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

1. 分析比较了8个阿尔茨海默病脑和18个年龄匹配的正常脑中cychn依赖性激酶5 （Cdk5）及其激活剂p35的表达水平和激酶活性。使用两种蛋白质特异性抗体的Western blot分析表明，与对照组相比，阿尔茨海默氏症大脑中的Cdk5和p35分别增加了20%和15%。老年痴呆症患者大脑中的Cdk5/p35活性比对照组高20%。特别是阿尔茨海默病患者大脑海马区活动增加了30%，而前脑区活动增加不明显。免疫组织化学研究表明，Cdk5和p35主要分布在阿尔茨海默病大脑特征的成对螺旋缠结区域。Cdk5和p35的Southern blot分析显示，阿尔茨海默病患者的大脑和对照组的大脑没有显著差异。检测了几种蛋白对Cdk5/p35活性的刺激或抑制作用，结果表明S100A和B对Cdk5/p35活性无刺激或抑制作用。我们最近克隆的Calbrain显示了对激酶活性的显著刺激。camp依赖性蛋白激酶、钙/磷脂依赖性蛋白激酶、钙调素依赖性蛋白激酶2和酪蛋白激酶均未使Cdk5/p35磷酸化，且未改变其活性。

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.