College of Biological Sciences and Biotechnology, School of Medicine, Chungnam National University, Daejeon, South Korea.
Hum Mol Genet. 2013 Apr 15;22(8):1558-73. doi: 10.1093/hmg/ddt006. Epub 2013 Jan 10.
This study reports the physical and functional interplay between Fas-associated factor 1 (FAF1), a death-promoting protein, and parkin, a key susceptibility protein for Parkinson's disease (PD). We found that parkin acts as an E3 ubiquitin ligase to ubiquitinate FAF1 both in vitro and at cellular level, identifying FAF1 as a direct substrate of parkin. The loss of parkin function due to PD-linked mutations was found to disrupt the ubiquitination and degradation of FAF1, resulting in elevated FAF1 expression in SH-SY5Y cells. Moreover, FAF1-mediated cell death was abolished by wild-type parkin, but not by PD-linked parkin mutants, implying that parkin antagonizes the death potential of FAF1. This led us to investigate whether FAF1 participates in the pathogenesis of PD. To address this, we used a gene trap mutagenesis approach to generate mutant mice with diminished levels of FAF1 (Faf1(gt/gt)). Using the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mouse model of PD, we found that FAF1 accumulated in the substantia nigra pars compacta (SNc) of MPTP-treated PD mice, and that MPTP-induced dopaminergic cell loss in the SNc was significantly attenuated in Faf1(gt/gt) mice versus Faf1(+/+) mice. MPTP-induced reduction of locomotor activity was also lessened in Faf1(gt/gt) mice versus Faf1(+/+) mice. Furthermore, we found that FAF1 deficiency blocked PD-linked biochemical events, including caspase activation, ROS generation, JNK activation and cell death. Taken together, these results suggest a new role for FAF1: that of a positive modulator for PD.
这项研究报告了 Fas 相关因子 1（FAF1）与帕金森病（PD）关键易感性蛋白 parkin 之间的物理和功能相互作用。我们发现 parkin 作为一种 E3 泛素连接酶，在体外和细胞水平上均可泛素化 FAF1，确定 FAF1 是 parkin 的直接底物。由于 PD 相关突变导致 parkin 功能丧失，发现 FAF1 的泛素化和降解受到破坏，导致 SH-SY5Y 细胞中 FAF1 的表达升高。此外，野生型 parkin 可消除 FAF1 介导的细胞死亡，但 PD 相关的 parkin 突变体则不能，这表明 parkin 拮抗了 FAF1 的死亡潜能。这促使我们研究 FAF1 是否参与 PD 的发病机制。为了解决这个问题，我们使用基因捕获诱变方法生成了 FAF1 水平降低的突变小鼠（Faf1(gt/gt)）。使用 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）处理的 PD 小鼠模型，我们发现 FAF1 在 MPTP 处理的 PD 小鼠的黑质致密部（SNc）中积累，并且 Faf1(gt/gt) 小鼠中 MPTP 诱导的 SNc 多巴胺能神经元丢失明显减轻与 Faf1(+/+) 小鼠相比。Faf1(gt/gt) 小鼠的 MPTP 诱导的运动活性降低也低于 Faf1(+/+) 小鼠。此外，我们发现 FAF1 缺乏阻断了 PD 相关的生化事件，包括 caspase 激活、ROS 生成、JNK 激活和细胞死亡。总之，这些结果表明 FAF1 具有新的作用：它是 PD 的正调节剂。
