Heparan Sulfate in Skeletal Development and Diseases

硫酸乙酰肝素在骨骼发育和疾病中的作用

• 批准号: 7812498
• 负责人: YU YAMAGUCHI
• 金额: $ 66.85万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7812498
• 关键词: Ablation; Acetylglucosamine; Adult; Affect; Alleles; Biological Models; Bone Development; Bone Diseases; Cartilaginous exostosis; Cells; Chondrocytes; Chondrogenesis; Clinical; Defect; Deformity; Dependence; Development; Disease; Dissection; EXT1 gene; EXT2 gene; Embryo; Exhibits; Exostoses; Funding; Future; Gene Mutation; Genes; Genetic; Genotype; Glucuronic Acids; Grant; Heparan Sulfate Biosynthesis; Heparitin Sulfate; Hereditary Disease; Hereditary Multiple Exostoses; Human; Human Genetics; In Vitro; Individual; Knockout Mice; Lead; Life; Loss of Heterozygosity; Masks; Medical; Methods; Molecular Genetics; Mus; Mutant Strains Mice; Mutation; Osteogenesis; Pathogenesis; Pattern; Penetrance; Phenocopy; Phenotype; Physiology; Play; Production; Recovery; Regulation; Research; Resistance; Role; Signal Transduction; Skeletal Development; Specificity; Staging; Testing; Time; Tissues; United States National Institutes of Health; base; bone; bone mass; cell type; glycosyltransferase; human disease; insight; long bone; mouse model; novel; parent grant; public health relevance; research study; response; skeletal; skeletogenesis

DESCRIPTION (provided by applicant): This competitive revision application is in response to NOT-OD-09-058: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. Heparan sulfate (HS) plays essential roles in development of various tissues. To understand how HS functions during skeletal development is of a great clinical importance. Hereditary multiple exostoses (HME) is a genetic disorder characterized by the formation of multiple osteochondromas ("exostoses"), which affects several thousands of people in the US. Individuals with HME carry heterozygous mutations of EXT1 or EXT2, which jointly encode a glycosyltransferase essential for the biosynthesis of HS. Despite the identification of its causative genes, there are a number of enigmas and unanswered questions on the pathogenic mechanism of HME. One of the most puzzling questions is the stark discrepancy between human HME manifestations and the phenotype of mice carrying the same genotype. Most importantly, both Ext1 and Ext2 heterozygous mice, which are supposed to mimic human HME faithfully, are resistant to the development of exostoses, especially in long bones. We have recently made a surprising observation that our new Ext1 conditional knockout mice (Col2a1- CreERT;Ext1flox/flox), which is based on stochastic homozygous Ext1 deletion in a small fraction of chondrocytes, develop exostoses in long bones at a 100% penetrance and phenocopy other skeletal defects of human HME to a degree not seen in any of the previous mutant mice. This competitive revision proposes to add the fourth aim (Investigate the genetic and cellular mechanisms of HME using novel HME mouse models) to characterize these mutant mice. By these studies, we wish to establish the Col2a1-CreERT;Ext1flox/flox mouse as the first mouse model directly relevant to HME, determine the significance of loss-of-heterozygocity in the pathogenesis of HME, and obtain baseline information for the future study to elucidate the signaling defects underlying osteochondroma development. PUBLIC HEALTH RELEVANCE: Heparan sulfate is essential for normal bone development, as illustrated by the existence of the human genetic bone disorder hereditary multiple exostosis (HME), which is caused by mutations of genes essential for heparan sulfate biosynthesis. In this competitive revision, we will characterize our novel conditional knockout mouse model that exhibits unprecedented levels of phenotypic similarities with human HME. The proposed studies will establish a novel mouse model for HME and generate new insights into the pathogenic mechanism of this human disorder.

描述（由申请人提供）：此竞争性修订申请是对 NOT-OD-09-058 的回应：NIH 宣布恢复法案资金可用于竞争性修订申请。硫酸乙酰肝素（HS）在各种组织的发育中发挥着重要作用。了解 HS 在骨骼发育过程中如何发挥作用具有重要的临床意义。遗传性多发性外生骨疣 (HME) 是一种以形成多发性骨软骨瘤（“外生骨疣”）为特征的遗传性疾病，影响着美国数千人。患有 HME 的个体携带 EXT1 或 EXT2 的杂合突变，它们共同编码对 HS 生物合成至关重要的糖基转移酶。尽管已鉴定出其致病基因，但 HME 的致病机制仍存在许多未解之谜。最令人困惑的问题之一是人类 HME 表现与携带相同基因型的小鼠表型之间的明显差异。最重要的是，Ext1 和 Ext2 杂合小鼠应该忠实地模仿人类 HME，能够抵抗外生骨疣的发展，尤其是在长骨中。我们最近做了一个令人惊讶的观察，我们的新型 Ext1 条件敲除小鼠（Col2a1-CreERT；Ext1flox/flox）基于一小部分软骨细胞中的随机纯合 Ext1 缺失，在长骨中以 100% 的外显率出现外生骨疣，并且表现出人类 HME 的其他骨骼缺陷，其程度在之前的任何突变小鼠中都没有见过。此次竞争性修订建议添加第四个目标（使用新型 HME 小鼠模型研究 HME 的遗传和细胞机制）来表征这些突变小鼠。通过这些研究，我们希望建立Col2a1-CreERT;Ext1flox/flox小鼠作为第一个与HME直接相关的小鼠模型，确定杂合性缺失在HME发病机制中的重要性，并为未来的研究获取基线信息，以阐明骨软骨瘤发展背后的信号缺陷。 公众健康相关性：硫酸乙酰肝素对于正常骨骼发育至关重要，人类遗传性骨病遗传性多发性外生骨疣 (HME) 的存在就说明了这一点，该病是由硫酸乙酰肝素生物合成所必需的基因突变引起的。在这次竞争性修订中，我们将描述我们的新型条件敲除小鼠模型，该模型与人类 HME 表现出前所未有的表型相似性。拟议的研究将建立一种新的 HME 小鼠模型，并为这种人类疾病的致病机制提供新的见解。