Mechanisms regulating normal and ectopic endochondral ossification

正常和异位软骨内骨化的调节机制

• 批准号: 9900719
• 负责人: Maurizio Pacifici
• 金额: $ 36.68万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9900719
• 关键词: ACVR1 gene; Ablation; Accounting; Activins; Adult; Affect; Birth; Bone Morphogenetic Proteins; Burn injury; Cartilage; Cell Fractionation; Cell Surface Receptors; Cell surface; Cells; Child; Chondrocytes; Chondrogenesis; Complex; Data; Drosophila pros protein; Elements; Embryonic Development; Epiphysial cartilage; Family member; Flare; Fracture; Future; Genetic; Health; Heterotopic Ossification; Hypertrophy; Immunoprecipitation; Implant; In Vitro; Inflammation; Inflammatory; Injury; Lead; Light; Limb Bud; Mesenchymal; Modeling; Mus; Mutant Strains Mice; Mutation; Operative Surgical Procedures; Osteogenesis; Pathogenesis; Pathogenicity; Pathology; Pharmacology; Physiologic Ossification; Process; Proteins; Receptor Signaling; Regulation; Role; Severities; Signal Transduction; Site; Skeleton; Source; Stimulus; Structure; Surface; Testing; Transforming Growth Factor beta; Trauma; Wild Type Mouse; Work; activin A; base; bone; bone morphogenetic protein receptor type I; cartilaginous; crosslink; cytokine; healing; in vivo; insight; interest; live cell imaging; long bone; macrophage; mast cell; matrigel; member; mouse model; mutant; non-genetic; novel; progenitor; progressive myositis ossificans; receptor; recruit; rib bone structure; skeletal; spine bone structure; stem cells; targeted treatment

Endochondral ossification is the process by which long bones, ribs, vertebrae and other skeletal elements form and grow during embryogenesis and after birth. During this process, preskeletal mesenchymal cells condense and differentiate into cartilaginous anlaga that provide the template and framework of the future skeleton. Within these incipient structures, the chondrocytes become organized in growth plates, undergo maturation and hypertrophy, and pave the way for endochondral bone formation. This critical multi- step process is recapitulated in healing of most bone fractures, but can also be usurped in pathologies such as heterotopic ossification. HO consists of formation of endochondral bone that forms and accumulates at ectopic sites and causes many health problems. One form of HO is common and non-genetic and is triggered by trauma, invasive surgeries and ensuing inflammation. A congenital, severe and often fatal form of HO is initiated by local flare-ups and is driven by activating mutations in ACVR1 encoding the type I bone morphogenetic protein (BMP) receptor ALK2. Up until recently, the acquired and congenital forms of HO were thought to follow the same pathogenic cascade given that they both involve an initial inflammatory stage and a subsequent endochondral process. However, recent studies by others suggested that congenital HO is caused by activin A, normally an antagonist of BMP/canonical signaling that in this condition, however, would interact with mutant ALK2 and elicit pSMAD1/5/8 signaling. If correct, the data would imply that genetic and non- genetic forms of HO are distinct processes distinguishable by the manner in which they are triggered at cell level and may require distinct therapies. Because we have long been working on the pathogenesis of genetic and non-genetic forms of HO and have a vested interest, we carried out preliminary studies to further assess those recent studies. We found that activin A is actually abundantly expressed in both non-genetic and genetic HO in mouse models, greatly stimulates chondrogenesis in wild type preskeletal mesenchymal cells, and promotes HO in wild type mice. These and other data lead to the central premise of this project that both genetic and non-genetic forms of HO involve, and are promoted by, activin A. The greater severity of genetic HO would result from greater responsiveness of mutant chondrogenic progenitors to activin A and unruly mutant ALK2 signaling and action, but both non-genetic and genetic forms of HO would be amenable to an anti-activin A-based therapy. Our Aims are: (1) To clarify the mechanisms of activin A action in chondrogenesis; (2) To determine activin A receptor composition and cell surface dynamics; and (3) To genetically test the roles of activin A in HO and its usefulness as a therapy target. We anticipate this project will provide novel insights into the pathogenesis of genetic and non-genetic forms of HO and also fundamental basic insights into the regulation of endochondral ossification. It will also provide a springboard toward an effective universal therapy for HO in both children and adults.

软骨内骨化是指长骨、肋骨、椎骨和其他骨骼 元素在胚胎发育和出生后形成和生长。在这一过程中，骨前间充质 细胞凝聚和分化为软骨孔，提供了模板和框架 未来的骷髅。在这些初生的结构中，软骨细胞形成生长板， 经历成熟和肥大，为软骨内骨形成铺平道路。这一关键的多- 步骤过程在大多数骨折的愈合过程中被概括，但也可以在病理中被篡改，例如 异位骨化。HO包括在异位处形成并聚集的软骨内骨 并导致许多健康问题。一种形式的HO是常见的非遗传性的，由 创伤、侵入性手术和随之而来的炎症。一种先天性的、严重的、通常是致命的HO形式 由局部突发引发，由编码I型骨的ACVR1的激活突变驱动 形态发生蛋白受体ALK2。直到最近，后天的和先天的HO是 被认为遵循相同的致病级联，因为它们都涉及初始炎症阶段和 随之而来的软骨内过程。然而，最近其他人的研究表明，先天性HO是由 通过激活素A，通常是BMP/Canonical信号的拮抗剂，然而，在这种情况下，将相互作用 与突变型ALK2结合，诱导pSMAD1/5/8信号转导。如果正确，数据将暗示基因和非基因 HO的遗传形式是不同的过程，通过它们在细胞中被触发的方式来区分 水平，可能需要不同的治疗方法。因为我们长期以来一直致力于研究遗传病的发病机制 和非遗传形式的HO，并有既得利益，我们进行了初步研究，以进一步评估 那些最近的研究。我们发现激活素A实际上在非遗传性和遗传性中都大量表达 在小鼠模型中，HO极大地刺激野生型骨骼前间充质细胞的软骨形成，以及 在野生型小鼠中促进HO。这些数据和其他数据导致了该项目的中心前提是 遗传性和非遗传性HO涉及激活素A，并由激活素A促进。 HO可能是由于突变的软骨祖细胞对激活素A和不守规矩的更大的反应性所致 突变的ALK2信号和作用，但非遗传和遗传形式的HO将服从于 以抗激活素A为基础的治疗。我们的目标是：(1)阐明激活素A的作用机制 软骨形成；(2)测定激活素A受体组成和细胞表面动力学；以及(3) 从基因上测试激活素A在HO中的作用及其作为治疗靶点的有效性。我们预计这个项目将 为遗传性和非遗传性HO的发病机制提供新的见解，也为基础 对软骨内骨化调节的基本见解。它还将提供迈向 对儿童和成人的HO有效的普遍治疗。