α-トコトリエノールは67kDaラミニン受容体に結合し、DGKαを活性化させる

抄録

Vitamin E is classified into two types: tocopherols (Toc) and tocotrienols. Although their structures are very similar, tocotrienols are known to have about 50 times the antioxidant capacity of Toc. Furthermore, it has been reported to have anticancer activity against various types of cancer. Recently, we have reported that α-Toc and epigallocatechin gallate (EGCg) activate diacylglycerol kinase α (DGKα), which is a lipid kinase to convert DG to phosphatidic acid, by direct binding to 67kDa laminin receptor (67LR) at respective different binding sites, contributing to improvement of nephropathy. The binding of αToc or EGCg to 67LR has been shown to induce palmitoylation of 67LR. These results suggest that α-tocotrienol also binds to 67LR and induces its palmitoylation, resulting in DGKα activation. Indeed, in this study, we showed that α-tocotrienol activated DGKα by binding to 67LR at the same site with α-Toc, and found that α-tocotrienol induced palmitoylation of 67LR with DGKα translocation (activation). In addition, the DGKα translocation rates of tocotrienol homologues were compared and found that d-tocotrienol had similar effect with a-tocotrienol. These results suggest that 67LR and subsequence activation of DGKa are involved in some functions of tocotrienols including anticancer effects.