Wang Jiejie, Lu Wen, Chen Lin, Zhang Ping, Qian Tingting, Cao Wei, Luo Jianhong
Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, 310058, China.
The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China.
Neurosci Bull. 2016 Aug;32(4):323-30. doi: 10.1007/s12264-016-0042-9. Epub 2016 Jun 14.
Accumulating evidence indicates that the synaptic activation of N-methyl-D-aspartate receptors (NMDARs) has a neuroprotective effect on neurons. Our previous study demonstrated that APPL1 (adaptor protein containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif) mediates the synaptic activity-dependent activation of PI3K-Akt signaling via coupling this pathway with NMDAR-PSD95 (postsynaptic density protein 95) complexes. However, the molecular mechanism underlying this process is still unknown. In the present study, we investigated the interaction of APPL1 with PSD95 using co-immunocytochemical staining and western blotting. We found that the PDZ2 domain of PSD95 is a binding partner of APPL1. Furthermore, we identified serine 707 of APPL1, a predicted phosphorylation site within the PDZ-binding motif at the C-terminus, as critical for the binding of APPL1 to PSD95, as well as for activation of the Akt signaling pathway during synaptic activity. This suggests that serine 707 of APPL1 is a potential phosphorylation site and may be involved in regulating the neuroprotective Akt signaling pathway that depends on synaptic NMDAR activity.
越来越多的证据表明，N-甲基-D-天冬氨酸受体（NMDARs）的突触激活对神经元具有神经保护作用。我们之前的研究表明，APPL1（含普列克底物蛋白同源结构域、磷酸酪氨酸结合结构域和亮氨酸拉链基序的衔接蛋白）通过将该信号通路与NMDAR-PSD95（突触后致密蛋白95）复合物偶联，介导PI3K-Akt信号通路的突触活动依赖性激活。然而，这一过程背后的分子机制仍然未知。在本研究中，我们使用共免疫细胞化学染色和蛋白质印迹法研究了APPL1与PSD95的相互作用。我们发现PSD95的PDZ2结构域是APPL1的结合伴侣。此外，我们确定了APPL1的丝氨酸707（C末端PDZ结合基序内的一个预测磷酸化位点）对于APPL1与PSD95的结合以及突触活动期间Akt信号通路的激活至关重要。这表明APPL1的丝氨酸707是一个潜在的磷酸化位点，可能参与调节依赖于突触NMDAR活动的神经保护Akt信号通路。
