Cytokine signal transduction in P19 embryonal carcinoma cells: regulation of Stat3-mediated transactivation occurs independently of p21ras-Erk signaling.
Ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) are members of a subfamily of related cytokines that share gp130 as common signal-transducing receptor component. CNTF has recently been demonstrated to induce increased survival and neuronal differentiation of P19 embryonal carcinoma (EC) cells; however, the molecular mechanisms underlying these effects are still elusive. Here we report that CNTF and LIF, but not interleukin-6, activated signal transducers and activators of transcription (STAT)-reporter constructs in P19 EC cells. Supershift analysis revealed that the STAT-element binding complex contained the transcription factor Stat3. Binding of Stat3 was inhibited by protein tyrosine kinase inhibitors, but not by the broad serine/threonine protein kinase inhibitor, H7. However, H7 inhibited CNTF-induced Stat3 transactivation. Using a dominant-negative p21ras construct and a specific inhibitor of mitogen-activated protein kinase kinase (MEK; PD098059) we demonstrated that CNTF-induced Stat3 transactivation was independent of the p21ras-mitogen-activated protein kinase (MAPK) pathway, while CNTF-induced MAPK activation was p21ras- and MEK-dependent. Taken together, our results demonstrate the activation of the p21ras-MAPK and STAT signal transduction pathways in response to CNTF and LIF in P19 EC cells and reveal that there is no modulating crosstalk between these pathways. Furthermore, our data suggest that CNTF- and LIF-induced Stat3 activation in P19 EC cells involves an H7-sensitive p21ras/MAPK- and Ca(2+)-independent kinase.
van Puijenbroek
A A
AA
Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands.
van der Saag
P T
PT
Coffer
P J
PJ
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D018236:Carcinoma, Embryonal; D002454:Cell Differentiation; D020934:Ciliary Neurotrophic Factor; D016207:Cytokines / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D017930:Genes, Reporter; D006131:Growth Inhibitors / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D009474:Neurons / Q000166:cytology*; D011485:Protein Binding; D047428:Protein Kinase Inhibitors; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D020032:Tyrphostins / Q000494:pharmacology
D020934:Ciliary Neurotrophic Factor; D016207:Cytokines; D004268:DNA-Binding Proteins; D005419:Flavonoids; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D020032:Tyrphostins; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras); D019311:Staurosporine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one