Holowka David, Korzeniowski Marek K, Bryant Kirsten L, Baird Barbara
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA.
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA.
Biochim Biophys Acta. 2014 Aug;1841(8):1210-6. doi: 10.1016/j.bbalip.2014.04.006. Epub 2014 Apr 24.
Polyunsaturated fatty acids (PUFAs) have been found to be effective inhibitors of cell signaling in numerous contexts, and we find that acute addition of micromolar PUFAs such as linoleic acid effectively inhibit of Ca(2+) responses in mast cells stimulated by antigen-mediated crosslinking of FcεRI or by the SERCA pump inhibitor, thapsigargin. In contrast, the saturated fatty acid, stearic acid, with the same carbon chain length as linoleic acid does not inhibit these responses. Consistent with this inhibition of store-operated Ca(2+) entry (SOCE), linoleic acid inhibits antigen-stimulated granule exocytosis to a similar extent. Using the fluorescently labeled plasma membrane Ca(2+) channel protein, AcGFP-Orai1, together with the labeled ER Ca(2+) sensor protein, STIM1-mRFP, we monitor stimulated coupling of these proteins that is essential for SOCE with a novel spectrofluorimetric resonance energy transfer method. We find effective inhibition of this stimulated coupling by linoleic acid that accounts for the inhibition of SOCE. Moreover, we find that linoleic acid induces some STIM1-STIM1 association, while inhibiting stimulated STIM1 oligomerization that precedes STIM1-Orai1 coupling. We hypothesize that linoleic acid and related PUFAs inhibit STIM1-Orai1 coupling by a mechanism that involves perturbation of ER membrane structure, possibly by disrupting electrostatic interactions important in STIM1 oligomerization. Thisarticle is part of a Special Issue entitled Tools to study lipid functions.
多不饱和脂肪酸（PUFAs）在许多情况下已被发现是细胞信号传导的有效抑制剂，并且我们发现急性添加微摩尔浓度的多不饱和脂肪酸（如亚油酸）可有效抑制肥大细胞中由抗原介导的FcεRI交联或由SERCA泵抑制剂毒胡萝卜素刺激引起的Ca(2+)反应。相比之下，与亚油酸具有相同碳链长度的饱和脂肪酸硬脂酸不会抑制这些反应。与这种对储存式Ca(2+)内流（SOCE）的抑制作用一致，亚油酸在相似程度上抑制抗原刺激的颗粒胞吐作用。使用荧光标记的质膜Ca(2+)通道蛋白AcGFP-Orai1以及标记的内质网Ca(2+)传感器蛋白STIM1-mRFP，我们用一种新型的荧光光谱共振能量转移方法监测这些对SOCE至关重要的蛋白的刺激偶联。我们发现亚油酸对这种刺激偶联有有效抑制作用，这解释了对SOCE的抑制。此外，我们发现亚油酸诱导一些STIM1-STIM1缔合，同时抑制在STIM1-Orai1偶联之前的刺激的STIM1寡聚化。我们推测亚油酸和相关的多不饱和脂肪酸通过一种涉及内质网膜结构扰动的机制抑制STIM1-Orai1偶联，可能是通过破坏STIM1寡聚化中重要的静电相互作用。本文是名为“研究脂质功能的工具”的特刊的一部分。
