Interleukin-2 family cytokines stimulate phosphorylation of the Pro-Ser-Pro motif of Stat5 transcription factors in human T cells: resistance to suppression of multiple serine kinase pathways.
Signal transducer and activator of transcription (Stat)5a and Stat5b are critical for normal immune function. Progression of T cells through G(1)-S phase of cell cycle requires T cell receptor (TCR)- and/or cytokine-inducible tyrosine phosphorylation of Stat5a/b. Stat5a/b may also, in a cell-dependent manner, be constitutively or cytokine-inducibly phosphorylated on a Pro-Ser-Pro (PSP) motif located within the transcriptional activation domain. Phosphorylation of the PSP motif is needed for maximal transcriptional activation by Stat5, at least in certain promoter contexts. The basal and cytokine-inducible serine phosphorylation state of Stat5a/b has not been determined in T cells. Using primary human T cells and T lymphocytic cell lines coupled with novel phospho-specific antibodies to this conserved phosphoserine motif in Stat5a or Stat5b, we report that: Stat5a and Stat5b were unphosphorylated on the PSP motif under basal conditions and became markedly phosphorylated in response to several T cell growth factor stimuli, including interleukin (IL)-2, -7, -9, and -15 and phorbol ester 12-myristate 13-acetate but not TCR engagement; inducible Stat5a/b serine phosphorylation differed quantitatively and temporally; and Stat5a/b serine phosphorylation was, in contrast to inducible Stat3 serine phosphorylation, insensitive to inhibitors of mitogen-activated protein kinase, phosphatidylinositol-3 kinase, and mammalian target of rapamycin or deletion of Raf-A, -B, or -C by antisense oligonucleotides. We conclude that IL-2 family cytokines tightly control Stat5 serine phosphorylation through a kinase distinct from the Stat3 serine kinase.
Nagy
Zsuzsanna S
ZS
Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 77030, USA.
Wang
Yuling
Y
Erwin-Cohen
Rebecca A
RA
Aradi
János
J
Monia
Brett
B
Wang
Li Hua
LH
Stepkowski
Stanislaw M
SM
Rui
Hallgeir
H
Kirken
Robert A
RA
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017252:CD3 Complex / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D019409:Interleukin-15 / Q000494:pharmacology; D007376:Interleukin-2 / Q000378:metabolism* / Q000494:pharmacology; D015851:Interleukin-7 / Q000494:pharmacology; D016906:Interleukin-9 / Q000494:pharmacology; D008894:Milk Proteins; D008969:Molecular Sequence Data; D020319:Oligodeoxyribonucleotides, Antisense; D010703:Phorbol Esters / Q000494:pharmacology; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D048491:Proto-Oncogene Proteins A-raf; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
D017252:CD3 Complex; D004268:DNA-Binding Proteins; D019409:Interleukin-15; D007376:Interleukin-2; D015851:Interleukin-7; D016906:Interleukin-9; D008894:Milk Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D010703:Phorbol Esters; D020033:Protein Isoforms; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; C494095:STAT5B protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D012694:Serine; D011392:Proline; D017346:Protein Serine-Threonine Kinases; D048491:Proto-Oncogene Proteins A-raf; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf