In the present study, we investigated the role of reactive oxygen species（ROS） elevation induced by an anti-diabetic vanadium compound, vanadyl acetylacetonate（VO（acac）2）, in the regulation of lipolysis and glucose metabolism using differentiated 3T3L1 adipocytes as a model system. By confocal laser scanning microscopy, we found that VO（acac）2 induced ROS generation under high glucose stimulation, and the pretreatment of NADPH oxidase inhibitors could significantly reduce the elevated ROS level. Meanwhile, the decreased phosphorylated levels of AKT and the two key modulators of lipolysis（HSL and perilipin） were observed by western blot analysis. We also found that the contents of glycerol release were further reduced as well. In addition, the levels of key regulatory proteins, AS160 and GSK3β, in glucose metabolism pathway were correspondingly reduced. These findings demonstrated that ROS induced by vanadium compounds could act as a metabolic signal to activate AKT pathway to inhibit lipolysis and promote glucose transport and glycogen synthesis rather than by direct action by themselves. Our study contributed to elucidate the anti-diabetic effects of vanadium compounds and provided a theoretical basis for the further development of new vanadium complexes in the prevention and therapeutics of diabetes.
Terbium （Tb） has been extensively used as a fluorescence probe for the identification of calcium-binding sites in proteins and for fluorometric analysis of organic ligands. In the current study, we reported that HEPES, a commonly used pH buffer reagent, significantly enhanced the characteristic emission of Tb at 585 nm. The maximum emission of Tb at 490 nm and 549 um were also enhanced by HEPES to a less extent. Thus, cautions should be taken when quantitative analysis is performed based on the fluorescence emission of Tb at 549 nm, since the emission may vary due to the buffer reagents. Additionally, the fluorescence intensity at 585 um was proportional to the concentration of both HEPES and terbium ions, which might be utilized to develop new fluorometric analytical methods.
In this study, we aimed to clarify the source of the reactive oxygen species （ROS） generation induced by vanadium compounds. We used vanadyl acetylacetonate （VO（acac）2）, a highly effective agent in controlling hyperglycemia, to determine the source of ROS generation in two renal cell lines LLC-PK1 and MDCK. Four commonly fluorescent dyes were used to assess VO（acac）2-induced H202 and ＂02 production and their location. It demonstrated that VO（acac）2 can induce significant ROS generation in both LLC-PKI and MDCK cells, which were primarily derived from mitochondria. The results obtained in this study raised the possibility to reduce ROS level induced by vanadium compounds locally and thus avoid affecting its activity.
In the present study, the effects of metavanadate on the human prostate cancer cell line DU145 and the underlying mechanism were investigated. The results showed that metavanadate can cause cell cycle arrest at G2/M phase which was evidenced by cell cycle analysis and the increased phosphorylation of Cdc2 at its inactive Tyr-15 site. In addition, the results showed that metavanadate can induce reactive oxygen species （ROS） elevation and decrease the level of Cdc25C. This process can be rescued by an antioxidant, N-acetyl cysteine. In conclusion, the results demonstrate that metavanadate can inhibit cell proliferation via cell cycle arrest at G2/M phase in DU145 ceils. Metavanadate-induced ROS formation may play an important role in this process by mediating the degradation of Cdc25C.
