The Role of Sphingosine Kinases in Bone Anabolism

鞘氨醇激酶在骨合成代谢中的作用

• 批准号: 9274156
• 负责人: KARL Leonard INSOGNA
• 金额: $ 36.85万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9274156
• 关键词: Adult; Affect; Anabolic Agents; Anabolism; Animals; Attenuated; Back; Binding; Biomechanics; Bone Resorption; Bone Surface; CSF1R gene; Calcium; Cells; Coculture Techniques; Data; Dual-Energy X-Ray Absorptiometry; Elements; Endocrine; Engineering; Enzymes; FDA approved; Feeds; Forteo; Gene Chips; Genes; Half-Life; Hematopoietic; Hormones; Hyperparathyroidism; Hypoparathyroidism; Impairment; Individual; Injection of therapeutic agent; Knockout Mice; Lead; Macrophage Colony-Stimulating Factor; Mediating; Messenger RNA; Modeling; Molecular; Mus; Mutation Analysis; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; PTH gene; Participant; Patients; Pharmacology; Phenotype; Phospholipids; Phosphorylation; Physiological; Play; Production; Protein Isoforms; RNA; Reporting; Role; S-1 Antimetabolite agent; SPHK1 enzyme; Serum; Signal Transduction; Testing; Time; Transcript; Transcriptional Activation; Transcriptional Regulation; Woman; activating transcription factor 1; base; bone; bone mass; c-fms Proto-Oncogenes; chromatin immunoprecipitation; cis acting element; deletion analysis; feeding; in vivo; interest; mouse model; paracrine; prevent; promoter; receptor; response; skeletal; sphingosine 1-phosphate; sphingosine kinase; substantia spongiosa; transcription factor

Project Summary/Abstract Parathyroid hormone is a major systemic regulator of the basal rate of bone formation, which is why patients with hypoparathyroidism have very low rates of bone formation, while bone formation rates are increased in hyperparathyroidism. The ability of PTH to stimulate bone formation is the basis for its use as the only FDA- approved anabolic agent (teriparatide) to treat low bone mass. CSF-1 is the principle colony stimulating activity released by osteoblasts constitutively and in response to PTH treatment, and its receptor, c-fms, is more highly expressed on osteoclasts than any other cell in bone or in the hematopoietic microenvironment. We have identified several key actions of CSF-1 on the formation and function of mature osteoclasts. We also have very recently discovered that CSF-1 transcriptionally activates the sphingosine kinase 1 gene (SPHK1) in mature osteoclasts, which is the rate-limiting enzyme required for the synthesis of sphingosine-1- phosphate (S-1-P), a phospholipid with anabolic effects in bone. This change results in an increase in S-1-P production by osteoclasts. Two recently reported mouse models in which a selective increase in osteoclast production of S-1-P results in an increased basal rate of bone formation in vivo and an increase in bone mass support the physiologic importance of this phospholipid as a key regulator of bone anabolism. Together with our data, these findings lead us to propose a new endocrine/paracrine loop in which PTH stimulates the production of CSF-1 from cells in the osteoblast lineage resulting in increased expression of SPHK1 and S-1-P production by osteoclasts. This locally produced S-1-P in bone “feeds back” on osteoblasts to contribute to the bone forming actions of PTH. Based on this model we hypothesize that SPHK1 and S-1-P are part of the downstream anabolic path entrained by single daily administration of PTH. To test this hypothesis we will undertake the following specific aims: 1. Directly determine the contribution of sphingosine kinases to the basal rate of bone formation by selectively deleting SPHK activity in osteoclasts in vivo to determine its contribution to bone anabolism as quantified by changes in bone mass and bone formation rates as well as changes in the function of osteoblasts isolated from SPHK null mice. 2. Determine the contribution of sphingosine kinases to the anabolic response to PTH by examining the anabolic response to single daily administration of PTH to SPHK null mice. If the anabolic response is attenuated we will undertake gene-profiling studies using PCR-expression arrays that target bone anabolism to begin to understand the molecular bases for the observed differences. 3. Examine how CSF-1 increases expression of sphingosine kinase 1 (SPHK1) by studying the mechanisms by which of CSF-1 transcriptionally activates the SPHK1 promoter and determining if blocking ERK signaling prevents this. We will also evaluate the effect of CSF-1 on the half-life of SPHK1 mRNA.

项目总结/摘要 甲状旁腺激素是骨形成基础速率的主要全身调节剂，这就是为什么患者 甲状旁腺功能减退的患者骨形成率非常低，而甲状旁腺功能减退的患者骨形成率增加， 甲状旁腺机能亢进PTH刺激骨形成的能力是其作为唯一FDA- 批准的合成代谢剂（teriparlitazone）治疗低骨量。CSF-1是主要的集落刺激活性 由成骨细胞组成性释放并响应PTH治疗，其受体c-fms更高， 在破骨细胞上的表达比骨或造血微环境中的任何其他细胞都要多。我们有 确定了CSF-1对成熟破骨细胞的形成和功能的几个关键作用。我们也有 最近发现CSF-1可转录激活鞘氨醇激酶1基因（SPHK 1）， 在成熟的破骨细胞中，它是合成鞘氨醇-1- 磷酸盐（S-1-P），一种在骨中具有合成代谢作用的磷脂。这一变化导致 破骨细胞产生S-1-P。最近报道的两种小鼠模型中， 破骨细胞产生S-1-P导致体内骨形成的基础速率增加， 骨质量支持这种磷脂作为骨粘附的关键调节剂的生理重要性。 结合我们的数据，这些发现使我们提出了一个新的内分泌/旁分泌回路， PTH刺激成骨细胞谱系中的细胞产生CSF-1，导致成骨细胞增殖增加。 破骨细胞SPHK 1的表达和S-1-P的产生。这种当地生产的S-1-P在骨“饲料” 在成骨细胞上的“背部”有助于PTH的骨形成作用。基于这个模型，我们 假设SPHK 1和S-1-P是由单一每日摄入所携带下游合成代谢途径的一部分， 给予PTH。为了检验这一假设，我们将采取以下具体目标： 1.直接测定鞘氨醇激酶对骨形成基础速率的贡献， 选择性地去除体内破骨细胞中的SPHK活性以确定其对骨愈合的贡献 通过骨量和骨形成率的变化以及成骨细胞功能的变化来量化 分离自SPHK缺失小鼠。 2.通过检查神经鞘氨醇激酶对PTH合成代谢反应的贡献， 对SPHK敲除小鼠每天单次给予PTH的合成代谢反应。如果合成代谢反应是 我们将使用PCR表达阵列进行基因分析研究， 开始理解观察到的差异的分子基础。 3.研究CSF-1如何增加鞘氨醇激酶1（SPHK 1）的表达， CSF-1转录激活SPHK 1启动子的机制，并确定是否阻断 ERK信号传导阻止了这一点。我们还将评估CSF-1对SPHK 1 mRNA半衰期的影响。