Vijayvergiya Chetan, De Angelis Dino, Walther Matthias, Kühn Hartmut, Duvoisin Robert M, Smith Deborah H, Wiedmann Martin
Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Biochemistry. 2004 Dec 7;43(48):15296-302. doi: 10.1021/bi048745v.
A critical step in the development of mammalian erythroblasts into mature red blood cells is the extrusion of the nucleus, followed by intracellular degradation of the remaining organelles. It has been hypothesized that the breakdown of cellular organelles in rabbit reticulocytes is initiated by 15-lipoxygenase. In vitro, the purified rabbit reticulocyte 15-lipoxygenase binds and permeabilizes organellar membranes, thereby releasing the lumenal contents of the organelle. Here, we demonstrate that ectopic expression of 15-lipoxygenase leads to the collapse of the mitochondrial pH gradient in nonerythroid cells, using a novel reporter of mitochondrial pH, mito-pHluorin. No change in mitochondrial pH was observed with a mutant of 15-lipoxygenase that lacks enzymatic activity. These data demonstrate that 15-lipoxygenase is capable of disrupting the pH gradient maintained by mitochondria in living cells without additional factors specific for red blood cell development.
哺乳动物成红细胞发育为成熟红细胞的关键步骤是细胞核的挤出，随后剩余细胞器在细胞内降解。据推测，兔网织红细胞中细胞器的分解是由15-脂氧合酶启动的。在体外，纯化的兔网织红细胞15-脂氧合酶可结合并使细胞器膜通透，从而释放细胞器腔内的内容物。在此，我们使用一种新型的线粒体pH报告基因mito-pHluorin证明，15-脂氧合酶的异位表达会导致非红细胞中线粒体pH梯度的崩溃。缺乏酶活性的15-脂氧合酶突变体未观察到线粒体pH的变化。这些数据表明，15-脂氧合酶能够在没有红细胞发育特异性额外因子的情况下破坏活细胞中线粒体维持的pH梯度。
