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

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 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。 髓鞘由中枢神经系统（CNS）中的少突胶质细胞和外周神经系统（PNS）中的许旺细胞形成。 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。 本研究的总体目标是阐明髓鞘脂质在髓鞘形成和细胞信号传导中的作用，特别强调2-羟基半乳糖脂和细胞迁移。 髓鞘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2-OH脂肪酸作为其N-酰基链。 没有其他哺乳动物组织含有如此高浓度的2-OH脂肪酸。 髓鞘中高2-OH半乳糖脂含量的意义还没有完全理解，但目前的知识水平提供了令人兴奋的可能性。 虽然髓磷脂中2-OH半乳糖脂的惊人丰度已得到充分认可，但我们对2-OH半乳糖脂合成的了解有限。 为了填补这一空白，我们已经克隆并鉴定了人脂肪酸2-羟化酶基因FA 2 H，该基因在大脑中高度表达。 我们已经开发了灵敏的气相色谱/质谱法为基础的测定脂肪酸2-羟化酶活性和组织2-OH脂肪酸。 随后，我们提供了强有力的证据表明FA 2 H负责中枢神经系统和外周神经系统中髓鞘2-OH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FA 2 H敲低显著增强了神经鞘瘤细胞的迁移。 这些发现使我们进一步发展该项目，以研究FA 2 H和2-OH鞘脂在细胞信号传导中的作用。 除了髓磷脂项目，我们还成功地合作确定了FA 2 H和2-OH鞘脂在表皮中的作用，表皮是另一种具有高水平2-OH鞘脂的组织。 我们获得了强有力的证据表明，FA_2H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.