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: 8186024
• 负责人: CAROL C. PILBEAM
• 金额: $ 34.65万
• 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/8186024
• 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; 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; Pattern; 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. PUBLIC HEALTH RELEVANCE: PTH is a major calcium regulating hormone, and intermittent PTH is the only approved anabolic therapy for osteoporosis. The PTH-induction of prostaglandins can modulate the bone responses to PTH. A better understanding of the role of prostaglandins in the responses to PTH could have an important impact on our understanding of the mechanisms that drive new bone formation, laying the basis for future development of new agents to treat osteoporosis and other skeletal defects, and might also lead to applications that will enhance current clinical therapy with PTH.

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诱导环氧合酶-2（考克斯-2）和考克斯-2产生的前列腺素（PG）而改变。PTH是主要作用于成骨细胞（OB）谱系细胞的全身激素，而PG是作用于OB和破骨细胞（OC）谱系细胞的自分泌/旁分泌脂质。PTH是OB中考克斯-2和PG的有效诱导剂。虽然PTH通常被认为仅在间歇给予时具有成骨或合成代谢作用，但在体外骨髓基质细胞培养中，当考克斯-2表达或活性（PG产生）缺失时，持续暴露于PTH显著刺激OB分化。PTH和考克斯-2之间的抑制性相互作用得到体内数据的支持，体内数据显示，与考克斯-2野生型（WT）小鼠相比，考克斯-2敲除（KO）小鼠对间歇性PTH的合成代谢应答增加。体外初步研究表明，PTH和考克斯-2相互作用对OB分化的抑制作用需要OC前体的存在和OC前体上PGE 2受体EP 4 R的表达。我们将检验以下假设：PTH诱导的PG通过EP 4 R受体作用于OC前体，抑制PTH刺激的体外OB分化和PTH刺激的体内合成代谢反应。对于体外和体内研究，我们将使用具有考克斯-2、Ep 4 r和Ep 2 r的全局和靶向缺失的小鼠。缺失将针对早期OC谱系（CD 11b-Cre）、晚期OC谱系（组织蛋白酶K-Cre（CtskCre/+））和早期OB谱系（3.6Col1a1-Cre）。我们将使用成骨与抑制条件下的基因表达模式来鉴定与成骨作用相关的潜在途径，如Wnt信号传导。在体内，我们将研究合成代谢和分解代谢的反应，间歇性和连续PTH与放射学和组织形态计量学的骨骼表型，骨转换的标志物和基因表达的措施。本研究探讨了PG和OC在PTH作用中的新作用。这是一个探索两种药物（两者都可以是合成代谢的）产生负相互作用的机制的机会，以了解所涉及的特定途径。这将导致更好地理解内源性PG在OB和OC谱系细胞中的作用以及PGE 2受体的差异效应，并且这一知识可能有助于更有效地靶向骨重建以治疗骨质疏松症和其他骨骼缺陷。操纵内源性PG可能会增加PTH的合成代谢作用的可能性可能具有临床应用。 公共卫生相关性：PTH是一种主要的钙调节激素，间歇性PTH是唯一批准的骨质疏松症合成代谢疗法。甲状旁腺素的PTH诱导可以调节骨对PTH的反应。更好地了解甲状旁腺素在对PTH的反应中的作用，可能会对我们理解新骨形成的机制产生重要影响，为未来开发治疗骨质疏松症和其他骨骼缺陷的新药奠定基础，也可能导致应用，这将增强目前的PTH临床治疗。