Differential post-translational modifications of transthyretin in Alzheimer's disease: A study of the cerebral spinal fluid
Differential post-translational modifications of transthyretin in Alzheimer's disease: A study of the cerebral spinal fluid
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DOI：
10.1002/pmic.200500285
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发表时间：
2006-04-01
期刊：
影响因子：
3.4
通讯作者：
Urbani, A
中科院分区：
文献类型：
--
作者：
Biroccio, A;del Boccio, P;Urbani, A
转甲状腺素(TTR)是一种55 kDa的同源四聚体蛋白。脑脊液中的TTR主要由脉络丛合成。TTR可以与P-淀粉样肽结合，许多家族性淀粉样变性疾病(家族性淀粉样多发性神经病)都与其等位基因变异有关。在转基因小鼠模型中，TTR的过度表达与致病APPsw突变的神经保护作用呈正相关。TTR在半胱氨酸(10)残基上有一个自由的反应性的巯基部分，该残基被认为经历了各种氧化反应。为了研究TTR的神经保护作用，我们研究了39名可能患有阿尔茨海默病(AD)的受试者和一组没有认知障碍的受试者(27名受试者)脑脊液中TTR与半胱氨酸(Cys)和半胱氨酸(CsyGly)的结合形式。利用线性MALDI-TOF MS实验获得高分辨率的TTR亚型蛋白质图谱。将纳米LC串联质谱仪与反射MALDI-TOF-MS联用，对所研究的TTR型共轭信号进行了明确的归属。我们的结果表明TTRCys和TTRCsyGly加合物的分布是不同的。在AD组中，这两种氧化形式的TTR值均显著低于AD组(p=0.0001)。调查人群(66名受试者)然后用每个受试者的结合Ttr与游离Ttr的比率进行诊断。当通过Ttr-Cys信号分析整个队列时，敏感度>；90%和特异度>；70%来自接收器操作特征曲线。这篇手稿是第一篇报道AD患者脑脊液中存在不同的TTR翻译后氧化的报道。
Transthyretin (TTR) is a 55 kDa homotetrameric protein. TTR in the cerebral spinal fluid (CSF) is primarily synthesized by the choroid plexus. TTR can bind to the P-amyloid peptide and a number of familial amyloidosis diseases (familial amyloid polyneuropathy) have been associated with its allele variants. In a transgenic mice model overexpression of TTR was positively correlated with a neuroprotective effect from the pathogenic APPsw mutation. TTR has a free reactive sulphydryl moiety located on the Cys(10) residue which has been implicated to undergo a variety of oxidation reactions. To examine the neuroprotective role of TTR, we investigated the conjugated forms of TTR with cysteine (Cys) and cysteinglycine (CsyGly) in the CSF of 39 probable Alzheimer's disease (AD)-affected subjects and in a cohort of subjects without cognitive impairment (27 subjects). Linear MALDI-TOF MS experiments were employed to obtain high-resolution protein profiling of TTR isoforms. Nano-LC-TANDEM MS combined with reflectron MALDI-TOF-MS was used to unequivocally assign the investigated TTR-conjugate signals. Our results indicate a differential distribution of TTR-Cys and TTR-CsyGly adducts. Both oxidized forms of TTR are significantly less abundant in the AD group (p = 0.0001). The investigated population (66 subjects) was then diagnosed using the ratio of conjugated TTR to free TTR in each subject. A sensitivity > 90% and a specificity > 70% were derived from a receiver operating characteristic curve when the overall cohort is analysed by the TTR-Cys signals. This manuscript is the first report describing the presence of differential post-translational oxidations of TTR in the CSF of AD patients.