SC COBRE: REGULATION OF MAMMALIAN FATTY ACID ALPHA-HYDROXYLASE GENE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 在高等脊椎动物中，髓鞘极大地促进了神经传导，髓鞘是一种包裹在轴突周围的富含脂质的膜。髓鞘是由中枢神经系统(CNS)中的少突胶质细胞和周围神经系统(PNS)中的雪旺细胞形成的。许多毁灭性的脱髓鞘疾病威胁着人类的健康，而且几乎没有有效的治疗方法。为了开发更好的治疗这些疾病的方法，我们必须了解髓鞘形成的机制。这项研究的总体目标是阐明髓鞘脂类在髓鞘形成和细胞信号转导中的作用，特别是2-羟基半乳糖脂和细胞迁移。 髓鞘具有不同的脂肪和蛋白质成分。半乳糖基神经酰胺(GalCer)和硫脂约占髓磷脂总量的30%，其中一半以上的半乳糖脂含有2-OH脂肪酸作为N-酰基链。没有其他哺乳动物组织含有如此高浓度的2-羟基脂肪酸。髓鞘中高含量的2-羟基半乳糖脂的意义还没有完全被理解，但目前的知识状态提供了令人兴奋的可能性。 虽然髓鞘中含有丰富的2-羟基半乳糖脂，但我们对2-羟基半乳糖脂的合成知之甚少。为了填补这一空白，我们克隆并鉴定了在大脑中高表达的人类脂肪酸2-羟基酶基因FA2H。我们已经建立了基于脂肪酸2-羟基酶活性和组织2-羟基脂肪酸的灵敏的气相色谱/质谱仪分析方法。随后，我们提供了强有力的证据表明，FA2H在中枢神经系统和三叉神经节中都参与了髓鞘2-羟基半乳糖脂的合成。在这些研究中，我们证明了半乳糖脂的2-羟基化在髓鞘形成过程中显著增加。最近，我们发现FA2H基因敲除显著促进了神经鞘瘤细胞的迁移。这些发现促使我们进一步发展项目，研究FA2H和2-OH鞘脂在细胞信号转导中的作用。 除了髓鞘项目，我们还成功地开展了一项合作，以确定FA2H和2-羟基鞘磷脂在表皮中的作用，这是另一种含有高水平2-羟基鞘磷脂的组织。我们得到了强有力的证据，表明FA2H和2-OH鞘脂在表皮通透性屏障功能的形成中起着关键作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In higher vertebrates, nerve conduction is greatly facilitated by myelin, a lipid-rich membrane that wraps around the axon. Myelin is formed by oligodendrocytes in the central nervous system (CNS) and by Schwann cells in the peripheral nervous system (PNS). A number of devastating demyelinating diseases threaten human health, and few effective treatments exist. To develop better treatment for these diseases, we must understand the mechanisms involved in myelination. The overall goal of this study is to elucidate roles myelin lipids in myelination and cell signaling, with particular emphasis on 2-hydroxy galactolipids and cell migration. Myelin has 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 2-OH fatty acids as their N-acyl chains. No other mammalian tissues contain such high concentrations of 2-OH fatty acids. The significance of the high 2-OH galactolipid content in myelin is not fully understood, but the current state of knowledge offers exciting possibilities. While the striking abundance of 2-OH galactolipids in myelin has been well-recognized, our knowledge about the synthesis of 2-OH galactolipids is limited. To fill this gap, we have cloned and characterized the human fatty acid 2-hydroxylase gene, FA2H, that is highly expressed in brain. We have developed sensitive gas chromatography/mass spectrometry-based assays for fatty acid 2-hydroxylase activity and tissue 2-OH fatty acids. Subsequently, we have provided strong evidence that FA2H is responsible for the synthesis of myelin 2-OH galactolipids in both CNS and PNS. In these studies, we demonstrated that 2-hydroxylation of galactolipids dramatically increased during myelination. More recently, we found that FA2H knockdown significantly enhanced migration of Schwannoma cells. There findings led us to further develop the project to investigate roles of FA2H and 2-OH sphingolipids in cell signaling. In addition to the myelin project, we have developed a successful collaboration to determine the roles of FA2H and 2-OH sphingolipids in epidermis, which is another tissue with high levels of 2-OH sphingolipids. We obtained strong evidence that FA2H and 2-OH sphingolipids play critical roles in formation of permeability barrier function of epidermis.