TableEdit

Numata, A, Shimoda, K, Kamezaki, K, Haro, T, Kakumitsu, H, Shide, K, Kato, K, Miyamoto, T, Yamashita, Y, Oshima, Y, Nakajima, H, Iwama, A, Aoki, K, Takase, K, Gondo, H, Mano, H and Harada, M (2005) Signal transducers and activators of transcription 3 augments the transcriptional activity of CCAAT/enhancer-binding protein alpha in granulocyte colony-stimulating factor signaling pathway. J. Biol. Chem. 280:12621-9

The Janus kinase (Jak)-Stat pathway plays an essential role in cytokine signaling. Granulocyte colony-stimulating factor (G-CSF) promotes granulopoiesis and granulocytic differentiation, and Stat3 is the principle Stat protein activated by G-CSF. Upon treatment with G-CSF, the interleukin-3-dependent cell line 32D clone 3(32Dcl3) differentiates into neutrophils, and 32Dcl3 cells expressing dominant-negative Stat3 (32Dcl3/DNStat3) proliferate in G-CSF without differentiation. Gene expression profile and quantitative PCR analysis of G-CSF-stimulated cell lines revealed that the expression of C/EBPalpha was up-regulated by the activation of Stat3. In addition, activated Stat3 bound to CCAAT/enhancer-binding protein (C/EBP)alpha, leading to the enhancement of the transcription activity of C/EBPalpha. Conditional expression of C/EBPalpha in 32Dcl3/DNStat3 cells after G-CSF stimulation abolishes the G-CSF-dependent cell proliferation and induces granulocytic differentiation. Although granulocyte-specific genes, such as the G-CSF receptor, lysozyme M, and neutrophil gelatinase-associated lipocalin precursor (NGAL) are regulated by Stat3, only NGAL was induced by the restoration of C/EBPalpha after stimulation with G-CSF in 32Dcl3/DNStat3 cells. These results show that one of the major roles of Stat3 in the G-CSF signaling pathway is to augment the function of C/EBPalpha, which is essential for myeloid differentiation. Additionally, cooperation of C/EBPalpha with other Stat3-activated proteins are required for the induction of some G-CSF responsive genes including lysozyme M and the G-CSF receptor.

PubMed Online version:10.1074/jbc.M408442200

Acute-Phase Proteins/metabolism; Animals; Blotting, Western; CCAAT-Enhancer-Binding Protein-alpha/metabolism; Cell Differentiation; Cell Line; Cell Proliferation; Cytokines/metabolism; DNA-Binding Proteins/metabolism; DNA-Binding Proteins/physiology; Flow Cytometry; Gene Expression Regulation; Genes, Dominant; Granulocyte Colony-Stimulating Factor/metabolism; Granulocytes/cytology; Granulocytes/metabolism; Humans; Immunoblotting; Immunoprecipitation; Interferon-alpha/metabolism; Interleukin-3/metabolism; Lipocalins; Mice; Muramidase/chemistry; Muramidase/metabolism; Myeloid Cells/metabolism; Neutrophils/metabolism; Oligonucleotide Array Sequence Analysis; Oncogene Proteins/metabolism; Promoter Regions, Genetic; Proto-Oncogene Proteins; RNA, Messenger/metabolism; Reverse Transcriptase Polymerase Chain Reaction; STAT3 Transcription Factor; Signal Transduction; Time Factors; Trans-Activators/metabolism; Trans-Activators/physiology; Transcription, Genetic