Gonzalez-Gronow Mario, Kaczowka Steven J, Payne Sturgis, Wang Fang, Gawdi Govind, Pizzo Salvatore V
Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.
J Biol Chem. 2007 Nov 9;282(45):32811-20. doi: 10.1074/jbc.M703342200. Epub 2007 Sep 11.
Both the voltage-dependent anion channel and the glucose-regulated protein 78 have been identified as plasminogen kringle 5 receptors on endothelial cells. In this study, we demonstrate that kringle 5 binds to a region localized in the N-terminal domain of the glucose-regulated protein 78, whereas microplasminogen does so through the C-terminal domain of the glucose-regulated protein 78. Both plasminogen fragments induce Ca(2+) signaling cascades; however, kringle 5 acts through voltage-dependent anion channel and microplasminogen does so via the glucose-regulated protein 78. Because trafficking of voltage-dependent anion channel to the cell surface is associated with heat shock proteins, we investigated a possible association between voltage-dependent anion channel and glucose-regulated protein 78 on the surface of 1-LN human prostate tumor cells. We demonstrate that these proteins co-localize, and changes in the expression of the glucoseregulated protein 78 affect the expression of voltage-dependent anion channel. To differentiate the functions of these receptor proteins, either when acting singly or as a complex, we employed human hexokinase I as a specific ligand for voltage-dependent anion channel, in addition to kringle 5. We show that kringle 5 inhibits 1-LN cell proliferation and promotes caspase-7 activity by a mechanism that requires binding to cell surface voltage-dependent anion channel and is inhibited by human hexokinase I.
电压依赖性阴离子通道和葡萄糖调节蛋白78均已被鉴定为内皮细胞上的纤溶酶原kringle 5受体。在本研究中，我们证明kringle 5与葡萄糖调节蛋白78的N端结构域中的一个区域结合，而微纤溶酶原则通过葡萄糖调节蛋白78的C端结构域结合。两种纤溶酶原片段均诱导Ca(2+)信号级联反应；然而，kringle 5通过电压依赖性阴离子通道起作用，而微纤溶酶原则通过葡萄糖调节蛋白78起作用。由于电压依赖性阴离子通道向细胞表面的转运与热休克蛋白相关，我们研究了1-LN人前列腺肿瘤细胞表面电压依赖性阴离子通道与葡萄糖调节蛋白78之间可能的关联。我们证明这些蛋白共定位，并且葡萄糖调节蛋白78表达的变化影响电压依赖性阴离子通道的表达。为了区分这些受体蛋白单独作用或作为复合物时的功能，除了kringle 5之外，我们还使用人己糖激酶I作为电压依赖性阴离子通道的特异性配体。我们表明，kringle 5通过一种需要与细胞表面电压依赖性阴离子通道结合且被人己糖激酶I抑制的机制抑制1-LN细胞增殖并促进caspase-7活性。
