Zeng Zhiwen, Wang Dejun, Gaur Uma, Rifang Liao, Wang Haitao, Zheng Wenhua
Faculty of Health Sciences, University of Macau, Taipa, China.
Shenzhen Mental Health Center and Shenzhen Kangning Hospital, Shenzhen, China.
Oncotarget. 2017 Jun 27;8(39):65313-65328. doi: 10.18632/oncotarget.18625. eCollection 2017 Sep 12.
Impairment of insulin-like growth factor I (IGF-I) signaling plays an important role in the development of neurodegeneration. In the present study, we investigated the effect of HO on the survival signaling of IGF-1 and its underlying mechanisms in human neuronal cells SH-SY5Y. Our results showed that IGF-1 promoted cell survival and stimulated phosphorylation of IGF-1R as well as its downstream targets like AKT and ERK1/2 in these cells. Meanwhile, these effects of IGF-1 were abolished by HO at 200μM concentration which did not cause any significant toxicity to cells itself in our experiments. Moreover, studies using various glutamate receptor subtype antagonists displayed that N-methyl-D -aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) blocked the effects of HO, whereas other glutamate receptor subtype antagonists, such as non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt, had no effect. Further studies revealed that NR2B-containing NMDARs are responsible for these effects as its effects were blocked by pharmacological inhibitor Ro25-698 or specific siRNA for NR2B, but not NR2A. Finally, our data also showed that Ca influx contributes to the effects of HO. Similar results were obtained in primary cultured cortical neurons. Taken together, the results from the present study suggested that HO attenuated IGF-1R tyrosine phosphorylation and its survival signaling properties via NR2B containing NMDA receptors and Ca influx in SH-SY5Y cells. Therefore, NMDAR antagonists, especially NR2B-selective ones, combined with IGF-1 may serve as an alternative therapeutic agent for oxidative stress related neurodegenerative disease.
胰岛素样生长因子I（IGF-I）信号通路受损在神经退行性疾病的发展中起重要作用。在本研究中，我们研究了HO对人神经母细胞瘤细胞SH-SY5Y中IGF-1存活信号通路及其潜在机制的影响。我们的结果表明，IGF-1可促进这些细胞的存活，并刺激IGF-1R及其下游靶点（如AKT和ERK1/2）的磷酸化。同时，在我们的实验中，200μM浓度的HO可消除IGF-1的这些作用，而该浓度的HO对细胞本身并无明显毒性。此外，使用各种谷氨酸受体亚型拮抗剂的研究表明，N-甲基-D-天冬氨酸（NMDA）受体拮抗剂马来酸氯氮平（MK-801）可阻断HO的作用，而其他谷氨酸受体亚型拮抗剂，如非NMDA受体拮抗剂6,7-二硝基喹喔啉-2,3-二酮（DNQX）、代谢型谷氨酸受体拮抗剂LY341495和CPCCOEt则无此作用。进一步的研究表明，含NR2B的NMDARs介导了这些作用，因为其作用可被药理学抑制剂Ro25-698或NR2B特异性siRNA阻断，但不能被NR2A阻断。最后，我们的数据还表明，钙离子内流参与了HO的作用。在原代培养的皮质神经元中也得到了类似的结果。综上所述，本研究结果表明，HO通过含NR2B的NMDA受体和钙离子内流减弱了IGF-1R酪氨酸磷酸化及其存活信号特性。因此，NMDAR拮抗剂，尤其是NR2B选择性拮抗剂，与IGF-1联合使用可能作为氧化应激相关神经退行性疾病的替代治疗药物。
