DIFFERENTIAL UTILIZATION OF JANUS KINASE-SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION SIGNALING PATHWAYS IN THE STIMULATION OF HUMAN NATURAL-KILLER-CELLS BY IL-2, IL-12, AND IFN-ALPHA
Cr. Yu et al., DIFFERENTIAL UTILIZATION OF JANUS KINASE-SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION SIGNALING PATHWAYS IN THE STIMULATION OF HUMAN NATURAL-KILLER-CELLS BY IL-2, IL-12, AND IFN-ALPHA, The Journal of immunology, 157(1), 1996, pp. 126-137
IL-2-, IL-12-, and IFN-alpha-mediated signaling pathways were analyzed
in primary NK cells and in the NK3.3 cell line. Gel mobility shift an
d immunoprecipitation analyses revealed that in addition to activating
STAT3 (signal transducer and activator of transcription-3) and STAT5,
IL-2 induced tyrosine and serine phosphorylation of STAT1 alpha, whic
h formed IFN-gamma-activated sequence-binding complexes by itself and
with STAT3. Although IL-2 and IFN-alpha activated STAT1 alpha and STAT
5, IL-2 predominantly activated STAT5, while IFN-alpha predominantly a
ctivated STAT1 alpha. IL-2 induced less STAT1 alpha activation and IFN
-alpha induced greater STAT5 activation in NK3.3 cells compared with p
reactivated primary NK cells. In NK3.3 cells, IL-2 induced comparable
formation of c-fos promoter sis-inducible element IFN-gamma-activated
sequence-binding complexes containing STAT3 alone with complexes conta
ining STAT3 and STAT1 alpha, while in preactivated primary NK cells, i
t preferentially induced complexes containing STAT3 and STAT1 alpha. T
hus, signaling in NK3.3 cells is not always identical with that in pri
mary NK cells. In contrast to IL-2 and IFN-alpha, IL-12 induced strong
tyrosine phosphorylation of STAT4 and variable weak phosphorylation o
f STAT3. However, supershift analyses using the c-fos promoter sis-ind
ucible element probe showed that IL-12 activated STAT4, STAT1 alpha, a
nd STAT3, acid induced complexes containing STAT4 only, STAT4 with STA
T1 alpha, STAT3 with STAT1 alpha, or STAT1 alpha only in preactivated
primary NK cells. STAT1 alpha activation by IL-12 correlated with incr
eased phosphorylation of serine, but not tyrosine. Finally, IL-2 induc
ed tyrosine phosphorylation of JAK1 and JAK3, while IL-12 induced phos
phorylation of JAK2 and TYK2 in both preactivated primary NK and NK3.3
cells. Differential phosphorylation and consequent differential activ
ation of both separate and overlapping STAT proteins by IL-2, IL-12, a
nd IFN-alpha may provide a molecular basis for the similarities and di
fferences in the actions of these cytokines on NK cells.