Functional modification of a murine macrophage cell line, J744A.1, transfected with rat csk genes.
In a previous study of this laboratory, a macrophage cell line, J774A.1, transfected with rat csk gene and overexpressing the Csk proteins has been established. These Csk transfectants showed depressed productions of monokines and nitric oxide (NO), but enhanced production of prostaglandin E2 (PGE2). In the present study, mechanism(s) underlying the reciprocal functions seen in NO and PGE2 productions was investigated. When aminoguanidine, an inhibitor of NO synthesis, was added to the Csk transfectants stimulated with lipopolysaccharide (LPS), not only NO production but also PGE2 production was suppressed. Exogenous NO showed no influence on PGE2 production by the transfectants stimulated with LPS. It was also shown that mitogenactivated protein kinase (MAPK) pathway was activated in the Csk transfectants as compared to parental J774A.1 or a vector control, J.pBK2, cells. Large amounts of phosphorylated MAPK were detected in the Csk transfectants compared to J774A.1. This finding appeared to be consistent with the result that MAPK inhibitor completely abolished NO production by J774A.1 cells upon stimulation with LPS + interferon-gamma (IFN-gamma), whereas the inhibitor partially blocked the NO production by J.Csk transfectants which expressed large amounts of Csk protein. The overexpressed Csk resulted in suppression of phagocytosis of latex beads and uptake of acetyl-low-density lipoprotein (LDL) by the transfectants. The present findings demonstrate that Csk regulates NO and PGE2 productions independently and suggest that introduction of csk gene may be applicable to understanding the pathogenesis of certain diseases where dysregulated macrophages are involved.
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Section of Pathology, Hokkaido University, Sapporo, Japan.
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D015232:Dinoprostone / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism / Q000502:physiology; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis; D010587:Phagocytosis; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000502:physiology; D051381:Rats; D014162:Transfection / Q000379:methods*; D019061:src-Family Kinases
D008070:Lipopolysaccharides; D009569:Nitric Oxide; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D015232:Dinoprostone