Regulation of Skeletal Growth by Soft Tissue Extracellular Matrix

软组织细胞外基质对骨骼生长的调节

• 批准号: 9654509
• 负责人: Dirk Hubmacher
• 金额: $ 28.3万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9654509
• 关键词: Regulation; Skeletal; Growth; Soft; Tissue

ABSTRACT Short stature is a hallmark of several human Mendelian disorders caused by mutations in extracellular matrix (ECM) proteins. These include acromelic dysplasias, a group of rare disorders featuring short stature, short digits (brachydactyly), stiff joints, and a “pseudomuscular” build. Acromelic dysplasias are caused by dominant mutations in specific exons of fibrillin-1 (FBN1) or by recessive mutations in select ADAMTS and ADAMTSL proteins. Relevant to this proposal, the identical clinical manifestations of ADAMTSL2 and FBN1 mutations in one such disorder, geleophysic dysplasia, suggests that their gene products cooperate in a shared ECM pathway regulating postnatal limb growth. Previous work showed that ADAMTSL2 is a secreted glycoprotein that bound both fibrillin isoforms, FBN1 and FBN2, and was implicated in the regulation of TGF signaling. FBN2 microfibrils were increased in the ECM of a mouse model for geleophysic dysplasia, suggesting a role for ADAMTSL2 in switching from prenatal FBN2 microfibrils to postnatal FBN1 microfibrils. My preliminary data show that the limb-specific deletion of ADAMTSL2 in mice impairs skeletal growth similar to human acromelic dysplasias, with exacerbated distal limb shortening and reduced Achilles tendon length. ADAMTSL2 is not expressed in growth plate chondrocytes or bone cells, but has its strongest expression in tendon. This led to the hypothesis that non-autonomous postnatal growth impairment in a mouse model for geleophysic dysplasia is caused by the disruption of fibrillin microfibril function in tendon ECM due to impairment of the ADAMTSL2-mediated fibrillin isoform switch. Despite the rarity of geleophysic dysplasia, the non- autonomous regulation of skeletal growth governed by mechanical or regulatory properties of tendon ECM would constitute a novel mechanism determining final bone length. In aim 1, I will test the hypothesis by analysing postnatal limb growth and ECM alterations in the microfibril system after Adamtsl2 deletion in tenocytes (tendon) using Scx-Cre and in an Achilles tendon transection model. In aim 2, I will investigate how ADAMTSL2 interacts with FBN1 and FBN2 and how ADAMTSL2 executes its role in the isoform switch from FBN2 to FBN1. I will analyze the genetic interaction of Adamtsl2 with Fbn1 and Fbn2 in mice and I will use protein-protein interaction studies and cell culture systems to gain mechanistic insights in the function of ADAMTSL2 in regulating the fibrillin isoform switch. The anticipated results will provide novel insights into the pathophysiology of geleophysic dysplasia and are relevant to the pathophysiology of acromelic dysplasias and other human genetic disorders involving fibrillin microfibrils (fibrillinopathies). An important and related one among these is the Marfan syndrome, which affects 1-2 in 5000 individuals and shows long bone overgrowth. These insights could be translated in novel therapeutic strategies targeting the ECM during postnatal growth. In addition, this proposal addresses fundamental questions of how tissue-specific ECM is formed and how functional properties of soft tissues determined by ECM might regulate postnatal limb growth.

抽象的 身材矮小是由细胞外基质突变引起的几种人类孟德尔疾病的标志 （ECM）蛋白质。其中包括雅亲粒发育不良，一组罕见的疾病，身材矮小，短暂 数字（臂杆菌），僵硬的接头和“假肌肉”的构建。雅亲域的发育不良是由主导性引起的 原纤维蛋白-1（FBN1）的特定外显子中的突变或选择ADAMTS和ADAMTSL中的隐性突变 蛋白质。与该提案相关，ADAMTSL2和FBN1突变的相同临床表现 一种这种疾病，地球物理发育不良，表明其基因产物在共享的ECM中坐标 途径调节产后肢体生长。以前的工作表明ADAMTSL2是一种分泌的糖蛋白 结合了纤维蛋白同工型，FBN1和FBN2，并在TGF信号传导的调节中实现。 在地球物理发育不良的小鼠模型的ECM中，FBN2微纤维增加了，这表明作用 对于ADAMTSL2，在从产前FBN2微纤维切换到产后FBN1微纤维时。我的初步数据 表明小鼠ADAMTSL2的肢体特异性缺失会损害类似于人类雅亲骨的骨骼生长 发育不良，远端肢体缩短和跟腱长度降低。 Adamtsl2不是 在生长板软骨细胞或骨细胞中表达，但在肌腱中具有强烈的表达。这导致了 地球物理模型中非自主产后生长障碍的假设 发育不良是由于受损肌腱ECM中纤维蛋白微纤维功能的破坏引起的 ADAMTSL2介导的纤维蛋白同工型开关的。尽管地球物理发育不良罕见，但非 - 由肌腱ECM的机械或调节特性控制的骨骼生长的自主调节 将构成确定最终骨长的新机制。在AIM 1中，我将通过 分析ADAMTSL2缺失后，产后肢体生长和ECM改变 使用SCX-CRE和跟腱翻译模型中的弯曲细胞（肌腱）。在AIM 2中，我将调查如何 ADAMTSL2与FBN1和FBN2相互作用，以及ADAMTSL2如何从 FBN2至FBN1。我将分析小鼠中ADAMTSL2与FBN1和FBN2的遗传相互作用，我将使用 蛋白质 - 蛋白质相互作用研究和细胞培养系统，以获取机械洞察力 ADAMTSL2在调查原纤维蛋白同工型开关时。预期的结果将为您提供新颖的见解 胶质物质发育不良的病理生理学，与雅亲骨发育不良的病理生理学有关 其他涉及纤维蛋白微纤维（纤维蛋白原）的人遗传疾病。一个重要且相关的 其中是马凡氏综合征，它影响了5000个个体中的1-2，并且显示出长长的骨过度生长。 这些见解可以在针对产后生长期间针对ECM的新型治疗策略中转化。 此外，该建议还解决了如何形成组织特异性ECM的基本问题以及如何 由ECM确定的软组织的功能特性可能调节产后肢体生长。