Haeme-oxygenase 1 expression in rat pancreatic beta cells is stimulated by supraphysiological glucose concentrations and by cyclic AMP
Haeme-oxygenase 1 expression in rat pancreatic beta cells is stimulated by supraphysiological glucose concentrations and by cyclic AMP
复制标题
DOI：
10.1007/s00125-003-1174-9
复制
发表时间：
2003-09-01
期刊：
影响因子：
8.2
通讯作者：
Henquin, JC
中科院分区：
文献类型：
--
作者：
Jonas, JC;Guiot, Y;Henquin, JC
目的/假说。血红素加氧酶1 （HO1）和其他抗氧化酶的表达增加可以改善胰腺β细胞在应激条件下的存活，包括高血糖。然而，高血糖如何增加胰岛HO1表达尚不清楚。大鼠胰岛在含10 mmol的RPMI培养基中预培养1周。l（-1）葡萄糖（G10），并在G5-G30加各种试验物质中进一步培养过夜。采用半定量RT-PCR、western blot和免疫组织化学检测胰岛HO1 mRNA和蛋白的表达。在G10中，胰岛HO1 mRNA的表达在过夜培养后最低，在G5中略有增加，在G30中，随着β细胞HO1蛋白表达的异质性增加，胰岛HO1 mRNA的表达增加了5至10倍。降低细胞内Ca2+（二氮氧化物、尼莫地平）的药物完全抑制了G30的作用，而升高Ca2+ （30 mmol的甲磺丁胺）的药物只略微复制了G30的作用。(1)钾)。它也被α(2)-肾上腺素能受体激动剂可乐定抑制，而二丁基环amp则大大增加了β细胞HO1的表达。G30对HO1 mRNA表达的诱导不依赖于中等胰岛素浓度的变化，但被混合抗氧化剂完全抑制。与HO1相比，胰岛谷胱甘肽过氧化物酶和组成型血红素加氧酶2的mRNA表达不受G30和二丁基环磷酸腺苷的影响。高糖和二丁基环amp刺激大鼠胰腺β细胞HO1的表达。尼莫地平、可乐定和抗氧化剂对G30中HO1表达的抑制表明，Ca2+内流和环amp对于G30产生氧化应激或通过增加氧化应激刺激β细胞HO1表达是必要的。
Aim/hypothesis. Increased expression of haeme-oxygenase 1 (HO1) and other antioxidant enzymes could improve pancreatic beta-cell survival under stressful conditions, including hyperglycaemia. However, how hyperglycaemia increases islet HO1 expression is not known.Methods. Rat islets were pre-cultured for 1 week in RPMI medium containing 10 mmol.l(-1) glucose (G10), and further cultured overnight in G5-G30 plus various test substances. Islet HO1 mRNA and protein expression was measured by semiquantitative RT-PCR, western blot, and immunohistochemistry.Results. Islet HO1 mRNA expression was minimal after overnight culture in G10, slightly increased in G5, and increased by five- to ten-fold in G30 in parallel with a heterogeneous increase in beta-cell HO1 protein expression. The effect of G30 was fully inhibited by agents decreasing cytosolic Ca2+ (diazoxide, nimodipine), but was only slightly reproduced by agents raising Ca2+ (tolbutamide, 30 mmol.l(-1) potassium). It was also suppressed by the alpha(2)-adrenoceptor agonist clonidine, whereas dibutyryl-cyclic-AMP largely increased beta-cell HO1 expression. The induction of HO1 mRNA expression by G30 was independent from changes in medium insulin concentration, but was completely inhibited by a cocktail of antioxidants. In contrast to HO1, islet mRNA expression of glutathione peroxidase and constitutive haeme-oxygenase 2 were not affected by G30, nor by dibutyryl-cyclic-AMP.Conclusion/interpretation. High glucose and dibutyryl-cyclic-AMP stimulate expression of HO1 in rat pancreatic beta cells. The inhibition of HO1 expression in G30 by nimodipine, clonidine, and antioxidants, suggests that Ca2+ influx and cyclic-AMP are necessary for the generation of oxidative stress by G30, or for the stimulation of beta-cell HO1 expression by increased oxidative stress.