COLLAGEN MRNAS & CRANIOFACIAL SKELETOGENESIS

胶原蛋白核磁共振谱

• 批准号: 2131888
• 负责人: HYUN-DUCK NAH-CEDERQUIST
• 金额: $ 4万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-02-01 至 1996-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2131888
• 关键词: RNA splicing; RNase protection assay; animal genetic material tag; cartilage development; chick embryo; chondrocytes; collagen; epiphysis; face; facial bones; gene expression; genetic promoter element; genetic transcription; genetic translation; head; in situ hybridization; messenger RNA; normal ossification; osteocytes; osteogenesis

Formation of the craniofacial skeleton appears to be far more complex than previously believed. For example, although both synchondroses (primary cartilage) and sutures and articulation (secondary cartilage) undergo endochondral ossification, they have different histological and biochemical profiles and different intrinsic growth potentials. In addition, although calvarial and facial bones appear to form by intramembranous ossification without cartilaginous primordia, we and other have observed transient expression of some cartilage-characteristic collagen genes during intramembranous ossification. The cellular and molecular mechanisms involved in the formation of primary and secondary cartilages and membranous bones of the craniofacial skeleton have not been elucidated. Collagens are crucial structural elements which determine the physicochemical properties of cartilage and bone. In addition, the genes encoding types I, II and III collagen may have additional functions in chondrogenesis that are unrelated to their roles in production of structural proteins. We have isolated two forms of a1(II) collagen mRNA produced by alternative splicing of the second exon; which encodes a cysteine-rich globular domain in the amino-propeptide. These two forms of alpha1(II) collagen mRNA are differentially expressed during chondrogenesis. In addition, alternative alpha2(I) and alpha1(III) collagen transcripts have been identified in cartilage. The cartilage a2(I) collagen mRNA is generated by transcription initiation from an alternative promotor, and the conceptual translation product of the mRNA is completely noncollagenous, indication from an alternative promotor, and the conceptual translation product of the mRNA is completely noncollagenous, indicating that it must have an alternative function in cartilage. The structure of the cartilage-specific type III collagen mRNA has not been completely determined. However, it is much too small to encode type III collagen; thus it may also have an alternative function in cartilage. In this application, we propose to use in situ hybridization and RNase protection assays to characterize the developing chick craniofacial skeleton in terms of the collagen mRNAs known to be important for chondrogenesis and osteogenesis, including the alternative mRNAs of the type I, II, and III collagen genes. We will compare the pattern of collagen gene expression in synchondroses (primary cartilage) and sutures and articulations (secondary cartilage) with that in the epiphyseal growth plate, which has been extensively characterized at the molecular and biochemical levels. We will also identify additional cartilage- characteristic collagen genes which are transiently expressed in differentiating calvaria (membranous bones). These experiments will permit us to further define the molecular mechanisms involved in endochondral ossification in primary and secondary cartilages and intramembranous ossification. More importantly, collective data from this project will form the foundation for a subsequent proposal regarding: 1) the functional roles of alternative type I, II and III collagen transcripts during normal and abnormal development of the craniofacial skeleton; and 2) the role of cartilage-characteristic collagen genes in intramembranous ossification.

颅面骨骼的形成似乎更为复杂 比以前相信的。 例如，尽管两个同步性 （主要软骨）和缝合线（次要软骨） 接受内软骨骨化，它们具有不同的组织学和 生化谱和不同的内在增长潜力。 在 补充，尽管颅骨和面部骨骼似乎是由 膜内骨化没有软骨原始，我们和 其他已经观察到某些软骨特征的瞬时表达 膜内骨化过程中的胶原蛋白基因。 细胞和 涉及主要和次级的分子机制 颅面骨骼的软骨和膜骨头尚未 被阐明了。 胶原是至关重要的结构元素，决定了 软骨和骨骼的物理化学特性。 另外，基因 编码I类型I，II和III胶原蛋白可能具有其他功能 软骨发生与它们在生产中的作用无关 结构蛋白。 我们已经隔离了两种形式的A1（II）胶原mRNA 通过第二个外显子的替代剪接产生；编码a 氨基肽中富含半胱氨酸的球状结构域。 这两种形式 α1（ii）胶原mRNA的含量差异 软骨发生。 此外，替代α2（i）和alpha1（iii） 胶原蛋白转录本已在软骨中鉴定出来。 软骨 A2（i）胶原mRNA是通过转录启动产生的 替代启动子和mRNA的概念翻译产物 是完全非胶原的，来自替代启动子的指示， mRNA的概念翻译产物完全是 非胶原性，表明它必须具有替代功能 软骨。 软骨特异性III胶原蛋白的结构 mRNA尚未完全确定。 但是，它太小了 编码III型胶原蛋白；因此，它也可能有替代 软骨的功能。 在此应用程序中，我们建议使用原位杂交和RNase 保护雏鸡颅面的保护测定法 就胶原蛋白mRNA而言，骨骼对 软骨发生和成骨，包括 I型，II和III胶原基因。 我们将比较 胶原蛋白基因表达（主要软骨）和缝合线 和邻二鼠（二次软骨） 生长板，已在分子上广泛表征 和生化水平。 我们还将确定其他软骨 - 特征性的胶原基因，在 区分瓦尔瓦里亚（膜骨头）。 这些实验会 允许我们进一步定义涉及的分子机制 初级和次要软骨中的内软骨软骨骨化以及 膜内骨化。 更重要的是，来自 该项目将构成后续提案的基础 关于：1）替代I型，II和III的功能作用 在正常和异常发育期间的胶原蛋白转录本 颅面骨骼； 2）软骨特征的作用 膜内骨化中的胶原蛋白基因。