The Laboratory of Cellular and Vascular Immunology, Felsenstein Medical Research Center, Tel-Aviv University Sackler School of Medicine, Rabin Medical Center, Beilinson Campus, Petach-Tikva, 49100, Israel.
J Mol Med (Berl). 2010 Nov;88(11):1157-67. doi: 10.1007/s00109-010-0657-7. Epub 2010 Jul 28.
Myocardial ischemia is a severe stress condition that causes extensive biochemical changes triggering cardiac cell death. The 78-kDa glucose-regulated protein (GRP78), a heat shock protein present in all cells and a widely used marker of endoplasmic reticulum stress, functions in controlling the structural maturation of nascent glycoproteins. However, GRP78 was also found to be expressed on the cell surface of several cells such as endothelial cells, macrophages, and tumor cells where it functions as a receptor for a variety of ligands in signaling pathways. Recently, we have identified peptides from two different sources that specifically bind GRP78 protein. We have shown that binding of these peptides to endothelial cell surface GRP78 resulted in angiogenesis. In this study, we first established the presence of cell surface GRP78 on cardiac myocytes. Analysis of cardiomyocytes under hypoxia determined the significant increase in cell surface GRP78 in addition to gene expression and total protein. Apoptosis that was significantly increased in cardiomyocytes under hypoxic conditions was inhibited by the presence of the peptide-binding GRP78 during hypoxia. Inhibition of apoptosis was mediated by the binding of the peptide to cardiomyocytes cell surface GRP78 resulting in blocking caspase-3/7 activation. Silencing GRP78 RNA that reduced GRP78 receptor abrogated the peptide activity. Apoptosis of cardiac cells induced by myocardial infarction in a mouse model was also significantly inhibited by the administration of the peptide to mouse hearts. Our findings may make ADoPep1 a useful therapeutic tool for relieving of ischemia.
心肌缺血是一种严重的应激状态，会引发广泛的生化变化，触发心肌细胞死亡。78kDa 葡萄糖调节蛋白（GRP78）是一种存在于所有细胞中的热休克蛋白，也是内质网应激的广泛应用标志物，其功能在于控制新生糖蛋白的结构成熟。然而，GRP78 也被发现存在于内皮细胞、巨噬细胞和肿瘤细胞等多种细胞的细胞表面，作为多种配体在信号通路中的受体发挥作用。最近，我们已经从两个不同的来源鉴定出了专门与 GRP78 蛋白结合的肽。我们已经表明，这些肽与内皮细胞表面的 GRP78 结合会导致血管生成。在这项研究中，我们首先确定了心肌细胞表面存在 GRP78。在缺氧条件下对心肌细胞进行分析，除了基因表达和总蛋白增加外，还确定了细胞表面 GRP78 的显著增加。在缺氧条件下，心肌细胞中凋亡显著增加，而在缺氧条件下存在肽结合 GRP78 时，凋亡被抑制。凋亡的抑制是通过肽与心肌细胞表面 GRP78 的结合介导的，从而阻断 caspase-3/7 的激活。沉默降低 GRP78 受体的 GRP78 RNA 会使肽的活性丧失。肽给药也显著抑制了心肌梗死小鼠模型中心脏细胞的凋亡。我们的研究结果可能使 ADoPep1 成为缓解缺血的一种有用的治疗工具。
