HORMONE ACTION IN THE CENTRAL NERVOUS SYSTEM

这个项目的目标是通过对机制(S)的描述 哪种甲状腺激素调节肌动蛋白聚合，从而影响 中枢神经细胞内肌动蛋白细胞骨架的完整性 系统。因为肌动蛋白细胞骨架聚合的变化 会极大地影响 细胞骨架网络和细胞外基质，导致 神经元生长和发育的衰减，研究 T4与肌动蛋白细胞骨架的相互作用将为深入了解 甲状腺激素在神经元生长和分化中的作用。这个 要考察的模型系统是II型的T4依赖调节 5‘-脱碘酶(5’D-II)对cAMP刺激的神经胶质细胞的作用 细胞。T4通过调节这种重要的大脑皮层酶的水平 通过一种新的方法降低5‘D-II的生物半衰期， 核外的行动模式。微丝块的断裂 这种T4介导的作用，表明肌动蛋白细胞骨架是一种 可能是甲状腺激素调节的部位。5‘D-II可以是亲和力 由T4导数标记，因此可以在单元格中使用 免疫细胞化学和组织化学技术。形态上的 T4、肌动蛋白和5‘D-II之间的相互作用的特征将是 在这个项目的第一阶段完成。第二阶段 该项目将涉及甲状腺介体(S)的确定 激素对细胞骨架的影响。肌动蛋白与T4亲和力 层析将被用来分离潜在的肌动蛋白结合蛋白 然后在无细胞系统中进行评估，以评估他们的能力 以影响肌动蛋白聚合。与细丝肌动蛋白结合的蛋白质(S) 和T4，它们显示了T4对肌动蛋白聚合的调节作用 将通过2D SDS-PAGE和多肽图谱进一步表征和 与以前有关肌动蛋白结合蛋白的信息相比 描述。对S作用机制的鉴定与表征 其中T4与细胞骨架相互作用，从而调节 一种短暂的膜蛋白的周转，然后将允许研究 关于甲状腺激素影响的更基本的问题， 以及参与发育中神经元的生长和随后的 细胞-细胞和细胞-基质附着物的建立。

The goal of this project is the characterization of the mechanism(s) by which thyroid hormone regulates actin polymerization and, thus, affects the integrity of the actin cytoskeleton in cells of the Central Nervous System. Because alterations in polymerization of the actin cytoskeleton would significantly affects the complex interactions between the cytoskeletal network and the extracellular matrix, resulting in attenuation of neuronal growth and development, studies of the interactions of T4 with the actin cytoskeleton will provide insight into thyroid hormone's role in the growth and differentiation of neurons. The model system to be examined is the T4- dependent regulation of type II iodothyronine 5'-deiodinase (5'D-II) in cultured, cAMP-stimulated glial cells. T4 modulates levels of this important cerebrocortical enzyme by decreasing the biological half-life of 5'D-II through a novel, extra-nuclear mode of action. Disruption of the microfilaments blocks this T4-mediated action, indicating that the actin cytoskeleton is a likely site for regulation by thyroid hormone. 5'D-II can be affinity labeled by a T4 derivative and, thus, can be visualized in the cell using immunocytochemical and histochemical techniques. The morphological characterization of the interactions between T4, actin and 5'D-II will be accomplished during the first phase of this project. The second phase of the project will involve the identification of the mediator(s) of thyroid hormone's effects on the cytoskeleton. Actin and T4 affinity chromatography will be used to isolate potential actin- binding proteins which will then be evaluated in a cell free system to asses their ability to affect actin polymerization. Protein(s) that bind to filaments actin and T4 and that demonstrate a T4-modulated effect on actin polymerization will be characterized further with 2D SDS-PAGE and peptide mapping and compared to information available on actin-binding proteins previously described. The identification and characterization of the mechanism(s) by which T4 interacts with the cytoskeleton, and thereby regulates the turnover of a short-lived membrane protein, will then allow the study of the more fundamental questions regarding thyroid hormone's influence on, and participation in, the growth of developing neurons and the subsequent establishment of cell-cell and cell-substratum attachments.