Cox-2 Regulation of Bone Responses to PTH: Role of Osteoclasts

Cox-2 调节骨对 PTH 的反应：破骨细胞的作用

• 批准号: 8485547
• 负责人: CAROL C. PILBEAM
• 金额: $ 32.92万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 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 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8485547
• 关键词: Accounting; Acute; Address; Adenoviruses; Anabolic Agents; Bone Marrow; Bone remodeling; Calcium; Candidate Disease Gene; Cell Culture Techniques; Cell Lineage; Clinical; Coculture Techniques; Data; Defect; Development; Dinoprostone; EP4 receptor; Enzymes; Exposure to; Fluorescence-Activated Cell Sorting; Future; Gene Expression; Gene Expression Profile; Genes; Hematopoietic; Hormones; ITGAM gene; In Vitro; Infusion procedures; Knockout Mice; Knowledge; Lead; Lipids; Marrow; Measures; Mediating; Mus; New Agents; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Parathyroid gland; Pathway interactions; Phenotype; Process; Production; Prostaglandin E Receptor; Prostaglandin Production; Prostaglandins; Protocols documentation; Regulation; Risedronate; Role; Secondary to; Signal Transduction; Stromal Cells; Subfamily lentivirinae; Testing; Wild Type Mouse; Work; autocrine; base; bone; bone loss; bone turnover; cathepsin K; clinical application; cyclooxygenase 2; in vivo; macrophage; novel; osteoblast differentiation; osteogenic; paracrine; progenitor; receptor; response; skeletal; small hairpin RNA

DESCRIPTION (provided by applicant): We propose that the actions of parathyroid hormone (PTH) are modified at the cellular level by the PTH induction of cyclooxygenase-2 (COX-2) and COX-2-produced prostaglandins (PGs). PTH is a systemic hormone acting predominantly on osteoblast (OB) lineage cells, whereas PGs are autocrine/paracrine lipids acting on both OB and osteoclast (OC) lineage cells. PTH is a potent inducer of COX-2 and PGs in OBs. Although PTH is generally thought to be osteogenic or anabolic only when given intermittently, continuous exposure to PTH markedly stimulates OB differentiation in vitro in bone marrow stromal cell cultures when COX-2 expression or activity (PG production) is absent. An inhibitory interaction between PTH and COX-2 is supported by in vivo data showing that COX-2 knockout (KO) mice have increased anabolic responses to intermittent PTH compared to COX-2 wild type (WT) mice. Preliminary studies in vitro suggest that the inhibitory effects of the interaction of PTH and COX-2 on OB differentiation require the presence of OC precursors and the expression of the PGE2 receptor EP4R on OC precursors. We will test the hypothesis that PTH-stimulated OB differentiation in vitro and PTH-stimulated anabolic responses in vivo are inhibited by PTH- induced PGs acting via the EP4R receptor on OC precursors. For both in vitro and in vivo studies, we will use mice with global and targeted deletions of Cox-2, Ep4r, and Ep2r. Deletions will be targeted to the early OC lineage with CD11b-Cre, to the later OC lineage with cathepsin K-Cre (CtskCre/+), and to the early OB lineage with 3.6Col1a1-Cre. We will use the pattern of gene expression in osteogenic vs. inhibitory conditions to identify potential pathways, such as Wnt signaling, associated with the osteogenic effects. In vivo, we will examine anabolic and catabolic responses to intermittent and continuous PTH with radiographic and histomorphometric measures of skeletal phenotype, markers of bone turnover, and gene expression. This study addresses a novel role for PGs and OCs in the effects of PTH. It is an opportunity to explore mechanisms by which two agents, both of which can be anabolic, produce a negative interaction, in an effort to understand the specific pathways involved. It should lead to a better understanding of the roles of endogenous PGs in both OB and OC lineage cells and the differential effects of PGE2 receptors, and this knowledge may help to target bone remodeling more effectively to treat osteoporosis and other skeletal defects. The possibility that manipulation of endogenous PGs might increase the anabolic effects of PTH could have clinical applications.

描述（由申请人提供）：我们提出甲状旁腺激素（PTH）的作用在细胞水平上通过PTH诱导环氧化酶-2 （COX-2）和COX-2产生的前列腺素（pg）而改变。PTH是一种主要作用于成骨细胞（OB）谱系细胞的系统性激素，而PGs是作用于OB和破骨细胞（OC）谱系细胞的自分泌/旁分泌脂质。甲状旁腺素是ob中COX-2和pg的有效诱导剂。虽然PTH通常被认为只有在间歇性给予时才具有成骨或合成代谢作用，但在缺乏COX-2表达或活性（PG生成）的情况下，持续暴露于PTH可显著刺激骨髓基质细胞体外OB分化。体内数据表明，与COX-2野生型（WT）小鼠相比，COX-2敲除（KO）小鼠对间歇性PTH的合成代谢反应增加，PTH和COX-2之间的抑制相互作用得到了支持。体外初步研究表明，PTH和COX-2相互作用对OB分化的抑制作用需要OC前体的存在以及PGE2受体EP4R对OC前体的表达。我们将验证PTH刺激的OB体外分化和PTH刺激的体内合成代谢反应被PTH诱导的PGs通过EP4R受体作用于OC前体所抑制的假设。在体外和体内研究中，我们将使用具有Cox-2、Ep4r和Ep2r全局和靶向缺失的小鼠。缺失将针对具有CD11b-Cre的早期OC谱系，具有组织蛋白酶K-Cre （CtskCre/+）的晚期OC谱系，以及具有3.6Col1a1-Cre的早期OB谱系。我们将使用成骨与抑制条件下的基因表达模式来识别与成骨作用相关的潜在途径，如Wnt信号。在体内，我们将通过骨骼表型、骨转换标记物和基因表达的放射学和组织形态学测量来检查间歇性和持续性甲状旁腺激素对合成代谢和分解代谢的反应。本研究探讨了PGs和OCs在PTH作用中的新作用。这是一个探索机制的机会，通过这两种药物，都可以合成代谢，产生负相互作用，努力了解所涉及的具体途径。这将有助于更好地理解内源性PGs在OB和OC谱系细胞中的作用以及PGE2受体的差异作用，这一知识可能有助于更有效地靶向骨重塑来治疗骨质疏松症和其他骨骼缺陷。操纵内源性PGs可能会增加甲状旁腺激素的合成代谢作用，这可能具有临床应用价值。