NOVEL FACTORS THAT REGULATE GNRH NEURONAL DEVELOPMENT

促性腺激素释放激素（GnRH）神经元显示出独特的模式 神经元迁移和基因表达的过程。 它们起源于嗅板并迁移到前脑 在胚胎发育过程中。 控制这一点的机制 精确的迁移模式尚不清楚;然而，疾病 导致神经元迁移失败， 成熟 研究GnRH合成调节的能力是 随着GnRH产生细胞系的发展而发展：GT 1 -7细胞 来自前脑中的迁移后GnRH神经元， 丰富的GnRH，和Gn 10细胞来源于迁移的GnRH神经元， 嗅觉区产生少量的GnRH。 根据不同的表型 在这两种产生GnRH的细胞中，我们鉴定出不同的基因产物， GnRH表达 神经元迁移和发育的分子技术， 差异显示聚合酶链反应扩增。初始 研究鉴定了10个cDNA克隆，它们在两种细胞中唯一表达， GT 1 -7或Gn 10神经元细胞。 克隆Gn 8 -01被鉴定为“粘附 相关激酶”，方舟，一个新的受体酪氨酸家族的成员 激酶，其胞外结构域具有细胞粘附的特征 分子。 该cDNA在迁移性Gn 10细胞中表达，而在正常细胞中不表达。 在迁移后的GT 1 -7细胞中。 当引入GT 1 -7细胞时，方舟 选择性抑制GnRH基因表达。 初步研究表明 该方舟与其配体，生长停滞特异性基因6（Gas 6）， 在调节GnRH合成、保护 程序性细胞死亡和神经元迁移过程中的细胞-细胞接触。 该提案将定义细胞和分子机制， 在GnRH神经元细胞中介导方舟的作用。

Gonadotropin releasing hormone (GnRH) neurons display a unique pattern of a developmentally programmed neuronal migration and gene expression. They originate in the olfactory placode and migrate to the forebrain during embryologic development. The mechanisms that control this precisely timed pattern of migration are unknown; however, disorders that result in failure of neuronal migration cause defects in sexual maturation. The ability to study the regulation of GnRH synthesis was advanced with the development of GnRH producing cell lines: GT1-7 cells derived from postmigratory GnRH neurons in the forebrain that make abundant GnRH, and Gn10 cells derived from migratory GnRH neurons in the olfactory area that make little GnRH. Based on the different phenotype of the two GnRH producing cells, we identified gene products divergently expressed across GnRH neuronal migration and development using the molecular technique of differential display polymerase chain reaction amplification. Initial studies identified ten cDNA clones uniquely expressed in either the GT1-7 or Gn10 neuronal cells. Clone Gn8-01 was identified as "adhesion related kinase", Ark, a member of a novel family of receptor tyrosine kinases, whose extracellular domain has features of a cell adhesion molecule. This cDNA is expressed in the migratory Gn10 cells and not in the postmigratory GT1-7 cells. When introduced into GT1-7 cells, Ark selectively represses GnRH gene expression. Preliminary studies suggest that Ark together with its ligand, growth arrest specific gene 6 (Gas6), play specific roles in modulation of GnRH synthesis, protection from programmed cell death and cell-cell contact during neuronal migration. This proposal will define the cellular and molecular mechanisms that mediate Ark's action in GnRH neuronal cells.