High glucose suppresses human islet insulin biosynthesis by inducing miR-133a leading to decreased polypyrimidine tract binding protein-expression.
High glucose suppresses human islet insulin biosynthesis by inducing miR-133a leading to decreased polypyrimidine tract binding protein-expression.
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DOI：
10.1371/journal.pone.0010843
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发表时间：
2010-05-26
期刊：
影响因子：
3.7
通讯作者：
Welsh N
中科院分区：
文献类型：
--
作者：
Fred RG;Bang-Berthelsen CH;Mandrup-Poulsen T;Grunnet LG;Welsh N
长期高糖暴露导致体外人胰岛功能障碍。然而，高葡萄糖这种效应背后的潜在机制尚不清楚。多聚嘧啶束结合蛋白（PTB）是稳定胰岛素mRNA所必需的，PTB mRNA 3′-UTR含有microRNA分子miR-133 a、miR-124 a和miR-146的结合位点。因此，本研究的目的是研究高葡萄糖是否增加了这三种miRNA的水平，并与较低的PTB水平和较低的胰岛素生物合成速率相关。在低（5.6mM）或高葡萄糖（20 mM）存在下培养人胰岛24小时。胰岛也暴露于棕榈酸钠或促炎细胞因子IL-1β和IFN-γ，因为饱和游离脂肪酸和细胞因子也会导致胰岛功能障碍。然后分离RNA用于miR-133 a、miR-124 a、miR-146、胰岛素mRNA和PTB mRNA含量的实时RT-PCR分析。胰岛素的生物合成率测定放射性标记和免疫沉淀。通过脂质转染将合成的miR-133 a前体和抑制剂递送至分散的胰岛细胞，并在低或高葡萄糖下培养后通过免疫印迹分析PTB。高糖培养导致胰岛中miR-133 a含量增加，miR-146含量减少。细胞因子增加miR-146的含量。胰岛素和PTB mRNA含量不受高糖的影响。然而，PTB蛋白水平和胰岛素生物合成速率均在高葡萄糖下降低。miR-133 a抑制剂阻止了高糖诱导的PTB和胰岛素生物合成的降低，miR-133 a前体降低了PTB水平和胰岛素生物合成，与高糖相似。长期高葡萄糖暴露通过增加miR-133 a水平下调人胰岛中PTB水平和胰岛素生物合成速率。我们认为，这种机制有助于高血糖症诱导的β细胞功能障碍。
Prolonged periods of high glucose exposure results in human islet dysfunction in vitro. The underlying mechanisms behind this effect of high glucose are, however, unknown. The polypyrimidine tract binding protein (PTB) is required for stabilization of insulin mRNA and the PTB mRNA 3′-UTR contains binding sites for the microRNA molecules miR-133a, miR-124a and miR-146. The aim of this study was therefore to investigate whether high glucose increased the levels of these three miRNAs in association with lower PTB levels and lower insulin biosynthesis rates. Human islets were cultured for 24 hours in the presence of low (5.6 mM) or high glucose (20 mM). Islets were also exposed to sodium palmitate or the proinflammatory cytokines IL-1β and IFN-γ, since saturated free fatty acids and cytokines also cause islet dysfunction. RNA was then isolated for real-time RT-PCR analysis of miR-133a, miR-124a, miR-146, insulin mRNA and PTB mRNA contents. Insulin biosynthesis rates were determined by radioactive labeling and immunoprecipitation. Synthetic miR-133a precursor and inhibitor were delivered to dispersed islet cells by lipofection, and PTB was analyzed by immunoblotting following culture at low or high glucose. Culture in high glucose resulted in increased islet contents of miR-133a and reduced contents of miR-146. Cytokines increased the contents of miR-146. The insulin and PTB mRNA contents were unaffected by high glucose. However, both PTB protein levels and insulin biosynthesis rates were decreased in response to high glucose. The miR-133a inhibitor prevented the high glucose-induced decrease in PTB and insulin biosynthesis, and the miR-133a precursor decreased PTB levels and insulin biosynthesis similarly to high glucose. Prolonged high-glucose exposure down-regulates PTB levels and insulin biosynthesis rates in human islets by increasing miR-133a levels. We propose that this mechanism contributes to hyperglycemia-induced beta-cell dysfunction.
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影响因子：
12.4
作者：
MANDRUPPOULSEN, T;BENDTZEN, K;NERUP, J
通讯作者：
NERUP, J
影响因子：
21.3
作者：
Knoch, KP;Bergert, H;Solimena, M
通讯作者：
Solimena, M
影响因子：
12.3
作者：
Gama-Carvalho, Margarida;Barbosa-Morais, Nuno L.;Carmo-Fonseca, Maria
通讯作者：
Carmo-Fonseca, Maria
影响因子：
0.9
作者：
Goto, T;Tanioka, Y;Kuroda, Y
通讯作者：
Kuroda, Y
影响因子：
7.7
作者：
Evans-Molina, Carmella;Garmey, James C.;Mirmira, Raghavendra G.
通讯作者：
Mirmira, Raghavendra G.