Eye Research Laboratory, Felsenstein Medical Research Center, Tel-Aviv University, School of Medicine, Rabin Medical Center, Beilinson Campus, Petah Tikva, Israel.
Apoptosis. 2012 Mar;17(3):278-88. doi: 10.1007/s10495-011-0678-x.
Brain ischemia has major consequences leading to the apoptosis of astrocytes and neurons. Glucose-regulated protein 78 (GRP78) known for its role in endoplasmic reticulum stress alleviation was discovered on several cell surfaces acting as a receptor for signaling pathways. We have previously described peptides that bind cell surface GRP78 on endothelial cells to induce angiogenesis. We have also reported that ADoPep1 binds cardiomyocytes to prevent apoptosis of ischemic heart cells. In this study we describe the effect of hypoxia on astrocytes and neurons cell surface GRP78. Under hypoxic conditions, there was an increase of more than fivefold in GRP78 on cell surface of neurons while astrocytes were not affected. The addition of the GRP78 binding peptide, ADoPep1, to neurons decreased the percentage of GRP78 positive cells and did not change the percent of astrocytes. However, a significant increase in early and late apoptosis of both astrocytes and neurons under hypoxia was attenuated in the presence of ADoPep1. Intravitreal administration of ADoPep1 to mice in a model of optic nerve crush significantly reduced retinal cell loss after 21 days compared to the crush-damaged eyes without treatment or by control saline vehicle injection. Histological staining demonstrated reduced GRP78 after ADoPep1 treatment. The mechanism of peptide neuroprotection was demonstrated by the inhibition of hypoxia induced caspase 3/7 activity, cytochrome c release and p38 phosphorylation. This study is the first report on hypoxic neuronal and astrocyte cell surface GRP78 and suggests a potential therapeutic target for neuroprotection.
脑缺血会导致星形胶质细胞和神经元凋亡，产生严重后果。葡萄糖调节蛋白 78（GRP78）因其在内质网应激缓解中的作用而被发现存在于几种细胞表面，作为信号通路的受体。我们之前描述了一些能够结合内皮细胞表面 GRP78 的肽，以诱导血管生成。我们还报告说，ADoPep1 结合心肌细胞以防止缺血性心肌细胞凋亡。在这项研究中，我们描述了缺氧对星形胶质细胞和神经元细胞表面 GRP78 的影响。在缺氧条件下，神经元细胞表面的 GRP78 增加了五倍以上，而星形胶质细胞没有受到影响。将 GRP78 结合肽 ADoPep1 添加到神经元中会减少 GRP78 阳性细胞的百分比，而不会改变星形胶质细胞的百分比。然而，在 ADoPep1 的存在下，缺氧诱导的星形胶质细胞和神经元的早期和晚期凋亡显著减少。在视神经挤压模型中，向小鼠玻璃体内给予 ADoPep1，与未经治疗或用对照生理盐水载体注射的挤压损伤眼相比，可显著减少 21 天后的视网膜细胞丢失。组织学染色显示 ADoPep1 治疗后 GRP78 减少。通过抑制缺氧诱导的半胱天冬酶 3/7 活性、细胞色素 c 释放和 p38 磷酸化，证明了肽神经保护的机制。这项研究首次报道了缺氧诱导的神经元和星形胶质细胞表面 GRP78，并为神经保护提供了一个潜在的治疗靶点。
