title: Nuclear factor of activated T cells (NFAT) mediates CD154 expression in megakaryocytes.
abstract: Platelets are an abundant source of CD40 ligand (CD154), an immunomodulatory and proinflammatory molecule implicated in the onset and progression of several inflammatory diseases, including systemic lupus erythematosus (SLE), diabetes, and cardiovascular disease. Heretofore considered largely restricted to activated T cells, we initiated studies to investigate the source and regulation of platelet-associated CD154. We found that CD154 is abundantly expressed in platelet precursor cells, megakaryocytes. We show that CD154 is expressed in primary human CD34+ and murine hematopoietic precursor cells only after cytokine-driven megakaryocyte differentiation. Furthermore, using several established megakaryocyte-like cells lines, we performed promoter analysis of the CD154 gene and found that NFAT, a calcium-dependent transcriptional regulator associated with activated T cells, mediated both differentiation-dependent and inducible megakaryocyte-specific CD154 expression. Overall, these data represent the first investigation of the regulation of a novel source of CD154 and suggests that platelet-associated CD154 can be biochemically modulated.
authors.affiliation: Department of Urology, University of Iowa, Iowa City, USA. scrist@purdue.edu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Crist
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Sprague
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Ratliff
mesh_terms: D000818:Animals; D023201:CD40 Ligand / Q000096:biosynthesis*; D002318:Cardiovascular Diseases / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D018922:HL-60 Cells; D006367:HeLa Cells; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism; D008213:Lymphocyte Activation / Q000502:physiology; D008533:Megakaryocytes / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D050778:NFATC Transcription Factors / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
chemical_list: D050778:NFATC Transcription Factors; D023201:CD40 Ligand