TY - JOUR
T1 - The extracellular and transmembrane domains of the γC and interleukin (IL)-13 receptor α1 chains, not their cytoplasmic domains, dictate the nature of signaling responses to IL-4 and IL-13
AU - Heller, Nicola M.
AU - Qi, Xiulan
AU - Gesbert, Franck
AU - Keegan, Achsah D.
PY - 2012/9/14
Y1 - 2012/9/14
N2 - Previously, we demonstrated that the -Csubunit of type I IL-4 receptor was required for robust tyrosine phosphorylation of the downstream adapter protein, IRS-2, correlating with the expression of genes (ArgI, Retnla, and Chi3l3) characteristic of alternatively activated macrophages. We located an I4R-like motif (IRS-2 docking sequence) in the -C cytoplasmic domain but not in the IL-13R-1. Thus, we predicted that the -C tail directed enhanced IRS-2 phosphorylation. To test this, IL-4 signaling responses were examined in a mutant of the key I4R motif tyrosine residue (Y325F) and different -C truncation mutants (-285, -308, -318, -323, and -FULL LENGTH (FL)) co-expressed in L-cells or CHO cells with wild-type (WT) IL-4R-. Surprisingly, IRS-1 phosphorylation was not diminished in Y325F L-cell mutants suggesting Tyr-325 was not required for the robust insulin receptor substrate response. IRS-2, STAT6, and JAK3 phosphorylation was observed in CHO cells expressing -323 and -FL but not in -318 and -285 mutants. In addition, when CHO cells expressed -318, -323, or -FL with IL-2R-, IL-2 induced phospho-STAT5 only in the -323 and -FL clones. Our data suggest that a smaller (5 amino acid) interval than previously determined is necessary for JAK3 activation/ -C-mediated signaling in response to IL-4 and IL-2. Chimeric receptor chains of the -C tail fused to the IL-13R-1 extracellular and transmembrane domain did not elicit robust IRS-2 phosphorylation in response to IL-13 suggesting that the extracellular/ transmembrane domains of the IL-4/IL-13 receptor, not the cytoplasmic domains, control signaling efficiency. Understanding this pathway fully will lead to rational drug design for allergic disease.
AB - Previously, we demonstrated that the -Csubunit of type I IL-4 receptor was required for robust tyrosine phosphorylation of the downstream adapter protein, IRS-2, correlating with the expression of genes (ArgI, Retnla, and Chi3l3) characteristic of alternatively activated macrophages. We located an I4R-like motif (IRS-2 docking sequence) in the -C cytoplasmic domain but not in the IL-13R-1. Thus, we predicted that the -C tail directed enhanced IRS-2 phosphorylation. To test this, IL-4 signaling responses were examined in a mutant of the key I4R motif tyrosine residue (Y325F) and different -C truncation mutants (-285, -308, -318, -323, and -FULL LENGTH (FL)) co-expressed in L-cells or CHO cells with wild-type (WT) IL-4R-. Surprisingly, IRS-1 phosphorylation was not diminished in Y325F L-cell mutants suggesting Tyr-325 was not required for the robust insulin receptor substrate response. IRS-2, STAT6, and JAK3 phosphorylation was observed in CHO cells expressing -323 and -FL but not in -318 and -285 mutants. In addition, when CHO cells expressed -318, -323, or -FL with IL-2R-, IL-2 induced phospho-STAT5 only in the -323 and -FL clones. Our data suggest that a smaller (5 amino acid) interval than previously determined is necessary for JAK3 activation/ -C-mediated signaling in response to IL-4 and IL-2. Chimeric receptor chains of the -C tail fused to the IL-13R-1 extracellular and transmembrane domain did not elicit robust IRS-2 phosphorylation in response to IL-13 suggesting that the extracellular/ transmembrane domains of the IL-4/IL-13 receptor, not the cytoplasmic domains, control signaling efficiency. Understanding this pathway fully will lead to rational drug design for allergic disease.
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U2 - 10.1074/jbc.M112.348896
DO - 10.1074/jbc.M112.348896
M3 - Article
C2 - 22829596
AN - SCOPUS:84866390174
SN - 0021-9258
VL - 287
SP - 31948
EP - 31961
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 38
ER -