Activation of Lck is critically required for sphingosine-induced conformational activation of Bak and mitochondrial cell death.
Despite extensive investigation, the molecular mechanism of anticancer activity of sphingolipid metabolites remains to be clarified. Here we demonstrate that sphingosine induces mitochondrial cell death via Lck-mediated conformational activation of Bak in Jurkat T cell lymphoma. Treatment of cells with sphingosine rapidly induced mitochondrial membrane potential loss, cytochrome c release from mitochondria, and apoptotic cell death. Sphingosine also induced conformational activation of Bak, but not Bax. siRNA targeting of Bak effectively attenuated sphingosine-induced mitochondrial cell death, indicating that Bak is involved in sphingosine-induced mitochondrial cell death. Sphingosine also induced activation of tyrosine kinase Lck. Inhibition of Lck by treatment of PP2, a Lck inhibitor or siRNA targeting of Lck suppressed sphingosine-induced conformational activation and oligomerization of Bak, mitochondrial membrane potential loss, and apoptotic cell death, implying that activation of Lck is critically required for sphingosine-induced conformational activation of Bak and mitochondrial cell death. The results elucidated in this study provide a novel cellular mechanism for the anticancer activity of sphingolipid metabolites.
Kim
Min-Jung
MJ
Laboratory of Molecular Biochemistry, Department of Chemistry, Hanyang University, 17 Haengdang-Dong, Seongong-Ku, Seoul 133-791, Republic of Korea.
Park
Moon-Taek
MT
Yoon
Chang-Hwan
CH
Byun
Joo-Yun
JY
Lee
Su-Jae
SJ
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D019169:Jurkat Cells; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology; D011487:Protein Conformation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D013110:Sphingosine / Q000494:pharmacology*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C412373:AG 1879; D000970:Antineoplastic Agents; C494772:BAK1 protein, human; C494826:BAX protein, human; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D034741:RNA, Small Interfering; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D053148:Caspase 3; D053453:Caspase 9; D013110:Sphingosine