Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Herestraat 49, Catholic University of Leuven, Leuven, Belgium.
J Proteome Res. 2011 Aug 5;10(8):3372-85. doi: 10.1021/pr101290n. Epub 2011 Jul 13.
High levels of fatty acids contribute to loss of functional beta cell mass in type 2 diabetes, in particular in combination with high glucose levels. The aim of this study was to elucidate the role of the unsaturated free fatty acid oleate in glucolipotoxicity and to unravel the molecular pathways involved. INS-1E cells were exposed to 0.5 mM oleate, combined or not with 25 mM glucose, for 24 h. Protein profiling of INS-1E cells was done by 2D-DIGE, covering pH ranges 4-7 and 6-9 (n = 4). Identification of differentially expressed proteins (P < 0.05) was based on MALDI-TOF analysis using Peptide Mass Fingerprint (PMF) and fragmentation (MS/MS) of the most intense peaks of PMF and proteomic results were confirmed by functional assays. Oleate impaired glucose-stimulated insulin secretion and decreased insulin content. 2D-DIGE analysis revealed 53 and 54 differentially expressed proteins for oleate and the combination of oleate and high glucose, respectively. Exposure to oleate down-regulated chaperones, hampered insulin processing and ubiquitin-related proteasomal degradation, and induced perturbations in vesicle transport and budding. In combination with high glucose, shunting of excess amounts of glucose toward reactive oxygen species production worsened beta cell death. The present findings provide new insights in oleate-induced beta cell dysfunction and identify target proteins for preservation of functional beta cell mass in type 2 diabetes.
高水平的脂肪酸导致 2 型糖尿病中功能性β细胞质量的丧失，尤其是与高葡萄糖水平结合时。本研究的目的是阐明不饱和游离脂肪酸油酸在糖脂毒性中的作用，并阐明所涉及的分子途径。将 INS-1E 细胞暴露于 0.5 mM 油酸中，与 25 mM 葡萄糖组合或不组合，持续 24 小时。通过 2D-DIGE 对 INS-1E 细胞进行蛋白质谱分析，涵盖 pH 值范围为 4-7 和 6-9（n = 4）。基于 MALDI-TOF 分析，使用肽质量指纹图谱（PMF）和最强烈 PMF 峰的碎片（MS/MS）鉴定差异表达的蛋白质（P < 0.05），并通过功能测定证实蛋白质组学结果。油酸损害葡萄糖刺激的胰岛素分泌并降低胰岛素含量。油酸和油酸与高葡萄糖的组合分别使 53 和 54 个差异表达的蛋白质。暴露于油酸会下调伴侣蛋白，阻碍胰岛素加工和泛素相关的蛋白酶体降解，并诱导囊泡运输和出芽的紊乱。与高葡萄糖结合时，过多的葡萄糖向活性氧产生的分流会加重β细胞死亡。本研究结果提供了油酸诱导的β细胞功能障碍的新见解，并确定了在 2 型糖尿病中保护功能性β细胞质量的靶蛋白。
