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NO 2 ‐induced expression of specific protein kinase C isoforms and generation of phosphatidylcholine‐derived diacylglycerol in cultured pulmonary artery endothelial cells
Author(s) -
Li Yong D.,
Patel Jawaharlal M.,
Block Edward R.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00550-9
Subject(s) - protein kinase c , diacylglycerol kinase , gene isoform , cytosol , phospholipase c , phorbol , phospholipase a2 , phosphatidylcholine , microbiology and biotechnology , biology , phospholipase , phosphoinositide phospholipase c , phospholipase a , diglyceride , chemistry , biochemistry , kinase , signal transduction , enzyme , phospholipid , membrane , gene
The present study examines whether nitrogen dioxide (NO 2 )‐induced activation of protein kinase C (PKC) is associated with increased expression of specific PKC isoforms and/or with enhanced generation of phosphatidylcholine(PC)‐derived diacylglycerol (DAG) in pulmonary artery endothelial cells (PAEC). Western blot analysis revealed that exposure to 5 ppm NO 2 resulted in increased expression of PKC α and ε isoforms in both cytosol and membrane fractions in a time‐dependent fashion compared with controls. A time‐dependent elevated expression of PKC isoform β was observed in the cytosol fraction only of NO 2 ‐exposed cells. PKC isoform λ was not detectable in either the cytosolic or membrane fractions from control or NO 2 ‐exposed cells. Scatchard analysis of [ 3 H]phorbol 12,13‐dibutyrate (PDBu) binding showed that exposure to NO 2 for 24 h increased the maximal number of binding sites ( B max ) from 15.2±2.3 pmollmg (control) to 42.3±5.3 pmol/mg ( p < 0.01, n = 4) (NO 2 ‐exposed). Exposure to NO 2 significantly increased PC specific‐phospholipase C and phospholipase D activities in the plasma membrane of PAEC ( p < 0.05 and p < 0.001, respectively). When [ 3 H]myristic acid‐labeled cells were exposed to NO 2 , significantly increased radioactivity was associated with cellular DAG. These results show for the first time that exposure of PAEC to NO 2 results in elevated expression of specific PKC isoforms and in enhanced generation of cellular DAG, and the latter appears to arise largely from the hydrolysis of plasma membrane PC.