title: Regulation of CXCR4 expression in human T lymphocytes by calcium and calcineurin.
abstract: Principally expressed on the surface of T lymphocytes, the chemokine and HIV receptor CXCR4 has been shown to serve key roles in both chemotaxis and HIV-1-entry into T cells. Understanding the regulation of CXCR4 expression is therefore of paramount importance to further elucidating its endogenous role and contributions to HIV-1 pathogenesis. Using an RNase protection assay (RPA), we have demonstrated that mitogenic stimulation of purified human peripheral blood T lymphocytes (PBL) decreased CXCR4 mRNA relative to unstimulated controls in a calcineurin-dependent manner; an expression pattern mimicked by the chemokine receptor CCR7. A change in transcriptional activity, not in mRNA stability, was required for control of CXCR4 and CCR7 expression. Changes in CXCR4 mRNA expression translated into a stimulation- and calcineurin-dependent decrease in cell surface CXCR4 expression. We have previously demonstrated that CXCR4 mRNA and protein is regulated by cAMP; here we show that calcium and calcineurin signaling pathways modify cAMP-driven changes. Moreover, we provide data supporting a role for the transcription factor YY1 in calcineurin-dependent regulation of CXCR4 expression.
authors.affiliation: Laboratory of Lymphocyte Biology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Cristillo
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Bierer
mesh_terms: D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003609:Dactinomycin / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000096:biosynthesis / Q000235:genetics*; D013601:T-Lymphocytes / Q000201:enzymology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism
chemical_list: D019718:Receptors, CXCR4; D003609:Dactinomycin; D011493:Protein Kinase C; D019703:Calcineurin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium