Carboxy-terminal truncated STAT5 is induced by interleukin-2 and GM-CSF in human neutrophils.
IL-2 and GM-CSF are potent activators of polymorphonuclear neutrophils (PMN) biologic activity. IL-2 and GM-CSF-mediated activation of STAT proteins was examined in nuclear extracts of human PMN. We found that both cytokines induced STAT5-like DNA-binding complexes that could not be supershifted using C-terminal-specific anti-STAT5 antibodies. Therefore, we performed oligoprecipitation experiments with a STAT5-biotinylated DNA probe (biotin-MGFe) and the precipitated proteins were identified by Western immunoblotting. We found that GM-CSF and IL-2 induced the DNA-binding activity of a C-terminal truncated isoform of STAT5. The truncated STAT5 form was present in the nucleus of PMN but the cytoplasmic extracts contained full-length STAT5, suggesting that PMN proteolytically process full-length STAT5 proteins. Proteolytic experiments demonstrated that PMN express a protease activity capable of producing C-terminal processed STAT5 proteins. In many settings, C-terminal truncation of the STAT5 protein leads to inhibition of STAT5 biological activity. Two known STAT5 regulated genes, encoding pim-1 and OSM proteins, failed to be induced by GM-CSF in PMN. These findings provide new insights to a mechanism by which PMN, a terminally differentiated cell, may regulate gene transcription by alternative proteolytic processing.
Epling-Burnette
P K
PK
Malignant Hematology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, USA. Burnetpk@moffitt.usf.edu
Garcia
Roy
R
Bai
Fanqi
F
Ismail
Sajid
S
Loughran
Thomas P
TP
Djeu
Julie Y
JY
Jove
Richard
R
Wei
Sheng
S
D001665:Binding Sites; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D007700:Kinetics; D008894:Milk Proteins; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D020033:Protein Isoforms / Q000096:biosynthesis; D020218:Response Elements; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D017384:Sequence Deletion; D012697:Serine Endopeptidases / Q000378:metabolism; D015534:Trans-Activators / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D014158:Transcription, Genetic; D014443:Tyrosine / Q000378:metabolism
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D008894:Milk Proteins; D020033:Protein Isoforms; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D012697:Serine Endopeptidases