Novel Mechanism for Fc epsilon RI-mediated Signal Transducer and Activator of Transcription 5 (STAT5) Tyrosine Phosphorylation and the Selective Influence of STAT5B over Mast Cell Cytokine Production

• Type of Material: Article
• Authors: Nicholas A. Pullen, Virginia Commonwealth University; Brian O. Barnstein, Virginia Commonwealth University; Yves T. Falanga, Virginia Commonwealth University; Zhengqi Wang, Emory University; Ryo Suzuki, NIAMS; Tenchee D. Tamang, Virginia Commonwealth University; Michele C. Khurana, Virginia Commonwealth University; Emily A. Harry, Virginia Commonwealth University; Petr Draber, Academy of Sciences of the Czech Republic; Kevin Bunting, Emory University; Kazuya Mizuno, Tokyo Metropolitan Organization for Medical Research; Bridget S. Wilson, University of New Mexico; John J. Ryan, Virginia Commonwealth University
• Language: English
• Date: 2012-01-13
• Publisher: American Society for Biochemistry and Molecular Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2012 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.
• Final Published Version (URL): http://dx.doi.org/10.1074/jbc.M111.311142
• Title of Journal or Parent Work: Journal of Biological Chemistry
• Volume: 287
• Issue: 3
• Start Page: 2045
• End Page: 2054
• Grant/Funding Information: This work was also supported by Virginia Commonwealth University Allergy Core Grant U19A1077435, Ministry of Education, Youth and Sports of the Czech Republic Project 1M0506 (to P. D.), and Grant Agency of the Czech Republic Grants P302/10/1759 and 301/09/1826 (to P. D.).; This work was supported, in whole or in part, by National Institutes of Health Grants 1R01 AI59638 (to J. R.), R01DK059380 (to K. D. B.), and AI051575 and GM065794 (to B. S. W.).
• Keywords: Science & Technology; Expression; Domains; Survival; Allergic responses; Life Sciences & Biomedicine; Proliferation; Asthma; Biochemistry & Molecular Biology; Pathway; Degranulation; Kinase; GAB2
• Research Categories: Health Sciences, Immunology; Biology, Molecular; Chemistry, Biochemistry

Abstract

Previous studies indicate that STAT5 expression is required for mast cell development, survival, and IgE-mediated function. STAT5 tyrosine phosphorylation is swiftly and transiently induced by activation of the high affinity IgE receptor, FcεRI. However, the mechanism for this mode of activation remains unknown. In this study we observed that STAT5 co-localizes with FcεRI in antigen-stimulated mast cells. This localization was supported by cholesterol depletion of membranes, which ablated STAT5 tyrosine phosphorylation. Through the use of various pharmacological inhibitors and murine knock-out models, we found that IgE-mediated STAT5 activation is dependent upon Fyn kinase, independent of Syk, PI3K, Akt, Bruton's tyrosine kinase, and JAK2, and enhanced in the context of Lyn kinase deficiency. STAT5 immunoprecipitation revealed that unphosphorylated protein preassociates with Fyn and that this association diminishes significantly during mast cell activation. SHP-1 tyrosine phosphatase deficiency modestly enhanced STAT5 phosphorylation. This effect was more apparent in the absence of Gab2, a scaffolding protein that docks with multiple negative regulators, including SHP-1, SHP-2, and Lyn. Targeting of STAT5A or B with specific siRNA pools revealed that IgE-mediated mast cell cytokine production is selectively dependent upon the STAT5B isoform. Altogether, these data implicate Fyn as the major positive mediator of STAT5 after FcεRI engagement and demonstrate importantly distinct roles for STAT5A and STAT5B in mast cell function.