K(+) channel activity and redox status are differentially required for JNK activation by UV and reactive oxygen species.
Upon exposure to ultraviolet (UV) radiation, osmotic changes or the presence of reactive oxygen species (ROS) c-Jun N-terminal kinases (JNKs) are rapidly activated. Extensive studies have elucidated molecular components that mediate the activation of JNKs. However, it remains unclear whether activation of JNKs by various stress signals involves different pathways. Here we show that K(+) channel activity is involved in mediating apoptosis induced by UV but not by H(2)O(2) in myelocytic leukemic ML-1 cells. Specifically, JNKs were rapidly phosphorylated upon treatment of ML-1 cells with UV and H(2)O(2). UV-induced, but not H(2)O(2)-induced, JNK-1 phosphorylation was inhibited by pretreatment with 4-aminopyridine (4-AP), a K(+) channel blocker. 4-AP also blocked UV-induced increase in JNK activity as well as p38 phosphorylation. Immunofluorescent microscopy revealed that phosphorylated JNKs were concentrated at centrosomes in ML-1 cells and that these proteins underwent rapid subcellular translocation upon UV treatment. Consistently, the subcellular translocation of JNKs induced by UV was largely blocked by 4-AP. Furthermore, UV-induced JNK activation was blocked by NEM, a sulfhydryl alkylating agent also affecting K(+) current. Both UV- and H(2)O(2)-induced JNK activities were inhibited by glutathione, suggesting that the redox status does play an important role in the activation of JNKs. Taken together, our findings suggest that JNK activation by UV and H(2)O(2) is mediated by distinct yet overlapping pathways and that K(+) channel activity and redox status are differentially required for UV- and H(2)O(2)-induced activation of JNKs.
Gao
Jie
J
Department of Medical Genetics, Shanghai Second Medical University, PR China.
Wu
Dan
D
Guo
Taylor B
TB
Ruan
Qin
Q
Li
Tie
T
Lu
Zhenyu
Z
Xu
Ming
M
Dai
Wei
W
Lu
Luo
L
D015761:4-Aminopyridine / Q000494:pharmacology; D017209:Apoptosis / Q000528:radiation effects; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000473:pathology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020298:U937 Cells; D014466:Ultraviolet Rays
D004791:Enzyme Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D015761:4-Aminopyridine; D020929:Mitogen-Activated Protein Kinase Kinases; D005978:Glutathione; D005033:Ethylmaleimide