Lipopolysaccharide-enhanced early proliferation of insulin secreting NIT-1 cell is associated with nuclear factor-kappaB- mediated inhibition of caspase 3 cleavage  

作　　者：LIU Shan-ying LIANG Qi-jun LIN Tian-xin FAN Xin-lan LIANG Ying Uwe Heemann LI Yan 

机构地区：[1]Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China

出　　处：《Chinese Medical Journal》2011年第22期3652-3656,共5页中华医学杂志（英文版）

基　　金：This work was supported by grants from the National Natural Science Foundation of China （No. 30671974 and 81070598）. The authors declare no conflict of interest.

摘　　要：Background Increased levels of plasma lipopolysaccharide （LPS） have been found in obesity and diabetes patients. This study was to investigate the effect of LPS on pancreatic beta-cell viability and the involvement of caspase 3 in NIT-1 cell line. Methods Mouse insulinoma NIT-1 cells were treated with LPS for the indicated time and dose. Cell viability was measured by cell counting kit-8 reagent. Toll-like receptor 4 （TLR4）, caspase 3 and cleaved caspase 3 were detected by Western blotting. Insulin was determined by radioimmunoassay （RIA）. Results LPS promoted NIT-1 cell proliferation at 1 μg/ml, peaked at 72 hours of incubation. A reduction in cleavage of caspase 3 was observed upon LPS treatment. Bay11-7082, a specific inhibitor of nuclear factor （NF）-κB, blunted LPS-induced inhibition of caspase 3 cleavage. Reduction in chronic insulin secretion was observed after treatment with LPS at 1 μg/ml for 48 and 72 hours, not for 24 hours. TLR4 protein was upregulated when NIT-1 cells were treated with LPS at 1 μg/ml for 24 hours. Conclusions LPS promotes early NIT-1 cell proliferation in association with NF-KB-mediated inhibition of caspase 3 cleavage. LPS exerts a time-dependent inhibitory effect on chronic insulin secretion from NIT-1 cells.Background Increased levels of plasma lipopolysaccharide （LPS） have been found in obesity and diabetes patients. This study was to investigate the effect of LPS on pancreatic beta-cell viability and the involvement of caspase 3 in NIT-1 cell line. Methods Mouse insulinoma NIT-1 cells were treated with LPS for the indicated time and dose. Cell viability was measured by cell counting kit-8 reagent. Toll-like receptor 4 （TLR4）, caspase 3 and cleaved caspase 3 were detected by Western blotting. Insulin was determined by radioimmunoassay （RIA）. Results LPS promoted NIT-1 cell proliferation at 1 μg/ml, peaked at 72 hours of incubation. A reduction in cleavage of caspase 3 was observed upon LPS treatment. Bay11-7082, a specific inhibitor of nuclear factor （NF）-κB, blunted LPS-induced inhibition of caspase 3 cleavage. Reduction in chronic insulin secretion was observed after treatment with LPS at 1 μg/ml for 48 and 72 hours, not for 24 hours. TLR4 protein was upregulated when NIT-1 cells were treated with LPS at 1 μg/ml for 24 hours. Conclusions LPS promotes early NIT-1 cell proliferation in association with NF-KB-mediated inhibition of caspase 3 cleavage. LPS exerts a time-dependent inhibitory effect on chronic insulin secretion from NIT-1 cells.

关 键 词：LIPOPOLYSACCHARIDE NIT-1 cell toll-like receptor 4 nuclear factor-κB caspase 3 

分 类 号：Q255[生物学—细胞生物学] Q487