SPARC and the Differentiation of Transparent Lens Fibers

SPARC 和透明透镜光纤的差异化

• 批准号: 6518699
• 负责人: JOHN Irwin CLARK
• 金额: $ 27.34万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6518699
• 关键词: cataract; cell adhesion; cell cell interaction; cell differentiation; cell migration; extracellular matrix proteins; fiber cell; gene expression; gene targeting; histogenesis; immunocytochemistry; laboratory mouse; lens; polymerase chain reaction; protein structure function; secretory protein; western blottings

DESCRIPTION (provided by applicant): SPARC (secreted protein acidic and rich in cysteine) is a major component of remodeling tissues and, as such, features prominently in morphogenesis, development, injury, and repair. It belongs to the matricellular class of secreted glycoproteins that, although structurally dissimilar, regulate interactions between cells and extracellular matrix (ECM). SPARC has been shown specifically to a) inhibit the cell cycle, b) prevent or disrupt cell adhesion, c) inactivate cellular responses to certain growth factors including basic fibroblast growth factor (bFGF or FGF2), d) regulate ECM production, e) bind to specific collagens including those of the basement membrane, and f) promote a rounded cell shape and reorganization of the actin cytoskeleton. These properties provide a strong rationale for a targeted disruption of the SPARC gene. Although SPARC -/- mice were viable and fertile, there were phenotypic abnormalities associated with connective tissue. The major, dominant phenotype, however, was the appearance of lenticular opacity at 1-2 mo. after birth and progression to mature cataracts by 8 mo. The explanation for the effect of SPARC on lens transparency in SPARC-null mice is unknown and forms the basis for this proposal. We will test the hypothesis that SPARC regulates lens epithelial cell differentiation via 1) its modulation of signaling pathway(s) activated by bFGF, and 2) its effects on lens cell-cell and cell-ECM (lens capsule) interactions. Our hypothesis is based on the following premises: a) throughout lens fiber differentiation, the basal surface of proliferating, migrating, and elongating fiber is directly attached to the ECM of the capsule, which contains SPARC, b) development and fiber differentiation are known to be regulated by FGF2, and c) cell differentiation in the lens is rigorously controlled from early in fetal development throughout the life of the animal (even minor perturbances are likely to be "recorded" as errors in the development of the lens that might not be apparent until adulthood, e.g., cataracts). The experiments proposed thus address the role of dysregulation in cell epithelium-ECM-interaction in lens transparency and afford a novel model for perturbations in differentiation that could be manifested later in life.

描述（由申请人提供）：SPARC（分泌的蛋白质酸性和富含 半胱氨酸）是重塑组织的主要组成部分，因此是特征 在形态发生，发育，损伤和修复方面显着。它属于 分泌的糖蛋白的母细胞类别，尽管在结构上 不同的，调节细胞与细胞外基质（ECM）之间的相互作用。 SPARC已专门显示a）抑制细胞周期，b）预防或 破坏细胞粘附，c）使细胞对某些生长的反应失活 包括基本成纤维细胞生长因子（BFGF或FGF2）在内的因素，d）调节 ECM生产，e）与特定的胶原蛋白结合，包括地下室的胶原蛋白 膜和f）促进肌动蛋白的圆形细胞形状和重组 细胞骨架。这些特性为目标提供了强大的理由 SPARC基因的破坏。尽管Sparc - / - 小鼠可行且肥沃，但 有与结缔组织有关的表型异常。这 然而，主要的，主要的表型是在 1-2 mo。出生后和成熟白内障后8个月。这 SPARC对SPARC-NULL小鼠晶状体透明度的影响的解释是 未知并构成了该提议的基础。我们将检验以下假设 SPARC通过1）调节晶状体上皮细胞分化 由BFGF激活的信号通路和2）其对透镜细胞细胞的影响 和细胞ECM（镜头胶囊）相互作用。我们的假设是基于 以下前提：a）在整个镜头纤维分化，基础表面 直接连接到增殖，迁移和伸长的纤维 胶囊的ECM，其中包含SPARC，b）发育和纤维 已知分化受FGF2调节，c）细胞分化 在整个镜头的早期，镜头都受到严格控制 动物的生活（即使是轻微的扰动也可能被“记录”为 镜头发展的错误，直到 成年，例如白内障）。提出的实验因此解决了 晶状体透明度和细胞上皮ECM相互作用的失调和 提供了一个新颖的模型，用于差异化的扰动 表现为后来的生活。