Senescence marker protein-30 (SMP30) rescues cell death by enhancing plasma membrane Ca2+-pumping activity in Hep G2 cells
Senescence marker protein-30 (SMP30) rescues cell death by enhancing plasma membrane Ca2+-pumping activity in Hep G2 cells
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DOI：
10.1006/bbrc.1998.9327
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发表时间：
1998-09-18
影响因子：
3.1
通讯作者：
Maruyama, N
中科院分区：
文献类型：
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作者：
Fujita, T;Inoue, H;Maruyama, N
据报道，衰老标记蛋白-30（SMP 30）在大鼠肝脏中随着年龄的增长而减少。SMP 30也被认为是肝细胞胞质溶胶中的Ca 2+结合蛋白。为了阐明SMP 30的功能意义，我们通过转染人SMP 30 cDNA产生了稳定表达大量SMP 30的Hep G2细胞系。使用这些细胞系，鉴于细胞内Ca 2+稳态，我们然后研究了细胞溶质游离Ca 2+浓度（[Ca 2 +]（i））和细胞外ATP刺激后Na+非依赖性Ca 2+流出。尽管用ATP刺激细胞引起了SMP 30和模拟转染子中的瞬时[Ca 2 +]增加，但通过转染SMP 30，[Ca 2 +]（i）峰值后的降低速率提高了S倍。相应地，与mock转染子相比，SMP 30转染子中的Ca 2+流出显著增加。此外，更多的SMP 30转染细胞存活比模拟转染细胞时，细胞死亡诱导的Ca 2+离子载体治疗。这些结果表明，SMP 30通过调节质膜Ca 2+泵活性来调节[Ca 2 +]（i），因此，在衰老过程中SMP 30的下调可能有助于细胞功能的恶化。(C)北京：科学出版社.
Senescence marker protein-30 (SMP30) has been reported to decrease with aging in the rat Liver. SMP30 has been also suggested to play a role as a Ca2+-binding protein localized in cytosol of hepatocytes. To elucidate the functional significance of SMP30, we have generated Hep G2 cell lines that stably express large amounts of SMP30 by transfection with human SMP30 cDNA. Using these cell lines, in view of the intracellular Ca2+ homeostasis, we then investigated cytosolic free Ca2+ concentration ([Ca2+](i)) and Na+-independent Ca2+ efflux from the cells after extracellular ATP stimulation. Although stimulation of cells with ATP caused transient [Ca2+], increase in both SMP30 and mock transfectants, rate of decrease after peak in [Ca2+](i) was enhanced S-fold by transfection of SMP30. Correspondingly, Ca2+ efflux was significantly increased in SMP30 transfectants compared with mock transfectants. In addition, more SMP30 transfectants survived than mock transfectants when cell death was induced by Ca2+ ionophore treatment. These results suggest that SMP30 regulates [Ca2+](i) by modulating plasma membrane Ca2+-pumping activity, and thus down-regulation of SMP30 during aging may contribute to deterioration of cellular functions. (C) 1998 Academic Press.