乳糖神经酰胺（GalCer）和硫苷脂占总髓鞘脂质的约30%，这些半乳糖脂中有一半以上含有在C2位具有羟基的脂肪酸（2-OH半乳糖脂）。没有其他哺乳动物组织含有如此高浓度的2-OH脂肪酸，这表明2-OH半乳糖脂可能在创造髓鞘的特殊特性中起着至关重要的作用。尽管髓鞘中2-OH半乳糖脂的含量非常丰富，但对2-OH半乳糖脂的基本生物化学和生理作用的了解却令人惊讶地很少。本研究的总体目标是阐明髓鞘2-OH脂质的途径及其在髓鞘形成、髓鞘功能和细胞信号传导中的作用。最近鉴定的脂肪酸2-羟化酶FA 2 H为少突胶质细胞和雪旺细胞中髓鞘2- OH半乳糖脂的合成提供前体。FA 2 H和其他酶负责髓鞘形成过程中半乳糖脂中2-OH极长链（>C20）脂肪酸含量的增加。本项目的第一个目的是建立参与髓鞘半乳糖脂独特脂质组成的生物合成途径。将对FA 2 H进行广泛的生化分析，以确定其生理底物、辅因子和潜在的反馈机制。将通过分子遗传学方法鉴定脂肪酸延伸酶和二氢神经酰胺脱氢酶的同种型。最近，发现通过RNAi降低FA 2 H表达显著增强D 6P 2 T细胞的运动性。细胞2-OH也部分阻断了细胞周期蛋白依赖性激酶抑制剂p21和p27的上调，以响应分化的刺激。这些观察结果表明，2-OH脂质不仅是髓鞘的主要结构成分，而且还作为信号分子调节细胞分化和运动。在第二个目标中，将确定2-OH脂质在细胞分化和运动中的作用机制。将研究p21和p27的转录调节以确定由2-OH脂质调节的靶蛋白，并确定具有信号传导功能的2-OH脂质种类的分子身份。第三个目的是确定2-OH半乳糖脂在成人脑髓鞘功能和髓鞘再生中的作用。铜腙诱导的脱髓鞘/髓鞘再生将用于显示FA 2 H参与髓鞘再生。随后，将使用新获得的条件性FA 2 H敲除小鼠在成年脑中敲除FA 2 H。该模型将用于研究髓鞘形态，功能和髓鞘再生的情况下，2-OH脂质。为了开发更好的治疗破坏性脱髓鞘疾病的方法，我们必须了解髓鞘形成的机制。该项目旨在揭示髓鞘脂质合成的复杂途径及其在髓鞘维持和功能中的作用，以及控制适当髓鞘形成的细胞信号传导。从这项研究中获得的结果将有助于开发更好的神经退行性疾病，如多发性硬化症的治疗药物。