Distinct signal transduction processes by IL-4 and IL-13 and influences from the Q551R variant of the human IL-4 receptor alpha chain

• Main Authors: Braun Sandra, Kruse Susanne, Deichmann Klaus A
• Format: Article
• Language: English
• Published: BMC 2002-08-01
• Series: Respiratory Research
• Subjects: asthma; IL-4; IL-13; SHP; STAT3
• Online Access: http://dx.doi.org/10.1186/rr174

<p>Abstract</p> <p>Background</p> <p>Although IL-4 and IL-13 share the IL-13 receptor, IL-13 exhibits unique functions. To elicit the cellular basis of these differences, signal transduction processes have been compared. Additionally, the role of the IL-4 receptor alpha (IL-4Rα) variant Q551R was investigated.</p> <p>Methods</p> <p>Peripheral blood mononuclear cells from donors were stimulated with IL-4 and IL-13. The phosphorylation status of effector substrates was detected by immunostaining. Binding of SHP-2 to IL-4Rα was investigated by using synthetic peptides.</p> <p>Results</p> <p>SHP-2 bound IL-4Rα synthetic peptide; this binding was reduced in the presence of the R551 variant. Stimulation with IL-4 increased SHP-1 phosphorylation, however, stimulation with IL-13 increased SHP-2 phosphorylation. PI3-kinase phosphorylation was elevated following stimulation with IL-13 in all individuals and with IL-4 only in R551 individuals. Jak1, Tyk2 and IRS-2 signals were reduced after IL-13 stimulation in Q551 individuals. STAT3 phosphorylation was markedly increased in R551 individuals, following stimulation with both IL-4 and IL-13. However, STAT3 was only detected immediately in nuclear extracts from variant individuals after stimulation with IL-13; in wildtype individuals STAT3 was only detected after IL-4 treatment.</p> <p>Conclusion</p> <p>IL-4 and IL-13 appear to promote distinct signal transduction cascades. SHP-1 seems to be predominately activated by IL-4 and to influence the PI3-kinase, in contrast, SHP-2 seems to be predominately activated by IL-13 and to influence Jak1, Tyk2 and IRS-2. Both phosphatases control STAT3. In the presence of the variant R551, SHP-1/2 activation is reduced and signal transduction is altered. STAT3 signaling appears be further regulated on the level of nuclear translocation.</p>