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）不仅是各种酶促重新发挥的必不可少的代谢底物 线粒体呼吸，也是控制和稳定性和活动的调节信号 低氧诱导因子1。 （Hif-1），一种对低O2张力的细胞适应（缺氧）的关键介体 胎儿生长板是ACH间充质组织，尽管它需要血管生成开关 为了被骨头代替，我们已经证明，与胎儿一致 生长板有较低的调节。是一个生存因素 体内缺氧软骨细胞。 缺乏HIF-1？在肢体中，间充质延迟了间充质细胞在体内分为chonedrocytes。 在这项赠款中，我们建议确定介导HIF-1»作用的分子机制。作为生存 和体内软骨的区分因子。 HIF-1的外围无效生长板和HIF-1？肢体芽的空间充质凝结为 此外，我们还提供了比对照的高度缺氧。 hif-1¿零细胞并不是O2对生长板的可用性降低的结果 假设这必须是O2消耗增加的努力。 HIF-1的记录能力为了基于发现，我们提出了线粒体呼吸。 HIF-1的关键功能是为了减少细胞中的O2消耗，这是Allyady低氧元件的 O2的可用性，以防止它们具有虚拟性缺氧，该状态与CELEST兼容 生存与区分。对于低氧生存至关重要 软骨细胞和及时的低氧分化 调节Mitchondrial呼吸，从而调节线粒体O2的消耗。 抑制HIF-1中的线粒体呼吸空软骨细胞（特定目标I）和HIF-1中空间充质 肢体芽的细胞（特定的目标II）在体内和体外，我们将确定HIF-1？降低O2 体外软骨细胞的消费（特定的目标III）。 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 低氧软骨细胞的区分阶段。 $