HIF-1alpha, a Survival and Differentiation Factor for Cartilage

HIF-1alpha，软骨的存活和分化因子

• 批准号: 8609400
• 负责人: Amato J. Giaccia
• 金额: $ 34.65万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-26 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8609400
• 关键词: Affect; Angiogenic Switch; Biochemical Reaction; Biology; Blood Vessels; Bone Development; Bone Diseases; Bone Regeneration; Cartilage; Cartilage Diseases; Cell Death; Cell Differentiation process; Cell Survival; Cells; Cessation of life; Chondrocytes; Chondrogenesis; Consumption; Disease; Ensure; Enzymes; Epiphysial cartilage; Extracellular Matrix; Fetal Growth; Genetic; Grant; HIF1A gene; Homeostasis; Hypoxia; Impairment; In Vitro; Investigation; Ischemia; Knockout Mice; Knowledge; Lead; Learning; Limb Bud; Malignant Neoplasms; Mediating; Mediator of activation protein; Mesenchymal; Mesenchymal Differentiation; Mesenchyme; Metabolic; Mitochondria; Molds; Molecular; Null Lymphocytes; Oxygen; Physical condensation; Reporting; Respiration; Respiratory Chain; Role; Signal Transduction; Staging; Testing; Tissues; base; bone; cartilage development; cartilage regeneration; hypoxia inducible factor 1; in vivo; insight; mouse model; mtTF1 transcription factor; mutant; novel; prevent; public health relevance; soft tissue; therapeutic target; transcription factor

ABSTRACT Oxygen (O2) is not only an indispensable metabolic substrate in various enzymatic reactions including mitochondrial respiration, but also a regulatory signal that controls stability and activity of !"#$transcription factor Hypoxia Inducible Factor-1¿ (HIF-1¿), a key mediator of the cellular adaptation to low O2 tension (hypoxia). The fetal growth plate is a unique mesenchymal tissue because it is avascular, albeit it requires the angiogenic switch in order to be replaced by bone. Over the years, we have demonstrated that, consistent with its avascularity, the fetal growth plate has an inner hypoxic region. We have provided genetic evidence that HIF-1¿ is a survival factor for hypoxic chondrocytes in vivo. We have shown that mesenchymal condensations of the limb bud are also hypoxic, and lack of HIF-1¿ in limb bud mesenchyme delays differentiation of mesenchymal cells into chondrocytes in vivo. In this grant, we propose to identify the molecular mechanisms that mediate the role of HIF-1¿ as a survival and differentiation factor in cartilage in vivo. Along these lines, we have reported that viable chondrocytes at the periphery of HIF-1¿ null growth plates and HIF-1¿ null mesenchymal condensations of the limb bud are considerably more hypoxic than controls. Moreover, we have provided genetic evidence that the extreme hypoxia of HIF-1¿ null cells is not the consequence of reduced availability of O2 to the growth plate. Therefore, we hypothesized it had to be the consequence of increased O2 consumption. Our hypothesis is in line with the well- documented ability of HIF-1¿ to impair mitochondrial respiration in vitro. Based on these findings, we now propose that a key function of HIF-1¿ is to reduce O2 consumption in cells that are already hypoxic because of limited availability of O2, in order to prevent them from becoming virtually anoxic, a status that is not compatible with cell survival and differentiation. Specifically, we hypothesize that HIF-1¿ is essential for survival of hypoxic chondrocytes and for timely differentiation of hypoxic mesenchymal cells into chondrocytes by negatively regulating mitochondrial respiration, and thus mitochondrial O2 consumption. We will test our hypothesis by inhibiting mitochondrial respiration in HIF-1¿ null chondrocytes (Specific Aim I) and in HIF-1¿ null mesenchymal cells of the limb bud (Specific Aim II) in vivo and in vitro. Moreover, we will establish whether HIF-1¿ lowers O2 consumption in chondrocytes in vitro (Specific Aim III). Our findings may lead to a paradigm shift if we determine that, differently from what has been reported in the context of well-oxygenated tissues, impairment of mitochondrial respiration is an indispensable requirement for survival and for early differentiation stages of hypoxic chondrocytes. $

抽象的 氧（O2）不仅是各种酶促反应中必不可少的代谢底物 线粒体呼吸，也是控制稳定性和活动的调节信号！”＃$转录因子 低氧诱导因子-1（HIF-1），这是细胞适应低O2张力（缺氧）的关键介体。 胎儿生长板是一种独特的间充质组织 为了用骨头代替。多年来，我们已经证明，与胎儿一致 生长板具有内部缺氧区域。我们提供了遗传证据，表明HIF-1是的生存因子 体内缺氧软骨细胞。我们已经表明，肢体芽的间充质冷凝也是低氧的， 肢体间充质中缺乏hif-1。延迟了间充质细胞在体内的软骨细胞中分化。 在这笔赠款中，我们建议确定介导HIF-1作为生存的作用的分子机制 体内软骨的分化因子。沿着这些线，我们报告了在 HIF-1？ 比对照组更缺氧。此外，我们提供了极端缺氧的遗传证据 HIF-1 null细胞的生长板对O2的可用性降低并不是降低的结果。因此，我们 假设这是O2消耗增加的结果。我们的假设符合良好 HIF-1。在体外损害线粒体呼吸的能力。根据这些发现，我们现在提出 HIF-1的关键功能是减少由于有限的细胞中已经缺氧的细胞消耗量 O2的可用性，以防止它们几乎没有缺氧，这种状态与细胞不兼容 生存和分化。具体而言，我们假设HIF-1€对于低氧生存至关重要 软骨细胞和及时分化低氧间充质细胞通过负面分化为软骨细胞 调节线粒体呼吸，从而调节线粒体O2的消耗。我们将通过 抑制hif-1 null软骨细胞中的线粒体呼吸（特定的目标I）和HIF-1 null间充质 肢体芽的细胞（特定AIM II）在体内和体外。而且，我们将确定HIF-1降低O2是否 体外软骨细胞的消耗（特定的目标III）。如果我们的发现可能会导致范式转变 确定，与在氧化组织良好的组织背景下报道的情况不同， 线粒体呼吸的损害是生存的必不可少的要求，并且 低氧软骨细胞的分化阶段。 $