Induction of hepatitis by JNK-mediated expression of TNF-alpha
Program in Molecular Medicine
Animals; Hepatitis; Hepatocytes; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinase 9; Tumor Necrosis Factor-alpha
Life Sciences | Medicine and Health Sciences
The c-Jun NH(2)-terminal kinase (JNK) signaling pathway has been implicated in the development of tumor necrosis factor (TNF)-dependent hepatitis. JNK may play a critical role in hepatocytes during TNF-stimulated cell death in vivo. To test this hypothesis, we examined the phenotype of mice with compound disruption of the Jnk1 and Jnk2 genes. Mice with loss of JNK1/2 expression in hepatocytes exhibited no defects in the development of hepatitis compared with control mice, whereas mice with loss of JNK1/2 in the hematopoietic compartment exhibited a profound defect in hepatitis that was associated with markedly reduced expression of TNF-alpha. These data indicate that JNK is required for TNF-alpha expression but not for TNF-alpha-stimulated death of hepatocytes. Indeed, TNF-alpha induced similar hepatic damage in both mice with hepatocyte-specific JNK1/2 deficiency and control mice. These observations confirm a role for JNK in the development of hepatitis but identify hematopoietic cells as the site of the essential function of JNK.
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Citation: Cell. 2009 Jan 23;136(2):249-60. Link to article on publisher's site