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.

摘要 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)proteins.这些包括肢端发育不良，一组罕见的疾病，特点是身材矮小， 手指（短指）、关节僵硬和“假肌型”体格。肢端发育不良是由显性 在选择的ADAMTS和ADAMTSL中的隐性突变 proteins.与此相关的是，ADAMTSL 2和FBN 1突变的相同临床表现， 其中一种疾病--胶质细胞发育不良，表明它们的基因产物在共同的ECM中相互协作 调节出生后肢体生长的途径。先前的工作表明ADAMTSL 2是一种分泌型糖蛋白 其结合TGF β 1和TGF β 2的同种型FBN 1和FBN 2，并参与TGF β 1信号传导的调节。 FBN 2微纤维在胶质细胞发育不良小鼠模型的ECM中增加，表明FBN 2微纤维在胶质细胞发育不良中的作用。 ADAMTSL 2从产前FBN 2微纤维转换为出生后FBN 1微纤维。我的初步数据 表明小鼠中ADAMTSL 2的肢体特异性缺失损害骨骼生长，类似于人类肢端病。 发育不良，远端肢体缩短加重，跟腱长度缩短。ADAMTSL 2不是 在生长板软骨细胞或骨细胞中表达，但在肌腱中表达最强。这导致 非自主性出生后生长障碍小鼠模型胶质瘤假说 发育不良是由于损伤导致肌腱ECM中的微纤维功能破坏而引起的 ADAMTSL 2介导的Ekalin亚型转换的机制。尽管胶状体发育不良的罕见，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 将构成决定最终骨长度的新机制。在目标1中，我将通过以下方式检验假设： 分析出生后肢体生长和微纤维系统中Adamts 12缺失后ECM的改变， 使用Scx-Cre和跟腱横断模型中的肌腱细胞（肌腱）。在目标2中，我将研究如何 ADAMTSL 2与FBN 1和FBN 2相互作用，以及ADAMTSL 2如何在从 FBN 2到FBN 1。我将在小鼠中分析Adamts 12与Fbn 1和Fbn 2的遗传相互作用， 蛋白质-蛋白质相互作用的研究和细胞培养系统，以获得机制的功能， ADAMTSL 2在调节β-内酰胺酶亚型开关中的作用。预期的结果将提供新的见解， 与肢端发育不良的病理生理学相关， 其他人类遗传性疾病，包括纤维蛋白微纤维（纤维蛋白病）。一个重要的和相关的 其中有马凡氏综合征（Marfan syndrome），其在5000个个体中影响1-2个，并表现出长骨过度生长。 这些见解可以转化为针对出生后生长期间ECM的新型治疗策略。 此外，该建议解决了组织特异性ECM是如何形成的以及ECM如何在细胞内形成的基本问题。 由ECM决定的软组织功能特性可能调节出生后肢体的生长。