title: TGF-β1 prevents up-regulation of the P2X7 receptor by IFN-γ and LPS in leukemic THP-1 monocytes.
abstract: The P2X7 receptor is an extracellular ATP-gated cation channel critical in inflammation and immunity, and can be up-regulated by IFN-γ and LPS. This study aimed to examine the effect of TGF-β1 on the up-regulation of P2X7 function and expression in leukemic THP-1 monocytes differentiated with IFN-γ and LPS. Cell-surface molecules including P2X7 were examined by immunofluorescence staining. Total P2X7 protein and mRNA was assessed by immunoblotting and RT-PCR respectively. P2X7 function was evaluated by ATP-induced cation dye uptake measurements. Cell-surface P2X7 was present on THP-1 cells differentiated for 3days with IFN-γ and LPS but not on undifferentiated THP-1 cells. ATP induced ethidium(+) uptake into differentiated but not undifferentiated THP-1 cells, and the P2X7 antagonist, KN-62, impaired ATP-induced ethidium(+) uptake. Co-incubation of cells with TGF-β1 plus IFN-γ and LPS prevented the up-regulation of P2X7 expression and ATP-induced ethidium(+) uptake in a concentration-dependent fashion with a maximum effect at 5ng/ml and with an IC(50) of ~0.4ng/ml. Moreover, ATP-induced YO-PRO-1(2+) uptake and IL-1β release were abrogated in cells co-incubated with TGF-β1. TGF-β1 also abrogated the amount of total P2X7 protein and mRNA induced by IFN-γ and LPS. Finally, TGF-β1 prevented the up-regulation of cell-surface CD86, but not CD14 and MHC class II, by IFN-γ and LPS. These results indicate that TGF-β1 prevents the up-regulation of P2X7 function and expression by IFN-γ and LPS in THP-1 monocytes. This suggests that TGF-β1 may limit P2X7-mediated processes in inflammation and immunity.
authors.affiliation: School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia.
authors.forename: Safina
authors.initials: S
authors.lastname: Gadeock
authors.forename: Jimmy N S N
authors.initials: JN
authors.lastname: Tran
authors.forename: Jennifer G
authors.initials: JG
authors.lastname: Georgiou
authors.forename: Iman
authors.initials: I
authors.lastname: Jalilian
authors.forename: Rosanne M
authors.initials: RM
authors.lastname: Taylor
authors.forename: James S
authors.initials: JS
authors.lastname: Wiley
authors.forename: Ronald
authors.initials: R
authors.lastname: Sluyter
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis; D001081:Apyrase / Q000032:analysis; D051940:B7-2 Antigen / Q000032:analysis; D002478:Cells, Cultured; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000737:chemistry / Q000187:drug effects*; D018048:Receptors, Purinergic P2 / Q000032:analysis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D058486:Receptors, Purinergic P2X7; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D015703:Antigens, CD; D051940:B7-2 Antigen; C497964:CD86 protein, human; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D053773:Transforming Growth Factor beta1; C063302:KN 62; D007371:Interferon-gamma; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D001081:Apyrase; C067869:CD39 antigen