Program Project Grant: Bone Cell Structue and Gene Expression

描述（由申请人提供）：我们的计划，配置为3个研究项目和2个核心，继续解决核结构参数（染色质组织和核基质相关转录亚核位点的组装和活性）有助于基因表达的假设，介导骨骼发育和稳态所需的骨细胞表型特性的发生，进展和维持。我们正在追求一个综合的，多学科的团队方法，结合分子，细胞，生物化学和体内遗传学的方法来定义机制，通过亚核组织的核酸和调节蛋白促进生理信号的整合，以支持骨骼基因表达和骨发育的能力在体内。我们的项目在结构和功能上都已经确定了（体外和体内）表征了核内运输信号，其将Runx 2转录因子引导到核内的调节机制所驻留的位点; 2）开创性地研究了染色质结构、核小体组织和染色质重塑与骨骼基因表达的功能性相互关系; 3）证明Runx 2为骨架基因表达的组合组分在靶基因启动子上的战略位点和在调节蛋白的阈值浓度动态配置功能复合物的核微环境中的组装提供支架; 4）通过促进调控网络的组织和活动，为理解介导骨骼基因表达的组合机制提供了新的维度;和5）观察到骨表型特异性转录因子在有丝分裂和分配到后代细胞期间在靶基因处的保留，为细胞命运确定和谱系定型提供了表观遗传控制的新组分。我们将通过鉴定依赖于亚核结构域中稳定复合物形成的靶基因和支持在有丝分裂过程中保留骨骼基因表达能力的机制，进一步确定骨骼基因表达调控复合物的时空组织和组装。 骨祖细胞（项目1），核微环境中具有特化共调节因子的多聚体复合物对成骨细胞发生的正向和负向调节（项目2），以及以维生素D依赖性方式诱导和发展成骨细胞表型的染色质重塑要求（项目3）。相关性：核结构-基因表达相互关系的评价将提供骨骼发育所必需的并且可能在代谢性骨病中受损的调节参数的生物学验证。我们的研究将提供深入了解核组织的组成部分，可以针对创新疗法。

DESCRIPTION (provided by applicant): Our program, configured as 3 research projects and 2 cores, continues to address the hypothesis that parameters of nuclear structure (chromatin organization and the assembly and activity of nuclear matrix-associated subnuclear sites for transcription) contribute to gene expression that mediates the onset, progression and maintenance of bone cell phenotypic properties required for skeletal development and homeostasis. We are pursuing an integrated, multidisciplinary team approach that combines molecular, cellular, biochemical and in vivo genetic approaches to define mechanisms by which subnuclear organization of nucleic acids and regulatory proteins facilitates integration of physiological signals to support competency for skeletal gene expression and bone development in vivo. Our program has 1) identified, structurally and functionally (in vitro and in vivo) characterized the intranuclear trafficking signal that directs the Runx2 transcription factor to sites within the nucleus where regulatory machinery governing transcription resides; 2) pioneered investigation of functional interrelationships of chromatin structure, nucleosome organization and chromatin remodeling with skeletal gene expression; 3) demonstrated that Runx2 provides a scaffold for assembly of combinatorial components of skeletal gene expression at strategic sites on target gene promoters and in nuclear microenvironments where threshold concentrations of regulatory proteins dynamically configure functional complexes; 4) provided a new dimension to understanding combinatorial mechanisms that mediate skeletal gene expression by facilitating the organization and activity of regulatory networks; and 5) observed the retention of bone phenotype-specific transcription factors at target genes during mitosis and partitioning to progeny cells providing a novel component of epigenetic control for cell fate determination and lineage commitment. We will focus on further defining spatial and temporal organization and assembly of regulatory complexes for skeletal gene expression by identifying target genes dependent on stable complex formation in subnuclear domains and mechanisms supporting retention of competency for skeletal gene expression during mitotic division of osteoprogenitor cells (project 1), the positive and negative regulation of osteoblastogenesis by multimeric complexes with specialized coregulatory factors in nuclear microenvironments (project 2), and the requirements for chromatin remodeling for induction and progression of the osteoblast phenotype in a vitamin D dependent manner (project 3). Relevance: evaluation of nuclear structure-gene expression interrelationships will provide biological validation of regulatory parameters that are obligatory for skeletal development and may be compromised in metabolic bone disease. Our studies will provide insights into components of nuclear organization that can be targeted for innovative therapy.