BACKGROUND Type 2 diabetes(T2 D) is characterized by insufficient insulin secretion caused by defective pancreatic β-cell function or insulin resistance,resulting in an increase in blood glucose.However,the mechanism...BACKGROUND Type 2 diabetes(T2 D) is characterized by insufficient insulin secretion caused by defective pancreatic β-cell function or insulin resistance,resulting in an increase in blood glucose.However,the mechanism involved in this lack of insulin secretion is unclear.The level of vascular endothelial growth factor B(VEGF-B) is significantly increased in T2 D patients.The inactivation of VEGF-B could restore insulin sensitivity in db/db mice by reducing fatty acid accumulation.It is speculated that VEGF-B is related to pancreatic β-cell dysfunction and is an important factor affecting β-cell secretion of insulin.As an in vitro model of normal pancreatic β-cells,the MIN6 cell line can be used to analyze the mechanism of insulin secretion and related biological effects.AIM To study the role of VEGF-B in the insulin secretion signaling pathway in MIN6 cells and explore the effect of VEGF-B on blood glucose regulation.METHODS The MIN6 mouse pancreatic islet β-cell line was used as the model system.By administering exogenous VEGF-B protein or knocking down VEGF-B expression in MIN6 cells,we examined the effects of VEGF-B on insulin secretion,Ca2+ and cyclic adenosine monophosphate(cAMP) levels,and the insulin secretion signaling pathway.RESULTS Exogenous VEGF-B inhibited the secretion of insulin and simultaneously reduced the levels of Ca2+ and cAMP in MIN6 cells.Exogenous VEGF-B also reduced the expression of phospholipase C gamma 1(PLCγ1),phosphatidylinositol 3-kinase(PI3 K),serine/threonine kinase(AKT),and other proteins in the insulin secretion pathway.Upon knockdown of VEGF-B,MIN6 cells exhibited increased insulin secretion and Ca2+ and cAMP levels and upregulated expression of PLCγ1,PI3 K,AKT,and other proteins.CONCLUSION VEGF-B can regulate insulin secretion by modulating the levels of Ca2+ and cAMP.VEGF-B involvement in insulin secretion is related to the expression of PLCγ1,PI3 K,AKT,and other signaling proteins.These results provide theoretical support and an experimental basis for the study of VEGF-B in the pathogenesis of T2 D.展开更多
Background Pancreatic β cells are susceptible to fatty acid-induced apoptosis. The 17β-estradiol （E2） protects pancreatic βcells from apoptosis, mediated by the estrogen receptor-a （ERa）. The mRNA level and pro...Background Pancreatic β cells are susceptible to fatty acid-induced apoptosis. The 17β-estradiol （E2） protects pancreatic βcells from apoptosis, mediated by the estrogen receptor-a （ERa）. The mRNA level and promoter activity of leukemia-related protein （LRP） 16 were significantly increased by E2 in E R-a and LRP 16 was a co-activator of ER-a. The aim of the study was to assess the effects of LRP16 on fatty acid-induced apoptosis in MIN6 cells. Methods Cells with over-expressing LRP16 were obtained by lipidosome transfection. Insulin content and glucose-stimulated insulin secretion （GSIS） were examined by radioimmunoassay. Western blotting was applied to detect protein expression. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL） and flow cytometry. The forkhead boxO1 （FoxO1） subcellular localization was determined by immunocytochemical analysis. Results MIN6-LRP16 cells with overexpression of LRP16 were successfully established, and protein expression of LRP16 was 2.29-fold of that of control cells （MIN6-3.1, P 〈0.05）. Insulin content and GSIS in MIN6-LRP16 were substantially increased compared with those in control cells. When cells were stimulated with glucose, increased phosphorylation of extracellular signal-regulated kinase （ERK） 1/2 and serine-threonine kinase （Akt） were observed in MIN6-LRP16. When cells were under palmitate pressure, the TUNEL-positive rate in MIN6-LRP16 was （17.0±0.5）%, while it in MIN6-3.1 was （22.0±0.4）%. In palmitate-treated cells, attenuated Akt phosphorylation was observed, but the attenuation in Akt activity was partially restored in MIN6-LRP16 cells. Meanwhile, nuclear localization of FoxO1 in MIN6-LRP16 was apparently reduced compared with that in control cells. Conclusions LRP16 regulated insulin content and GSIS in MIN6 cells by ERK1/2 and Akt activated way. Meanwhile, LRP16 overexpression protected MIN6 cells from fatty acid-induced apoptosis by partially restoring Akt phosphorylation and inhibiting FoxO1 nuclear redistribution. Therefore, LRP16 played important roles not only in insulin content and GSIS but also in the antilipotoxic effect mediated by Akt/FoxO1 signaling.展开更多
目的探讨LIGHT(lymphotoxin like,exhibits inducible expression and competes with HSV glycoprotein D for HVEM,a receptor expressed by T lymphocytes)协同γ-干扰素(interferon-gamma,IFN-γ)诱导小鼠胰岛β细胞株MIN6细胞凋亡...目的探讨LIGHT(lymphotoxin like,exhibits inducible expression and competes with HSV glycoprotein D for HVEM,a receptor expressed by T lymphocytes)协同γ-干扰素(interferon-gamma,IFN-γ)诱导小鼠胰岛β细胞株MIN6细胞凋亡的作用及机制。方法 LIGHT、IFN-γ单独或联合处理MIN6细胞。分别运用CCK-8法、流式细胞术检测MIN6细胞增殖与凋亡率。Western blot检测信号转导和转录激活子1(signal transducers and activators of transcription 1,STAT1)及STAT1的磷酸化水平,以及凋亡与增殖相关基因Bcl-xL、Bax和增殖细胞核抗原(PCNA)的表达。MIN6细胞经STAT1特异的抑制剂弗达拉滨(fludarabine,Flu)预处理后再用LIGHT和IFN-γ联合处理,Western blot检测STAT1、p-STAT1、Bcl-xL、Bax的变化,CCK-8法检测MIN6细胞的增殖能力。结果 LIGHT协同IFN-γ呈时间依赖性抑制MIN6细胞增殖,诱导细胞凋亡,降低抗凋亡基因Bcl-xL表达、增加促凋亡基因Bax表达,对PCNA表达无明显影响;LIGHT促进IFN-γ激活STAT1,而STAT1抑制剂fludarabine抑制STAT1活化后,Bcl-xL表达上调,Bax表达下调,MIN6细胞增殖率上升。结论 LIGHT协同IFN-γ通过激活STAT1调节Bcl-xL、Bax表达而诱导小鼠胰岛β细胞株MIN6细胞凋亡。展开更多
基金Supported by National Natural Science Foundation of China,No.31771284National Natural Science Foundation of China Youth Project,No.31702024+1 种基金Major Basic Research Project of Shandong Provincial Natural Science Foundation,No.ZR2019ZD27Shandong Province Higher Educational Science and Technology Plan Project,No.J17KA258。
文摘BACKGROUND Type 2 diabetes(T2 D) is characterized by insufficient insulin secretion caused by defective pancreatic β-cell function or insulin resistance,resulting in an increase in blood glucose.However,the mechanism involved in this lack of insulin secretion is unclear.The level of vascular endothelial growth factor B(VEGF-B) is significantly increased in T2 D patients.The inactivation of VEGF-B could restore insulin sensitivity in db/db mice by reducing fatty acid accumulation.It is speculated that VEGF-B is related to pancreatic β-cell dysfunction and is an important factor affecting β-cell secretion of insulin.As an in vitro model of normal pancreatic β-cells,the MIN6 cell line can be used to analyze the mechanism of insulin secretion and related biological effects.AIM To study the role of VEGF-B in the insulin secretion signaling pathway in MIN6 cells and explore the effect of VEGF-B on blood glucose regulation.METHODS The MIN6 mouse pancreatic islet β-cell line was used as the model system.By administering exogenous VEGF-B protein or knocking down VEGF-B expression in MIN6 cells,we examined the effects of VEGF-B on insulin secretion,Ca2+ and cyclic adenosine monophosphate(cAMP) levels,and the insulin secretion signaling pathway.RESULTS Exogenous VEGF-B inhibited the secretion of insulin and simultaneously reduced the levels of Ca2+ and cAMP in MIN6 cells.Exogenous VEGF-B also reduced the expression of phospholipase C gamma 1(PLCγ1),phosphatidylinositol 3-kinase(PI3 K),serine/threonine kinase(AKT),and other proteins in the insulin secretion pathway.Upon knockdown of VEGF-B,MIN6 cells exhibited increased insulin secretion and Ca2+ and cAMP levels and upregulated expression of PLCγ1,PI3 K,AKT,and other proteins.CONCLUSION VEGF-B can regulate insulin secretion by modulating the levels of Ca2+ and cAMP.VEGF-B involvement in insulin secretion is related to the expression of PLCγ1,PI3 K,AKT,and other signaling proteins.These results provide theoretical support and an experimental basis for the study of VEGF-B in the pathogenesis of T2 D.
基金This work was supported by a grant from the National Natural Science Foundation of China （No. 30771042）.
文摘Background Pancreatic β cells are susceptible to fatty acid-induced apoptosis. The 17β-estradiol （E2） protects pancreatic βcells from apoptosis, mediated by the estrogen receptor-a （ERa）. The mRNA level and promoter activity of leukemia-related protein （LRP） 16 were significantly increased by E2 in E R-a and LRP 16 was a co-activator of ER-a. The aim of the study was to assess the effects of LRP16 on fatty acid-induced apoptosis in MIN6 cells. Methods Cells with over-expressing LRP16 were obtained by lipidosome transfection. Insulin content and glucose-stimulated insulin secretion （GSIS） were examined by radioimmunoassay. Western blotting was applied to detect protein expression. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL） and flow cytometry. The forkhead boxO1 （FoxO1） subcellular localization was determined by immunocytochemical analysis. Results MIN6-LRP16 cells with overexpression of LRP16 were successfully established, and protein expression of LRP16 was 2.29-fold of that of control cells （MIN6-3.1, P 〈0.05）. Insulin content and GSIS in MIN6-LRP16 were substantially increased compared with those in control cells. When cells were stimulated with glucose, increased phosphorylation of extracellular signal-regulated kinase （ERK） 1/2 and serine-threonine kinase （Akt） were observed in MIN6-LRP16. When cells were under palmitate pressure, the TUNEL-positive rate in MIN6-LRP16 was （17.0±0.5）%, while it in MIN6-3.1 was （22.0±0.4）%. In palmitate-treated cells, attenuated Akt phosphorylation was observed, but the attenuation in Akt activity was partially restored in MIN6-LRP16 cells. Meanwhile, nuclear localization of FoxO1 in MIN6-LRP16 was apparently reduced compared with that in control cells. Conclusions LRP16 regulated insulin content and GSIS in MIN6 cells by ERK1/2 and Akt activated way. Meanwhile, LRP16 overexpression protected MIN6 cells from fatty acid-induced apoptosis by partially restoring Akt phosphorylation and inhibiting FoxO1 nuclear redistribution. Therefore, LRP16 played important roles not only in insulin content and GSIS but also in the antilipotoxic effect mediated by Akt/FoxO1 signaling.
文摘目的探讨LIGHT(lymphotoxin like,exhibits inducible expression and competes with HSV glycoprotein D for HVEM,a receptor expressed by T lymphocytes)协同γ-干扰素(interferon-gamma,IFN-γ)诱导小鼠胰岛β细胞株MIN6细胞凋亡的作用及机制。方法 LIGHT、IFN-γ单独或联合处理MIN6细胞。分别运用CCK-8法、流式细胞术检测MIN6细胞增殖与凋亡率。Western blot检测信号转导和转录激活子1(signal transducers and activators of transcription 1,STAT1)及STAT1的磷酸化水平,以及凋亡与增殖相关基因Bcl-xL、Bax和增殖细胞核抗原(PCNA)的表达。MIN6细胞经STAT1特异的抑制剂弗达拉滨(fludarabine,Flu)预处理后再用LIGHT和IFN-γ联合处理,Western blot检测STAT1、p-STAT1、Bcl-xL、Bax的变化,CCK-8法检测MIN6细胞的增殖能力。结果 LIGHT协同IFN-γ呈时间依赖性抑制MIN6细胞增殖,诱导细胞凋亡,降低抗凋亡基因Bcl-xL表达、增加促凋亡基因Bax表达,对PCNA表达无明显影响;LIGHT促进IFN-γ激活STAT1,而STAT1抑制剂fludarabine抑制STAT1活化后,Bcl-xL表达上调,Bax表达下调,MIN6细胞增殖率上升。结论 LIGHT协同IFN-γ通过激活STAT1调节Bcl-xL、Bax表达而诱导小鼠胰岛β细胞株MIN6细胞凋亡。
