NELL-1, A Cbfa1 DOWNSTREAM TARGET, IN BONE FORMATION

NELL-1，Cbfa1 下游靶标，在骨形成中

• 批准号: 7253251
• 负责人: KANG TING
• 金额: $ 32.96万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7253251
• 关键词: Active Sites; Affect; Biological Assay; Bone Growth; Calvaria; Cells; Cephalic; Chickens; Cleft Lip; Cleft Palate; Clinical; Commit; Complement; Coupled; Coupling; Data; Defect; Development; Disruption; Distraction Osteogenesis; Dominant-Negative Mutation; Embryo; Epidermal Growth Factor; Exhibits; Financial compensation; Genes; Genetic Transcription; Human; In Vitro; Invasive; Knock-out; Knockout Mice; Knowledge; Luciferases; Mediating; Mediator of activation protein; Mesenchymal; Molecular; Mus; Natural regeneration; Nature; Nuclear Extract; Numbers; Operative Surgical Procedures; Osteoblasts; Osteocalcin; Osteogenesis; Patients; Phenotype; Protein Overexpression; Proteins; Recombinants; Regulation; Response Elements; Site; Site-Directed Mutagenesis; Specificity; Surgical sutures; Testing; Therapeutic; Tin; Tissues; Wild Type Mouse; Work; base; bone; cell type; cis acting element; craniofacial; craniofacial repair; embryonic stem cell; in vivo; intramembranous bone; intramembranous bone formation; intramembranous development; mineralization; preconditioning; promoter; reconstruction; relating to nervous system; suture fusion; tool; vector

DESCRIPTION (provided by applicant): Cbfa1 mediates mesenchymal cell commitment to an osteochondroprogenitor lineage and supports continued differentiation and function in committed osteoblasts. However, definitive downstream mediators of Cbfa1 that critically impact osteoblast differentiation and bone formation have yet to be described. Ne1 (a protein strongly expressed in neural tissue encoding epidermal growth factor like domain) was first identified in chicken embryos. The preliminary data shows that Nell-1 (Ne1-like molecule-1) in vivo is associated with normal and pathological suture fusion, while Nell- 1 in vitro is associated with increased osteoblast differentiation and mineralization. Furthermore, the human Nell-1 promoter contains three osteoblast-specific cis-acting element 2 (OSE2) response elements for Cbfa1 and that Nell-1 overexpression mice can functionally compensate for some aspects of intramembranous bone deficiency in heterozygous Cbfa1 deficient mice. These data have led to the hypothesis that Nell-1 is a central downstream target of Cbfa1 that supports continued differentiation and function in committed osteoblasts and proper Nell-1 expression is required for normal membranous bone growth and formation. To test this hypothesis, this proposal will analyze the following: 1) the regulation of Nell-1 transcription by Cbfa1 during osteoblast formation and function and by Cbfa1 through OSE2 response elements; 2) the functional compensation of Cbfa1 deficiency by Nell-1 in vivo and in vitro; and 3) the effects of targeted Nell-1 disruption in vivo. If Nell-1 is proven to be a critical mediator of intramembranous bone formation, it can further aid in understanding the development of intramembranous vs. endochondral bone. In addition, since sutures are major sites of calvarial intramembranous bone growth the close association of Nell-1 with calvarial sutures can also impact present knowledge on cranial vault development. Lastly, Nell-1 can be tremendously useful as a clinical tool to inhibit or induce intramembranous bone growth, with the secretory nature of Nell-1 making this utility even more feasible. Controlled inhibition of intramembranous bone growth by anti-Nell-1 strategies in CS patients may offer a less invasive, biologically based, therapeutic alternative to radical surgical craniofacial reconstruction. In addition, the ability of Nell- 1 to induce calvarial osteoblast differentiation may be clinically applied to situations where membranous bone formation and regeneration are desirable (e.g., cleft lip or cleft palate repair and craniofacial distraction osteogenesis).

描述(由申请人提供)：Cbfa1介导间充质细胞向骨软骨前体细胞的分化，并支持定向成骨细胞的持续分化和功能。然而，对成骨细胞分化和骨形成有重要影响的Cbfa1的明确下游介体尚未被描述。NE1(一种在神经组织中强表达的编码表皮生长因子样域的蛋白)首次在鸡胚胎中被发现。初步研究表明，Nell-1在体内与正常缝合和病理性缝合有关，而在体外与成骨细胞分化和矿化增加有关。此外，人类Nell-1启动子包含三个针对Cbfa1的成骨细胞特异性顺式作用元件2(OSE2)反应元件，并且Nell-1过表达的小鼠可以在功能上补偿Cbfa1杂合缺陷小鼠膜内骨缺乏的某些方面。这些数据导致假设Nell-1是Cbfa1的中心下游靶点，支持定向成骨细胞的持续分化和功能，正常的膜性骨生长和形成需要适当的Nell-1表达。为了验证这一假说，这项建议将分析以下几个方面：1)Cbfa1在成骨细胞形成和功能过程中对Nell-1转录的调控，以及Cbfa1通过OSE2反应元件对Nell-1转录的调节；2)Nell-1在体内和体外对Cbfa1缺陷的功能补偿；以及3)体内靶向干扰Nell-1的效果。 如果Nell-1被证明是膜内骨形成的关键介质，它可以进一步帮助理解膜内骨与软骨内骨的发育。此外，由于缝线是颅骨膜内骨生长的主要部位，Nell-1与颅骨缝线的密切联系也可以影响目前关于颅顶发育的知识。最后，Nell-1可以作为一种非常有用的临床工具来抑制或诱导膜内骨生长，Nell-1的分泌性质使这一用途更加可行。在CS患者中，通过抗Nell-1策略控制膜内骨生长的抑制，可能为根治性颅面外科重建提供一种侵入性更小、基于生物学的治疗替代方案。此外，Nell-1诱导颅骨成骨细胞分化的能力可能被临床应用于需要膜性骨形成和再生的情况(例如，唇裂或腭裂修复和颅面牵引成骨)。