title: Zap70 signaling pathway mediates glucocorticoid receptor-dependent transcriptional activation: role in the regulation of annexin 1 expression in T cells.
abstract: We have recently shown that Zap70 is important in retinoid receptor-dependent transactivation in T lymphocytes. We report that Zap70 signaling is also essential in dexamethasone-inducible glucocorticoid receptor (GR)-mediated transactivation in T lymphocytes. Zap70-negative Jurkat T cells and cells reconstituted with inactive Zap70 exhibited attenuated GR-mediated activation as compared with Zap70 reconstituted and wild-type cells. Lck-lacking Jurkat cells were also found to show markedly reduced GR activation, and reconstitution with Lck restored the activation. Gene array and protein analysis showed that the level of annexin 1 (ANXA1), an anti-inflammatory protein known to be induced and released by the glucocorticoid action, was significantly reduced in Zap70-negative and Zap70-inactive Jurkat cells as compared with wild-type cells. Lck-lacking cells were also found to have markedly reduced ANXA1 levels and reconstitution with Lck restored the ANXA1 expression. RNA interference-induced knockdown of Zap70 or Lck in Jurkat cells and peripheral blood T lymphocytes also resulted in the loss of ANXA1 expression. Transcriptional analysis revealed that dexamethasone-inducible GR-mediated activation of ANXA1 promoter was compromised in both Zap70 knocked down peripheral blood T cells and Zap70 or Lck-deficient/Lck-inactive Jurkat cells, indicating an essential role of these kinases in GR-mediated ANXA1 promoter activation in T lymphocytes. To summarize, our data demonstrate an important role for Zap70 signaling in GR-mediated transactivation in T lymphocytes and also point out a crucial role of this kinase in maintaining normal ANXA1 levels in these cells.
authors.affiliation: Laboratory of Molecular Cell Biology, SAIC-Frederick, National Cancer Institute, Frederick, MD 21702, USA. mishaq@mail.nih.gov
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ishaq
authors.forename: Gerald
authors.initials: G
authors.lastname: DeGray
authors.forename: Kathy
authors.initials: K
authors.lastname: Mou
authors.forename: Angelica
authors.initials: A
authors.lastname: Aguilera
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Richard A
authors.initials: RA
authors.lastname: Lempicki
authors.forename: Allison
authors.initials: A
authors.lastname: Hazen
authors.forename: Ven
authors.initials: V
authors.lastname: Natarajan
mesh_terms: D017305:Annexin A1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D003907:Dexamethasone / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000502:physiology*; D020218:Response Elements / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics / Q000276:immunology*; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*