Novel translocation responses of cytosolic phospholipase A₂α fluorescent proteins

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• 作者：Rhonda E. Wooten ; Mark C. Willingham ; Larry W. Daniel ; Christina C. Leslie ; LeAnn C. Rogers ; Susan Sergeant ; Joseph T. O'Flaherty
• 关键词：cPLA₂ ; //www.sciencedirect.com/scidirimg/entities/204e.gif"" alt=""greek small letter alpha"" title=""greek small letter alpha"" border=""0""> ; C2 domain ; Translocation ; Arachidonic acid ; Lipid body ; Cellular calcium ; Cancer cell
• 刊名：Biochimica et Biophysica Acta (BBA)/Molecular Cell Research
• 出版年：2008
• 出版时间：August 2008
• 年：2008
• 卷：1783
• 期：8
• 页码：1544-1550
• 全文大小：1576 K

文摘

Cytosolic phospholipase A₂ (cPLA₂) responds to the rise in cytosolic Ca²⁺ ([Ca²⁺]_i) attending cell stimulation by moving to intracellular membranes, releasing arachidonic acid (AA) from these membranes, and thereby initiating the synthesis of various lipid mediators. Under some conditions, however, cPLA₂ translocation occurs without any corresponding changes in [Ca²⁺]_i. The signal for such responses has not been identified. Using confocal microscopy to track fluorescent proteins fused to cPLA₂ or cPLA₂'s C2 domain, we find that AA mimics Ca²⁺ ionophores in stimulating cPLA₂ translocations to the perinuclear ER and to a novel site, the lipid body. Unlike the ionophores, AA acted independently of [Ca²⁺]_i rises and did not translocate the proteins to the Golgi. AA's action did not involve its metabolism to eicosanoids or acylation into cellular lipids. Receptor agonists also stimulated translocations targeting lipid bodies. We propose that AA is a signal for Ca²⁺-independent cPLA₂ translocation and that lipid bodies are common targets of cPLA₂ and contributors to stimulus-induced lipid mediator synthesis.