Osteoclastic Protein-Tyrosine Phosphatase and Resorption

破骨蛋白酪氨酸磷酸酶和吸收

• 批准号: 7790122
• 负责人: Kin-Hing William Lau
• 金额: --
• 依托单位: VA LOMA LINDA HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7790122
• 关键词: Actins; Address; Adhesions; Adult; Affinity; Aging; Attenuated; B-Lymphocytes; Binding; Biology; Bone Diseases; Bone Marrow Transplantation; Bone Resorption; Bone Resorption Inhibition; CD29 Antigen; Cell Differentiation process; Cell fusion; Cells; Chimeric Proteins; Clinical; Complex; Cytoskeleton; Data; Dendritic Cells; Development; Dimerization; Disease; Enzymes; EphA Receptors; EphA4 Receptor; Ephrin B Receptor; Ephrins; Equilibrium; Estrogen Receptor 1; Estrogen Receptor alpha; Estrogen Replacements; Estrogens; Etiology; Evaluation; Exhibits; FOS gene; Family; Female; Foundations; Fracture; Functional disorder; Future; Gene Expression; Genes; Glutathione S-Transferase; Growth; Guanosine Triphosphate; Health; Hematopoietic; Hematopoietic stem cells; Hip Fractures; Human; ITAM; ITIM; In Vitro; Incidence; Integral Membrane Protein; Integrin Inhibition; Integrin beta3; Integrins; Knock-out; Knockout Mice; Knowledge; Laboratories; Ligand Binding; Ligands; MAPK9 gene; Marrow; Mediating; Mediator of activation protein; Medical; Metabolic; Mission; Modality; Molecular; Molecular Mechanisms of Action; Monomeric GTP-Binding Proteins; Morbidity - disease rate; Mus; Mutate; NR0B2 gene; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Ovariectomy; Pathway interactions; Patient Care; Patients; Pattern Formation; Pharmacogenomics; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotyrosine; Physiology; Play; Postmenopausal Osteoporosis; Process; Protein Dephosphorylation; Protein Tyrosine Kinase; Protein Tyrosine Phosphatase; Proteins; Quality of life; RU-486; Recombinants; Regulation; Research Project Grants; Retroviral Vector; Role; SRC gene; Signal Transduction; Signaling Protein; Small Interfering RNA; Stem cells; Symptoms; TNFSF11 gene; Tail; Talin; Testing; Transgenic Mice; Transgenic Organisms; Tyrosine Phosphorylation; Up-Regulation; Vertebral column; Veterans; Wasting Syndrome; Wild Type Mouse; Work; base; bone; bone loss; bone mass; cell motility; cell type; clinically relevant; cost; effective therapy; ephexin; improved; in vitro activity; in vivo; inhibitor/antagonist; insight; interest; macrophage; male; member; migration; monocyte; mutant; novel; overexpression; patient population; paxillin; prepuberty; prevent; protein-tyrosine kinase c-src; receptor; repaired; research study; rho; rho GTP-Binding Proteins; sex; skeletal; substantia spongiosa; therapeutic target

DESCRIPTION (provided by applicant): The ultimate objective of this research project is to identify the molecular mechanism (and/or key mediators) by which osteoclastic resorption is regulated. In this regard, recent studies showed that targeted over-expression of a structurally unique osteoclastic protein-tyrosine phosphatase (PTP-oc) in osteoclastic cells led to a large increase in bone resorption and a marked decrease in bone mass in male but not female transgenic mice, compared to corresponding wild-type littermates. Very recent preliminary studies discovered two novel molecular mechanisms of PTP-oc to regulate the overall osteoclast activity: 1) the EphA4 signaling may function as a negative regulatory mechanism of osteoclastic resorption and PTP-oc stimulates osteoclast differentiation and activity through relieving the inhibitory actions of the EphA4 signaling via dephosphorylation of EphA4; and 2) the PTP-oc signaling increases estrogen receptor (ER) 1 signaling through an upregulation of the c-Src-dependent phosphorylation of ER1 in osteoclasts, which in turn suppresses bone resorption in adult female but not male PTP-oc transgenic mice. This proposal has three Specific Objectives to investigate these two novel mechanisms of PTP-oc. The first Objective is to demonstrate that the EphA4 signaling is negative regulator of osteoclasts through differential regulation of the various Rho GTPases and through suppression of the Erk1/2-c-Fos-NFAT1c cascade. This will be accomplished through evaluation of the bone phenotype of EphA4-deficient mice in vivo and to determine the effects of deficient EphA4 expression in osteoclast precursors of EphA4 null mice or transgenic over-expression of EphA4 in wild-type precursors on the formation, fusion, adhesion, migration, actin cytoskeleton re-organization, and resorption activity of osteoclasts in vitro. Effects of deficient EphA4 signaling in EphA4 null osteoclasts on the activation states of the various Rho GTPases and the Erk1/2-c-Fos-NFATc1 signaling cascade are also determined. The second Objective is to determine whether PTP-oc enhances by osteoclastic resorption, in part, through suppressing the inhibitory actions of the EphA4 on osteoclasts through direct dephosphorylation of EphA4. This is achieved by confirming that EphA4 is a cellular substrate of PTP-oc, and by demonstrating that over-expression of WT-PTP-oc, but not PD-PTP-oc, would inhibit the suppressive effects of the EphA4 signaling on osteoclast differentiation and activity. It is also tested by showing that the hemotopoietic stem cell-based marrow transplantation with WT- EphA4, but not the mutant lacking the key phosphotyrosine residues, would reverse the osteoporotic phenotype of EphA4 null mice. The third Objective is to determine whether the PTP-oc signaling increases estrogen receptor (ER) 1 signaling through the c-Src-dependent phosphorylation of ER1 in osteoclasts, which in turn suppresses bone resorption in adult female but not male PTP-oc transgenic mice. This is achieved by a) comparing the bone phenotype and the ER1 signaling in osteoclasts of pre-pubertal male and female PTP-oc transgenic mice, 2) evaluating the effects of ovariectomy and estrogen replacement on the osteoclastic phenotype of adult female PTP-oc transgenic mice, and 3) evaluating the effects of PTP-oc over-expression in osteoclasts of ER1 null female mice. Our work should provide important insights into the molecular mechanism of the osteoclast activation and/or the role of a unique osteoclastic enzyme (PTP-oc) in the regulation of two novel signaling mechanisms of osteoclastic resorption. Potential clinical relevance is that aberration in PTP-oc function could be involved in some patients with excess bone resorption and, as such, PTP-oc could be a target for pharmacogenomic treatments of osteoporosis and related bone-wasting diseases. PUBLIC HEALTH RELEVANCE: Bone diseases, including osteoporosis and related bone-wasting diseases, are common in the VA patient population. The increase in incidence of osteoporosis and related diseases is particularly high in female veterans. Identification of the etiology and molecular mechanism of such bone loss and effective therapies to overcome and/or even prevent osteoporosis would significantly reduce the morbidity with aging and improve the quality of life. A reduction in hip fractures, which can be a particular debilitating symptom of osteoporosis, would be desirable with respect to reduction of medical costs and human suffering. Increased understanding of the cause and mechanisms of osteoclastic resorption, which is the major objective of this project, should provide a foundation of knowledge to improve our understanding of the cause of bone-wasting diseases. This project may allow disclose novel targets for development of more effective anti-resorptive therapies for osteoporosis and related disease. Thus, this project is highly relevant to the VA patient care mission.

描述（由申请人提供）： 本研究项目的最终目的是确定骨吸收调节的分子机制（和/或关键介质）。在这方面，最近的研究表明，有针对性的过度表达的结构独特的骨细胞蛋白酪氨酸磷酸酶（PTP-oc）的骨细胞导致骨吸收的大幅增加和骨量显着下降，在男性而不是女性的转基因小鼠，与相应的野生型同窝仔。最近的初步研究发现了PTP-oc调节破骨细胞活性的两种新的分子机制：1）EphA 4信号可能作为骨吸收的负调节机制，PTP-oc通过EphA 4的去磷酸化解除EphA 4信号的抑制作用，从而刺激破骨细胞的分化和活性;和2）PTP-α信号传导通过破骨细胞中ER 1的c-Src依赖性磷酸化的上调而增加雌激素受体（ER）1信号传导，这反过来抑制成年雌性而非雄性PTP-α转基因小鼠的骨吸收。本提案有三个具体目标来研究PTP-oc的这两种新机制。第一个目的是证明EphA 4信号是通过不同Rho GTP酶的差异调节和通过Erk 1/2-c-Fos-NFAT 1c级联的抑制来负调节破骨细胞。这将通过评估EphA 4缺陷小鼠的体内骨表型来实现，并确定EphA 4缺失小鼠的破骨细胞前体中EphA 4表达缺陷或野生型前体中EphA 4的转基因过表达对体外破骨细胞的形成、融合、粘附、迁移、肌动蛋白细胞骨架重组和再吸收活性的影响。还测定了EphA 4缺失型破骨细胞中EphA 4信号传导缺陷对各种Rho GTP酶和Erk 1/2-c-Fos-NFATc 1信号传导级联的活化状态的影响。第二个目的是确定PTP-α是否通过骨细胞再吸收而增强，部分地通过抑制EphA 4对破骨细胞的抑制作用（通过EphA 4的直接去磷酸化）。这是通过确认EphA 4是PTP-α的细胞底物，并通过证明WT-PTP-α而不是PD-PTP-α的过表达将抑制EphA 4信号传导对破骨细胞分化和活性的抑制作用来实现的。还通过显示使用WT-EphA 4而不是缺乏关键磷酸酪氨酸残基的突变体的基于造血干细胞的骨髓移植将逆转EphA 4缺失小鼠的造血表型来测试。第三个目的是确定PTP-oc信号是否通过破骨细胞中雌激素受体（ER）1的c-Src依赖性磷酸化来增加ER 1信号，从而抑制成年雌性而非雄性PTP-oc转基因小鼠的骨吸收。这是通过以下方式实现的：a）比较青春期前雄性和雌性PTP-oc转基因小鼠的骨表型和破骨细胞中的ER 1信号传导，2）评估卵巢切除术和雌激素替代对成年雌性PTP-oc转基因小鼠的骨表型的影响，和3）评估ER 1缺失雌性小鼠的破骨细胞中PTP-oc过表达的影响。我们的工作应该提供重要的见解破骨细胞活化的分子机制和/或一个独特的骨钙素酶（PTP-OC）的作用，在两个新的信号机制的骨钙素吸收的调节。潜在的临床相关性是，PTP-oc功能的异常可能涉及一些过度骨吸收的患者，因此，PTP-oc可能是骨质疏松症和相关骨消耗性疾病的药物基因组学治疗的靶点。 公共卫生相关性： 骨疾病，包括骨质疏松症和相关骨消耗性疾病，在VA患者人群中很常见。骨质疏松症和相关疾病的发病率在女性退伍军人中特别高。明确骨质疏松症的病因和分子机制，并采取有效的治疗措施来克服和/或预防骨质疏松症，将显著降低老年人骨质疏松症的发病率，提高老年人的生活质量。髋骨骨折可能是骨质疏松症的一种特别使人衰弱的症状，减少髋骨骨折对于减少医疗费用和人类痛苦是理想的。本项目的主要目标是增加对骨吸收的原因和机制的了解，这将为我们提高对骨消耗性疾病原因的了解提供知识基础。该项目可能允许公开用于开发针对骨质疏松症和相关疾病的更有效的抗吸收疗法的新靶点。因此，该项目与VA患者护理使命高度相关。