DIFFERENTIATION OF TRANSPORT MECHANISMS IN LENS CELLS

晶状体细胞中传输机制的差异

• 批准号: 6179999
• 负责人: Nicholas A Delamere
• 金额: $ 25.73万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-01-01 至 2002-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6179999
• 关键词: RNase protection assay; SDS polyacrylamide gel electrophoresis; cell differentiation; electrolyte balance; enzyme activity; enzyme biosynthesis; epithelium; fiber cell; fibroblast growth factor; fluorescent dye /probe; ion transport; isozymes; laboratory rabbit; laboratory rat; lens; membrane permeability; microelectrodes; oxidative phosphorylation; prostaglandin E; protein biosynthesis; sodium potassium exchanging ATPase; western blottings

The project emphasizes the importance of the transport function of the antiporter Na, K-ATPase in maintaining ion homeostasis (Na+ and K+) in the whole lens. The fibers have Na,K-ATPase but the enzyme appears to be inactive save for those newly developed cortical fibers. AIM 1: determine if the lens epithelial cells synthesize new Na,K-ATPase by following labeled methionine incorporation into the transporter, determine if inhibition of protein synthesis or actinomycin D blocks the purported turnover. AIM 2 Determine if the epithelium D blocks the purported turnover. AIM 2 Determine if the epithelium selectively upregulates the Na,K-ATPase alpha 2 isoform thus increasing the pump activity. The up-regulation is though to be a physiological response to compromised permeability found in older lenses. Aim 3: Determine if depolarization triggers increased Na-K- ATPase a2 expression. Determine if depolarization triggers increased Na,K-ATPase a2 expression. Determine if the a2 isoform is insensitive to pump inhibition by increased [Ca]. The PI feels that this may be explained by the lack of a tyrosine phosphorylation site on the a2 isoform. Determine the extent to which the a2 isoform increases with age in human lenses - based on the view tht ionic changes accompany aging in the lens. Determine if isoform change in fibers occurs whenrat lens epithelial cells are induced to differentiate following exposure to fibroblast growth factor. Since fibers have low Na,K- ATPase activity, investigate what inactivtes Na,K-ATPase in the fibers with specific emphasis on possible tyrosine phosphorylation of Na,K- ATPase a1 protein. Determine if slow turnover of Na,K-ATPase in the fibers makes the enzyme susceptible tooxidative modification.

该项目强调了运输功能的重要性， Na，K-ATP酶在维持离子稳态（Na+ 和K+）在整个透镜中。 肌纤维有Na，K-ATPase， 酶似乎是无活性的，除了那些新开发的皮层， 纤维 目的1：确定透镜上皮细胞是否合成新的 Na，K-ATPase的标记甲硫氨酸掺入后， 转运蛋白，确定是否抑制蛋白质合成或放线菌素 D阻止了所谓的营业额。 目的2确定上皮是否 D阻止了所谓的营业额。 目的2确定上皮是否 选择性上调Na，K-ATP酶α 2亚型， 增加泵的活性。 上调虽然是一个 老年人对渗透性受损的生理反应 眼镜. 目的3：确定去极化是否触发Na-K- ATP酶a2表达。 确定去极化触发是否增加 Na，K-ATPase α 2表达。 确定a2亚型是否不敏感 增加[Ca]的泵抑制作用。 PI认为这可能是 这可以用A2上缺乏酪氨酸磷酸化位点来解释。 同种型 确定α 2亚型随着 人类晶状体的年龄--基于离子变化的观点 透镜老化。 确定纤维中是否发生亚型变化 当大鼠透镜上皮细胞被诱导分化时， 暴露于成纤维细胞生长因子。 因为纤维的钠钾含量低- ATP酶活性，研究什么使纤维中的Na，K-ATP酶失活 特别强调Na，K- ATP酶a1蛋白。 确定是否缓慢周转的Na，K-ATP酶， 纤维使酶易于氧化修饰。