Regulation of apoptosis in osteoblasts by Runx2 and NFkB

Runx2 和 NFkB 对成骨细胞凋亡的调节

• 批准号: 8299020
• 负责人: Roman Eliseev
• 金额: $ 7.73万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8299020
• 关键词: Address; Aging; Apoptosis; Apoptotic; Binding; Biological Assay; Bone Tissue; Bone neoplasms; Cell Line; Cell Proliferation; Cells; DNA Binding; Data; EMSA; Elements; Equilibrium; Future; Genes; Genetic Transcription; Goals; Growth; Homeostasis; Life Cycle Stages; Literature; Malignant Bone Neoplasm; Mesenchymal Stem Cells; Mitotic; Molecular; Mus; Mutagenesis; NF-kappa B; Neoplasms; Osteoblasts; Osteocytes; Play; Proliferating; Regulation; Reporter; Repression; Response Elements; Role; Signal Transduction; base; bone; bone cell; cytokine; expression vector; inhibitor/antagonist; insight; loss of function; novel; osteoblast differentiation; osteosarcoma; p65; promoter

DESCRIPTION (provided by applicant): Delicate balance between cellular proliferation, differentiation and apoptosis is required for normal bone tissue composition and function. Disruption of such balance leads to bone neoplasia or degeneration. Our long-term goal is to elucidate the mechanisms of disregulation of apoptosis in bone neoplasms and find novel treatments targeted at modulation of apoptosis in neoplasia. The goal of this proposal is to expand our previous findings on counter-regulation of apoptosis in osteoblasts (OB) by Runx2 and NF-kB that will serve as preliminary data for our future RO1 project. During growth and remodeling of bone tissue, bone cells differentiate from mesenchymal stem cells to early proliferating OBs to mature post-mitotic OBs of which 30 percent become either osteocytes or lining cells while 70 percent are eliminated by apoptosis. OB apoptosis is, therefore an ultimate part of OB life cycle which is regulated by the microenvironment and bone-specific cytokines. Despite the importance of apoptosis in bone homeostasis, its regulation in OBs remains elusive. We have collected new data indicating that: 1) A key OB differentiation factor, Runx2, also plays a central role in regulation of OB apoptosis by inducing pro-apoptotic Bax via direct binding and activation of the bax gene promoter; 2) Apoptosis is increased in more differentiated OBs in concert with the increase in Runx2 and Bax; 3) Induction of Bax by Runx2 is negatively regulated by the NF-kB signaling. Bax promoter contains NF-kB binding elements; and 4) NF-kB activity is increased in proliferating OBs and in osteosarcoma cells and plays a role in suppression of apoptosis. In addition, others have found that in Bax KO mice, bone volumes are significantly increased in aging mice implicating Bax in regulation of OB function. In this proposal we will determine the specific role of the Runx2/Bax axis in regulation of apoptosis in OBs and get an insight on the role of NF-kB as a modulator of the Runx2/Bax apoptotic axis. Based on our preliminary results and the literature we hypothesize that apoptosis in osteoblasts is counter-regulated by Runx2 and NF-kB which correspondingly induce or repress transcription of pro-apoptotic Bax. To prove our hypothesis we will address the two Specific Aims: 1) To confirm the inhibitory role of NF-kB in regulation of Bax transcription; and 2) To elucidate the effect of interaction of the Runx2/Bax axis with NF-kB on apoptosis sensitivity in osteoblasts and in osteosarcoma cells. This proposal seeks to understand regulatory mechanisms involved in OB apoptosis and how the Runx2/Bax axis and NF-kB interact at the molecular level. This will provide us a rationale for a RO1 project focused on the mechanism of suppression of apoptosis in bone cancer. 1

描述（由申请人提供）：正常骨组织组成和功能需要细胞增殖，分化和凋亡之间的微妙平衡。这种平衡的破坏会导致骨肿瘤或变性。我们的长期目标是阐明骨骼肿瘤中凋亡凋亡的机制，并找到针对肿瘤凋亡调节的新型治疗方法。该提案的目的是扩大我们以前关于runx2和nf-kb对成骨细胞（OB）中凋亡的调节的发现，该发现将作为我们未来RO1项目的初步数据。 在骨骼组织的生长和重塑过程中，骨细胞从间充质干细胞区分化为早期增殖，从而成熟的有丝分裂后观察，其中30％变成骨细胞或内膜细胞，而凋亡消除了70％。因此，OB凋亡是OB生命周期的最终部分，它受微环境和骨特异性细胞因子的调节。尽管凋亡在骨稳态中的重要性很重要，但其在OBS中的调节仍然难以捉摸。我们已经收集了新数据，表明：1）关键的OB分化因子Runx2也通过通过直接结合和激活Bax Gene启动子诱导促凋亡Bax来调节OB凋亡中的核心作用； 2）与Runx2和Bax的增加，在更分化的OBS中，凋亡增加了； 3）runx2诱导BAX受NF-KB信号传导负面调节。 Bax启动子包含NF-KB结合元件； 4）NF-KB活性在增殖的OBS和骨肉瘤细胞中增加，并在抑制细胞凋亡中起作用。此外，其他人发现，在Bax KO小鼠中，与Bax有关OB功能调节的衰老小鼠的骨骼体积显着增加。在此提案中，我们将确定RUNX2/BAX轴在OBS中调节凋亡中的特定作用，并深入了解NF-KB作为Runx2/Bax凋亡轴的调节剂的作用。 根据我们的初步结果和文献，我们假设成骨细胞中的细胞凋亡由Runx2和NF-KB对抗，这相应地诱导或抑制了促凋亡Bax的转录。为了证明我们的假设，我们将解决两个具体目的：1）确认NF-KB在调节BAX转录中的抑制作用； 2）为了阐明Runx2/Bax轴与NF-KB的相互作用对成骨细胞和骨肉瘤细胞中凋亡敏感性的影响。 该提案旨在了解与OB凋亡有关的调节机制，以及Runx2/Bax轴和NF-KB如何在分子水平上相互作用。这将为我们提供一个RO1项目的基本原理，该项目的重点是抑制骨癌凋亡的机理。 1