Role of cyclin-dependent kinase 5 in Alzheimer's brain.

1.分析比较8例阿尔茨海默病患者和18例年龄匹配的正常脑组织中细胞周期蛋白依赖性蛋白激酶5(CDK5)及其激活物p35的表达水平和活性。利用两种蛋白的特异性抗体进行的Western印迹分析表明，与对照组相比，阿尔茨海默病患者大脑中的CDK5和p35分别增加了20%和15%。阿尔茨海默病患者脑内CDK5/p35活性比对照组高20%。4.免疫组织化学研究表明，CDK5和p35主要分布在成对的螺旋缠结区域，这是阿尔茨海默病患者脑内的特点。对CDK5和p35的Southern印迹分析表明，阿尔茨海默病患者的大脑和对照组的大脑没有显著差异。检测了几种蛋白质对CDK5/p35活性的刺激或抑制活性，S100A和B没有表现出刺激或抑制活性。我们最近克隆的钙脑蛋白对该蛋白的活性有显著的刺激作用。CAMP依赖的蛋白激酶、钙/磷脂依赖的蛋白激酶、钙调蛋白依赖的蛋白激酶2和酪蛋白激酶均不能使CDK5/p35磷酸化，也不改变其活性。

1. Expression levels and kinase activity of cychn-dependent kinase 5 (Cdk5) and its activator p35 were analyzed and compared using 8 Alzheimer's brains and 18 age-matched normal brains.2. Western blot analysis using specific antibodies for two proteins elucidated that Cdk5 and p35 increased by 20% and 15%, respectively, in Alzheimer's brains as compare with those in control brains.3. Cdk5/p35 activity in Alzheimer's brains was 20% higher than that in control brains. Especially, the activity in hippocampus in Alzheimer' s brains increased by 30%, however, that in forebrain did not increase significantly,4. Immunohistochemical study elucidated that distribution of both Cdk5 and p35 was dominantly observed at the regions of paired helical tangles which is characteristic in Alzheimer's brains.5. Southern blot analysis of Cdk5 and p35 showed no significant difference between Alzheimer's brains and control brains.6. Several proteins were assayed for the stimulatory or inhibitory activity of Cdk5/p35 activity, and S100A and B showed no stimulation or inhibition. Calbrain which we recently cloned showed a significant stimulation on the kinase activity.7. None of cAMP-dependent protein kinase, calcium/phospholipid-dependent protein kinase, calmodulin-dependent protein kinase 2 and casein kinase phosphorylated Cdk5/p35 and did not alter its activity.