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）：晶状体分化或稳态的缺陷可能导致白内障，这是人类视觉障碍的主要原因。因此，了解控制晶状体发展和维持晶状体透明度的机制是解决重大国际健康问题的重要组成部分。间隙连接参与将晶状体上皮细胞和纤维细胞连接成对晶状体清晰度必不可少的代谢和离子合胞体。透镜中的间隙连接介导的间隙介导的细胞间耦合（GJIC）的最高水平是在赤道，上皮细胞分化为二级纤维的区域。申请人先前已经开发了一种无血清系统，以培养周围上皮的原代胚胎鸡透镜细胞，该细胞类型在体外最紧密地概括了上皮纤维分化和纤维型间隙间隙连接形成的体内过程。我们报告说，在该系统中，FGF（重组或玻璃体幽默）上调了所检查的纤维分化标记物的表达，并在并联但至少部分独立的过程中增加了GJIC。 FGF活性被证明是从完整的玻璃体中扩散的，玻璃体是晶状体生长因子的主要体内储层。这些和其他研究导致了一个新的模型，即FGF介导的ERK MAP激酶如何持续激活有助于GJIC的不对称性，认为GJIC对镜片的清晰度至关重要（Le and Musil 2001 J Cell Biol 154：197-216）。本应用中提出的初步结果提供了第一个证据，即BMP还上调了纤维标记物的表达，并且在培养的晶状体细胞中（与FGF协同）GJIC（通过FGF协同作用），并且玻璃体幽默含有可扩散的BMP样活性。其他研究支持了新的假设，即可以通过细胞粘附分子NCAM的独特后倾斜后修饰（多酰基化）调节上皮到纤维分化。拟议的研究的目标是：（1）研究FGF和/或BMP在培养的雏鸡和大鼠透镜细胞中上调GJIC和纤维标记表达的信号转导途径，并阐明玻璃体幽默衍生的BMP在VIVO中这些过程中的作用； （2）研究FGF和/或BMP如何上调GJIC而不增加间隙连接通道编号； （3）确定NCAM多酰化在上皮到纤维分化中的作用； （4）要利用我在间隙结的形成和降解方面的专业知识来研究透镜间隙连接的周转如何从小于或相等5小时的T1/2降低到在上皮细胞区分到成熟纤维后稳定多年的稳定性。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晶状体的独特结构和功能提供新的见解。