1: Int J Mol Med. 2005 Feb;15(2):269-75. Functional analysis of the effect of forced activation of STAT3 on M1 mouse leukemia cells. Yoshida T, Iwamoto T, Adachi K, Yokota T, Miyake Y, Hamaguchi M. Department of Ophthalmology, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan. M1 mouse myeloid leukemia cells exhibit growth arrest and differentiation to monocytes/macrophages in response to leukemia inhibitory factor (LIF) stimulation. Although recent studies have demonstrated that STAT3 plays a central role in this process, it is unknown whether STAT3 activation alone is sufficient. To address this issue, we have established M1/STAT3ER cells, where STAT3 is selectively activated by 4-hydroxytamoxifen (4HT). 4HT stimulation did not have any effect on growth and morphology of M1/ STAT3ER cells, and did not induce the down-regulation of mRNA of c-myc and c-myb, which is necessary for M1 cell differentiation. On the other hand, mRNA of jun-B, IRF1 and p19 was increased by 4HT. DNA precipitation assay indicated that both stimulation of LIF and 4HT similarly activated STAT3ER. Introduction of a constitutive active MAP kinase kinase (MEK1) into M1/STAT3ER cells did not induce differentiation either. Together, our present data suggest that signaling other than the activation of STAT3 and MEK1 may be necessary for M1 cell-growth arrest and differentiation, while a set of early genes of LIF are induced by only STAT3 activation. PMID: 15647843 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 2: Int Rev Immunol. 1998;16(3-4):249-84. Interleukin 6 and its receptor: ten years later. Hirano T. Department of Molecular Oncology, Osaka University Medical School, Japan. hirano@molonc.med.osaka-u.ac.jp Ten years have passed since the molecular cloning of interleukin 6 (IL-6) in 1986. IL-6 is a typical cytokine, exhibiting functional pleiotropy and redundancy. IL-6 is involved in the immune response, inflammation, and hematopoiesis. The IL-6 receptor consists of an IL-6 binding alpha chain and a signal transducer, gp130, which is shared among the receptors for the IL-6 related cytokine subfamily. The sharing of a receptor subunit is a general feature of cytokine receptors and provides the molecular basis for the functional redundancy of cytokines. JAK tyrosine kinase is a key molecule that can initiate multiple signal-transduction pathways by inducing the tyrosine-phosphorylation of the cytokine receptor, gp130 in the case of IL-6, on which several signaling molecules are recruited, including STAT, a signal transducer and activator of transcription, and SHP-2, which links to the Ras-MAP kinase pathway. JAK can also directly activate signaling molecules such as STAT and Tec. These multiple signal-transduction pathways intimately regulate the expression of several genes including c-myc, c-myb, junB, IRF1, egr-1, and bcl-2, leading to the induction of cell growth, differentiation, and survival. The deregulated expression of IL-6 and its receptor is involved in a variety of diseases. Publication Types: Review Review, Tutorial PMID: 9505191 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Biochem Biophys Res Commun. 1997 Sep 29;238(3):764-8. Association of Stat3-dependent transcriptional activation of p19INK4D with IL-6-induced growth arrest. Narimatsu M, Nakajima K, Ichiba M, Hirano T. Department of Oncology, Biomedical Research Center, Osaka University Medical School, Suita, Japan. Signal transducer and activator of transcription 3 (Stat3) is the major mediator of the IL-6-induced signals regulating growth and differentiation. In the M1 myeloleukemic cell line, Stat3 is a critical transcription factor causing repression of c-myc and c-myb genes, expression of junB and IRF1, growth arrest at G1, and subsequent macrophage differentiation. To understand the mechanisms by which Stat3 causes such effects, we searched for other Stat3-regulated genes possibly involved in growth arrest. We identified this inducible molecule as p19INK4D using a specific antibody. Both p19INK4D mRNA and protein were rapidly induced by IL-6 treatment without requiring de novo protein synthesis and the induction was fully suppressed by dominant-negative forms of Stat3. Thus both Stat3-regulated events, repressions of c-myc and c-myb and induction of p19INK4D, are likely to be involved in IL-6-induced growth arrest in M1 cells. PMID: 9325164 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: EMBO J. 1996 Apr 1;15(7):1557-65. Differentiation and growth arrest signals are generated through the cytoplasmic region of gp130 that is essential for Stat3 activation. Yamanaka Y, Nakajima K, Fukada T, Hibi M, Hirano T. Department of Molecular Oncology, Osaka University Medical School, Japan. Interleukin-6 (IL-6) induces growth arrest and macrophage differentiation through its receptor in a murine myeloid leukaemic cell line, M1, although it is largely unknown how the IL-6 receptor generates these signals. By using chimeric receptors consisting of the extracellular domain of growth hormone receptor and the transmembrane and cytoplasmic domain of gp130 with progressive C-terminal truncations, we showed that the membrane-proximal 133, but not 108, amino acids of gp130 could generate the signals for growth arrest, macrophage differentiation, down-regulation of c-myc and c-myb, induction of junB and IRF1 and Stat3 activation. Mutational analysis of this region showed that the tyrosine residue with the YXXQ motif was critical not only for Stat3 activation but also for growth arrest and differentiation, accompanied by down-regulation of c-myc and c-myb and immediate early induction of junB and IRF1. The tight correlation between Stat3 activation and other IL-6 functions was further observed in the context of the full-length cytoplasmic region of gp130. The result suggest that Stat3 plays an essential role in the signals for growth arrest and differentiation. PMID: 8612579 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------