1 State Key Laboratory of Pharmaceutical Biotechnology, College of Life Sciences, School of Stomatology, Affiliated Stomatological Hospital, Nanjing University , Nanjing, People's Republic of China .
Antioxid Redox Signal. 2014 Jul 1;21(1):33-45. doi: 10.1089/ars.2013.5390. Epub 2014 Mar 6.
Reactive oxygen species (ROS) plays important roles in aging. However, the specific mechanisms for intracellular ROS accumulation, especially during aging, remain elusive.
We have reported that Fas-associated protein with death domain (FADD) phosphorylation abolishes the recruitment of phosphatase type 2A C subunit (PP2Ac) to protein kinase C (PKC)βII, which specifically regulates mitochondrial ROS generation by p66shc. Here, we have studied the role of FADD phosphorylation in an FADD constitutive-phosphorylation mutation (FADD-D) mouse model. In FADD-D mice, the constitutive FADD phosphorylation led to ROS accumulation (hydrogen peroxide [H₂O₂]), in a process that was dependent on PKCβ and accompanied by increased PKCβ and p66shc phosphorylation, impaired mitochondrial integrity, and enhanced sensitivity to oxidative stress-mediated apoptosis. Moreover, FADD-D mice exhibited premature aging-like phenotypes, including DNA damage, cellular senescence, and shortened lifespan. In addition, we demonstrate that FADD phosphorylation and the recruitment of PP2A and FADD to PKCβ are induced responses to oxidative stress, and that the extent of FADD phosphorylation in wild-type mice was augmented during aging, accompanied by impairment of the interaction between PKCβ and PP2A.
The present study first addresses the role of FADD phosphorylation in aging through controlling mitochondrial ROS specifically generated by PKCβ.
These data identify that FADD phosphorylation is critical for the PKCβ-p66shc signaling route to generate H₂O₂ and to implicate enhanced FADD phosphorylation as a primary cause of ROS accumulation during aging.
活性氧（ROS）在衰老过程中起着重要作用。然而，细胞内 ROS 积累的具体机制，尤其是在衰老过程中，仍不清楚。
我们曾报道过 Fas 相关死亡结构域蛋白（FADD）的磷酸化会阻止磷酸酶 2A C 亚基（PP2Ac）募集到蛋白激酶 C（PKC）βII，这一过程特异性调节 p66shc 引起的线粒体 ROS 生成。在这里，我们研究了 FADD 组成性磷酸化突变（FADD-D）小鼠模型中 FADD 磷酸化的作用。在 FADD-D 小鼠中，组成性 FADD 磷酸化导致 ROS 积累（过氧化氢[H₂O₂]），这一过程依赖于 PKCβ，伴随着 PKCβ和 p66shc 磷酸化增加、线粒体完整性受损以及对氧化应激介导的细胞凋亡的敏感性增加。此外，FADD-D 小鼠表现出类似早衰的表型，包括 DNA 损伤、细胞衰老和寿命缩短。此外，我们证明 FADD 磷酸化和 PP2A 以及 FADD 向 PKCβ 的募集是对氧化应激的诱导反应，野生型小鼠中 FADD 磷酸化的程度在衰老过程中增加，同时 PKCβ 和 PP2A 之间的相互作用受损。
本研究首次通过控制 PKCβ特异性产生的线粒体 ROS 来研究 FADD 磷酸化在衰老中的作用。
这些数据表明，FADD 磷酸化对于 PKCβ-p66shc 信号通路生成 H₂O₂是至关重要的，并表明衰老过程中 ROS 积累的主要原因是 FADD 磷酸化增强。
