Wei Xiu-E, Zhang Feng-Yu, Wang Kai, Zhang Qing-Xiu, Rong Liang-Qun
The Second Affiliated Hospital of Xuzhou Medical University, Xuzhou 221000, China.
Liaocheng Hospital, Liaocheng 252000, China.
Brain Res. 2014 May 30;1566:60-8. doi: 10.1016/j.brainres.2014.04.009. Epub 2014 Apr 16.
The imbalance of cell pro-death and pro-survival signaling pathways determines the neuronal fate during cerebral ischemia/reperfusion (I/R) injury. However, the biological mechanisms regulating the balance between activation of the pro-death or the pro-survival signaling pathways remain unclear. In this study, a rat model of I/R injury was established using four-vessel occlusion followed by different times of reperfusion. I/R injury did not affect the level of FK506 binding protein 51 (FKBP51), PH domain and leucine rich repeat protein phosphatases (PHLPP)-2, and AKT, but induced assembly of the FKBP51-PHLPP2-AKT signaling complex, as indicated by the enhancement of interactions among these compounds following reperfusion. Using an antisense oligonucleotide, PHLPP2 expression was effectively inhibited. Critically, the inhibition of PHLPP2 prohibited the interactions of FKBP51, PHLPP2 and AKT, reversed the decrease of p-AKT expression and increased the expression of p-JNKs and p-c-Jun elicited by I/R injury. In addition, PHLPP2 inhibition reversed I/R-injury-induced Caspase-3 cleavage and loss of pyramid neurons in the CA1 region of hippocampus. The results of the current study indicate that the assembly of the FKBP51-PHLPP2-AKT signaling complex plays a critical role in mediating cell death in I/R injury. The inhibition of PHLPP2 via antisense oligonucleotide treatment may be an effective method to prohibit the assembly of the FKBP51-PHLPP-AKT signaling complex, thus balancing the cell pro-survival and pro-death signaling pathways ultimately mitigating cell death in I/R injury.
细胞促死亡和促生存信号通路的失衡决定了脑缺血/再灌注（I/R）损伤期间的神经元命运。然而，调节促死亡或促生存信号通路激活之间平衡的生物学机制仍不清楚。在本研究中，采用四血管闭塞法并给予不同时长的再灌注，建立了I/R损伤大鼠模型。I/R损伤不影响FK506结合蛋白51（FKBP51）、PH结构域和富含亮氨酸重复序列蛋白磷酸酶（PHLPP）-2以及AKT的水平，但诱导了FKBP51-PHLPP2-AKT信号复合物的组装，再灌注后这些化合物之间相互作用的增强表明了这一点。使用反义寡核苷酸有效抑制了PHLPP2的表达。至关重要的是，抑制PHLPP2可阻止FKBP51、PHLPP2和AKT之间的相互作用，逆转p-AKT表达的降低，并增加I/R损伤诱导的p-JNKs和p-c-Jun的表达。此外，抑制PHLPP2可逆转I/R损伤诱导的Caspase-3裂解以及海马体CA1区锥体细胞的丢失。本研究结果表明，FKBP51-PHLPP2-AKT信号复合物的组装在介导I/R损伤中的细胞死亡方面起关键作用。通过反义寡核苷酸处理抑制PHLPP2可能是阻止FKBP51-PHLP-AKT信号复合物组装的有效方法，从而平衡细胞促生存和促死亡信号通路，最终减轻I/R损伤中的细胞死亡。
