FGF signaling during growth and mechanical adaptation of tendon-bone interfaces

腱-骨界面生长和机械适应过程中的 FGF 信号传导

基本信息

批准号：
10469630
负责人：
MEGAN Leigh KILLIAN
金额：
$ 41.06万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-15 至 2026-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10469630
关键词：
ACTA1 gene Alleles Behavior Biomechanics Bone Growth Cells Chemicals Chondrocytes Clinical Cytoskeleton Deformity Denervation Development Disease Embryo Epiphysial cartilage Equilibrium Extracellular Matrix FGFR1 gene FGFR3 gene Fibroblast Growth Factor Fibroblast Growth Factor Receptors Fibrocartilages Genetic Genotype Goals Growth Hypertrophy Impairment Joints Knock-out Knowledge Lead Ligands Light Limb structure LoxP-flanked allele Mechanics Mediating Modification Mus Muscle Muscle Contraction Mutation Osteoblasts Pathological fracture Phenocopy Phenotype Physiologic pulse Population Property Reporter Role Secondary to Signal Pathway Signal Transduction Skeletal Muscle Skeleton Source Specificity Structure Techniques Tendon structure Testing Tissues United States National Institutes of Health Work bone bone loss fibroblast growth factor 9 gain of function healing in vivo innovation loss of function mechanical load mouse model mutant neonatal mice neonate nerve supply novel optogenetics postnatal progenitor receptor response skeletal stem cells tendon development therapeutic target tomography tool

项目摘要

ABSTRACT The tendon-bone interface is a structurally graded fibrocartilage interface that is critical for transducing mechanical loads from muscle to the skeleton. Reduced muscle loading can lead to impaired interface growth and skeletal deformities. Recently, we have shown that the size of tendon-bone interfaces in the embryonic mouse limb are negatively regulated by fibroblast growth factor 9 (FGF9), and skeletal muscle-specific knockout of FGF9 phenocopies the effects we see in global FGF9 mutants. These strong preliminary findings have led us to hypothesize that FGF signaling, mediated by muscle specific FGF9, contributes to interface growth in a non- cell autonomous manner. However, it remains unclear if and how FGF signaling between adjacent muscle, tendon, and bone alters the behavior of interface progenitor cells, or whether interface growth is secondary to FGF-mediated changes to mechanical loading from muscle. In this proposal, we will use innovative mouse models for FGF ligand- and receptor-loss of function (LOF) and gain-of-function (GOF) in tissue-specific Cre alleles to isolate the cell population required for FGF-induced changes. We will rigorously compare the structural (i.e., microcomputed tomography), cellular/ECM (i.e., histomorphology) and biomechanical properties (i.e., tensile, indentation tests) of the tendon-bone interface in LOF/GOF genotypes and controls. We will test FGFR- dependent mechanoresponsive structural adaptation of interfaces following muscle unloading using chemical denervation or increased muscle loading using optogenetic stimulation. In this project, we will use innovative, in vivo optogenetics to induce repetitive skeletal muscle contraction in neonatal mice using pulsed blue light, a technique we established with recent NIH R03 support. This approach, combined with novel FGFR LOF/GOF mouse models, will allow us to determine the role of FGF signaling in muscle loading induced adaptation of the tendon-bone interface. We aim to (1) demonstrate muscle-derived Fgf9 is responsible for regulating the development of tendon-bone interfaces during embryonic and postnatal growth and (2) Establish the mechanism by which cell-specific FGF signaling regulates loading-induced structural adaptations of tendon-bone interfaces. This R01 proposal will establish the non-cell autonomous contributions of Fgf9 in interface growth and structure/function of tendon-bone interfaces as well as the cell autonomous roles of FGFR signaling in interface growth and mechanical adaptation. Additionally, findings from this work will identify both conserved and unique downstream signaling pathways associated with FGF receptors that guide postnatal growth of tendon-bone interfaces.

抽象的腱-骨界面是结构分级的纤维软骨界面，对于传导至关重要从肌肉到骨骼的机械负荷。肌肉负荷减少可能导致界面生长受损和骨骼畸形。最近，我们发现胚胎时期肌腱-骨界面的大小小鼠肢体受到成纤维细胞生长因子 9 (FGF9) 和骨骼肌特异性敲除的负调节 FGF9 表型复制了我们在全球 FGF9 突变体中看到的效果。这些强有力的初步发现使我们假设由肌肉特异性 FGF9 介导的 FGF 信号传导有助于非细胞自主方式。然而，目前尚不清楚相邻肌肉之间是否以及如何 FGF 信号传导，肌腱和骨骼改变了界面祖细胞的行为，或者界面生长是否是继发性的 FGF 介导的肌肉机械负荷变化。在这个提案中，我们将使用创新的鼠标组织特异性 Cre 中 FGF 配体和受体功能丧失 (LOF) 和功能获得 (GOF) 模型等位基因以分离 FGF 诱导变化所需的细胞群。我们将严格比较结构（即微计算机断层扫描）、细胞/ECM（即组织形态学）和生物力学特性（即 LOF/GOF 基因型和对照中肌腱-骨界面的拉伸、压痕测试）。我们将测试 FGFR- 使用化学物质卸载肌肉后界面的依赖机械响应结构适应使用光遗传学刺激去神经或增加肌肉负荷。在这个项目中，我们将使用创新的、体内光遗传学利用脉冲蓝光诱导新生小鼠重复骨骼肌收缩我们在最近 NIH R03 支持下建立的技术。这种方法与新颖的 FGFR LOF/GOF 相结合小鼠模型，将使我们能够确定 FGF 信号在肌肉负荷诱导的适应中的作用腱-骨界面。我们的目标是 (1) 证明肌肉来源的 Fgf9 负责调节胚胎和出生后生长过程中肌腱-骨界面的发育以及（2）建立机制细胞特异性 FGF 信号传导通过其调节负荷诱导的肌腱-骨界面的结构适应。该 R01 提案将确定 Fgf9 在界面生长和腱-骨界面的结构/功能以及界面中FGFR信号传导的细胞自主作用生长和机械适应。此外，这项工作的结果将确定保守的和独特的与指导腱骨出生后生长的 FGF 受体相关的下游信号通路接口。