A novel cell-autonomous role for β-adrenergic receptor signaling in osteoclasts

破骨细胞中β-肾上腺素能受体信号传导的新型细胞自主作用

• 批准号: 10633271
• 负责人: Katherine Jean Motyl
• 金额: $ 36.88万
• 依托单位: MAINEHEALTH
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10633271
• 关键词: Adrenergic Antagonists; Adrenergic beta-Agonists; Adrenergic beta-Antagonists; Age; Age-Related Bone Loss; Aging; Agonist; Albuterol; Alleles; Attenuated; Binding; Biological Assay; Bone Density; Bone Diseases; Bone Marrow; Bone Resorption; Bone remodeling; Ca(2+)-Calmodulin Dependent Protein Kinase; Calcineurin; Calcineurin inhibitor; Cells; Clinical; Cohort Studies; Cyclic AMP-Dependent Protein Kinases; Data; Dose; Ensure; G Protein-Coupled Receptor Signaling; Genes; Genetic; Goals; Hand; Human; In Vitro; Laboratories; Ligand Binding; Ligands; Marrow; Mass Spectrum Analysis; Mediating; Mediator; Meta-Analysis; Mus; Myelogenous; Nervous System; Nuclear; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; PPP3CA gene; Pathology; Pathway interactions; Pharmaceutical Preparations; Phenotype; Physiological; Postmenopause; Propranolol; Receptor Signaling; Refractory; Role; Serum; Signal Pathway; Signal Transduction; Sympathetic Nervous System; Testing; Woman; Work; beta-adrenergic receptor; bone; bone loss; fracture risk; improved; in vivo; in vivo evaluation; monocyte; novel; nuclear factors of activated T-cells; osteoclastogenesis; pharmacologic; preclinical study; prevent; prospective; receptor; recruit; transcriptome sequencing

The sympathetic nervous system (SNS) is an important regulator of bone, and may contribute to bone pathology during aging. SNS activity is also heightened in post-menopausal women, causing reduced bone formation by osteoblasts and increased bone resorption by osteoclasts, which leads to bone loss. Large meta- analyses, osteoporosis cohort studies (preliminary data from co-I Dr. Lary) and new prospective trials, consistently show that β-adrenergic receptor (βAR) antagonists (i.e. β-blockers) are associated with reduced fracture risk, increased bone mineral density (BMD), and reduced bone resorption. However, mechanistic studies have focused largely on the osteoblast as the target of SNS activity. Humans and mice have three βARs: β1AR, β2AR and β3AR. The gene encoding β2AR (Adrb2) is highly expressed in bone, which also expresses lower levels of Adrb1, but does not express Adrb3. In mice, Adrb2 deletion in osteoblasts improves bone formation and prevents receptor activator of nuclear factor-kappa B ligand (RANKL)-mediated osteoclast recruitment after stimulation with a β-agonist. In humans, β1-selective β-blockers are used most often, but their selectivity is not absolute, and many still bind β2AR. Propranolol, a non-selective β-blocker, increases BMD in the majority of preclinical studies. Results from our laboratory show that propranolol can limit bone resorption directly in vitro, and in vivo without changing RANKL levels. This is in contrast to the established dogma that osteoblast expression of β2AR regulates osteoclasts only indirectly via RANKL. Our proposed work will resolve the outstanding mechanistic questions of how β1AR and β2AR directly influence osteoclast differentiation and what their contributions are to age- and SNS-related bone loss. We propose a novel hypothesis that βAR signaling in osteoclasts promotes differentiation and resorption and contributes to bone loss in vivo. To fully characterize βAR receptor subtypes and novel signaling mechanisms in osteoclasts, and to determine the contribution of βAR subtypes to in vivo phenotypes of bone density and bone remodeling, we propose a combination of genetic and pharmacologic in vivo and in vitro approaches in the following Specific Aims. Specific Aim 1: We will identify signaling mechanisms activated by specific βARs in osteoclasts. We expect that we will identify novel and established target pathways to test in vivo for efficacy in modulating bone resorption. Specific Aim 2: We will test the relative contributions of osteoclast β1AR and β2AR to SNS- mediated and aging-related bone loss in vivo. The SNS has been implicated in osteoporosis, but the role of βARs in osteoclasts has never been investigated in this condition. We hypothesize that both deletion of β1AR and β2AR, specifically in the osteoclasts, will attenuate βAR agonist-induced and aging-related bone loss in mice. Our work will provide a more complete understanding of the role of SNS signaling in age-related bone loss in vivo, and will lead to studies targeting specific osteoclast βARs and downstream signaling pathways for treatment of bone diseases.

交感神经系统（SNS）是骨的重要调节者，可能有助于骨 衰老过程中的病理学也是绝经后女性的哮喘，导致骨质减少。 成骨细胞的形成和破骨细胞的骨吸收增加，导致大量骨质流失。 分析、骨质疏松症队列研究（来自 co-I Lary 博士的初步数据）和新的前瞻性试验， 一致表明β-肾上腺素能受体（βAR）拮抗剂（即β-受体阻滞剂）与减少 骨折风险、骨矿物质密度（BMD）增加和骨吸收减少然而，机械作用。 研究主要集中在作为 SNS 活动目标的成骨细胞上，人类和小鼠有三种。 βAR：β1AR、β2AR 和 β3AR 编码 β2AR (Adrb2) 的基因在骨骼中高度表达。 表达较低水平的 Adrb1，但不表达 Adrb3 在小鼠中，成骨细胞中 Adrb2 的缺失得到改善。 骨形成并阻止核因子 kappa B 配体 (RANKL) 介导的破骨细胞受体激活剂 β-激动剂刺激后的募集在人类中，最常用的是 β1-选择性 β-受体阻滞剂，但它们的用途不同。 选择性不是绝对的，许多仍与 β2AR（一种非选择性 β 受体阻滞剂）结合，增加骨密度。 我们实验室的大多数临床前研究结果表明普萘洛尔可以限制骨吸收。 直接在体外和体内进行，而不改变 RANKL 水平，这与既定的教条相反。 β2AR 的成骨细胞表达仅通过 RANKL 间接调节破骨细胞。 β1AR和β2AR如何直接影响破骨细胞分化这一突出的机制问题 它们对年龄和 SNS 相关的骨质流失有何贡献？我们提出了一个新的假设：βAR。 破骨细胞中的信号传导促进分化和吸收，并导致体内骨质流失。 表征破骨细胞中的 βAR 受体亚型和新的信号传导机制，并确定 βAR亚型对体内骨密度和骨重塑表型的贡献，我们提出了 在以下具体目标中结合体内和体外遗传和药理学方法。 具体目标 1：我们期望确定破骨细胞中特定 βAR 激活的信号传导机制。 我们将确定新的和已建立的目标途径来测试体内调节骨的功效 具体目标 2：我们将测试破骨细胞 β1AR 和 β2AR 对 SNS- 的相对贡献。 SNS 与骨质疏松症有关，但其作用与体内衰老相关。 在这种情况下，破骨细胞中的 βAR 从未被研究过，我们追求的是 β1AR 的缺失。 β2AR，特别是在破骨细胞中，将减轻 βAR 激动剂诱导的和衰老相关的骨质流失 我们的工作将使人们更全面地了解 SNS 信号在年龄相关骨骼中的作用。 体内损失，并将导致针对特定破骨细胞βAR和下游信号通路的研究 治疗骨骼疾病。