ERK MAP kinase signaling in post-mortem brain of suicide subjects: differential regulation of upstream Raf kinases Raf-1 and B-Raf
ERK MAP kinase signaling in post-mortem brain of suicide subjects: differential regulation of upstream Raf kinases Raf-1 and B-Raf
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DOI：
10.1038/sj.mp.4001744
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发表时间：
2006-01-01
影响因子：
11
通讯作者：
Pandey, GN
中科院分区：
文献类型：
--
作者：
Dwivedi, Y;Rizavi, HS;Pandey, GN
Raf激酶Raf-1和B-Raf是细胞外信号调节激酶（ERK）信号通路的上游激活剂，因此参与脑中的许多生理功能，包括神经元存活和突触可塑性。以前，我们观察到ERK-1/2的激活，ERK信号的下游组件，在自杀受害者死后的大脑中显着减少。本研究旨在进一步研究自杀脑是否也与ERK信号上游分子的异常有关。研究对象为28名自杀者和21名正常对照者的前额叶皮层（PFC）和海马。通过定量RT-PCR测量Raf-1、B-Raf和亲环素的mRNA水平。蛋白质水平的Raf-1和B-Raf的蛋白质印迹法测定，而它们的催化活性测定通过免疫沉淀和酶法。结果发现，自杀者PFC和海马中B-Raf的催化活性显著降低。这种降低与其蛋白质水平的降低有关，而与mRNA水平无关。另一方面，Raf-1的催化活性、mRNA和蛋白水平在自杀受试者死后的大脑中没有改变。观察到的变化与混杂变量无关;然而，Raf-1与年龄呈负相关。此外，无论精神病诊断如何，所有自杀受试者都存在B-Raf的变化。我们的结果，选择性降低催化活性和表达的B-Raf，而不是Raf-1表明，B-Raf可能在改变ERK信号在自杀受试者的大脑中发挥重要作用，从而在自杀的病理生理。
The Raf kinases Raf-1 and B-Raf are upstream activators of the extracellular signal-regulated kinase (ERK)-signaling pathway and therefore participates in many physiological functions in brain, including neuronal survival and synaptic plasticity. Previously, we observed that activation of ERK-1/2, the downstream component of ERK signaling, is significantly reduced in post-mortem brain of suicide victims. The present study was undertaken to further examine whether suicide brain is also associated with abnormalities in upstream molecules in ERK signaling. The study was performed in prefrontal cortex (PFC) and hippocampus obtained from 28 suicide victims and 21 normal controls. mRNA levels of Raf-1, B-Raf, and cyclophilin were measured by quantitative RT-PCR. Protein levels of Raf-1 and B-Raf were determined by Western blot, whereas their catalytic activities were determined by immunoprecipitation and enzymatic assays. It was observed that the catalytic activity of B-Raf was significantly reduced in PFC and hippocampus of suicide subjects. This decrease was associated with a decrease in its protein, but not mRNA, level. On the other hand, catalytic activity, and mRNA and protein levels, of Raf-1 were not altered in post-mortem brain of suicide subjects. The observed changes were not related to confounding variables; however, Raf-1 showed a negative correlation with age. Also, the changes in B-Raf were present in all suicide subjects, irrespective of psychiatric diagnosis. Our results of selective reduction in catalytic activity and expression of B-Raf but not Raf-1 suggest that B-Raf may be playing an important role in altered ERK signaling in brain of suicide subjects, and thus in the pathophysiology of suicide.