title: Expression of a constitutively active Stat6 in vivo alters lymphocyte homeostasis with distinct effects in T and B cells.
abstract: IL-4 is a critical cytokine in the regulation of immune responses and genesis of atopy. Engagement of the IL-4R activates multiple signaling pathways, including the transcription factor Stat6. Stat6-deficient mice demonstrate the importance of this factor in lymphocyte proliferation, gene expression, and Th cell differentiation. Recently, a mutant Stat6 (Stat6VT) was generated that is transcriptionally active independent of IL-4 stimulation. To determine the ability of a constitutively active Stat6 to mimic IL-4-stimulated responses, we have generated transgenic mice expressing Stat6VT under control of the CD2 locus control region, restricting expression to lymphoid populations. The phenotype of Stat6VT transgenic mice is similar, but not identical, to IL-4 transgenic mice, suggesting a critical role for Stat6-independent signaling pathways in the generation of some IL-4 responses in vivo. The expression of a constitutively active Stat6 in vivo increases surface expression of IL-4-induced genes and increases serum levels of IgG1 and IgE, compared with nontransgenic mice. Stat6VT expression increases Th2 differentiation in vivo and in vitro. Stat6VT expression also dramatically alters homeostasis of peripheral lymphocyte populations resulting in decreased CD3(+) cells and increased B220(+) cells, compared with nontransgenic littermates. Altered T and B cell populations correlate with an activated phenotype and increased cell death in transgenic T cell, but not B cell, populations. Together these results suggest that expression of a constitutively active Stat6 has distinct effects on B and T lymphocytes.
authors.affiliation: Department of Microbiology and Immunology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Bruns
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schindler
authors.forename: Mark H
authors.initials: MH
authors.lastname: Kaplan
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*; D018801:CD2 Antigens / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D003433:Crosses, Genetic; D005786:Gene Expression Regulation / Q000276:immunology; D006706:Homeostasis / Q000235:genetics / Q000276:immunology*; D017578:Immunoglobulin Class Switching / Q000235:genetics; D007073:Immunoglobulin E / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D016130:Immunophenotyping; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D050800:STAT6 Transcription Factor; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics* / Q000502:physiology; D019076:Transgenes / Q000276:immunology*; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D018801:CD2 Antigens; D007074:Immunoglobulin G; D050800:STAT6 Transcription Factor; C494100:Stat6 protein, mouse; D015534:Trans-Activators; D015847:Interleukin-4; D007073:Immunoglobulin E