Regulation of Lens Cell Coupling and Differentiation

晶状体细胞耦合和分化的调节

• 批准号: 7189830
• 负责人: LINDA S MUSIL
• 金额: $ 29.21万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7189830
• 关键词: Address; Behavior; Biochemical; Biological; Biological Assay; Cataract; Cell Adhesion Molecules; Cell Communication; Cell Culture System; Cell Differentiation process; Cell Line; Cell Nucleus; Cell membrane; Cell surface; Cells; Complication; Connexins; Coupling; Crystallins; Data; Defect; Development; Differentiation Antigens; Differentiation and Growth; Diffuse; Down-Regulation; Embryo; Employee Strikes; Endocytosis; Endoglycosidases; Epithelial; Epithelial Cells; Epithelium; Event; Excision; Extracellular Signal Regulated Kinases; Fiber; Fibroblast Growth Factor; Gap Junctions; Giant Cells; Goals; Growth Factor; Health; Homeostasis; Human; In Vitro; International; Investigation; Length; Lens Fiber; Link; Lysosomes; Mammalian Cell; Maps; Measures; Mediating; Metabolic; Mitogen-Activated Protein Kinases; Modeling; Modification; Molecular; NCAM1 gene; National Eye Institute; Numbers; Operative Surgical Procedures; Pathway interactions; Peripheral; Polysialic Acid; Principal Investigator; Process; Protein Biosynthesis; Proteins; Rate; Rattus; Recombinants; Regulation; Reporting; Research; Residual state; Rodent; Role; Serum; Signal Transduction; Signal Transduction Pathway; Structure; Surface; System; Techniques; Ubiquitin; Up-Regulation; Vision; Visual impairment; Vitreous body structure; Vitreous humor; Xenopus oocyte; bone morphogenic protein; cell type; endo-alpha-sialidase; fiber cell; gap junction channel; in vivo; inhibitor/antagonist; insight; intercellular communication; lens; lens gap junction; lens transparency; multicatalytic endopeptidase complex; novel; polysialyl neural cell adhesion molecule; prevent; programs; response; small molecule

DESCRIPTION (provided by applicant): Defects in lens differentiation or homeostasis can result in cataract, the major cause of visual impairment in humans. An understanding of the mechanisms that control lens development and maintain lens transparency is therefore an essential part of addressing a major international health issue. Gap junctions participate in joining lens epithelial and fiber cells into a metabolic and ionic syncytium essential for lens clarity. The highest level of gap junction-mediated intercellular coupling (GJIC) in the lens is at the equator, the region where epithelial cells differentiate into secondary fibers. The applicant has previously developed a serum-free system to culture primary embryonic chick lens cells from the peripheral epithelium, the cell type that in vitro most closely recapitulates the in vivo processes of epithelial-to-fiber differentiation and fiber-type gap junction formation. We have reported that in this system, FGF (either recombinant or from vitreous humor) upregulates the expression of the fiber differentiation markers examined and increases GJIC in parallel but at least partially independent processes. FGF activity was shown to diffuse out of intact vitreous bodies, the major in vivo reservoir of growth factors for the lens. These and additional studies led to a novel model of how FGF-mediated sustained activation of the ERK MAP kinase contributes to the asymmetry of GJIC believed to be essential for lens clarity (Le and Musil 2001 J Cell Biol 154:197-216). Preliminary results presented in this application provide the first evidence that BMP also upregulates fiber marker expression and (synergistically with FGF) GJIC in cultured lens cells, and that vitreous humor contains a diffusible BMP-like activity. Other studies support the novel hypothesis that epithelial-to-fiber differentiation may be modulated by a unique postranslational modification (polysialylation) of the cell adhesion molecule NCAM. The goals of the proposed studies are: (1) to investigate the signal transduction pathways by which FGF and/or BMP upregulate GJIC and fiber marker expression in cultured chick and rat lens cells, and elucidate the role of vitreous humor-derived BMP in these processes in vivo; (2) to study how FGF and/or BMP upregulate GJIC without increasing gap junction channel number; (3) to determine the role of NCAM polysialylation in epithelial-to-fiber differentiation; and (4) to utilize my expertise in gap junction formation and degradation to investigate how the turnover of lens gap junctions is decreased from a t1/2 less than or equal too 5 h to being stable for years upon differentiation of epithelial cells to mature fibers. These studies will provide new insights into how growth factor signaling and cell-cell interactions contribute to the unique structure and function of the lens.

描述（由申请人提供）：透镜分化或稳态缺陷可导致白内障，这是人类视力损害的主要原因。因此，了解控制透镜发育和保持透镜透明度的机制是解决重大国际健康问题的重要组成部分。缝隙连接参与将透镜上皮细胞和纤维细胞连接成透镜清晰度所必需的代谢和离子合胞体。透镜中最高水平的间隙连接介导的细胞间偶联（GJIC）位于赤道部，即上皮细胞分化为次级纤维的区域。本申请人先前已经开发了一种无血清系统来培养来自外周上皮的原代鸡胚透镜细胞，该细胞类型在体外最接近地再现了上皮至纤维分化和纤维型间隙连接形成的体内过程。我们已经报道，在这个系统中，FGF（重组或从玻璃体液）上调纤维分化标志物的表达检查和增加GJIC平行，但至少部分独立的过程。FGF活性显示扩散出完整的玻璃体，透镜的生长因子的主要体内储库。这些和另外的研究导致了FGF介导的ERK MAP激酶的持续活化如何有助于GJIC的不对称性的新模型，GJIC的不对称性被认为是透镜透明度所必需的（Le和Musil 2001 J Cell Biol 154：197-216）。本申请中呈现的初步结果提供了第一个证据，即BMP还上调培养的透镜细胞中的纤维标记物表达和（与FGF协同）GJIC，并且玻璃体液含有可扩散的BMP样活性。其他研究支持新的假设，上皮纤维分化可能是由一个独特的翻译后修饰（聚唾液酸化）的细胞粘附分子NCAM调制。本研究的主要目的是：（1）探讨FGF和/或BMP上调培养的鸡和大鼠透镜细胞GJIC和纤维标记物表达的信号转导途径，并阐明玻璃体液来源的BMP在这些过程中的作用;（2）研究FGF和/或BMP上调GJIC而不增加缝隙连接通道数量的机制;（3）确定NCAM多聚唾液酸化在上皮向纤维分化中的作用;和（4）利用我在缝隙连接形成和降解方面的专业知识来研究透镜缝隙连接的周转是如何从t1/2小于或等于5小时，在上皮细胞分化为成熟纤维后稳定多年。这些研究将为生长因子信号传导和细胞-细胞相互作用如何促进透镜的独特结构和功能提供新的见解。