Program Project Grant: Bone Cell Structue and Gene Expression

描述（由申请人提供）：我们的项目配置为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亚核转录位点的组装和活性）有助于基因表达的假设，这些基因表达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。我们正在寻求一种综合的、多学科的团队方法，结合分子、细胞、生化和体内遗传方法来定义核酸和调节蛋白的亚核组织促进生理信号整合的机制，以支持骨骼基因表达和体内骨骼发育的能力。我们的项目已经1)在结构和功能上（体外和体内）鉴定了核内运输信号，该信号将Runx2转录因子引导到细胞核内控制转录的调节机制所在的位置；2)率先研究染色质结构、核小体组织和染色质重塑与骨骼基因表达的功能相互关系；3)证明Runx2在靶基因启动子的策略位点和核微环境中为骨骼基因表达的组合成分的组装提供了一个支架，在核微环境中，调节蛋白的阈值浓度动态配置功能复合物；4)为理解通过促进调控网络的组织和活动介导骨骼基因表达的组合机制提供了一个新的维度；5)观察到骨表型特异性转录因子在有丝分裂和向后代细胞分配过程中在靶基因上的保留，为细胞命运决定和谱系承诺提供了一种新的表观遗传控制成分。我们将通过识别依赖于亚核结构域稳定复合物形成的靶基因和支持有丝分裂期间骨骼基因表达能力保留的机制，进一步定义骨骼基因表达调控复合物的时空组织和组装

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.