Microfilament-associated Toxicity Of Tributyltin

Tributyltin(TBT)has been widely used for various industrial purposes,and it has toxic effects on multiple organs and tissues.Previous studies have found that TBT could induce cytoskeletal disruption,especially of the actin filaments.However,the underlying mechanisms remain unclear.The aim of the present study was to determine whether TBT could induce microfilament disruption using HL7702 cells and then to assess for the total levels of various microfilament-associated proteins;finally,the involvement of the MAPK pathway was investigated.Methods:1.In the present study,cell proliferation was detected by MTT assay on exposure of HL7702 cells to different concentrations of TBT,and the subsequent exposure concentration was determined by the results of MTT.2.We further examined the effect of TBT on the structure and distribution of microfilament using FITC-phalloidin.3.We detect the expression levels of microfilament-associated proteins by Western-Blot.Results:1.After treatment with 2 or 4?M TBT,cell proliferation increased significantly(P?0.05).However,when treated with 8?M TBT or more,cell proliferation decreased dramatically(P?0.05).2.Treatment with TBT resulted in microfilament undergoing extensive depolymerization,and microfilament network collapsed significantly.3.After TBT treatment,the protein level of Ezrin and Cofilin remained unchanged,the actin-related protein(Arp)2/3 levels decreased slightly,and the vasodilator-stimulated phosphoprotein(VASP)decreased dramatically.However,the phosphorylation level of VASP increased severely.4.Total ERK1/2,JNK and P38 remained unchanged.However,phosphorylated ERK1/2 and JNK were markedly upregulated by TBT treatment.5.Inhibition of ERK1/2 and JNK not only largely diminished the TBT-induced hyperphosphorylation of VASP but also recovered the cellular morphology and rescued the cells from death..Conclusion:1.Low-dose TBT promotes cell proliferation of HL7702 cells,while high-dose TBT induces cell death.2.TBT causes severe damage to microfilament in HL7702 cells.3.TBT induces hyperphosphorylation of microfilament-associated protein VASP.4.The MAPK pathway was activated after TBT exposure,and ERK1/2 and JNK involved in TBT-induced hyperphosphorylation of microfilament-associated proteins.