Examination of the Pre-pubertal Mammalian Growth Plate

青春期前哺乳动物生长板的检查

• 批准号: 7247862
• 负责人: MICHELE Rebecca HUTCHISON
• 金额: $ 12.26万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7247862
• 关键词: Adolescent; Alkaline Phosphatase; Anatomy; Animals; Biological Assay; Biology; Bone Growth; Bos taurus; Cattle; Cell Density; Cell Fraction; Cell Proliferation; Cell Size; Cell model; Cells; Centrifugation; Characteristics; Child; Chondrocytes; Collagen; Data; Density Gradient Centrifugation; Development; Discrimination; Epiphysial cartilage; Erinaceidae; Exhibits; Fractionation; Genes; Glycogen; Glycogen (Starch) Synthase; Growth; Histologic; Hormone Responsive; Human; Hypertrophy; IGFBP5 gene; In Situ Hybridization; In Vitro; Insulin-Like Growth Factor Binding Protein 5; Insulin-Like Growth Factor I; Insulin-Like-Growth Factor I Receptor; Interphase Cell; MAP Kinase Gene; MEKs; Mediating; Mediator of activation protein; Messenger RNA; Metacarpal bone; Microarray Analysis; Modeling; Pathway interactions; Pattern; Physiology; Proliferating; Proteins; Public Health; Relative (related person); Rest; Reverse Transcriptase Polymerase Chain Reaction; Rodent; Rodent Model; Serum; Side; Signal Pathway; Signal Transduction; Signaling Molecule; Sirolimus; Small Interfering RNA; Somatomedins; Somatotropin; Stream; Techniques; Testing; Thinking; Thymidine; Time; Tyrosine; Western Blotting; base; cell type; density; fetal; inhibitor/antagonist; long bone; protein expression; response; size

DESCRIPTION (provided by applicant): Long bone growth in children is dependent on the constant and consistent proliferation and differentiation of chondrocytes at the growth plate. The orderly pattern of growth is regulated by a long list of both systemic and locally derived factors, including growth hormone (GH) and insulin-like growth factor-l (IGF-I). We have isolated chondrocytes from juvenile bovine metacarpals because we believe the bovine growth plate physiology approximates the human better than rodent models. The chondrocytes have been separated by density gradient centrifugation into fractions that correspond to the recognized zones of the growth plate, based on cell size, glycogen content and expression patterns of genes known to be differentially expressed in histologic growth plate zones (collagen X, alkaline phosphatase, Indian hedgehog, and IGFBP5). In short term primary cultures, all fractions exhibited significant baseline proliferative activity, but no response to GH. Also, IGF-I levels in bovine chondrocytes are extremely low, and are not increased by GH. All fractions responded to IGF-I with proliferation, and the degree of proliferation correlated with cell density and IGFBP5 expression; the fully differentiated hypertrophic cells responded the least to IGF-I. In addition, while in the high density cells IGF-I readily activated MAPK, IGF-I did not increase MAPK activity in the hypertrophic cells, suggesting that IGF-I had become de-coupled from MAPK with progressive differentiation. In other cell models, IGF-I has been proposed to provide divergent signals for both proliferation and differentiation, with the particular cellular response determined by the relative amounts of signaling molecules downstream of the IGF-I receptor. The overall aim of this project is to support our claim that GH has little direct effect at the growth plate, that systemic IGF-I is the main signal for proliferation, differentiation and hypertrophy in growth plate chondrocytes, and that the different signals mediated by IGF-I are managed by the relative levels of signaling molecules downstream of IGF-IR within the chondrocyte fractions. The relevance to public health is to better understand mechanisms regulating bone growth in children, by using cells from young non-rodent animals for in vitro studies.

描述（由申请人提供）： 儿童的长骨生长取决于生长板上软骨细胞的恒定和一致的增殖和分化。生长的有序模式受到全身和局部衍生因子的长期调节，包括生长激素（GH）和胰岛素样生长因子-L（IGF-I）。我们从青少年牛元素中分离了软骨细胞，因为我们认为牛生长板生理学比啮齿动物模型更好地近似人类。软骨细胞通过密度梯度离心分为分数分离为与生长板的公认区域相对应的分数，基于细胞大小，基因的糖原含量和基因表达模式，已知在组织学生长板区域中差异表达的基因（胶原蛋白X，collagaline phastase X，碱性磷酸盐酶，印度磷酸盐酶，印第安人HedgeDhog和igfbp5）。在短期的原发性培养物中，所有分数均表现出明显的基线增殖活性，但对GH没有反应。同样，牛软骨细胞中的IGF-I水平极低，GH不会增加。所有分数都以增殖对IGF-I响应，增殖程度与细胞密度和IGFBP5表达相关。完全分化的肥厚细胞对IGF-I的反应最少。此外，尽管在高密度细胞IGF-I很容易激活的MAPK中，IGF-I并未增加肥厚细胞中的MAPK活性，这表明IGF-I已与MAPK偶联而与MAPK进行了逐步分化。在其他细胞模型中，已提出IGF-I为增殖和分化提供不同的信号，其特定的细胞反应由IGF-I受体下游的信号分子的相对量确定。该项目的总体目的是支持我们的说法：GH在生长板上几乎没有直接影响，全身IGF-I是生长板软骨细胞中增殖，分化和肥大的主要信号，而由IGF-I介导的不同信号由IGF-ir信号分子的相对水平在Chondractions内部的信号分子中管理。与公共卫生的相关性是通过使用年轻非腐蚀动物的细胞进行体外研究，以更好地理解调节儿童骨骼生长的机制。