Role of Serotonin in Osteoclast Differentation

描述（由申请人提供）：最近的研究结果表明，调节相互作用发生在神经和骨骼系统之间。使用DNA微阵列，我们发现5-羟色胺转运蛋白（5-HTT）的表达在RANKL诱导的破骨细胞（OC）中强烈上调。氟西汀（百忧解），一种选择性5-HTT抑制剂，剂量依赖性地抑制OC的形成和再吸收活性。5-htt基因缺失的纯合子小鼠表现出皮质骨质量增加，氟西汀治疗的Swiss-Webster小鼠增加了骨小梁。这些发现导致了新的假设，即5-羟色胺（5-HT）系统通过影响破骨细胞的发育和/或活化在骨形成和重塑中起着至关重要的作用。目的1将在mRNA和蛋白质水平上表征破骨细胞（OC）中5-羟色胺系统的元素的表达，并将确认每个都是功能性的。目的2将确定5-羟色胺（5-HT），5-HTT，5-羟色胺受体（SIR），囊泡单胺转运蛋白1（VMAT 1）和单胺氧化酶（MAO）A在体外OC的形成和/或激活中的作用，使用一组特定的激动剂和抑制剂。在目标3中，我们将检验以下假设：通过对RANK刺激的NFkB激活的影响，细胞内5-HT升高是观察到的效应所必需的。目的4将使用适当的敲除小鼠分析5-HTT、SIRs、VMAT 1和MAO A在体内破骨细胞生成中的作用。目的5将确定这些血清素系统成分在病理性骨吸收模型中的功能，包括雌激素耗竭或感染引起的骨吸收。我们的目标是描述OC中存在的5-羟色胺系统的元素，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.