Activation of JAK-STAT and MAP kinases by leukemia inhibitory factor through gp130 in cardiac myocytes.
BACKGROUND: Interleukin (IL)-6-related cytokines share gp130 as the signal-transducing protein. Downstream of gp130, two signal-transducing pathways have been recognized, the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway and the Ras- mitogen-activated protein kinase ( MAPK) pathway. To determine whether these two signaling pathways through gp130 are present in cardiac myocytes, we examined their activation by using leukemia inhibitory factor (LIF), which is a member of the IL-6 cytokine family. METHODS AND RESULTS: Lysates from neonatal rat cardiac myocytes were immunoprecipitated with anti-gp130, anti-JAK1, or anti-STAT3 antibody and blotted with anti-phosphotyrosine antibody. Tyrosine phosphorylation of gp130, JAK1, and STAT3 was observed after LIF stimulation in cardiac myocytes. MAPKs were maximally activated 5 minutes after LIF stimulation. Furthermore, anti-gp130 antibody significantly inhibited the LIF- induced activation of JAK1, STAT3, and MAPKs. To examine whether these signaling pathways were also activated in the adult heart in vivo, LIF was injected intravenously into a 6-week-old mouse, and the heart was examined subsequently. gp130, STAT3, and MAPKs were activated in the heart after LIF treatment. CONCLUSIONS: These results demonstrate for the first time that a JAK-STAT pathway and a MAPK pathway are present down-stream of gp130 in cardiac myocytes and are rapidly activated by LIF both in vitro and in vivo. Activation of gp130 constitutes a novel signaling pathway in cardiac myocytes.[1]References
- Activation of JAK-STAT and MAP kinases by leukemia inhibitory factor through gp130 in cardiac myocytes. Kunisada, K., Hirota, H., Fujio, Y., Matsui, H., Tani, Y., Yamauchi-Takihara, K., Kishimoto, T. Circulation (1996) [Pubmed]
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