Ranganathan Srikanth, Bowser Robert
Department of Pathology, Pittsburgh, PA, USA.
Open Pathol J. 2010 Jan 1;4:11-22. doi: 10.2174/1874375701004010011.
Apoptosis has been implicated in many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). We previously demonstrated a role for G1 to S phase cell cycle regulators in ALS with increased levels of hyperphosphorylated retinoblastoma (ppRb) and E2F-1 in ALS spinal cord motor neurons. In this study we examined the levels of the cell cycle checkpoint tumor suppressor protein p53 with concurrent changes in cell death markers during ALS. Expression and subcellular distribution of p53, retinoblastoma, Bax, Fas, and caspases were explored by immunoblot, immunohistochemistry and double-label confocal microscopy in the spinal cord and motor cortex of ALS and control subjects. We identified elevated levels of p53 in ALS spinal cord motor neurons but not neurons in the motor cortex. In addition, there was an increase in Bax, Fas, caspases-8 and -3 proteins in ALS spinal motor neurons. While caspase-3 and TUNEL labeled neurons were positive for ppRb, E2F-1 and p53 in spinal motor neurons, and Fas co-localized with caspase-8 in spinal motor neurons, we failed to observe these results in large neurons in the motor cortex of ALS subjects. We have linked p53 and activation of G1 to S phase cell cycle regulators to an apoptotic mode of cell death ALS spinal cord motor neurons.
细胞凋亡与许多神经退行性疾病有关，包括肌萎缩侧索硬化症（ALS）。我们之前证明了G1期到S期细胞周期调节因子在ALS中的作用，ALS脊髓运动神经元中视网膜母细胞瘤（ppRb）和E2F-1的磷酸化水平升高。在本研究中，我们检测了ALS患者细胞周期检查点肿瘤抑制蛋白p53的水平以及细胞死亡标志物的同时变化。通过免疫印迹、免疫组织化学和双标共聚焦显微镜，研究了ALS患者和对照者脊髓和运动皮层中p53、视网膜母细胞瘤、Bax、Fas和半胱天冬酶的表达及亚细胞分布。我们发现ALS脊髓运动神经元中p53水平升高，但运动皮层中的神经元未出现这种情况。此外，ALS脊髓运动神经元中Bax、Fas、半胱天冬酶-8和-3蛋白增加。虽然脊髓运动神经元中半胱天冬酶-3和TUNEL标记的神经元对ppRb、E2F-1和p53呈阳性，且Fas与脊髓运动神经元中的半胱天冬酶-8共定位，但在ALS患者运动皮层的大神经元中未观察到这些结果。我们已将p53以及G1期到S期细胞周期调节因子的激活与ALS脊髓运动神经元的细胞凋亡死亡模式联系起来。
