McPhie Donna L, Coopersmith Robert, Hines-Peralta Andrew, Chen Yuzhi, Ivins Kathryn J, Manly Susan P, Kozlowski Michael R, Neve Kim A, Neve Rachael L
Department of Psychiatry, Harvard Medical School and McLean Hospital, Belmont, Massachusetts 02478, USA.
J Neurosci. 2003 Jul 30;23(17):6914-27. doi: 10.1523/JNEUROSCI.23-17-06914.2003.
Apoptotic pathways and DNA synthesis are activated in neurons in the brains of individuals with Alzheimer disease (AD). However, the signaling mechanisms that mediate these events have not been defined. We show that expression of familial AD (FAD) mutants of the amyloid precursor protein (APP) in primary neurons in culture causes apoptosis and DNA synthesis. Both the apoptosis and the DNA synthesis are mediated by the p21 activated kinase PAK3, a serine-threonine kinase that interacts with APP. A dominant-negative kinase mutant of PAK3 inhibits the neuronal apoptosis and DNA synthesis; this effect is abolished by deletion of the PAK3 APP-binding domain or by coexpression of a peptide representing this binding domain. The involvement of PAK3 specifically in FAD APP-mediated apoptosis rather than in general apoptotic pathways is suggested by the facts that a dominant-positive mutant of PAK3 does not alone cause neuronal apoptosis and that the dominant-negative mutant of PAK3 does not inhibit chemically induced apoptosis. Pertussis toxin, which inactivates the heterotrimeric G-proteins Go and Gi, inhibits the apoptosis and DNA synthesis caused by FAD APP mutants; the apoptosis and DNA synthesis are rescued by coexpression of a pertussis toxin-insensitive Go. FAD APP-mediated DNA synthesis precedes FAD APP-mediated apoptosis in neurons, and inhibition of neuronal entry into the cell cycle inhibits the apoptosis. These data suggest that a normal signaling pathway mediated by the interaction of APP, PAK3, and Go is constitutively activated in neurons by FAD mutations in APP and that this activation causes cell cycle entry and consequent apoptosis.
在阿尔茨海默病（AD）患者大脑的神经元中，凋亡途径和DNA合成被激活。然而，介导这些事件的信号传导机制尚未明确。我们发现，在培养的原代神经元中表达淀粉样前体蛋白（APP）的家族性AD（FAD）突变体可导致细胞凋亡和DNA合成。细胞凋亡和DNA合成均由p21激活激酶PAK3介导，PAK3是一种与APP相互作用的丝氨酸 - 苏氨酸激酶。PAK3的显性负性激酶突变体可抑制神经元凋亡和DNA合成；删除PAK3的APP结合结构域或共表达代表该结合结构域的肽可消除这种作用。PAK3特异性参与FAD APP介导的细胞凋亡而非一般凋亡途径的证据如下：PAK3的显性正性突变体单独不会导致神经元凋亡，且PAK3的显性负性突变体不会抑制化学诱导的细胞凋亡。百日咳毒素可使异源三聚体G蛋白Go和Gi失活，它能抑制FAD APP突变体引起的细胞凋亡和DNA合成；共表达对百日咳毒素不敏感的Go可挽救细胞凋亡和DNA合成。在神经元中，FAD APP介导的DNA合成先于FAD APP介导的细胞凋亡，抑制神经元进入细胞周期可抑制细胞凋亡。这些数据表明，由APP、PAK3和Go相互作用介导的正常信号通路在神经元中因APP的FAD突变而被组成性激活，这种激活导致细胞周期进入并进而引发细胞凋亡。
