Function of Regulator of G protein signaling in aging skeleton

G蛋白信号调节因子在骨骼衰老中的作用

• 批准号: 9346657
• 负责人: SHUYING YANG
• 金额: $ 35.26万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9346657
• 关键词: Adverse effects; Affect; Age; Age-Related Bone Loss; Age-Related Osteoporosis; Aging; Binding; Biological Assay; Bone Diseases; Bone Resorption; Bone remodeling; Calcium Channel; Calcium Signaling; Calcium-Sensing Receptors; Cell Lineage; Data; Disease; Ectopic Expression; Family; Fc Receptor; Fracture; GTP-Binding Protein Regulators; Goals; Guanosine Triphosphate Phosphohydrolases; Health; Hematopoietic; Heterodimerization; Heterogeneity; Immunoprecipitation; Impairment; In Vitro; Knockout Mice; Ligands; Marrow; Mass Spectrum Analysis; Mediating; Mesenchymal; Molecular; Mus; Nuclear; Osteoclasts; Osteoporosis; PTB Domain; PTH gene; Pathologic; Pathway interactions; Patients; Phenotype; Phosphorylation; Phosphotyrosine; Play; Proteins; Public Health; RGS Domain; RGS Proteins; RGS1 gene; Regulation; Research; Role; Selective Estrogen Receptor Modulators; Series; Skeleton; Specificity; Testing; Therapeutic Intervention; Treatment Efficacy; Woman; aged; base; bisphosphonate; bone; bone mass; bone metabolism; cathepsin K; insight; knock-down; lipid biosynthesis; men; mutant; nuclear factors of activated T-cells; osteoclastogenesis; phospholipase C gamma; postnatal; public health relevance; receptor; response; skeletal; therapeutic target

DESCRIPTION (provided by applicant): Age-associated osteoporosis is a major health problem, which is characterized by an imbalance in bone remodeling and metabolism due to the increase of osteoclastogenesis and activity with age. The current treatment options have been constrained with lower response rates or side-effects and ineffectively tackle the burden and heterogeneity of osteoporosis. Further progress in establishing successful treatment urgently requires a clearer understanding of the mechanisms of osteoclast (OC) differentiation and bone remodeling with age. Evidences have documented that RANKL -evoked Ca2+ oscillations play a switch-on role in the activation of PLC� and NFATc1, and OC differentiation. Further study showed that FcR� and DAP 12 regulate the phosphorylation of PLC�, which is the critical component involved in the RANKL-induced Ca2+ oscillations- NFATc1 pathway. Despite these new insights, it remains unclear how RANKL evokes the essential Ca2+ oscillations that triggers NFATc1 activation and OC differentiation, and it is unknown whether and how this mechanism is involved in age-associated bone loss. Our recent research demonstrated that Regulator of G protein signaling protein 12 (RGS12) was prominently expressed during OC differentiation and that RGS12 expression was significantly increased with increasing age. Knockdown of RGS12 expression inhibited Ca2+ oscillations, NFATc1 expression and OC differentiation. Deletion of RGS12 from hematopoietic/early OC lineage cells (RGS12 / /cre) led to a significantly increase of bone mass, and this increase of bone mass was protected from age-associated bone loss in RGS12 / /cre mice. We also found that loss of RGS12 in mice decreased OC number and levels of marrow adipogenesis with age. Based on these results, we hypothesize that age-associated bone remodeling and metabolism requires RGS12 expression and function, and RGS12 is a critical regulator in controlling Ca2+ oscillation and OC differentiation during aging. We will test the hypothesis through the following two specific aims. In Aim 1, we will reveal the function of RGS12 in OC differentiation and function during aging through characterization of the phenotypes and pathomechanism of RGS12 conditional knockout mice. We will analyze bone phenotypes in young (6 months (m)), mid-aged (14m) and aged (24m) mice to determine how deletion of RGS12 in early and late OC lineage cells affect postnatal age-associated bone metabolism by using Mx1-cre and Cathepsin K-Cre mice. We will further characterize in vitro of OCs derived from aging RGS12 / /cre mice and determine the contribution of mesenchymal lineage cells to the OCs and skeletal phenotype in aging RGS12 / /cre mice. In Aim 2, we will elucidate the mechanism of RGS12 interactions that confer specificity of Ca2+ oscillation and OCs with age by characterizing pathomechanism and pathways, RGS12 domain functions and its heterodimerization partners. The goal of this project is to discover the role and mechanism of RGS12 in OC differentiation and activation in pathologic age condition, and provide new and more effective therapeutic targets to age-associated osteoporosis and other bone diseases.

描述（由申请人提供）：与年龄相关的骨质疏松症是一个主要的健康问题，其特征是由于破骨细胞生成和活性随着年龄的增加而导致骨重塑和代谢失衡。目前的治疗方案受到反应率较低或副作用的限制，并且无法有效解决骨质疏松症的负担和异质性。建立成功治疗方法的进一步进展迫切需要更清楚地了解破骨细胞（OC）随年龄的分化和骨重塑机制。有证据表明，RANKL 诱发的 Ca2+ 振荡在 PLC� 和 NFATc1 的激活以及 OC 分化中发挥着开关作用。进一步的研究表明，FcR�和DAP 12调节PLC�的磷酸化，PLC�是参与RANKL诱导的Ca2+振荡-NFATc1途径的关键成分。尽管有这些新见解，但仍不清楚 RANKL 如何引发必要的 Ca2+ 振荡，从而触发 NFATc1 激活和 OC 分化，并且尚不清楚这种机制是否以及如何参与与年龄相关的骨质流失。我们最近的研究表明，G 蛋白信号调节蛋白 12 (RGS12) 在 OC 分化过程中显着表达，并且 RGS12 表达随着年龄的增长而显着增加。 RGS12 表达的敲低抑制了 Ca2+ 振荡、NFATc1 表达和 OC 分化。从造血/早期 OC 谱系细胞 (RGS12 / /cre) 中删除 RGS12 会导致骨量显着增加，并且这种骨量的增加可以保护 RGS12 / /cre 小鼠免受与年龄相关的骨质流失。我们还发现，随着年龄的增长，小鼠中 RGS12 的缺失会降低 OC 数量和骨髓脂肪生成水平。基于这些结果，我们假设与年龄相关的骨重塑和代谢需要RGS12的表达和功能，并且RGS12是控制衰老过程中Ca2+振荡和OC分化的关键调节因子。我们将通过以下两个具体目标来检验该假设。在目标 1 中，我们将通过表征 RGS12 条件敲除小鼠的表型和病理机制来揭示 RGS12 在 OC 分化和衰老过程中的功能。我们将使用 Mx1-cre 和组织蛋白酶 K-Cre 小鼠分析年轻（6 个月（m））、中年（14m）和老年（24m）小鼠的骨表型，以确定早期和晚期 OC 谱系细胞中 RGS12 的缺失如何影响出生后年龄相关的骨代谢。我们将进一步在体外表征来自衰老 RGS12 / /cre 小鼠的 OC，并确定间充质谱系细胞对衰老 RGS12 / /cre 小鼠中 OC 和骨骼表型的贡献。在目标 2 中，我们将通过表征病理机制和途径、RGS12 结构域功能及其异二聚化伙伴，阐明 RGS12 相互作用的机制，该相互作用赋予 Ca2+ 振荡和 OCs 随年龄变化的特异性。该项目的目标是发现RGS12在病理年龄条件下OC分化和激活中的作用和机制，为年龄相关性骨质疏松症和其他骨疾病提供新的、更有效的治疗靶点。