Synthesis of Osteocalcin in Bone

骨中骨钙素的合成

• 批准号: 7904360
• 负责人: Jane B. Lian
• 金额: $ 39.11万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7904360
• 关键词: Accounting; Acetylation; Acute; Address; Adult; Architecture; Binding; Biological Assay; Bone Density; Bone Marrow; Boxing; C-terminal; Calvaria; Cell Line; Cells; Chromatin; Chromatin Remodeling Factor; Complex; Development; Dissociation; Embryo; Enhancers; Environment; Epigenetic Process; Event; Fibroblasts; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; Genetic Transcription; Goals; Histone Acetylation; Histone Code; Histone H3; Homeodomain Proteins; Human; In Vitro; Investigation; Knockout Mice; Long-Term Effects; Lysine; Mediating; Methylation; Modification; Molecular; Mus; Mutation; Null Lymphocytes; Osteoblasts; Osteocalcin; Osteogenesis; Pathway interactions; Patients; Pattern; Phenotype; Property; Proteins; Rattus; Regulation; Regulatory Element; Regulatory Pathway; Reporter; Repression; Role; Site; Skeleton; Small Interfering RNA; Staging; Stromal Cells; Testing; Time; Tissues; Transcription Coactivator; Transcriptional Regulation; Work; base; bone; bone quality; chromatin modification; chromatin remodeling; genetic regulatory protein; histone modification; homeodomain; in vivo; insight; loss of function; mineralization; mutant; novel; null mutation; osteoblast differentiation; osteogenic; osteoprogenitor cell; programs; promoter; protein protein interaction; small hairpin RNA; stable cell line; transcription factor

DESCRIPTION (provided by applicant): This program continues to study the tissue specific and developmental regulation of the osteocalcin (OC) gene and the factors that contribute to induction and progression of osteoblast (OB) maturation. In the current program period, we discovered a regulatory network of homeodomain (HD) proteins that provide molecular switches for mediating the temporal expression of OC with a pivotal activating role for Dlx3 at the onset of OC transcription. A novel regulatory element for the Hox transcription factors was discovered that binds Hoxa10 for activation of OC transcription. Hoxa10 and Dlx3 are bound to the OC gene prior to Runx2 and increase again with Runx2 binding. In addition, these factors can activate the OC gene in Runx2 null cells, thus providing evidence for molecular events contributing to expression of the OC and bone related genes upstream of Runx2. These findings justify further investigation of their functional roles in osteoblasts in vivo and in vitro. We postulate that these two regulatory factors have key roles in regulating gene expression throughout OB differentiation, a function distinct from their activities in embryonic patterning of the skeleton. We will identify these OB- related functions by determining the mechanism by which they regulate developmental expression of OC which include contributing to chromatin remodeling, regulating activation and repression of gene transcription through interactions with co-regulatory factors, and functioning both independent of Runx2 and coordinated with Runx2 for establishment of the OB phenotype. Aim1 tests the hypothesis that dynamic association/dissociation of these factors with osteocalcin chromatin occurs at specific stages of phenotype development due to formation of transcription factor complexes modifying chromatin architecture of OC. Aim 2 addresses the hypothesis that Hoxa10 functions upstream of Runx2 to promote epigenetic marking of the OC gene for tissue specific activation, and regulation of target gene expression in OBs. Its deletion from OB in vitro and in vivo is postulated to alter OB maturation and contribute to a mild bone phenotype in adult mice. Aim 3 postulates that Dlx3 has a transient role in gene regulation, responsible for the timing of transcription of the OC gene and coordinated occupancy of Runx2 which will be addressed ex vivo in cells from the Dlx3 null and conditional knockout mice. We further postulate that the human Dlx3 tricho-dento-osseous (TDO) mutation alters the transient function of Dlx3 in osteoblasts as a result of loss-of-function of interacting co-regulatory proteins. These studies will identify novel mechanisms and regulatory pathways required for induction and regulation of OC and regulation of OB maturation to the differentiated phenotype in a mineralizing matrix.PROJECT NARRATIVE

描述（由申请人提供）：该程序继续研究骨钙素（OC）基因的组织特异性和发育调控，以及有助于成骨细胞（OB）成熟的因素。在当前的程序期间，我们发现了同源域（HD）蛋白的调节网络，该网络提供了分子开关，用于在OC转录开始时DLX3的关键性激活作用介导OC的时间表达。发现HOX11的新型调节元件是结合HOXA10以激活OC转录的。 HOXA10和DLX3在RUNX2之前与OC基因结合，并随着Runx2结合而再次增加。此外，这些因素可以激活Runx2无效细胞中的OC基因，从而为Runx2上游的OC和骨骼相关基因表达的分子事件提供了证据。这些发现证明了其在体内和体外成骨细胞中其功能作用的进一步研究是合理的。我们假设这两个调节因素在调节整个OB分化的基因表达方面具有关键作用，该功能与它们在骨骼的胚胎构图中的活性不同。我们将通过确定调节OC的发育表达的机制来确定这些相关的功能，包括促进染色质重塑，通过与共同调节因子的相互作用来调节基因转录的激活和抑制，以及独立于Runx2和与Runx2相关的功能，以建立OB现象的Runx2。 AIM1检验了以下假设：由于转录因子复合物的形成，这些因素与骨钙素染色质的动态关联/解离发生在表型发育的特定阶段，这会改变OC的染色质结构。 AIM 2解决了Runx2上游的HOXA10在组织特异性激活中促进OC基因的表观遗传标记的假设，并调节obs中靶基因表达。它从OB在体外和体内的缺失被假定是为了改变OB成熟，并导致成年小鼠的轻度骨表型。 AIM 3假设DLX3在基因调节中具有短暂的作用，负责OC基因转录的时间和RUNX2的协调占用时间，该时间将在DLX3 NULL和有条件敲除小鼠的细胞中离体解决。我们进一步假设，人类DLX3 Tricho-Dento-Osseous（TDO）突变会因相互作用的共调节蛋白的功能丧失而改变成骨细胞中DLX3的瞬态功能。这些研究将确定诱导和调节OC所需的新机制和调节途径，并调节OB成熟到矿化矩阵中分化表型。