Autophagy in human type 2 diabetes pancreatic beta cells
Autophagy in human type 2 diabetes pancreatic beta cells
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DOI：
10.1007/s00125-009-1347-2
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发表时间：
2009-06-01
期刊：
影响因子：
8.2
通讯作者：
Marchetti, P.
中科院分区：
文献类型：
--
作者：
Masini, M.;Bugliani, M.;Marchetti, P.
β细胞损失导致2型糖尿病，细胞凋亡增加是其潜在机制之一。自噬，即受损细胞器和蛋白质的生理降解，如果发生改变，可能与一种不同形式的细胞死亡有关。我们研究了2型糖尿病患者β细胞自噬的几个特征，并评估了代谢扰动和药物干预的作用。胰腺样本来自于器官供体和分离的胰岛，通过胶原酶消化和密度梯度离心制备。电镜观察β细胞形态及形态测定。采用定量RT-PCR进行基因表达研究。电镜观察，糖尿病组β细胞死亡（2.24 +/- 0.53%）高于对照组（0.66 +/- 0.52%）（p < 0.01）。大量液泡过载（提示自噬改变）与2型糖尿病样本中1.18 +/- 0.54%的β细胞死亡相关，与对照样本中的0.36 +/- 0.26%相关（p < 0.05）。糖尿病β细胞中自噬空泡和自噬小体的密度、体积显著增高。在2型糖尿病胰岛中，beclin-1和ATG1（也称为ULK1）的基因表达不变，LAMP2和组织蛋白酶B和D的转录减少。非糖尿病胰岛暴露于增加的NEFA浓度导致液泡积累显著增加，同时β细胞死亡增强，这与LAMP2表达降低有关。二甲双胍改善糖尿病β细胞和暴露于NEFA的β细胞的自噬改变，这是一个与LAMP2表达正常化相关的过程。人类2型糖尿病的β细胞有自噬改变的迹象，这可能导致β细胞质量的损失。为了保持糖尿病患者的β细胞质量，可能有必要针对多种细胞死亡途径。
Beta cell loss contributes to type 2 diabetes, with increased apoptosis representing an underlying mechanism. Autophagy, i.e. the physiological degradation of damaged organelles and proteins, may, if altered, be associated with a distinct form of cell death. We studied several features of autophagy in beta cells from type 2 diabetic patients and assessed the role of metabolic perturbation and pharmacological intervention.Pancreatic samples were obtained from organ donors and isolated islets prepared both by collagenase digestion and density gradient centrifugation. Beta cell morphology and morphometry were studied by electron microscopy. Gene expression studies were performed by quantitative RT-PCR.Using electron microscopy, we observed more dead beta cells in diabetic (2.24 +/- 0.53%) than control (0.66 +/- 0.52%) samples (p < 0.01). Massive vacuole overload (suggesting altered autophagy) was associated with 1.18 +/- 0.54% dead beta cells in type 2 diabetic samples and with 0.36 +/- 0.26% in control samples (p < 0.05). Density volume of autophagic vacuoles and autophagosomes was significantly higher in diabetic beta cells. Unchanged gene expression of beclin-1 and ATG1 (also known as ULK1), and reduced transcription of LAMP2 and cathepsin B and D was observed in type 2 diabetic islets. Exposure of non-diabetic islets to increased NEFA concentration led to a marked increase of vacuole accumulation, together with enhanced beta cell death, which was associated with decreased LAMP2 expression. Metformin ameliorated autophagy alterations in diabetic beta cells and beta cells exposed to NEFA, a process associated with normalisation of LAMP2 expression.Beta cells in human type 2 diabetes have signs of altered autophagy, which may contribute to loss of beta cell mass. To preserve beta cell mass in diabetic patients, it may be necessary to target multiple cell-death pathways.