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Interleukin‐2 activation of STAT5 requires the convergent action of tyrosine kinases and a serine/threonine kinase pathway distinct from the Raf1/ERK2 MAP kinase pathway.
Author(s) -
Beadling C.,
Ng J.,
Babbage J. W.,
Cantrell D. A.
Publication year - 1996
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1996.tb00541.x
Subject(s) - biology , map kinase kinase kinase , mitogen activated protein kinase , map2k7 , kinase , threonine , protein serine threonine kinases , c raf , mitogen activated protein kinase kinase , tyrosine kinase , mapk14 , serine , microbiology and biotechnology , ask1 , biochemistry , phosphorylation , signal transduction , cyclin dependent kinase 2 , protein kinase a
Interleukin‐2 (IL‐2) induces DNA binding of STAT5, a member of the family of cytokine‐regulated transcription factors termed ‘signal transducers and activators of transcription’. IL‐2‐stimulated STAT5‐DNA complexes include two tyrosine phosphoproteins which exhibit distinct mobilities in SDS‐PAGE gels. Our studies have shown that IL‐2 rapidly induces both tyrosine phosphorylation and serine phosphorylation of STAT5 and that the two STAT5 tyrosine phosphoproteins detected in IL‐2‐activated cells differ in their levels of phosphorylation on serine residues. The two different phosphoforms of STAT5 have identical in vitro DNA binding specificity and reactivity with tyrosine phosphopeptides, but differ in their cellular localization. As well, the present data indicate that the transcriptional activity of STAT5 is regulated by serine kinases in T lymphocytes. Two previously characterized serine kinases activated by IL‐2, MAP kinase/ERK2 and p70 S6 kinase, do not appear to be involved in STAT5 regulation by this cytokine. Accordingly, STAT5 activation in T cells requires the convergent action of tyrosine kinases and a distinct serine/threonine kinase which has not previously been implicated in IL‐2 signalling.