Overexpression of Plasma Membrane Annexin II In NO2-Exposed Pulmonary Artery Endothelial Cells

Abstract Because exposure to nitrogen dioxide (NO 2 ) alters plasma membrane structure and function in pulmonary artery endothelial cells (PAEC), we examined whether NO 2 exposure is associated with upregulation of plasma membrane-specific proteins in PAEC. Exposure to 5 ppm NO 2 for 24 h had no significant effect on total protein synthesis. However, two-dimensional gel electrophoresis of isolated plasma membranes from [ 35 S]-methionine pulse-labeled PAEC exposed to NO 2 for 24 h demonstrated 3- to 9-fold increases in the synthesis of several proteins with molecular masses of 36, 39, and 40 kDa compared with controls. N-terminal amino acid sequencing and immunodetection analysis identified the 36 kDa plasma membrane protein as annexin II (lipocortin II). Northern blotting analysis demonstrated that the mRNA expression for annexin II in NO 2 -exposed cells was also increased. These results suggest that exposure to NO 2 results in induction of plasma membrane annexin II, an important multifunctional calcium- and phospholipid-binding protein in PAEC.