Role of Serotonin in Osteoclast Differentation

描述(由申请人提供)：最近的研究结果表明，神经和骨骼系统之间发生了调节相互作用。利用DNA芯片，我们发现5-羟色胺转运体(5-HTT)在RANKL诱导的破骨细胞(OC)中表达强烈上调。氟西汀(Prozac)是一种选择性的5-HTT抑制剂，可剂量依赖性地抑制OC的形成和吸收活性。5-HTT基因纯合缺失的小鼠表现出皮质骨量增加，而氟西汀治疗的Swiss-Webster小鼠的骨小梁增加。这些发现导致了一种新的假说，即5-羟色胺(5-HT)系统通过影响破骨细胞的发育和/或激活，在骨形成和重塑中发挥关键作用。目的1研究破骨细胞(OC)中5-羟色胺系统成分在mRNA和蛋白质水平的表达，并证实每种成分都具有功能。目的研究5-羟色胺(5-HT)、5-羟色胺(5-HTT)、5-羟色胺受体(SIR)、囊泡单胺转运体1(VMAT1)和单胺氧化酶(MAO)A在体外OC形成和/或激活中的作用。在目标3中，我们将通过对RANK刺激的NFkB激活的影响来检验细胞内5-羟色胺的升高对于观察到的效应是必要的这一假设。目的4利用合适的基因敲除小鼠，分析5-HTT、SIRS、VMAT1和MAO A在体内破骨细胞形成中的作用。目的5确定这些5-羟色胺系统成分在病理性骨吸收模型中的作用，包括雌激素耗竭或感染引起的骨吸收。我们的目标是确定OC中存在的5-羟色胺系统的成分，并确定它们在生理和病理条件下调节骨量的作用。

DESCRIPTION (provided by applicant): Recent findings suggest that regulatory interactions occur between the neural and skeletal systems. Using DNA microarrays, we found that expression of the serotonin transporter (5-HTT) is strongly up-regulated in RANKL-induced osteoclasts (OC). Fluoxetine ('Prozac'), a selective 5-HTT inhibitor, dose-dependently inhibited OC formation and resorptive activity. Mice homozygous for a deletion of the 5-htt gene exhibited increased cortical bone mass, and fluoxetine treatment of Swiss-Webster mice increased trabecular bone. These findings lead to the novel hypothesis that the serotonin (5-HT) system plays a crucial role in bone formation and remodeling, via effects on osteoclast development and/or activation. Aim 1 will characterize the expression of elements of the serotonin system in osteoclasts (OC) at the mRNA and protein levels, and will confirm that each is functional. Aim 2 will determine the role of serotonin (5-HT), the 5-HTT, serotonin receptors (SIR), vesicular monoamine transporter 1 (VMAT1), and monoamine oxidase (MAO) A in the formation and/or activation of OC in vitro, using a panel of specific agonists and inhibitors. In Aim 3, we will test the hypothesis that elevations in intracellular 5-HT are necessary for the observed effects, via effects on RANK-stimulated NFkB activation. Aim 4 will analyze the roles of the 5-HTT, SIRs, VMAT1, and MAO A in osteoclastogenesis in vivo using appropriate knockout mice. Aim 5 will determine the function of these serotonin system components in models of pathologic bone resorption, including resorption caused by estrogen-depletion or infection. The goal is to characterize the elements of the serotonin system that are present in OC, and determine their role in the regulation of bone mass under physiologic and pathologic conditions.