Assembly and function of basement membrane proteins

描述(申请人提供)：基底膜是包围所有上皮细胞、内皮细胞、周围神经、肌肉细胞和脂肪细胞的特殊细胞外基质的薄片。它们被认为在过滤、组织完整性和区隔以及细胞黏附、增殖、迁移和分化中发挥作用。基底膜的缺陷导致了一系列人类疾病，而基因敲除小鼠的表型表明，基底膜在发育过程中和成熟组织中发挥着关键作用。这项研究的长期目标是了解基底膜在哺乳动物发育和生理中的作用，以及基底膜组成的异质性如何转化为体内的功能特异性。我们对所有基底膜的一个主要成分--层粘连蛋白特别感兴趣。我们之前的研究表明，广泛表达的层粘连蛋白Alpha5在包括胎盘形成和肾脏发育在内的多个发育过程中发挥着关键作用。此外，体内用嵌合层粘连蛋白替换α5表明，α5的球状(G)结构域是系膜细胞介导的肾小球毛细血管组织所必需的。在这里，我们将重点介绍层粘连蛋白α1和α5 G结构域在早期胚胎发育和胎盘形成中的作用。我们还将使用CRE/LOX技术确定胎盘形态发生缺陷的细胞来源。此外，我们将测试在层粘连蛋白α5基因敲除中观察到的缺陷部分源于BMP信号改变的假设，这可能是由于BMP或其拮抗剂与细胞外基质的异常相互作用造成的。这些研究的结果将导致关于层粘连蛋白在体内的组装和功能的新信息。

DESCRIPTION (provided by applicant): Basement membranes are thin sheets of specialized extracellular matrix that surround all epithelia, endothelia, peripheral nerves, muscle cells, and fat cells. They are thought to play roles in filtration, in tissue integrity and compartmentalization, and in cell adhesion, proliferation, migration, and differentiation. Defects in basement membranes are responsible for a diverse array of human diseases, and the phenotypes of knockout mice show that basement membranes play critical roles during development and in mature tissues. The broad, long term goals of the research proposed here are to understand 1) the functions of basement membranes in mammalian development and physiology, and 2) how heterogeneity in basement membrane composition translates into functional specificity in vivo. We are particularly interested in one major component of all basement membranes, laminin. We previously showed that laminin alpha5 which is widely expressed, plays a crucial role in multiple developmental processes, including placentation and kidney development. In addition, replacement of alpha5 with a chimeric laminin in vivo demonstrated that the globular (G) domain of alpha5 is required for mesangial cell-mediated organization of the kidney glomerular capillaries. Here we will focus on the roles of the laminin alpha1 and alpha5 G domains in early embryogenesis and in formation of the placenta. We will also determine the cellular origin of the placental morphogenesis defect using Cre/lox technology. In addition, we will test the hypothesis that defects observed in the laminin alpha5 knockout stem in part from alterations in BMP signaling, which could result from abnormal interactions of BMPs or their antagonists with the extracellular matrix. The results of these studies will lead to new information regarding the assembly and function of laminins in the in vivo setting.