Activation of the Stat3 signaling pathway is required for differentiation by interleukin-6 in PC12-E2 cells.
The role of signal transducer and activator of transcription (STAT) signaling pathways in the interleukin-6 (IL-6)-induced morphological differentiation of PC12-E2 cells was assessed using wild type and dominant negative mutants of Stat1 and Stat3, containing Tyr --> Phe (YF), Ser --> Ala (SA), and the double mutations (DM), respectively. FS3-YF or FS3-DM markedly inhibited the IL-6-induced response, but overexpression of FS3-SA caused only a modest inhibition. Expression of all Stat3 mutants had no effect on NGF-induced neurite outgrowth. Overexpression of wild type Stat1 protein inhibited IL-6 activated DNA binding complexes containing Stat3 homodimers, which may explain the partial negative effect of Stat1 on IL-6-induced neurite outgrowth. Specificity of these STAT constructs was confirmed using luciferase reporter gene assays, which showed that IL-6-activated transcription was blocked by expression of FS3-YF and FS3-DM and that FS1 enhanced the interferon gamma-activated transcription. Thus, in PC12-E2 cells, Stat3 homodimers are preferentially activated by IL-6, indicating a role for Stat3 in the regulation of cellular differentiation. Furthermore, IL-6 induced robust neurite outgrowth in PC12-E2 cells expressing dominant negative forms of RAS or SHC or in cells pretreated with the mitogen-activated protein kinase mitogen-activated protein kinase kinase inhibitor, PD98059. Thus, activation of the Stat3 signaling pathway, but not RAS/ERK dependent pathways, is essential for differentiation of PC12-E2 cells by IL-6.
Wu
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Departments of Physiology and Biophysics, College of Medicine, University of California, Irvine, California 92697, USA.
Bradshaw
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D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells; D010766:Phosphorylation; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D051381:Rats; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D012694:Serine / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D015850:Interleukin-6; D009414:Nerve Growth Factors; D011506:Proteins; C528024:SHC1 protein, human; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; C494081:Stat1 protein, rat; C494088:Stat3 protein, rat; D015534:Trans-Activators; D014443:Tyrosine; D012694:Serine; D007371:Interferon-gamma; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one