Reciprocal modulation of surface expression of annexin A2 in a human umbilical vein endothelial cell-derived cell line by eicosapentaenoic acid and docosahexaenoic acid.
BACKGROUND
Annexin A2 (ANXA2), a member of the annexin family of cytosolic Ca(2+)-binding proteins, plays a pivotal role in vascular biology. Small amounts of this protein and S100A10 protein are exposed on the surface of endothelial cells (ECs). They control fibrinolysis by recruiting tissue-type and urokinase-type plasminogen activators from the plasma. Nutritional studies indicate that two major long-chain polyunsaturated fatty acids (PUFAs), i.e., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), provide benefits for EC functions. The effects of EPA and DHA on the plasminogen/plasmin system have not been characterized.


RESULTS
Proteomic analysis of a cultured human umbilical vein EC-derived cell line, HUV-EC-C, showed that cell-associated ANXA2 decreased with EPA treatment and increased with DHA. A small fraction of ANXA2 was bound to the cell surface, which was also affected by these PUFAs following the same trends. Cell surface expression was negatively regulated by protein kinase C (PKC) α-mediated Ser-phosphorylation, which was up- and down-regulated by EPA and DHA, respectively. These PUFAs differentially affected a small fraction of caveolae/rafts-associated ANXA2. In addition to chymotrypsin-like activity in the serum, newly activated plasmin cleaved the ANXA2 on the cell surface at distinct sites in the N-terminal sequence. ANXA2 also bound to membranes released in the medium, which was similarly processed by these proteases. Both the PUFAs did not directly affect the release.


CONCLUSIONS
These results suggest that EPA and DHA reciprocally control cell surface location of ANXA2. Moreover, cleavage of this protein by plasmin likely resulted in autodigestion of the platform for formation of this protease. In conjunction with termination of the proteolysis by rapid inactivation of plasmin by α-2-antiplasmin and other polypeptide inhibitors, this feedback mechanism may emphasize the benefits of these PUFA in regulation of the initiation of fibrinolysis on the surface of ECs.
Research Center for Low Temperature and Materials Sciences, Kyoto University, Kyoto, Kyoto, Japan.
Jungha
J
Park
Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
Takayuki
T
Yamaura
Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
Jun
J
Kawamoto
Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
Tatsuo
T
Kurihara
Research Center for Low Temperature and Materials Sciences, Kyoto University, Kyoto, Kyoto, Japan.
Satoshi B
SB
Sato
D017306:Annexin A2 / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D005341:Fibrinolysin / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000979:alpha-2-Antiplasmin / Q000494:pharmacology; D000099248:S100 Calcium Binding Protein A10
D017306:Annexin A2; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D005341:Fibrinolysin; D051571:Protein Kinase C-alpha; D009418:S100 Proteins; D000979:alpha-2-Antiplasmin; D000099248:S100 Calcium Binding Protein A10; C472822:ANXA2 protein, human