In NGF-differentiated PC-12 cells, inhibition of O-GlcNAcase by Thiamet G increases the cellular levels of O-GlcNAc with EC50 of approximately 30 nM. Thiamet G (100 mM) reduces tau phosphorylation by approximately 2.1-fold, 2.7-fold, 1.2-fold and 1.3-fold for Ser396, Thr231, Ser422 and Ser262, respectively. Thiamet G (12.5 nM and 25 nM) significantly enhances p38 phosphorylation by increasing O-GlcNAcylation in mesangial cells. In O-GlcNAc transferase or O-GlcNAcase gain of function cells, thiamet-G restores the assembly of the spindle and partially rescues histone phosphorylation.
In vivo
In rats, thiamet G (50 mg/kg) administrated by i.v. crosses the blood brain barrier and then results in increase in brain O-GlcNAc levels in a dose- and time-dependent manner, and reduction of tau phosphorylation in rat brain. Thiamet G is also orally bioavailable. O-GlcNAc accumulation induced by thiamet G stimulates chondrogenic differentiation in C57/bl mice by increasing the gene expression of differentiation markers, as well as the activity of MMP-2 and -9.
