Role of NFAT in the Skeleton

NFAT 在骨骼中的作用

基本信息

批准号：
9146275
负责人：
Ernesto Canalis
金额：
$ 39.63万
依托单位：
UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-18 至 2020-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9146275
关键词：
Accounting Binding Proteins Biomechanics Bone Resorption Bone remodeling Cell model Cells Collagen Collagen Type I Disease Elements Event Exhibits Failure Gene Expression Gene Expression Regulation Goals Half-Life Health Homeostasis Hour Immune response In Vitro Inflammatory Response Investigation Laboratories Messenger RNA MicroRNAs Modeling Mus Mutant Strains Mice Mutation Nucleic Acid Regulatory Sequences Osteoblasts Osteogenesis Osteopenia Phenotype Physiology Play Positioning Attribute Post-Transcriptional Regulation Property Proteins RNA Sequences RNA-Binding Proteins Regulation Research Role Signal Transduction Skeleton T-Cell Activation Transcript Transgenic Organisms Uncertainty Up-Regulation Work bone bone mass cytokine gain of function in vivo inhibitor/antagonist mouse model mutant notch protein novel nuclear factors of activated T-cells osteoblast differentiation osteoclastogenesis promoter response skeletal tomography transcription factor

项目摘要

DESCRIPTION (provided by applicant): Investigations from our laboratory revealed that skeletal cells synthesize Nuclear factor of activated T- cells (NFAT)c1 through c4. Characterization of cells expressing constitutively active (ca) Nfatc1 or Nfatc2 indicates an inhibitory role of Nfat in osteoblastic differentiation and function. This was confirmed in vivo, ad transgenics expressing caNfatc2 in osteoblasts under the control of the type I α1 collagen promoter (Col3.6- Nfatc2) are osteopenic and have impaired bone formation. Studies in mouse models of global Nfatc2 inactivation are difficult to interpret because they have non-specific inflammatory responses and upregulation of various cytokines. To understand the function of Nfatc2 in osteoblasts, we obtained conditional Nfatc1loxP/loxP and created conditional Nfatc2loxP/loxP mice placing us in a unique position to establish its function, singly and in the context of the Nfatc1 inactivation. In accordance with the osteopenic phenotype of the Col3.6-Nfatc2 transgenics, inactivation of Nfatc1 or Nfatc2 in Osterix expressing cells resulted in an increase in cancellous bone volume. In independent studies, we discovered that Notch induces Nfatc2 expression in osteoblasts selectively and acts by post-transcriptional mechanisms. In a Notch2 gain-of-function model, Notch2Q2319X mutant mice exhibited osteopenia due to increased bone resorption and lack of a compensatory bone forming response. In this model, Nfatc2 is induced in osteoblasts and may account for the uncoupling of the two remodeling events. The goal of this project is to understand the function of Nfatc2 in cells of the osteoblastc lineage. For this purpose, we will study mouse and cellular models misexpressing Nfatc2 in cells of the osteoblastic lineage. Our specific aims are: 1) To establish the function of Nfatc2 in osteoblasts. To this end, the skeletal phenotype of conditional deletion mutants of Nfatc2, singly and in combination with Nfatc1, will be established in cells of the osteoblastic lineage using microcomputed tomography and bone histomorphometric analysis. In addition, we will examine the biomechanical properties of bone and study mechanisms responsible for the effects; 2) To establish the post-transcriptional control of Nfatc2 by Notch in osteoblasts. This Aim will define the control of Nfatc2 expression by Notch and identify RNA sequences, binding proteins and microRNAs responsible for Nfatc2 post-transcriptional regulation; and 3) To establish the contribution of Nfatc2 to Notch actions in osteoblasts and determine whether the Nfatc2 induction by Notch is responsible for the failure of Notch2Q2319X mutants to manifest a bone forming response to enhance bone resorption. To this end, the Notch2Q2319X phenotype will be examined in the context of the Nfatc2 inactivation. These investigations should clarify the function of Nfatc2 in cells of the osteoblastic lineage, and identify novel mechanisms by which the skeleton integrates distinct signals to regulate bone remodeling.

描述（由适用提供）：我们实验室的研究表明，骨骼细胞合成了活化的T细胞（NFAT）C1至C4的核因子。表达一致活性（CA）NFATC1或NFATC2的细胞表征表明NFAT在成骨细胞分化和功能中的抑制作用。在体内证实了这一点，在I型Iα1胶原蛋白启动子（Col3.6-NFATC2）的控制下，在成骨细胞中表达CANFATC2的AD转化学是骨质减少的，并且骨形成受损。在整体NFATC2失活的小鼠模型中的研究很难解释，因为它们具有非特异性炎症反应和各种细胞因子的上调。为了了解NFATC2在成骨细胞中的功能，我们获得了有条件的NFATC1LOXP/LOXP，并创建了有条件的NFATC2LOXP/LOXP小鼠，使我们处于独特的位置，可以单独地建立其功能，并在NFATC1灭绝的上下文中。根据Col3.6-NFATC2转化的骨质减少表型，在表达细胞中NFATC1或NFATC2失活导致取消骨体积的增加。在独立研究中，我们发现Notch有选择地诱导成骨细胞中的NFATC2表达，并通过转录后机制起作用。在Notch2功能获得模型中，Notch2Q2319X突变小鼠由于骨骼的分辨率增加和缺乏代偿性骨形成反应而表现出骨质减少。在此模型中，NFATC2在成骨细胞中诱导，可能解释了两个重塑事件的解偶联。该项目的目的是了解NFATC2在成骨细胞谱系细胞中的功能。为此，我们将研究成骨细胞谱系细胞中NFATC2的小鼠和细胞模型。我们的具体目的是：1）在成骨细胞中建立NFATC2的功能。为此，使用微观层析成像和骨骼组态学分析，将在成骨细胞谱系的细胞中单独建立NFATC2的条件缺失突变体的骨骼表型。此外，我们将研究骨骼和研究机制的生物力学特性。 2）在成骨细胞中建立Notch对NFATC2的转录后控制。该目标将通过Notch定义NFATC2表达的控制，并识别RNA序列，结合蛋白和负责NFATC2后转录后调节的MicroRNA； 3）建立NFATC2对成骨细胞中Notch作用的贡献，并确定Notch的NFATC2诱导是否负责Notch2Q22319X突变体的失败，无法表现出骨骼形成以增强骨骼分辨率的反应。为此，将在NFATC2失活的背景下检查Notch2Q2319X表型。这些研究应阐明NFATC2在成骨细胞谱系细胞中的功能，并确定骨骼整合不同信号以调节骨骼重塑的新机制。