title: TCR stimulation upregulates MS4a4B expression through induction of AP-1 transcription factor during T cell activation.
abstract: MS4a4B is a novel member of the membrane-spanning 4-domain family, subfamily A (MS4A) specifically expressed in mouse T cells. We have shown previously that expression of MS4a4B in T cells is upregulated upon T cell activation, suggesting that MS4a4B may play a functional role in regulation of T cell responses. However, little is known about the mechanisms that regulate MS4a4B gene expression. In this study, we explored the potential mechanism underlying TCR-stimulation-induced expression of MS4a4B by promoter analysis. We cloned 2495bp of 5'-flanking region upstream of the MS4a4B start code and inserted the DNA fragment into pGL4.20 reporter plasmid. To analyze promoter activity of the cloned DNA fragment, we transiently transfected EL4 thymoma cells and the T32 cell line with reporter plasmids. Expression of reporter gene was determined by dual-luciferase assay. Potential activator- and repressor-binding sites were analyzed by serial length of 5'-deletion. We have identified at least two potential activator binding regions and two potential repressor binding regions. The activator binding sites have been localized to two fragments, which are a 442-base pair region (region A) positioned from -1176 to -735, and a 119-base pair region (region B) positioned -188 to -70 respectively. MatInspector analysis showed that region A contains the consensus binding motif of the AP-1 family of transcription factors. Machinery analysis showed that nuclear proteins extracted from anti-CD3/anti-CD28-activated primary T cells specifically bind to the AP-1 binding element. In contrast, blockade by AP-1 inhibitor in culture decreased MS4a4B expression in T cells. Our data demonstrate that TCR-stimulation induces transactivation of AP-1 transcription factor, which subsequently binds to the MS4a4B promoter and upregulates expression of MS4a4B in activated T cells.
authors.affiliation: Department of Neurology, Thomas Jefferson University, 900 Walnut Street, JHN 300, Philadelphia, PA 19107, USA.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Yan
authors.forename: Guang-Xian
authors.initials: GX
authors.lastname: Zhang
authors.forename: Mark S
authors.initials: MS
authors.lastname: Williams
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Carey
authors.forename: Hongmei
authors.initials: H
authors.lastname: Li
authors.forename: Jingxian
authors.initials: J
authors.lastname: Yang
authors.forename: Abdolmohamad
authors.initials: A
authors.lastname: Rostami
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics; D005260:Female; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics*; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: D008565:Membrane Proteins; C411486:Ms4a4b protein, mouse; D011948:Receptors, Antigen, T-Cell; D018808:Transcription Factor AP-1; D004247:DNA