Cytosolic O-GlcNAc accumulation is not involved in beta-cell death in HIT-T15 or Min6

O-linked N-acetylglucosamine (O-GlcNAc) is attached to and detached from pr oteins by O-GlcNAc transferase (OGT) and O-GlcNAcase, respectively. It has been proposed that streptozotocin induces pancreatic beta -cell death by bl ocking O-GlcNAcase and increasing O-GlcNAc. To elucidate the relationship b etween cytosolic O-GlcNAc accumulation and beta -cell death, we treated bet a -cell lines HIT-T15 and Min6 with glucosamine. Glucosamine markedly reduc ed cell viability in both cell lines only at 10 mM. The measurement of cyto solic O-GlcNAc under glucosamine treatment revealed that O-GlcNAc accumulat ion was observed even at 2 mM glucosamine and maximized at 5 mM, but did no t occur very well at 10 mM. Furthermore, 100 muM PUGNAc, an inhibitor of O- GlcNAcase, increased cytosolic O-GlcNAc but did not induce cell death in th ese cells. Therefore, no correlation between accumulation of cytosolic O-Gl cNAc and beta -cell death was suggested. Alternatively, inosine partially r escued cell death induced by glucosamine in Min6 cells, suggesting that ene rgy depletion partly contributes to,beta -cell death by glucosamine. (C) 20 01 Academic Press.