Biology of cortical bone of long bones and calvarium: Role of Sfrp4 in periosteal bone formation

长骨和颅骨皮质骨生物学：Sfrp4 在骨膜骨形成中的作用

• 批准号: 10160871
• 负责人: FRANCESCA GORI
• 金额: $ 40.26万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-08 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10160871
• 关键词: Address; Adult; Affect; Biology; Bone Regeneration; Bone Surface; Calvaria; Cells; Characteristics; Clinic; Clinical; Collaborations; Defect; Deformity; Development; Diagnostic radiologic examination; Genes; Goals; Growth; Homeostasis; Human; Impairment; Individual; Injury; Killer Cells; Label; Lead; Limb structure; Mediating; Metaphyseal dysplasia Pyle type; Modeling; Molecular; Mus; Online Mendelian Inheritance In Man; Osteoblasts; Osteogenesis; PTH gene; Parathyroid Hormone Receptor; Patients; Periosteal Cell; Periosteum; Pharmaceutical Preparations; Phenotype; Physiological; Play; Population; Porosity; Process; Regenerative capacity; Regulation; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Skeleton; Source; Surface; Surgical sutures; Testing; Therapeutic; Therapeutic Intervention; Thick; Thinness; WNT Signaling Pathway; bone; bone fragility; bone healing; cathepsin K; clinically significant; cortical bone; fragility fracture; human disease; in vivo; inhibitor/antagonist; injury and repair; insight; long bone; loss of function mutation; mouse model; novel; novel sequencing technology; paracrine; progenitor; receptor; regeneration potential; regenerative; repair model; response; response to injury; skeletal; skeletal disorder; stem; stem cell function; stem cells

The periosteum plays a critical role in cortical bone expansion and homeostasis, has regenerative capabilities and responds to anabolic drugs. However, in spite of its clinical significance our basic understanding of periosteal cellular characteristics, local or paracrine regulatory factors as well as the specific mechanisms by which anabolic drugs regulate it, remain elusive. Thanks to powerful new sequencing technologies, a periosteal population of cells labeled by Cathepsin K (Ctsk+), which includes bona fide periosteal stem cells (PSCs) and non-stem periosteal progenitor (PP1 and PP2) cells has been recently identified in the long bones and calvarium, providing a great opportunity for studying the regulation and physiological relevance of the periosteum in skeletal phenotypes. In this context, our recent studies have established that loss of function mutations of the Wnt inhibitor SFRP4 lead to Pyle’s disease, a rare skeletal disease characterized by limb deformity and fragility fractures. Using the Sfrp4-/- mouse model we uncovered that Sfrp4 contributes to cortical bone expansion and homeostasis by regulating endosteal remodeling and periosteal formation. The studies proposed here are focused on the biology of the periosteal surface. Our objective is to identify the role of Sfrp4-mediated signaling in regulating its activity. We have found that Sfrp4+ cells in the periosteum constitute a specific pool of Ctsk+ “periosteal” progenitors (PP1 and PP2) and that Sfrp4 deletion alters the % of PSCs and PP2 cells. The goal of the studies proposed in Aim 1 is to address whether Sfrp4 regulates the expansion, differentiation and/or function of periosteal stem cells and progenitors and the mechanisms by which this occurs. Given that PTH is a potent stimulator of periosteal bone formation, the findings that PSCs, bona fide stem cells, express the PTH receptor together with the findings that PTH positively regulates Sfrp4 in the periosteum are of significance and may have clinical consequences for the treatment of Pyle’s disease patients. The goal of the studies proposed in Aim 2 is therefore to explore whether Sfrp4-Wnt mediated signaling cooperate with PTH to regulate periosteal formation. Compelling evidences have demonstrated that stem cells in the calvarium suture and periosteum serve as growth centers for bone formation during development and support bone repair in response to injury. In the calvarium PSCs are mainly within the suture, while PP2 cells are predominant in the calvarial periosteum outside of the suture and PP1 are found at both sites. Despite canonical and non-canonical Wnt signaling activation, the absence of Sfrp4 results in lack of new bone formation in response to injury. The goal of the studies proposed in Aim 3 is to explore the mechanism(s) by which Sfrp4+ cells contribute to the bone regenerative potential of stem cells/progenitors using calvarial defects as injury repair model. Analysis of signaling pathways regulating periosteal stem cells and progenitors may open novel and specific therapeutic options for human diseases associated with bone fragility and impaired bone healing and bone regeneration.

Perosteum在皮质骨扩展和稳态中起着至关重要的作用，具有再生能力 并回应合成代谢药物。但是，尽管具有临床意义，但我们对 骨膜细胞特征，局部或旁分泌调节因素以及特定机制 合成代谢药物对其进行调节，仍然难以捉摸。感谢强大的新测序技术， 由组织蛋白酶K（CTSK+）标记的细胞的骨膜群，其中包括真正的骨膜干细胞 （PSC）和非茎骨膜祖细胞（PP1和PP2）细胞最近已在长骨头中鉴定 和钙钙，为研究研究的监管和身体相关性提供了绝佳的机会 骨骼表型中的骨膜。在这种情况下，我们最近的研究确定了功能丧失 Wnt抑制剂SFRP4的突变导致Pyle氏病，这是一种罕见的骨骼疾病，以肢体为特征 畸形和脆弱性骨折。使用SFRP4 - / - 鼠标模型，我们发现SFRP4有助于皮质 骨扩展和体内平衡，通过调节内骨重塑和骨膜形成。研究 这里提出的重点是骨膜表面的生物学。我们的目标是确定 SFRP4介导的信号在确定其活性时。我们发现perosteum中的SFRP4+细胞构成 CTSK+“骨膜”祖细胞（PP1和PP2）的特定库，SFRP4删除会改变PSC的％ 和PP2细胞。 AIM 1提出的研究的目的是解决SFRP4是否调节扩展， 骨膜干细胞和祖细胞的分化和/或功能以及该机制的机制 发生。鉴于PTH是骨膜骨形成的潜在刺激剂，因此PSC，真正的发现 干细胞，表达PTH受体，以及PTH对SFRP4积极调节的发现 骨膜具有重要意义，可能对Pyle病的治疗产生临床后果 患者。因此，AIM 2中提出的研究的目的是探索SFRP4-WNT是否介导 与PTH的信号合作以调节骨膜形成。令人信服的证据表明 颅缝合线和骨膜中的干细胞充当生长中心 响应损伤的发展和支持骨修复。在瓦尔瓦里姆PSC中，主要在缝合线内， 虽然PP2细胞在缝合线外的钙化骨膜中占主导 站点。尽管规范和非典型的Wnt信号传导激活，但缺乏SFRP4导致缺乏新的 响应损伤的骨形成。目标3中提出的研究的目的是探索机制 SFRP4+细胞使用钙细胞/祖细胞的骨骼再生潜力有助于使用钙 作为伤害修复模型的缺陷。分析调节骨膜干细胞和祖细胞的信号通路 可以为与骨骼脆弱性相关的人类疾病打开新颖和特定的治疗选择 骨骼愈合和骨骼再生受损。