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.

项目摘要/摘要 甲状旁腺激素是基础骨形成速率的主要系统调节器，这就是为什么患者 甲状旁腺功能减退症患者的骨形成率非常低，而骨形成率在 甲状旁腺机能亢进。甲状旁腺激素刺激骨形成的能力是其作为唯一的FDA- 批准的合成代谢剂(Teriparatide)用于治疗低骨量。脑脊液-1是主要的集落刺激活性 成骨细胞对甲状旁腺激素的结构性和反应性释放，其受体c-fms的水平更高。 在破骨细胞上的表达高于骨骼或造血微环境中的任何其他细胞。我们有 确定了CSF-1在成熟破骨细胞的形成和功能上的几个关键作用。我们还有 最近发现，脑脊液-1可转录激活鞘氨醇激酶1基因(SPHK1) 在成熟的破骨细胞中，这是合成鞘氨醇-1-所需的限速酶。 磷酸(S-1-P)，一种在骨骼中具有合成代谢作用的磷脂。这一变化导致了 破骨细胞产生S-1-P。最近报道的两个小鼠模型，在这些模型中， 破骨细胞S-1-P的产生导致体内基础成骨速度增加，并增加 骨量支持这种磷脂作为骨合成代谢的关键调节因子的生理重要性。 结合我们的数据，这些发现导致我们提出了一个新的内分泌/旁分泌循环，在这个循环中 甲状旁腺激素刺激成骨细胞系细胞产生CSF-1，导致 破骨细胞产生SPHK1和S-1-P的表达这是当地生产的骨饲料中的S-1-P Back“作用于成骨细胞，参与甲状旁腺激素的成骨作用。基于这个模型，我们 假设SPHK1和S-1-P是每日单次携带的下游合成代谢途径的一部分 甲状旁腺素的给药。为了验证这一假设，我们将采取以下具体目标： 1.通过以下方法直接确定鞘氨醇激酶对基础骨形成速率的贡献 体内选择性删除破骨细胞中SPHK活性以确定其对骨合成代谢的贡献 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基因缺失小鼠。 2.通过研究鞘氨醇激酶在甲状旁腺激素合成代谢反应中的作用 SPHK基因缺失小鼠每日单次注射甲状旁腺素的合成代谢反应。如果合成代谢反应是 我们将使用针对骨合成代谢的聚合酶链式反应表达阵列进行基因图谱研究 开始了解所观察到的差异的分子基础。 3.研究CSF-1如何促进鞘氨醇激酶1(SPHK1)的表达 CSF-1转录激活SPHK1启动子的机制及是否阻断 ERK信令阻止了这一点。我们还将评估CSF-1对SPHK1mRNA半衰期的影响。