Involvement of extracellular calcium in phosphatidylserine exposure during apoptosis

FEBS Letters

Isabella Pörn-Ares, M.¹  Orrenius, Sten¹  Hampton, Mark B.¹  Vanags, Daina M.¹ 

[1] Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden

关键词: Apoptosis;    Phosphatidylserine;    Ca2+;    Thapsigargin;    Tumor necrosis factor;    Anti-fas;    PS;    phosphatidylserine;    TNF;    tumour necrosis factor;    EGTA;    ethylene glycol-bis(β-aminoethylether)-N;    N;    N′;    N′-tetraacetic acid;    BAPTA-AM;    acetoxymethyl ester of 1;    2-bis(2-aminophenoxy)ethane-N;    N′-tetraacetic acid;    FITC;    fluorescein isothiocyanate;    ICE;    interleukin-1β converting enzyme;    PARP;    poly(ADP-ribose) polymerase;    AMC;    amino-4-methylcoumarin;    cmk;    chloromethylketone;    CHX;    cycloheximide;    FSC;    forward scatter;    PMSF;    phenylmethylsulfonyl fluoride;   

DOI  :  10.1016/S0014-5793(96)01341-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The appearance of phosphatidylserine (PS) on the outer surface of apoptotic cells is an important signal for their ingestion. In platelets, elevation of intracellular Ca²⁺ with thapsigargin can trigger large amounts of PS exposure within minutes. We detected PS exposure in U937 promonocytes and Jurkat T-cells after incubation with thapsigargin, but in only 10% of the cells, and it took up to 6 h to occur. Tumor necrosis factor and anti-Fas antibody rapidly trigger apoptosis in these cells, and chelation of extracellular Ca²⁺ with 5 mM EGTA inhibited PS exposure by 65% and 50%, respectively. Chelation of intracellular Ca²⁺ with BAPTA-AM had no effect. Other parameters of apoptosis, including cell blebbing, shrinkage, nuclear fragmentation, activation of the ICE-like proteases, and fodrin cleavage, were not inhibited by extracellular EGTA. We conclude that while an elevation of intracellular Ca²⁺ is an ineffective trigger of apoptosis in the cells investigated, extracellular Ca²⁺ is required for efficient PS exposure during apoptosis.

【 授权许可】

Unknown