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，其中包括肢端发育不良，这是一组以身材矮小、矮小为特征的罕见疾病。 手指（短指）、关节僵硬和“假肌肉”体形是由显性畸形引起的。 fibrillin-1 (FBN1) 特定外显子的突变或选定 ADAMTS 和 ADAMTSL 的隐性突变 与该提议相关的是，ADAMTSL2 和 FBN1 突变的临床表现相同。 一种这样的疾病，即地质物理发育不良，表明它们的基因产物在一个共享的 ECM 中合作 先前的研究表明 ADAMTSL2 是一种分泌型糖蛋白。 结合原纤维蛋白亚型 FBN1 和 FBN2，并参与 TGF 信号传导的调节。 FBN2 微纤维在凝胶物理发育不良小鼠模型的 ECM 中增加，表明 FBN2 微纤维的作用 ADAMTSL2 从产前 FBN2 微纤维转变为产后 FBN1 微纤维 我的初步数据。 表明小鼠肢体特异性缺失 ADAMTSL2 会损害骨骼生长，与人类肢端发育类似 发育不良，伴有远端肢体缩短和跟腱长度缩短，ADAMTSL2 则不然。 在生长板软骨细胞或骨细胞中表达，但在肌腱中表达最强。 地质物理学小鼠模型中非自主性出生后生长障碍的假设 发育不良是由于肌腱 ECM 中原纤维蛋白微原纤维功能受损所致 ADAMTSL2 介导的原纤维蛋白亚型转换尽管凝胶物理发育不良很少见，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 将构成一种确定最终骨骼长度的新机制。在目标 1 中，我将通过以下方式检验该假设。 分析 Adamtsl2 缺失后微纤维系统的出生后肢体生长和 ECM 变化 在目标 2 中，我将研究如何使用 Scx-Cre 和跟腱横断模型来研究肌腱细胞（肌腱）。 ADAMTSL2 与 FBN1 和 FBN2 相互作用，以及 ADAMTSL2 如何在异构体转换中发挥作用 FBN2 到 FBN1 我将分析 Adamtsl2 与 Fbn1 和 Fbn2 在小鼠中的遗传相互作用，并且我将使用 蛋白质-蛋白质相互作用研究和细胞培养系统，以获得有关蛋白质功能的机制见解 ADAMTSL2 调节原纤维蛋白亚型转换的预期结果将为我们提供新的见解。 凝胶体发育不良的病理生理学，与肢端发育不良的病理生理学相关 其他人类遗传性疾病原纤维微原纤维（原纤维病）是一种重要的涉及和相关疾病。 其中包括马凡氏综合症，每 5000 人中就有 1-2 人受此病影响，并表现出长骨过度生长。 这些见解可以转化为针对产后生长期间 ECM 的新治疗策略。 此外，该提案还解决了组织特异性 ECM 是如何形成以及如何形成的基本问题。 ECM 确定的软组织的功能特性可能会调节出生后肢体的生长。