Reciprocal regulation of mTOR complexes in pancreatic islets from humans with type 2 diabetes
Reciprocal regulation of mTOR complexes in pancreatic islets from humans with type 2 diabetes
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2型糖尿病患者胰岛中mTOR复合物的相互调节
DOI：
10.1007/s00125-016-4188-9
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发表时间：
2017-04
期刊：
影响因子：
8.2
通讯作者：
T. Yuan;Sahar Rafizadeh;K. D. D. Gorrepati-K.-D.-D.-Gorrepati-6370876;Blaz Lupse;J. Oberholzer;K. Maedler;A. Ardestani
中科院分区：
文献类型：
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作者：
T. Yuan;Sahar Rafizadeh;K. D. D. Gorrepati-K.-D.-D.-Gorrepati-6370876;Blaz Lupse;J. Oberholzer;K. Maedler;A. Ardestani
雷帕霉素复合物1（mTORC 1）的机制靶标是细胞和器官水平上营养状态的主要调节剂。虽然mTORC 1介导β细胞生长和扩增，但在2型糖尿病动物模型的胰岛中观察到其过度活化，并导致β细胞损失。我们试图确定这种mTORC 1激活是否发生在患有2型糖尿病的人或代谢应激的人胰岛中，以及mTORC 1阻断是否可以恢复糖尿病胰岛的β细胞功能。（22.2 mmol/l），通过mTORC 1下游靶核糖体蛋白S6激酶1（S6 K1）、S6和真核翻译起始因子4 E结合蛋白1（4 E-BP 1）以及mTORC 2下游靶Akt和N-myc下游调节蛋白1（NDRG 1）的磷酸化的蛋白质印迹分析来检测mTORC 1/2活性。通过免疫沉淀和随后的蛋白质印迹分析来评估mTORC 1/2复合物的完整性。通过人胰岛切片中pS 6（Ser 235/236）的免疫染色检测人胰岛中活化mTORC 1的细胞类型特异性表达。β细胞功能测定葡萄糖刺激的胰岛素分泌（GSIS）。ResultsWhile mTORC 2信号被削弱，mTORC 1活性显着增加，胰岛2型糖尿病患者和胰岛和β细胞暴露于增加的葡萄糖浓度。在代谢应激的人类胰岛中，在高糖条件下，我们确定了不同mTOR复合物的相互调节，mTORC 1的功能上调和mTORC 2的下调。pS 6免疫染色显示从2型糖尿病患者分离的胰岛中mTORC 1的β细胞特异性上调。抑制mTORC 1-S6 K1信号改善GSIS和恢复mTORC 2活性的胰岛2型糖尿病患者，以及在胰岛分离的diabeticdb/db小鼠和小鼠喂养的高脂肪/高蔗糖diet.Conclusions/interpretationOur数据显示异常mTORC 1活性的胰岛2型糖尿病患者，在人类胰岛培养下糖尿病相关的葡萄糖增加的条件和糖尿病小鼠胰岛。这表明mTORC 1激活升高是2型糖尿病胰岛的显著致病标志，有助于在代谢应激存在下受损的β细胞功能和存活。
Aims/hypothesisMechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of nutritional status at the cellular and organismic level. While mTORC1 mediates beta cell growth and expansion, its hyperactivation has been observed in pancreatic islets from animal models of type 2 diabetes and leads to beta cell loss. We sought to determine whether such mTORC1 activation occurs in humans with type 2 diabetes or in metabolically stressed human islets and whether mTORC1 blockade can restore beta cell function of diabetic islets.MethodsHuman islets isolated from non-diabetic controls and individuals with type 2 diabetes, as well as human islets and INS-1E cells exposed to increased glucose (22.2 mmol/l), were examined for mTORC1/2 activity by western blotting analysis of phosphorylation of mTORC1 downstream targets ribosomal protein S6 kinase 1 (S6K1), S6 and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) and mTORC2 downstream targets Akt and N-myc downstream regulated 1 (NDRG1). mTORC1/2 complexes’ integrity was assessed by immunoprecipitation and subsequent western blot analysis. Cell-type specific expression of activated mTORC1 in human islets was examined by immunostaining of pS6 (Ser 235/236) in human islet sections. Beta cell function was measured by glucose-stimulated insulin secretion (GSIS).ResultsWhile mTORC2 signalling was diminished, mTORC1 activity was markedly increased in islets from patients with type 2 diabetes and in islets and beta cells exposed to increased glucose concentrations. Under high-glucose conditions in metabolically stressed human islets, we identified a reciprocal regulation of different mTOR complexes, with functional upregulation of mTORC1 and downregulation of mTORC2. pS6 immunostaining showed beta cell-specific upregulation of mTORC1 in islets isolated from patients with type 2 diabetes. Inhibition of mTORC1–S6K1 signalling improved GSIS and restored mTORC2 activity in islets from patients with type 2 diabetes as well as in islets isolated from diabeticdb/dbmice and mice fed a high-fat/high-sucrose diet.Conclusions/interpretationOur data show the aberrant mTORC1 activity in islets from patients with type 2 diabetes, in human islets cultured under diabetes-associated increased glucose conditions and in diabetic mouse islets. This suggests that elevated mTORC1 activation is a striking pathogenic hallmark of islets in type 2 diabetes, contributing to impaired beta cell function and survival in the presence of metabolic stress.