Increased lymphocytic aminopeptidase N/CD13 promoter activity after cell-cell contact.
Aminopeptidase N (APN)/CD13 is a transmembrane ectoenzyme expressed on a wide variety of cells. With respect to haematopoietic cells, APN/CD13 has been considered specific for the myeloid lineage, because granulocytes and monocytes/macrophages, but not lymphocytes of peripheral blood, show a surface expression of CD13 antigen. However, we could recently show that cell-cell contact of lymphocytes with endothelial cells, monocytes, and fibroblast-like synoviocytes (SFCs) results in an increase of steady-state APN/CD13 mRNA and a rapid expression of cell-surface protein on the lymphocytes. In this study using the Dual-Luciferase reporter assay, we demonstrate that interaction of the T-cell line Jurkat with SFCs results in a higher activity of the APN/CD13 myeloid promoter in T cells. An enhancer located between the myeloid and epithelial APN/CD13 promoter increases the response of the promoter to the cell-cell contact-induced expression of APN/CD13 in lymphocytes. Adhesion of lymphocytes to extracellular matrix did not result in increased promoter activity. The lymphocytic promoter response induced by direct cell-cell contact with SFCs is not affected by mutations of a proximal promoter element (nucleotides -48 to -35), which has a possible functional role in the basal APN/CD13 gene expression in lymphocytes. Upregulated peptidase-promoter activity via cell-cell contact shown in this study for the first time is discussed as a general mechanism in peptidase induction.
Kehlen
A
A
Department of Immunology, Martin Luther University Halle-Wittenberg, Halle, Germany. astrid.kehlen@medizin.uni-halle.de
Olsen
J
J
Langner
J
J
Riemann
D
D
D001483:Base Sequence; D018826:CD13 Antigens / Q000235:genetics*; D002448:Cell Adhesion; D018983:DNA Footprinting; D017931:DNA Primers; D004742:Enhancer Elements, Genetic; D006801:Humans; D019169:Jurkat Cells; D008214:Lymphocytes / Q000201:enzymology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D017931:DNA Primers; D012333:RNA, Messenger; D018826:CD13 Antigens