Effect of diabetic induced thioredoxin interacting protein (TXNIP) on islet cell senescence

Abstract

Objective: To investigate whether the increased expression of thioredoxin interacting protein (TXNIP) in diabetes affects the senescence of islet β cells. Methods: Six normal mice (db/m) and six diabetic mice (db/db) were randomly selected. Fasting blood glucose was measured by blood sugar meter, the expression levels of TXNIP protein, p16, p21 and Rb in pancreatic tissues were detected by Western blot, senescence-associated beta-galactosidase activity in pancreatic tissue was determined by immunochemical staining. INS-1 islet beta cells were randomly divided into 7 groups (n=6), and transfected with lentiviruses (30 μl) for 4 to 6 hours, then was screened with puromycin (PM, 3 μg/m) for 7 days to construct normal group, scramble ShRNA group (interference with airborne poison group), TXNIP-ShRNA-1 group (TXNIP silence group-1), TXNIP-ShRNA-2 group (TXNIP silence group 2), TXNIP-ShRNA-3 group (TXNIP silence group 3), Ad-GFP group (overexpression of the air virus group), Ad-TXNIP-GFP group (TXNIP overexpression group) stably transferred INS-1 islet beta cell line. TXNIP protein expression was detected by Western blot, aging-related beta-galactosidase activity was detected by immunochemical staining, the changes of expression of p16, p21 and Rb was determined by Western blot. Results: Compared with normal mice, the fasting blood glucose of db/db group was increased significantly (P＜0. 01), the expression of TXNIP protein was increased significantly in pancreatic tissues(P＜0. 05), positive staining rate of β- galactosidase was increased significantly in pancreatic tissues, p16/p21/Rb protein expression levels were increased significantly (P＜0. 05). Compared with Ad-GFP group, the positive staining rate of β- galactosidase in Ad-TXNIP-GFP group was increased significantly, p16/p21/Rb protein expression levels were increased significantly (P＜0. 01). Compared to the scramble ShRNA group, the positive staining rate of β- galactosidase in TXNIP-ShRNA group was decreased, p16/p21/Rb protein expression levels were decreased significantly (P＜0. 05). Conclusion: Diabetes can induce islet β-cell senescence by up-regulating TXNIP expression.