| |
|
|
|
|
|
|
|||
|
Blood, 1 September 2005, Vol. 106, No. 5, pp. 1703-1710. Prepublished online as a Blood First Edition Paper on May 17, 2005; DOI 10.1182/blood-2004-12-4790.
IMMUNOBIOLOGY Rapid immunosuppressive effects of glucocorticoids mediated through Lck and FynFrom the Laboratory of Experimental Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands; the Department of Rheumatology and Clinical Immunology (Charité University Hospital) and Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany; the Department of Cell Biology, University of Groningen, Groningen, The Netherlands; and the Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
Glucocorticoids (GCs) are effective immunosuppressive agents and mediate well-defined transcriptional effects via GC receptors. There is increasing evidence that GCs also initiate rapid nongenomic signaling events. Using activated human CD4+ lymphocytes and a peptide array containing 1176 different kinase consensus substrates, we generated a comprehensive profile of GC-induced rapid effects on signal transduction. The results show marked early differences in phosphorylation between GC-pretreated cells and control cells, including impaired phosphorylation of p56lck/p59fyn (Lck/Fyn) consensus substrates. Immunoprecipitation and in vitro kinase assays reveal rapid GC-induced down-modulation of Lck and Fyn kinases using SAM68 (Src [pp60c-src]-associated in mitosis 68 kDa) as a substrate. Additionally, immunoprecipitation experiments revealed reduced Lck-CD4 and Fyn-CD3 associations, suggesting GC inhibited recruitment of these kinases to the T-cell receptor complex. Western blot analysis revealed reduced phosphorylation of a series of downstream signaling intermediates following GC treatment, including protein kinase B (PKB), protein kinase C (PKC), and mitogen-activated protein kinases (MAPKs). Experiments with GC receptor-negative Jurkat cells and a pharmacologic GC receptor ligand (RU486) indicated that rapid inhibition of Lck and Fyn kinases is GC receptor dependent. Parallel experiments conducted following the application of GCs in healthy individuals confirmed suppression of Lck/Fyn in T cells within 1 hour in vivo. These results identify the inhibition of Lck and Fyn kinases as rapid targets of GCs, mediated via a GC receptor-dependent pathway. (Blood. 2005; 106:1703-1710)
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Copyright © 2005 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||