Mechanisms of IKK Regulation of Basal and Inflammatory Osteoclastogenesis

IKK 调节基础和炎症破骨细胞生成的机制

• 批准号: 7651373
• 负责人: YOUSEF ABU-AMER
• 金额: $ 33.44万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-07 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7651373
• 关键词: Arthritis; Attenuated; Binding; Cell Nucleus; Chimera organism; Complement; Complementary DNA; Complex; Conflict (Psychology); Defect; Disease; Dominant-Negative Mutation; Event; Failure; Family; Gene Deletion; Genes; Germ Lines; IKK alpha; ITGAM gene; In Vitro; Individual; Inflammation Mediators; Inflammatory; Inflammatory Response; Knockout Mice; Lead; Mediating; Modeling; Molecular; Mus; Mutate; Null Lymphocytes; Osteoclasts; Osteolysis; Osteolytic; Pathway interactions; Phosphorylation; Phosphotransferases; Protein-Serine-Threonine Kinases; Proteins; Regulation; Relative (related person); Rheumatoid Arthritis; Role; Signal Transduction; Stimulus; TNF gene; TNFRSF5 gene; TNFSF11 gene; Tertiary Protein Structure; Time; Tissues; Transcription Initiation; Tyrosine; Tyrosine Phosphorylation; base; bone; cytokine; design; gain of function; in vivo; inhibitor/antagonist; molecular domain; novel; osteoclastogenesis; p65; public health relevance; research study; response; transcription factor

DESCRIPTION (provided by applicant): The transcription factor NF-(B is essential for osteoclastogenesis and is considered a key modulator of inflammatory responses. Activation of NF-(B entails induction of a large I(B kinase (IKK) complex that comprises IKK1, IKK2, and IKK(/NEMO. IKK2 and IKK1 activate the canonical (p50/p65) and non- canonical (p52/relB) NF-(B pathways, respectively. Recent studies implicate IKK2 and IKK1 as essential for osteoclastogenesis, yet the mechanisms underling this function, remain unclear. In addition, IKK2 is considered as a key mediator of inflammatory events induced by TNF, LPS, and other pro-inflammatory agents (through the classical NF-(B pathway), whereas less is known about the role of IKK1 is such responses. In the past few years we have investigated molecular pathways regulating osteoclast activity in osteolytic responses, such as inflammatory osteolysis and arthritic bone erosion, and unveiled critical regulatory steps modulating NF-(B activation in osteoclast precursors. In this regard, we find that disruption of NF-(B activation at multiple levels attenuates osteoclastogenesis and inflammatory bone erosion. Specifically, we have shown that administration of dominant-negative forms of I(B(, that resist phosphorylation by IKK2; and most recently inhibition of IKK assembly with NEMO, using a decoy NEMO binding domain (NBD) peptide, all are successful approaches to inhibit osteoclastogenesis and bone erosion, in vitro and in vivo. Most importantly, we have preliminary evidence that, 1) failure of RANKL-induced osteoclastogenesis by IKK1-null OCPs is rescued by re-introduction of IKK1 cDNA constructs, and that 2) tissue-specific deletion of IKK2 in OCPs (using CD11b-cre) results with skeletally deformed mice. It is evident that osteoclastogenesis is impaired in the absence of IKK1 or IKK2, however, the precise mechanism(s) underlying signaling of IKKs in basal and inflammatory osteoclastogenesis remain scarce. Moreover, the relative contribution of either protein to these responses is indefinite. It is also known that IKK1 and IKK2 share considerable sequence and domain similarities, albeit they maintain distinct and non-overlapping functions. Thus, we hypothesize that IKK1 and IKK2 differentially regulate basal and inflammatory osteoclastogenesis through the alternative and classical NF-(B activation pathways. Hence, clarifying the individual roles of IKKs in osteoclastogenesis by investigating the details of their molecular signaling in osteoclasts, utilizing germ-line and specific tissue deletions of the relevant genes, will enable us to design strategies and selective inhibitors directed against IKK1 and IKK2 that may be useful for regulating osteoclastogenesis and alleviating inflammatory osteolysis in various bone resorptive disorders. Thus, we propose to investigate the following specific aims: 1) Determine the molecular role of IKK1 and IKK2 in basal and inflammatory osteoclastogenesis. 2) Determine the mechanism by which tyrosine phosphorylation regulates the fate and activity of IKK2 in the osteoclast lineage and it's impact on osteoclastogenesis. 3) Determine the role of IKK1 and IKK2 in inflammatory osteolysis, in vivo. PUBLIC HEALTH RELEVANCE: The transcription factor NF-(B is essential for osteoclastogenesis and modulates inflammatory responses. NF-(B is activated by the serine kinases, I(B kinase (IKK)-1, IKK-2, and IKK(/NEMO. Gene deletions of IKK1 or IKK2 led to defects in osteoclasts and inflammatory responses. Using IKK1 and IKK2-null mice, we propose to investigate the molecular domain contributions of IKK1 and IKK2 to osteoclastogenesis and inflammatory osteolysis, as is the case in inflammatory arthritis. Our proposal holds promise to identify novel selective anti-osteolytic therapies.

描述（由申请人提供）：转录因子 NF-(B 对于破骨细胞生成至关重要，被认为是炎症反应的关键调节剂。NF-(B 的激活需要诱导包含 IKK1 的大型 I(B 激酶 (IKK) 复合物） 、IKK2 和 IKK(/NEMO。IKK2 和 IKK1 激活规范 (p50/p65) 和非规范 (p52/relB) NF-(B 通路分别。最近的研究表明 IKK2 和 IKK1 对于破骨细胞生成至关重要，但其作用机制仍不清楚。此外，IKK2 被认为是 TNF、LPS 和其他物质诱导的炎症事件的关键介质。促炎剂（通过经典的 NF-（B 途径）），而对于 IKK1 的作用知之甚少。在过去的几年中，我们研究了调节破骨细胞活性的分子途径溶骨反应，例如炎症性骨溶解和关节炎性骨侵蚀，并揭示了调节破骨细胞前体中 NF-(B) 激活的关键调节步骤。在这方面，我们发现在多个水平上破坏 NF-(B(B) 激活会减弱破骨细胞生成和炎症性骨侵蚀。具体来说，我们已经表明，施用显性失活形式的 I(B(，可抵抗 IKK2 的磷酸化；并且大多数最近用 NEMO 抑制 IKK 组装，使用诱饵 NEMO 结合域 (NBD) 肽，所有这些都是在体外和体内抑制破骨细胞生成和骨侵蚀的成功方法。最重要的是，我们已经有了初步的结果。有证据表明，1) IKK1 缺失 OCP 导致 RANKL 诱导的破骨细胞生成失败，可通过重新引入 IKK1 cDNA 结构来挽救，2) OCP 中 IKK2 的组织特异性缺失（使用 CD11b-cre）会导致小鼠骨骼畸形显然，在缺乏 IKK1 或 IKK2 的情况下，破骨细胞生成会受到损害，但是，其信号转导的精确机制并不明确。此外，IKK 在基础和炎症破骨细胞生成中的作用仍然很少，而且这两种蛋白质对这些反应的相对贡献是不确定的。还已知 IKK1 和 IKK2 具有相当大的序列和结构域相似性，尽管它们保持不同且不重叠的功能。因此，我们假设 IKK1 和 IKK2 通过替代和经典 NF-(B 激活途径) 差异性地调节基础和炎症破骨细胞生成。因此，通过研究破骨细胞中 IKK 分子信号传导的细节，利用细菌-相关基因的系和特定组织缺失，将使我们能够设计针对 IKK1 和 IKK2 的策略和选择性抑制剂，这可能有助于调节破骨细胞生成因此，我们建议研究以下具体目标：1）确定 IKK1 和 IKK2 在基础和炎症破骨细胞生成中的分子作用。 2)确定酪氨酸磷酸化调节破骨细胞谱系中IKK2命运和活性的机制及其对破骨细胞生成的影响。 3) 确定 IKK1 和 IKK2 在体内炎症性骨溶解中的作用。公共健康相关性：转录因子 NF-(B 对于破骨细胞生成和调节炎症反应至关重要。NF-(B 由丝氨酸激酶、I(B 激酶 (IKK)-1、IKK-2 和 IKK(/NEMO) 激活） IKK1 或 IKK2 基因缺失导致破骨细胞和炎症反应缺陷，我们建议使用 IKK1 和 IKK2 缺失小鼠研究分子结构域的贡献。 IKK1 和 IKK2 与破骨细胞生成和炎症性骨溶解的关系，如炎症性关节炎的情况，我们的建议有望确定新型选择性抗溶骨疗法。