A lipidomic screen of palmitate-treated MIN6 β-cells links sphingolipid metabolites with endoplasmic reticulum (ER) stress and impaired protein trafficking
A lipidomic screen of palmitate-treated MIN6 β-cells links sphingolipid metabolites with endoplasmic reticulum (ER) stress and impaired protein trafficking
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DOI：
10.1042/bj20101867
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发表时间：
2011-04-01
影响因子：
4.1
通讯作者：
Biden, Trevor J.
中科院分区：
文献类型：
--
作者：
Boslem, Ebru;MacIntosh, Gemma;Biden, Trevor J.
饱和脂肪酸促进与2型糖尿病相关的胰腺β细胞的脂毒性ER(内质网)应激。为了解决潜在的机制，我们利用MS对用棕榈酸酯处理48小时的MIN6β细胞进行了全面的脂体筛选。棕榈酸酯对主要中性脂和磷脂的总质量和饱和度都只有轻微的增加。在此条件下，GlcCer(葡萄糖神经酰胺)的质量增加了70%，神经酰胺或神经鞘磷脂的量没有明显变化。然而，慢性棕榈酸酯增加了进入神经酰胺的流量(通过[H-3]丝氨酸掺入)，抑制神经酰胺的合成减少了内质网应激和细胞凋亡。棕榈酸预处理也减少了内质网到高尔基体的蛋白转运，但被GlcCer合成酶的过度表达所克服。这伴随着神经酰胺转化为GlcCer的增加，减少了内质网应激和细胞凋亡，但没有改变磷脂去饱和度。棕榈酸酯引起的鞘脂改变不是内质网应激的继发性改变，因为它们既不是由药物内质网应激源复制的，也不是用化学伴侣苯丁酸克服的。总之，鞘磷脂代谢的改变，而不是磷脂代谢的改变，更有可能与蛋白质运输缺陷和脂毒性β细胞内质网应激和凋亡的增加有关。
Saturated fatty acids promote lipotoxic ER (endoplasmic reticulum) stress in pancreatic beta-cells in association with Type 2 diabetes. To address the underlying mechanisms we employed MS in a comprehensive lipidomic screen of MIN6 beta-cells treated for 48 h with palmitate. Both the overall mass and the degree of saturation of major neutral lipids and phospholipids were only modestly increased by palmitate. The mass of GlcCer (glucosylceramide) was augmented by 70% under these conditions, without any significant alteration in the amounts of either ceramide or sphingomyelin. However, flux into ceramide (measured by [H-3]serine incorporation) was augmented by chronic palmitate, and inhibition of ceramide synthesis decreased both ER stress and apoptosis. ER-to-Golgi protein trafficking was also reduced by palmitate pre-treatment, but was overcome by overexpression of GlcCer synthase. This was accompanied by increased conversion of ceramide into GlcCer, and reduced ER stress and apoptosis, but no change in phospholipid desaturation. Sphingolipid alterations due to palmitate were not secondary to ER stress since they were neither reproduced by pharmacological ER stressors nor overcome using the chemical chaperone phenylbutyric acid. In conclusion, alterations in sphingolipid, rather than phospholipid, metabolism are more likely to be implicated in the defective protein trafficking and enhanced ER stress and apoptosis of lipotoxic beta-cells.