Irisin Ameliorates Oxidative Stress-Induced Injury in Pancreatic Beta-Cells by Inhibiting Txnip and Inducing Stat3-Trx2 Pathway Activation

Figure 4

Stat3 inhibition by Stat3 siRNAs blocked Irisin-induced Trx2 activation and insulin secretion in INS-1 cells. Irisin at 100 nM with NC set as the control. (a) Protein expression of Trx2 and Stat3 in INS-1 cells with Stat3 siRNAs was measured by immunoblotting and is shown in histograms ( independent experiments). (b) Trx2 activity was detected by insulin disulfide reduction assay and shown in a histogram ( independent experiments). (c) Stat3 nuclear translocation in INS-1 cells was detected by immunofluorescence analysis and captured by fluorescence microscopy (100×) ( independent experiments). (d) Expression of Trx2, Txnip, MafA, Pdx-1, Ins, and Stat3 was measured by qPCR in INS-1 cells after Irisin treatment. β-Actin was the internal standard ( independent experiments). (e) The secretory function of INS-1 cells is presented as the ratio of insulin secretion after 16.7 mM glucose treatment to insulin secretion after 3.3 mM glucose treatment. (f) Insulin secretion after 3.3 mM glucose or 16.7 mM glucose was measured by ELISA ( independent experiments). The data are shown as the ; vs. Stat3 NC; ^# vs. Stat3 NC treated with Irisin. NC: nonsense control. (g) Protein expression of Trx2, Txnip, and Stat3 in INS-1 cells after Stat3 siRNA administration with or without PA and Irisin cotreatment was detected by immunoblotting and is shown in histograms ( independent experiments). (h) The secretory function of INS-1 cells is presented as the ratio of insulin secretion after 16.7 mM glucose treatment to that after 3.3 mM glucose treatment. (i) Insulin secretion after 3.3 mM glucose or 16.7 mM glucose stimulation was measured by ELISA ( independent experiments). The data are shown as ; vs. the BSA+Stat3 NC group; ^# vs. the Stat3 siR+BSA group; ^& vs. the Stat3 siR+PA group. NC: nonsense control.

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