Two different IL-13 receptor chains are expressed in normal human skin fibroblasts, and IL-4 and IL-13 mediate signal transduction through a common pathway.
IL-13 and IL-4, pleiotropic immune regulatory cytokines, have been shown to mediate similar prominent effects in human fibroblast cell lines. However, molecular mechanisms for their redundant effects are not known. Here, we have investigated the structure of IL-13 receptors (IL-13R) and molecular mechanisms of signal transduction through IL-13 and IL-4 receptors in non-transformed normal skin fibroblast cell lines. We demonstrate that high-affinity IL-13R is expressed in normal skin fibroblast cell lines. Upon [125I]1L-13 cross-linking, a approximately 60-70 kDa band was observed in sk559 and sk574 fibroblast cell lines. By RT-PCR analysis, mRNA for IL-13R alpha, IL-13R alpha' and IL-4Rbeta chains were expressed; however, the IL-2Rgamma chain, shown to participate and modulate IL-4 and IL-13 binding, was not expressed in any of the cell lines examined. The Janus kinase (JAK)2 and Tyk2 were phosphorylated in response to IL-4 or IL-13 in sk559 and sk574 cell lines. JAK1 was also phosphorylated in one of two cell lines while JAK3 was present but not phosphorylated in any of the cell lines studied. A signal transduction and activator of transcription (STAT)6 was also activated in response to both IL. An insulin receptor substrate (IRS)-1 was constitutively phosphorylated and its phosphorylation level was augmented in response to both IL. These results suggest that the mechanism of signal transduction through IL-13 and IL-4 receptors in human fibroblast cell lines is similar, and this may, at least in part, be responsible for the redundant effects of these two cytokines. In addition, JAK2 tyrosine kinase instead of JAK3 appears to play a major role in IL-4- and IL-13-induced signal transduction in human fibroblasts.
Laboratory of Molecular Tumor Biology, Division of Cellular and Gene Therapy, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
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T
Murata
S R
SR
Husain
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H
Mohri
R K
RK
Puri
D000345:Affinity Labels; D001665:Binding Sites; D002460:Cell Line; D003432:Cross-Linking Reagents; D005347:Fibroblasts; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D018793:Interleukin-13 / Q000378:metabolism / Q000494:pharmacology*; D053661:Interleukin-13 Receptor alpha1 Subunit; D015847:Interleukin-4 / Q000494:pharmacology*; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin / Q000235:genetics / Q000378:metabolism*; D053660:Receptors, Interleukin-13; D015375:Receptors, Interleukin-2 / Q000235:genetics; D019948:Receptors, Interleukin-4 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050800:STAT6 Transcription Factor; D015398:Signal Transduction; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000345:Affinity Labels; D003432:Cross-Linking Reagents; C508181:IL13RA1 protein, human; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; D018793:Interleukin-13; D053661:Interleukin-13 Receptor alpha1 Subunit; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin; D053660:Receptors, Interleukin-13; D015375:Receptors, Interleukin-2; D019948:Receptors, Interleukin-4; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D015847:Interleukin-4; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507933:JAK3 protein, human; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D053634:TYK2 Kinase; C070139:TYK2 protein, human