Barnes K A, Samson S E, Grover A K
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Mol Cell Biochem. 2000 Jan;203(1-2):17-21. doi: 10.1023/a:1007053802481.
Endo/sarcoplasmic reticulum (ER) Ca2+-pumps are important for cell survival and communication but they are inactivated by reactive oxygen species (ROS). We have previously reported that the Ca2+-pump isoform SERCA3a is more resistant than SERCA2b to damage by peroxide. Since peroxide and superoxide differ in their redox potentials, we now report the effects of superoxide on the two Ca2+-pump isoforms. We isolated microsomes from HEK293 cells transiently transfected with SERCA2b or SERCA3a cDNA. We exposed these microsomes to superoxide which was generated using xanthine plus xanthine oxidase and catalase to prevent accumulation of peroxide due to superoxide dismutation. Superoxide damaged the Ca2+-transport activity of both isoforms but SERCA3a was damaged at higher concentrations of superoxide and upon longer periods of exposures than was SERCA2b. Thus the SERCA3a isoform is more resistant than SERCA2b to inactivation by both superoxide and peroxide.
内质网/肌浆网（ER）钙离子泵对细胞存活和通讯至关重要，但它们会被活性氧（ROS）灭活。我们之前报道过，钙离子泵亚型SERCA3a比SERCA2b对过氧化物损伤更具抗性。由于过氧化物和超氧化物的氧化还原电位不同，我们现在报道超氧化物对这两种钙离子泵亚型的影响。我们从瞬时转染了SERCA2b或SERCA3a cDNA的HEK293细胞中分离出微粒体。我们将这些微粒体暴露于用黄嘌呤加黄嘌呤氧化酶产生的超氧化物中，并加入过氧化氢酶以防止由于超氧化物歧化而导致过氧化物积累。超氧化物损害了两种亚型的钙离子转运活性，但与SERCA2b相比，SERCA3a在更高浓度的超氧化物和更长时间的暴露下受到损害。因此，SERCA3a亚型比SERCA2b对超氧化物和过氧化物的灭活更具抗性。
