vitamin e isoforms differentially regulate intercellular adhesion molecule-1 activation of pkcα in human microvascular endothelial cells维生素e亚型不同调节细胞间粘附molecule-1 pkcα人类微血管内皮细胞的激活.pdfVIP

Vitamin E Isoforms Differentially Regulate Intercellular Adhesion Molecule-1 Activation of PKCa in Human Microvascular Endothelial Cells Hiam Abdala-Valencia, Sergejs Berdnikovs, Joan M. Cook-Mills* Allergy-Immunology Division, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America Abstract Aims: ICAM-1-dependent leukocyte recruitment in vivo is inhibited by the vitamin E isoform d-a-tocopherol and elevated by d-c-tocopherol. ICAM-1 is reported to activate endothelial cell signals including protein kinase C (PKC), but the PKC isoform and the mechanism for ICAM-1 activation of PKC are not known. It is also not known whether ICAM-1 signaling in endothelial cells is regulated by tocopherol isoforms. We hypothesized that d-a-tocopherol and d-c-tocopherol differentially regulate ICAM-1 activation of endothelial cell PKC. Results: ICAM-1 crosslinking activated the PKC isoform PKCa but not PKCb in TNFa-pretreated human microvascular endothelial cells. ICAM-1 activation of PKCa was blocked by the PLC inhibitor U73122, ERK1/2 inhibitor PD98059, and xanthine oxidase inhibitor allopurinol. ERK1/2 activation was blocked by inhibition of XO and PLC but not by inhibition of PKCa, indicating that ERK1/2 is downstream of XO and upstream of PKCa during ICAM-1 signaling. During ICAM-1 activation of PKCa, the XO-generated ROS did not oxidize PKCa. Interestingly, d-a-tocopherol inhibited ICAM-1 activation of PKCa but not the upstream signal ERK1/2. The d-a-tocopherol inhibition of PKCa was ablated by the addition of d-c-tocopherol. Conclusions: Crosslinking ICAM-1 stimulated XO/ROS which activated ERK1/2 that then activated PKCa. ICAM-1 activation of PKCa was inhibited by d-a-tocopherol and this inhibition was ablated by the addition of d-c-tocopherol. These