Neurochemical Actions of Psychotropic Drugs

描述(由申请人提供)：多年来，我们的研究一直集中在识别和表征新的神经信使分子及其在精神药物作用中的作用上，由这笔资金支持。我们建议在这一领域最新进展的基础上进行新的研究，特别是涉及气体传递体和D-氨基酸。基于我们早期对NO和CO的研究，我们最近发现硫化氢(H_2S)是一种值得注意的信号分子。我们通过CSE和CBS基因敲除来证明它的生物合成是由胱硫醚-γ-裂解酶(CSE)和胱硫醚-β-合成酶(CBS)完成的。我们发现，H_2S通过硫化靶蛋白中的半胱氨酸来传递信号，类似于NO通过亚硝化的作用。我们将通过一种新的半胱氨酸生成硫化氢的组织化学染色来绘制CBS/CSE及其催化活性的图谱。我们将对新的硫化目标进行表征。根据我们对CSE转录诱导的研究结果，我们将阐明该酶在不同条件下的周转。最近，我们在亨廷顿病(HD)中发现了CSE的深度缺失，反映了突变的Hunting tin影响CSE转录因子SP1。在细胞培养和补充半胱氨酸的完整小鼠中，通过挽救HD表型而减轻HD表型的病理生理学相关性明显。我们将进一步研究HD小鼠和神经培养中半胱氨酸/硫化氢的动力学。半胱氨酸耗竭也可能是HD患者营养缺乏的原因。因此，我们还将研究CSE对肥胖的调节作用。 我们建立了D-丝氨酸作为谷氨酸-NMDA受体的内源性激动剂，鉴定、克隆和鉴定了其生物合成酶丝氨酸消旋酶(SR)。最近，我们发现SR可以将AMPA和NMDA谷氨酸传递联系起来。SR与AMPA受体辅助蛋白Stargazin结合，导致膜结合和SR抑制。SR还与PSD-95结合，通过NMDA处理将其从PSD-95上解离。我们将在AMPA和NMDA受体系统之间的明显串扰中阐明SR的生理学意义。我们最近在哺乳动物的大脑和其他组织中发现了大量的D-半胱氨酸。我们建立了一种新的检测组织D-半胱氨酸的灵敏和特异的方法。我们将在不同情况下监测不同组织中D-半胱氨酸的水平。我们将通过已知或迄今未知的酶来寻找D-半胱氨酸的生物合成机制。

DESCRIPTION (provided by applicant): Our research, supported by this grant over the years, has focused on identifying and characterizing novel neural messenger molecules and their roles in psychotropic drug actions. We propose new studies based on recent advances in this area involving, in particular, gasotransmitters and D-amino acids. Based on our earlier work on NO and CO, we have recently identified hydrogen sulfide (H2S) as a notable signaling molecule. We established its biosynthesis by cystathionine-gamma-lyase (CSE) and cystathionine- beta-synthase (CBS) by demonstrating its depletion with CSE and CBS knockout. We showed that H2S signals by sulfhydrating cysteines in target proteins, analogous to NO acting by nitrosylation. We will map CBS/CSE and their catalytic activity via a novel histochemical stain for H2S generation from cysteine. We will characterize new sulfhydrated targets. Based on our findings regarding CSE's transcriptional induction, we will elucidate the enzyme's turnover under diverse conditions. Recently we discovered a profound depletion of CSE in Huntington's Disease (HD) reflecting mutant huntingtin affecting the CSE transcription factor SP1. Pathophysiologic relevance was evident in the alleviation of the HD phenotype by rescue in cultures and intact mice by cysteine supplementation. We will further characterize cysteine/H2S dynamics in HD mice and neural cultures. The cysteine depletion may also account for the inanition of HD patients. Accordingly, we will also investigate the regulation by CSE of adiposity. We established D-serine as an endogenous agonist for glutamate-NMDA receptors, identifying, cloning and characterizing its biosynthetic enzyme serine racemase (SR). Recently, we discovered that SR can link AMPA and NMDA glutamate transmission. SR binds the AMPA receptor accessory protein stargazin leading to membrane association and SR inhibition. SR also binds PSD-95 from which it is dissociated by NMDA treatment. We will elucidate the physiologic significance of SR in an apparent cross-talk between AMPA and NMDA receptor systems. We recently identified substantial levels of D-cysteine in mammalian brain and other tissues. We have developed a novel sensitive and specific assay for tissue D-cysteine. We will monitor D-cysteine levels in diverse tissues under varying circumstances. We will seek biosynthetic mechanisms for D-cysteine via known or hitherto unidentified enzymes.