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Cationic liposomes induce apoptosis through p38 MAP kinase–caspase‐8–Bid pathway in macrophage‐like RAW264.7 cells
Author(s) -
Iwaoka Sayaka,
Nakamura Tomoko,
Takano Shuhei,
Tsuchiya Seishi,
Aramaki Yukihiko
Publication year - 2006
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0405181
Subject(s) - p38 mitogen activated protein kinases , apoptosis , microbiology and biotechnology , biology , caspase , programmed cell death , liposome , reactive oxygen species , cationic liposome , mapk/erk pathway , kinase , mitogen activated protein kinase , cell culture , transfection , biochemistry , genetics
We have demonstrated that cationic liposomes composed of stearylamine (SA‐liposomes) induce apoptosis in a variety of cells, but the mechanism responsible for the cellular death is not clear. In this paper, we investigated the signaling pathways implicated in SA‐liposome‐induced apoptosis in the macrophage‐like cell line RAW264.7. Treatment with SA‐liposomes caused the activation of mitogen‐activated proein kinases (MAPKs), especially p38 and c‐jun N ‐terminal kinase, and apoptosis was only inhibited upon the addition of a specific inhibitor for p38. N ‐acetylcysteine, a scavenger of reactive oxygen species (ROS), effectively inhibited the activation of p38 and cellular death, indicating that the activation induced by ROS is an initial step in the process of apoptosis triggered by SA‐liposomes. Caspase‐8 was activated by p38, and caspase‐8‐dependent cleavage of Bid was also observed. No down‐regulation of bcl‐2 expression, and no cleavage of Bax protein were observed. Taken together, our results suggest that apoptosis of RAW264.7 by SA‐liposomes was mediated by the MAPK p38 and a caspase‐8‐dependent Bid‐cleavage pathway. Moreover, we found that ROS can contribute intimately to the SA‐liposome‐induced cell death in RAW264.7.