Glycated human serum albumin enhances macrophage inflammatory protein-1beta mRNA expression through protein kinase C-delta and NADPH oxidase in macrophage-like differentiated U937 cells.
BACKGROUND
In a previous report (Higai K et al., Biol Pharm Bull, 2007), glycated human serum albumin (Glc-HSA) was found to induce interleukin-8 (IL-8) mRNA expression in human monocyte-derived U937 cells through a reactive oxygen species (ROS)-dependent pathway; however, Glc-HSA signaling has not been elucidated in macrophages.


METHODS
U937 cells were differentiated by treatment with 50 ng/mL phorbol 12-myristate 13-acetate (PMA) for 2 days and the macrophage-like differentiated U937 (differentiated U937) cells were stimulated with Glc-HSA and glycolaldehyde dimer-modified HSA (GA-HSA) in the presence of various signaling inhibitors. Macrophage inflammatory protein-1beta (MIP-1beta) mRNA expression was determined by real-time PCR. Intracellular ROS generation was estimated by confocal laser microscopy.


RESULTS
Glc-HSA and GA-HSA markedly enhanced MIP-1beta mRNA expression in differentiated U937 cells. Enhanced MIP-1beta mRNA expression was completely suppressed by the ROS scavenger N-acetyl-l-cysteine, the NADPH oxidase inhibitors diphenylene iodonium and apocynin, and the protein kinase C (PKC)-delta inhibitor rottlerin. Furthermore, ROS generation was suppressed completely by rottlerin but not by the PKC-gamma inhibitor Ro318425 or the PKC-alpha, -beta1 and -micro inhibitor Go6976.


CONCLUSIONS
Glc-HSA and GA-HSA enhance MIP-1beta mRNA expression in differentiated U937 cells through PKC-delta-dependent activation of NADPH oxidase.
D002460:Cell Line; D054407:Chemokine CCL4 / Q000096:biosynthesis* / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry / Q000494:pharmacology*; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
C066507:CCL4 protein, human; D054407:Chemokine CCL4; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012709:Serum Albumin; D014409:Tumor Necrosis Factor-alpha; D019255:NADPH Oxidases; D051745:Protein Kinase C-delta