The Effects Of Txnip On Cellular Senescence And The Pathways Of TXNIP Mediated In Islet Beta Cell

Objective:To study the effect of TXNIP on cellular senescence and the signaling pathway of islet β cell. Looking for a potential therapeutic targets of islet β cell aging, provide new ideas for the prevention of diabetes.Methods:Mouse insulinoma(MTN6)cells with down-regulated or overexpression of Thioredoxin interacting protein (TXNIP) stable transfection with shTXNIP and pCMV6-TXNIP plasmid. RT-PCR and western blot were measured the senescence marker protein P16ink4a,as well as EZH2 and TRX expression after TXNIP silencing or overexpression in different passage. Senescence associated-β-galactosidase (SA-β-gal) staining was tested the senescence of MTN6 cells. Cell cycle analysis with flow cytometry. TRX activity was assayed by insulin reduction method.MTT detection the proliferation of MTN6. Western blot was used to detected P38MAPK and ERK1/2 phosphorylation after high glucose stimulated in TXNIP silencing MIN6 cells.Observation the change of P38MAPK,ERK1/2 protein phosphorylation and the expression of TXNIP, P16ink4a, TRX and EZH2 after blocking P38MAPK and ERK1/2 pathways.Results:The expression of TXNIP was increased in high passage compared with low passage of MIN6 cells. TXNIP overexpression could up-regulate P16ink4a, reduce the expression of EZH2, accompanied with reduce TRX expression as well as reduce TRX activity.TXNIP gene slience in MIN6 cells could down-regulate p16lnk4a and increase the EZH2(no statistical significance),also increase TRX expression as well as activity. TXNIP overexpression promoted cell senescence and knockdown TXNIP could delay the cell aging.The phosphorylation of P38MAPK was reduced and the phosphorylation of ERK1/2 was increased after sliencing TXNIP gene when high glucose stimulate. The expression of TXNIP and P16ink4a were decreased,while the TRX and EZH2 were not changed significantly when blocking P38MAPK signaling pathway by using PD169316,however, TRX activity was increased.After inhibiting ERK1/2 pathway via PD98059,the expression of TXNIP and P16ink4a were increased,and the EZH2 was down-regulated.The expression of TRX and the activity were not changed. Conclusion:TXNIP increased when beta cell aging,and TXNIP is importance protein in the regulation of islet beta cell aging. TXNIP overexpression could promote islet beta cell aging, inhibition of proliferation. What’s more, the senility of islet beta cells was slow down and the proliferation was increased when TXNIP silence.TXNIP konckdown could inhibite the activation of P38MAPK and promote the phosphorylation of ERK1/2 when high glucose stimulated.P38MAPK and ERK1/2 pathways could regulating the expression of TXNIP and P16ink4a in pancreaticβ cells,which may the pathway of TXNIP mediated the aging in β cell.