TNF-induced death of adult human oligodendrocytes is mediated by c-jun NH2-terminal kinase-3.
Tumour necrosis factor (TNF) induces death of oligodendrocytes, the putative cell target in multiple sclerosis. We defined that the intracellular transduction pathway involved in TNF- induced death of human adult oligodendrocytes (hOLs) is dependent on c-jun NH(2)-terminal kinase (JNK) activation, but not the other mitogen-activated protein kinase ( MAPK), p38. JNK activation, measured by c-jun phosphorylation and induction of the phosphorylated form of JNK, was enhanced, prolonged and correlated with cell death in hOLs exposed to TNF. Comparative autoradiographic analysis revealed that JNK-3, but not JNK-1 or JNK-2, is responsible for prolonged JNK activation in TNF exposed hOLs. Expression of a dominant-negative mutant of JNK upstream kinase, MKK4/SEK1, inhibited apoptosis induced by TNF, whereas expression of a constitutive active mutant of MEKK1, an upstream kinase to JNK, accelerates TNF-induced apoptosis. JNK activation occurred prior to changes of mitochondrial membrane potential in hOLs exposed to TNF. These results demonstrate that TNF- induced death in adult hOLs depends on prolonged JNK-3 activation, and that this apoptosis requires the mitochondrial dysfunction that occurs after JNK activation. This is the first evidence that a JNK-3 isoform is involved in oligodendrocyte death and might have significant importance in designing new molecules to protect hOLs demise in multiple sclerosis.[1]References
- TNF-induced death of adult human oligodendrocytes is mediated by c-jun NH2-terminal kinase-3. Jurewicz, A., Matysiak, M., Tybor, K., Selmaj, K. Brain (2003) [Pubmed]
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