Protein expression profiling of the drosophila fragile X mutant brain reveals up-regulation of monoamine synthesis.
Protein expression profiling of the drosophila fragile X mutant brain reveals up-regulation of monoamine synthesis.
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果蝇脆性 X 突变体大脑的蛋白质表达谱揭示了单胺合成的上调。
DOI：
10.1074/mcp.m400174-mcp200
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Broadie,Kendal
中科院分区：
文献类型：
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作者：
Zhang,YongQ;Friedman,DavidB;Wang,Zhe;Woodruff3rd,Elvin;Pan,Luyuan;O'donnell,Janis;Broadie,Kendal
脆性X染色体综合征是遗传性智力低下的最常见形式，与认知和行为异常有关。这种疾病是由脆性X智力低下1（fmr 1）基因沉默引起的，该基因编码mRNA结合的翻译调节因子FMRP。以前，我们通过果蝇fmr 1（dfmr 1）突变建立了一个疾病模型，并表明dFMRP的缺失导致神经元结构，功能和行为输出的缺陷，类似于人类疾病状态。为了揭示dFMRP在大脑中的分子靶点，我们在这里使用蛋白质组学方法，包括二维差异凝胶电泳分析，然后通过质谱鉴定具有显着改变的表达indfmr 1 null突变体的蛋白质。然后，我们专注于两个失调的酶，苯丙氨酸羟化酶（指甲花）和GTP环化水解酶（冲床），这两个调解音乐会的两个关键的单胺神经调节剂，多巴胺和5-羟色胺的合成途径。脑酶测定显示出近2倍的升高冲床活动indfmr 1无效突变体。一致的脑神经化学分析表明，多巴胺和5-羟色胺显着增加indfmr 1无效突变体。在细胞水平上，dfmr 1 null突变神经元显示出高度显著的致密核心囊泡的升高，这些囊泡包装这些单胺神经调节剂用于分泌。总之，这些数据表明dFMRP通常下调单胺途径，因此在突变体条件下上调。大脑中多巴胺和血清素水平的升高为人类患者的认知和行为缺陷提供了一个合理的机制解释。
Fragile X syndrome is the most common form of inherited mental retardation, associated with both cognitive and behavioral anomalies. The disease is caused by silencing of the fragile X mental retardation 1 (fmr1) gene, which encodes the mRNA-binding, translational regulator FMRP. Previously we established a disease model through mutation ofDrosophila fmr1(dfmr1) and showed that loss of dFMRP causes defects in neuronal structure, function, and behavioral output similar to the human disease state. To uncover molecular targets of dFMRP in the brain, we use here a proteomic approach involving two-dimensional difference gel electrophoresis analyses followed by mass spectrometry identification of proteins with significantly altered expression indfmr1null mutants. We then focus on two misregulated enzymes, phenylalanine hydroxylase (Henna) and GTP cyclohydrolase (Punch), both of which mediate in concert the synthetic pathways of two key monoamine neuromodulators, dopamine and serotonin. Brain enzymatic assays show a nearly 2-fold elevation of Punch activity indfmr1null mutants. Consistently brain neurochemical assays show that both dopamine and serotonin are significantly increased indfmr1null mutants. At a cellular level,dfmr1null mutant neurons display a highly significant elevation of the dense core vesicles that package these monoamine neuromodulators for secretion. Taken together, these data indicate that dFMRP normally down-regulates the monoamine pathway, which is consequently up-regulated in the mutant condition. Elevated brain levels of dopamine and serotonin provide a plausible mechanistic explanation for aspects of cognitive and behavioral deficits in human patients.