Novel PKC signaling is required for LPS-induced soluble Flt-1 expression in macrophages.
In vitro activation of macrophages by LPS induces rapid release of vascular endothelial growth factor (VEGF) and soluble fms-like tyrosine kinase-1 receptor (sFlt-1), which are thought to be the effectors to cause sepsis. However, the signal pathway that controls the VEGF and sFlt-1 expressions in LPS-activated macrophages remains unclear. In this study, we demonstrated that phosphorylation of protein kinase C (PKC)delta played a key role in the VEGF and sFlt-1 signaling pathway of LPS-activated macrophages. PKC is a family of serine-threonine kinases, which are classified into three major groups based on homology and cofactor requirements: conventional PKCs, novel PKCs, and atypical PKCs. In the murine RAW264.7 cells, as well as in primary human monocytes/macrophages, pretreatment with a general PKC inhibitor GF109203X or with a novel PKCdelta inhibitor rottlerin or overexpression of a kinase-inactive form of PKCdelta (K376R) eliminated LPS-induced sFlt-1 expression and augmented LPS-induced VEGF expression at the protein and the transcription levels. In contrast, Gö6976, an inhibitor for the conventional PKCs, or myristoylated PKCzeta pseudosubstrate peptide, an inhibitor for the atypical PKCs, failed to exert the same effects. These data suggest that PKCdelta signaling is involved in LPS-induced sFlt-1 expression and serves as a negative mediator in LPS-induced VEGF expression in macrophages. A novel strategy controlling the LPS-induced PKC pathways, especially the PKCdelta isoform, may be developed based on this study.
Lee
Ming-Cheng
MC
Departments of Pediatrics, National Taiwan University Hospital, Taipei 100, Taiwan.
Wei
Shu-Chen
SC
Tsai-Wu
Jyy-Jih
JJ
Wu
C H Herbert
CH
Tsao
Po-Nien
PN
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002227:Carbazoles / Q000494:pharmacology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005799:Genes, Dominant; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D014158:Transcription, Genetic; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism*
D000098:Acetophenones; D001578:Benzopyrans; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D008070:Lipopolysaccharides; D008301:Maleimides; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C081021:Go 6976; C085746:rottlerin; C501162:FLT1 protein, human; C501163:Flt1 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1; D051745:Protein Kinase C-delta; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C070515:bisindolylmaleimide I