RI COBRE: ENDOCRINE AND NUTRITIONAL CONTROL OF LONG BONE GROWTH

RI COBRE：长骨生长的内分泌和营养控制

• 批准号: 8168036
• 负责人: Chanika Phornphutkul
• 金额: $ 19.62万
• 依托单位: RHODE ISLAND HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8168036
• 关键词: Affect; Anorexia Nervosa; Bone Growth; Cell Line; Cells; Child; Chondrocytes; Chondrogenesis; Computer Retrieval of Information on Scientific Projects Database; Crohn' s disease; Deposition; Developed Countries; Developing Countries; Differentiation and Growth; Endocrine; Epiphysial cartilage; Erinaceidae; Essential Amino Acids; Extracellular Matrix; Funding; Grant; Growth; Impairment; Institution; Lead; Leucine; Malnutrition; Mediating; Medical; Metatarsal bone structure; MicroRNAs; Modeling; Molecular; Nutrient; Nutritional; Nutritional status; Physiological; Regulation; Research; Research Personnel; Resources; Role; Signal Transduction; Source; System; United States National Institutes of Health; base; bone; bone health; fetal; long bone; mRNA Expression; mTOR protein

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Malnutrition remains a worldwide problem in developing countries. In developed countries, many medical conditions, ranging from anorexia nervosa to Crohn's disease, result in severe growth impairment in children. The objective of this study is to identify mechanisms by which nutrient availability, specifically leucine which is the most abundant essential amino acids, affects chondrocyte proliferation, differentiation, deposition of extracellular matrix (ECM) and their interactions. It has long been known that nutritional status effect linear growth by modulating GH/IGF-I axis. Recently signaling mechanism by which nutrients directly regulate cells via mammalian Target Of Rapamycin (mTOR) has been elucidated. We hypothesize that leucine directly regulates chondrogenesis directly by affecting chondrocyte proliferation, differentiation and ECM deposition, 3 key components of bone growth. Our hypothesis is based on our observations. First, mTOR directly regulates chondrogenesis. MTOR inhibition results in decreased expression of Indian hedgehog (Ihh), a key regulator of chondrogenesis. Decreased Ihh could be central to mTOR action. Regulation of Ihh by mTOR is a new observation. Second, leucine restriction and mTOR inhibition result in significant reduction of ECM mRNA expression likely via miRNA regulation. Lastly, we utilized an ex vivo metatarsal explant system to demonstrate the physiological relevance of observations we made in the chondrogenic ATDC5 cell line. Based on our preliminary findings, we propose the following specific aims. Specific Aim 1: Identify the molecular mechanisms that mediate the effect of mTOR inhibition and leucine restriction on Ihh regulation and, as a consequence, chondrocyte growth and differentiation. . Specific Aim 2: Determine the effect of mTOR inhibition and leucine restriction on miRNA-29 regulation resulting in altered ECM expression and functional role in chondrocyte growth and differentiation Specific Aim 3: Utilizing a fetal metatarsal explant model, we will study the effect of mTOR inhibition and leucine restriction on bone growth, growth plate dynamics and chondrogenic markers, in particular Ihh and miRNA-29. We will study the effect of restoring Ihh and miRNA-29 expression in bones subjected to mTOR inhibition and leucine restriction. Understanding the direct effect of nutrients on bone growth may lead to a better understanding of long term bone health as well as management of the impaired growth in nutrient restriction or related medical conditions.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 营养不良仍然是发展中国家的一个世界性问题。在发达国家，从神经性厌食症到克罗恩病等许多疾病都会导致儿童严重生长障碍。本研究的目的是确定营养物质的有效性（特别是最丰富的必需氨基酸亮氨酸）影响软骨细胞增殖、分化、细胞外基质（ECM）沉积及其相互作用的机制。人们早就知道营养状况通过调节 GH/IGF-I 轴来影响线性生长。最近，营养物质通过哺乳动物雷帕霉素靶点（mTOR）直接调节细胞的信号传导机制已被阐明。我们假设亮氨酸通过影响软骨细胞增殖、分化和 ECM 沉积（骨生长的 3 个关键组成部分）来直接调节软骨形成。我们的假设是基于我们的观察。首先，mTOR 直接调节软骨形成。 MTOR 抑制会导致软骨形成的关键调节因子 Indian Hedgehog (Ihh) 的表达减少。 Ihh 减少可能是 mTOR 作用的核心。 mTOR 对 Ihh 的调节是一个新的观察结果。其次，亮氨酸限制和 mTOR 抑制可能通过 miRNA 调节导致 ECM mRNA 表达显着减少。最后，我们利用离体跖骨外植体系统来证明我们在软骨形成 ATDC5 细胞系中进行的观察的生理相关性。根据我们的初步调查结果，我们提出以下具体目标。具体目标 1：确定介导 mTOR 抑制和亮氨酸限制对 Ihh 调节以及软骨细胞生长和分化影响的分子机制。 。具体目标 2：确定 mTOR 抑制和亮氨酸限制对 miRNA-29 调节的影响，从而改变 ECM 表达以及软骨细胞生长和分化中的功能作用 具体目标 3：利用胎儿跖骨外植体模型，我们将研究 mTOR 抑制的效果亮氨酸对骨生长、生长板动力学和软骨形成标记物（特别是 Ihh 和 miRNA-29）的限制。我们将研究在 mTOR 抑制和亮氨酸限制下恢复骨骼中 Ihh 和 miRNA-29 表达的效果。了解营养物质对骨骼生长的直接影响可能有助于更好地了解长期骨骼健康以及对营养限制或相关医疗条件下生长受损的管理。