INCREASES OF INTRACELLULAR MAGNESIUM PROMOTE GLYCODEOXYCHOLATE-INDUCED APOPTOSIS IN RAT HEPATOCYTES
INCREASES OF INTRACELLULAR MAGNESIUM PROMOTE GLYCODEOXYCHOLATE-INDUCED APOPTOSIS IN RAT HEPATOCYTES
复制标题
DOI：
10.1172/jci117579
复制
发表时间：
1994-12-01
影响因子：
15.9
通讯作者：
GORES, GJ
中科院分区：
文献类型：
--
作者：
PATEL, T;BRONK, SF;GORES, GJ
在胆汁淤积过程中，肝细胞滞留胆盐会造成肝损伤。虽然细胞损伤可以通过两种机制中的一种发生，即坏死和凋亡，但关于细胞凋亡作为胆盐导致细胞死亡的机制的信息尚不清楚。我们的目的是确定胆盐甘氨酸脱氧胆酸盐(GDC)是否诱导大鼠肝细胞凋亡。形态学评价包括电子显微镜和荧光显微镜下的核碎裂定量。生化检测包括DNA片段化、体外核酸内切酶活性、细胞内游离钙离子(Ca-I(2+))和细胞内游离镁离子(Mg-I(2+))。形态学研究显示，GDC(50 MM)处理的细胞呈现典型的细胞凋亡特征。从GDC处理的细胞中获得的DNA也存在“梯形”DNA片段化。在体外，含镁离子的核酸内切酶活性是含钙离子的2.5倍。虽然加入GDC后基础Ca-i(2+)值没有变化，但Mg-i(2+)增加了一倍。在无镁培养液中孵育细胞可阻止镁离子浓度的升高，并减少细胞核和DNA的碎裂。综上所述，GDC诱导肝细胞凋亡的机制是通过刺激依赖于镁的核酸内切酶促进镁离子浓度的升高而实现的。这些数据首次表明，Mg-I(2+)的变化可能参与了最终导致细胞凋亡的细胞事件。
Retention of bile salts by the hepatocyte contributes to liver injury during cholestasis. Although cell injury can occur by one of two mechanisms, necrosis versus apoptosis, information is lacking regarding apoptosis as a mechanism of cell death by bile salts. Our aim was to determine if the bile salt glycodeoxycholate (GDC) induces apoptosis in rat hepatocytes. Morphologic assessment included electron microscopy and quantitation of nuclear fragmentation by fluorescent microscopy. Biochemical studies included measurements of DNA fragmentation, in vitro endonuclease activity, cytosolic free Ca2+ (Ca-i(2+)), and cytosolic free Mg2+ (Mg-i(2+)). Morphologic studies demonstrated typical features of apoptosis in GDC (50 mu M) treated cells. The ''ladder pattern'' of DNA fragmentation was also present in DNA obtained from GDC-treated cells. In vitro endonuclease activity was 2.5-fold greater with Mg2+ than Ca2+. Although basal Ca-i(2+) values did not change after addition of GDC, Mg-i(2+) increased twofold. Incubation of cells in an Mg2+-free medium prevented the rise in Mg-i(2+) and reduced nuclear and DNA fragmentation. In conclusion, GDC induces apoptosis in hepatocytes by a mechanism promoted by increases of Mg-i(2+) with stimulation of Mg2+-dependent endonucleases. These data suggest for the first time that changes of Mg-i(2+) may participate in the program of cellular events culminating in apoptosis.