ABSTRACT

Cerebral ischemia is a pathology involving a cascade of cellular mechanisms, leading to the deregulation of proteostasis, including macroautophagy/autophagy, and finally to neuronal death. If it is now accepted that cerebral ischemia induces autophagy, the effect of thrombolysis/energy recovery on proteostasis remains unknown. Here, we investigated the effect of thrombolysis by PLAT/tPA (plasminogen activator, tissue) on autophagy and neuronal death. In two in vitro models of hypoxia reperfusion and an in vivo model of thromboembolic stroke with thrombolysis by PLAT/tPA, we found that ischemia enhances neuronal deleterious autophagy. Interestingly, PLAT/tPA decreases autophagy to mediate neuroprotection by modulating the PI3K-AKT-MTOR pathways both in vitro and in vivo. We identified IGF1R (insulin-like growth factor I receptor; a tyrosine kinase receptor) as the effective receptor and showed in vitro, in vivo and in human stroke patients and that PLAT/tPA is able to degrade IGFBP3 (insulin-like growth factor binding protein 3) to increase IGF1 (insulin-like growth factor 1) bioavailability and thus IGF1R activation.

Abbreviations: AKT/protein kinase B: thymoma viral proto-oncogene 1; EGFR: epidermal growth factor receptor; Hx: hypoxia; IGF1: insulin-like growth factor 1; IGF1R: insulin-like growth factor I receptor; IGFBP3: insulin-like growth factor binding protein 3; Ka: Kainate; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MAPK/ERK: mitogen-activated protein kinase; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; OGD: oxygen and glucose deprivation; OGD_reox: oxygen and glucose deprivation + reoxygentation; PepA: pepstatin A1; PI3K: phosphoinositide 3-kinase; PLAT/tPA: plasminogen activator, tissue; PPP: picropodophyllin; SCH77: SCH772984; ULK1: unc-51 like kinase 1; Wort: wortmannin

摘要

脑缺血是一种涉及一系列细胞机制的病理学，导致蛋白质稳态的失调，包括巨自噬/自噬，并最终导致神经元死亡。如果现在接受脑缺血诱导自噬，那么溶栓/能量恢复对蛋白质稳态的影响仍然未知。在这里，我们研究了 PLAT/tPA（纤溶酶原激活剂，组织）溶栓对自噬和神经元死亡的影响。在两个缺氧再灌注的体外模型和一个血栓栓塞性卒中的体内模型中，通过 PLAT/tPA 溶栓，我们发现缺血会增强神经元有害的自噬。有趣的是，PLAT/tPA 通过在体外调节 PI3K-AKT-MTOR 通路来降低自噬以介导神经保护和体内。我们将 IGF1R（胰岛素样生长因子 I 受体；一种酪氨酸激酶受体）鉴定为有效受体，并在体外、体内和人类中风患者中显示，PLAT/tPA 能够降解 IGFBP3（胰岛素样生长因子结合蛋白 3) 增加 IGF1（胰岛素样生长因子 1）的生物利用度，从而增加 IGF1R 的激活。

缩写： AKT/蛋白激酶 B：胸腺瘤病毒原癌基因 1；EGFR：表皮生长因子受体；Hx：缺氧；IGF1：胰岛素样生长因子 1；IGF1R：胰岛素样生长因子 I 受体；IGFBP3：胰岛素样生长因子结合蛋白 3；卡：红藻氨酸；MAP1LC3/LC3：微管相关蛋白 1 轻链 3；MAPK/ERK：丝裂原活化蛋白激酶；MTOR：雷帕霉素激酶的机制靶点；MTORC1：MTOR复合物1；OGD：氧气和葡萄糖剥夺；OGD _reox：氧气和葡萄糖剥夺+复氧；PepA：胃蛋白酶抑制剂 A1；PI3K：磷酸肌醇 3-激酶；PLAT/tPA：纤溶酶原激活剂，组织；PPP：鬼臼苦素；SCH77：SCH772984；ULK1：unc-51 样激酶 1；麦芽汁：渥曼青霉素