Zhong Jiahong, Li Mengfan, Xu Jiangping, Dong Wenli, Qin Yunyun, Qiu Shuqing, Li Xing, Wang Haitao
School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China.
School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; Center for Brain Science and Brain-Inspired Intelligence, Guangdong-Hong Kong-Macao Greater Bay Area, China; Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou 510515, China.
Toxicol Appl Pharmacol. 2022 Feb 1;436:115859. doi: 10.1016/j.taap.2021.115859. Epub 2022 Jan 4.
We have previously shown that inhibition of cAMP-specific 3',5'-cyclic phosphodiesterase 4 (PDE4) protects against cellular toxicity in neuronal cells. Since α-synuclein (α-syn) toxicity contributes to the neurodegeneration of Parkinson's disease (PD). The aim of this study was to explore the effects and mechanisms of PDE4 on α-syn-induced neuronal toxicity. Using mutant human A53T α-syn overexpressed SH-SY5Y cells, we found that PDE4B knockdown reduced cellular apoptosis. Roflupram (ROF, 20 μM), a selective PDE4 inhibitor, produced similar protective effects and restored the morphological alterations of mitochondria. Mechanistic studies identified that α-syn enhanced the phosphorylation of Parkin at Ser131, followed by the decreased mitochondrial translocation of Parkin. Whereas both PDE4B knockdown and PDE4 inhibition by ROF blocked the effects of α-syn on Parkin phosphorylation and mitochondrial translocation. Moreover, PDE4 inhibition reversed the increase in the phosphorylation of p38 mitogen-activated protein kinase (MAPK) induced by α-syn. ROF treatment also reduced the binding of p38 MAPK to Parkin. Consistently, overexpression of PDE4B blocked the roles of ROF on p38 MAPK phosphorylation, Parkin phosphorylation, and the subsequent mitochondrial translocation of parkin. Furthermore, PDE4B overexpression attenuated the protective role of ROF, as evidenced by reduced mitochondria membrane potential and increased cellular apoptosis. Interestingly, ROF failed to suppress α-syn-induced cytotoxicity in the presence of a protein kinase A (PKA) inhibitor H-89. Our findings indicate that PDE4 facilitates α-syn-induced cytotoxicity via the PKA/p38 MAPK/Parkin pathway in SH-SY5Y cells overexpressing A53T mutant α-synuclein. PDE4 inhibition by ROF is a promising strategy for the prevention and treatment of α-syn-induced neurodegeneration.
我们之前已经表明，抑制环磷酸腺苷（cAMP）特异性3',5'-环磷酸二酯酶4（PDE4）可保护神经元细胞免受细胞毒性。由于α-突触核蛋白（α-syn）毒性导致帕金森病（PD）的神经退行性变。本研究的目的是探讨PDE4对α-syn诱导的神经元毒性的影响及其机制。使用过表达突变型人A53T α-syn的SH-SY5Y细胞，我们发现敲低PDE4B可减少细胞凋亡。选择性PDE4抑制剂咯利普兰（ROF，20 μM）产生了类似的保护作用，并恢复了线粒体的形态改变。机制研究表明，α-syn增强了Parkin在Ser131位点的磷酸化，随后Parkin的线粒体转位减少。而敲低PDE4B和ROF抑制PDE4均阻断了α-syn对Parkin磷酸化和线粒体转位的影响。此外，PDE4抑制可逆转α-syn诱导的p38丝裂原活化蛋白激酶（MAPK）磷酸化增加。ROF处理还减少了p38 MAPK与Parkin的结合。一致地，过表达PDE4B阻断了ROF对p38 MAPK磷酸化、Parkin磷酸化以及随后Parkin线粒体转位的作用。此外，PDE4B过表达减弱了ROF的保护作用，线粒体膜电位降低和细胞凋亡增加证明了这一点。有趣的是，在存在蛋白激酶A（PKA）抑制剂H-89的情况下，ROF未能抑制α-syn诱导的细胞毒性。我们的研究结果表明，在过表达A53T突变型α-突触核蛋白的SH-SY5Y细胞中，PDE4通过PKA/p38 MAPK/Parkin途径促进α-syn诱导的细胞毒性。ROF抑制PDE4是预防和治疗α-syn诱导的神经退行性变的一种有前景的策略。
