Sp7 Mediated Control of Runx2 Function for Osteoblast Differentiation

Sp7介导的Runx2功能对成骨细胞分化的控制

基本信息

批准号：
8427272
负责人：
Amjad Javed
金额：
$ 31.31万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-03-01 至 2017-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8427272
关键词：
Ablation Address Affinity Anatomy Animals BMP2 gene Biochemical Biological Biological Process Biology Bone Diseases Bone Matrix Bone Morphogenetic Proteins Bone Regeneration Bone Tissue Cartilage Cartilage Diseases Cell Differentiation process Cell Maturation Cell model Cells Chondrocytes Cleidocranial Dysplasia Complex Cues DNA Binding DNA Binding Domain Data Deposition Development Differentiation and Growth Embryo Erinaceidae Event Failure Family Functional disorder Gene Deletion Gene Expression Gene Expression Profile Gene Targeting Genes Genetic Genetic Transcription Goals Growth Human In Situ Hybridization Inherited Innovative Therapy Intervention Knockout Mice Knowledge MAP Kinase Gene Maintenance Mammals Mediating Mesenchymal Metabolic Bone Diseases Modeling Modification Molecular Molecular Biology Monitor Mus Mutagenesis Mutation Null Lymphocytes Osteoblasts Osteogenesis Pathway interactions Pattern Phenotype Process Protein Biochemistry Proteins RNA Regulation Research Role Runx2 protein Signal Transduction Skeleton Specific qualifier value Specificity Subgroup Testing Tissues To specify Ubiquitin Ubiquitination Vertebrates Work Zinc Fingers base bone bone cell improved in vivo insight interdisciplinary approach intramembranous bone formation mineralization morphogens multicatalytic endopeptidase complex mutant novel osteoblast differentiation osteogenic osteoprogenitor cell prevent protein function reconstitution repaired skeletal skeletal disorder skeletal tissue skeletogenesis stable cell line transcription factor ubiquitin ligase

项目摘要

DESCRIPTION (provided by applicant): Development of skeleton in mammals is an exceedingly complex process and involves both intramembranous and endochondral ossification. Completion of either class of ossification implies a highly intricate but well coordinated process of patterning, cell fate commitment, differentiation, growth and remodeling. These events are specified by a coordinated temporal and spatial pattern of gene expression. At first, secreted morphogens such as bone morphogenetic proteins, hedgehog, wingless proteins and others, signal to key transcription factors to specify gene expression. Runx2 is an essential transcription factor for chondrocyte and osteoblast differentiation. Runx2 gene deletion results in complete failure of skeleton formation and embryonic lethality. In humans, mutation of Runx2 gene causes cleidocranial dysplasia, a dominantly inherited skeletal disorder. Other master regulator of skeletogenesis is the Specificity protein-7 (Sp7). Sp7 belongs to the Sp subgroup of the Kruppel-like family of transcription factors characterized by three zinc-finger DNA-binding domains. Targeted disruption of Sp7/Osterix gene, results in absence of endochondral and intramembranous bone formation. The Sp7 deficient mesenchymal cells do not deposit bone matrix and cannot differentiate into osteoblasts. Very little is known about the underlying molecular mechanism for the surprisingly similar phenotype from the two seemingly unrelated proteins. Runx2 is required for the expression of Sp7 and possibly for its function as mice with targeted disruption of Runx2 do not show expression of Sp7. Interestingly, Runx2 expression is normal in the mesenchymal cells of membranous and the endochondral skeleton of Sp7 null animals. The functional incompetency of Runx2 in Sp7 deficient cells, suggest that Sp7 presence is obligatory for completion of Runx2 osteogenic activity. It is important to note that the observation of Runx2 presence in Sp7 null mice is limited to only RNA, determined by in situ hybridization of tissue section from Sp7 null embryos. Our recent data demonstrate that in skeletal cells, Sp7 acts as a molecular rheostat and is necessary for functional stability and turnover of Runx2 protein. Given that a complex post-transcription regulatory network is operative in skeletal cells, a strong possibility exist that Runx2 protein is never made or rapidly degraded in Sp7 null cells. We will experimentally address this by assessing endogenous levels of Runx2 protein in Sp7 null cells and by a regulated and selective gene reconstitution/ ablation in osteoprogenitor cells. The goal of this application is to identify and define a) spatial and temporal organization and assembly of Runx2 and Sp7 regulatory complexes for formation/maintenance of osteoblasts and b) mechanisms supporting stable complex formation and retention of competency for skeletal gene expression. Knowledge obtained from this study will provide molecular insights into components of bone regulatory complex that can be targeted for innovative therapy to improve cartilage and bone formation and repair.

描述（由申请人提供）：哺乳动物中骨骼的发展是一个非常复杂的过程，涉及膜内和内软骨骨化。两类骨化的完成意味着一个高度复杂但协调的构图，细胞命运承诺，分化，生长和重塑的过程。这些事件是通过基因表达的协调时间和空间模式来指定的。最初，分泌的形态剂，例如骨形态发生蛋白，刺猬，无翅蛋白等，向关键转录因子发出信号，以指定基因表达。 RUNX2是软骨细胞和成骨细胞分化的基本转录因子。 RUNX2基因缺失导致骨骼形成和胚胎致死性的完全失败。在人类中，runx2基因的突变会导致cle骨发育不良，这是一种主要遗传的骨骼疾病。骨骼生成的其他主要调节剂是特异性蛋白-7（SP7）。 SP7属于以三个锌指DNA结合域为特征的Kruppel样转录因子家族的SP亚组。 SP7/Osterix基因的靶向破坏导致缺乏内软骨内和膜内骨形成。 SP7缺乏间充质细胞不会沉积骨基质，也不能区分成骨细胞。关于与两种看似无关的蛋白质相似的表型的基本分子机制知之甚少。 runx2是SP7表达的表达所必需的，可能是其作为靶向破坏Runx2的小鼠的功能不显示SP7的表达所必需的。有趣的是，runx2表达在膜的间充质细胞和SP7无效动物的内骨骨骼中是正常的。 RUNX2在SP7缺乏细胞中的功能无能，这表明SP7的存在对于完成Runx2成骨活性是必不可少的。重要的是要注意，SP7 NULL小鼠中Runx2存在的观察仅限于RNA，这是由SP7无效胚胎的组织截面的原位杂交确定的。我们最近的数据表明，在骨骼细胞中，SP7充当分子的变势，对于runx2蛋白的功能稳定性和周转是必不可少的。鉴于复杂的转录后调节网络在骨骼细胞中是可操作的，因此存在很可能Runx2蛋白在SP7无效细胞中从未产生或迅速降解。我们将通过评估SP7无效细胞中的Runx2蛋白的内源性水平以及通过骨源细胞中受调节和选择性的基因重建/消融来解决这一问题。该应用的目的是识别和定义a）runx2和sp7调节络合物的空间和时间组织以及组装成骨细胞的形成/维护和b）支持稳定的复合形成的机制，并保留了骨骼基因表达能力的能力。从这项研究中获得的知识将为骨调节复合物的组成部分提供分子见解，该综合体可以用于创新治疗，以改善软骨，骨形成和修复。