Human monocytes lose 5-lipoxygenase and FLAP as they mature into monocyte-derived macrophages in vitro.
Previous studies in mononuclear phagocytes have shown that macrophages have substantially greater 5-lipoxygenase activity than monocytes and that this is associated with greater amounts of 5-lipoxygenase and its activating protein (FLAP). The aim of this study was to examine the effect of mononuclear phagocyte maturation in vitro on 5-lipoxygenase expression. At baseline, monocytes had significant 5-lipoxygenase activity, but then lost all detectable 5-lipoxygenase activity over 7 days. Immunoblot and Northern blot analysis revealed that immunoreactive protein and mRNA for both 5-lipoxygenase and FLAP were significantly decreased over time. These studies demonstrate that in vitro differentiation of monocytes into a macrophage phenotype is not accompanied by the enhanced expression of 5-lipoxygenase and FLAP seen in macrophages derived from in vivo sources. In fact, baseline expression of 5-lipoxygenase and FLAP by monocytes is lost in vitro. These studies have clear implications for the use of cultured monocytes as a model of macrophages, and they also further our understanding of the regulation of the 5-lipoxygenase pathway.
Ring
W L
WL
Department of Medicine, University of California, San Diego, USA.
Riddick
C A
CA
Baker
J R
JR
Munafo
D A
DA
Bigby
T D
TD
D058927:5-Lipoxygenase-Activating Proteins; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D016922:Cellular Senescence; D006801:Humans; D015151:Immunoblotting; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism*
D058927:5-Lipoxygenase-Activating Proteins; C548592:ALOX5AP protein, human; D002352:Carrier Proteins; D008565:Membrane Proteins; D001094:Arachidonate 5-Lipoxygenase