Chong Ketpin, Almsherqi Zakaria A, Zhuo Ruijiang, Deng Yuru
Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
School of Ophthalmology and Optometry, Eye Hospital, School of Biomedical Engineering, Wenzhou Medical University, China.
FEBS Open Bio. 2021 Aug;11(8):2319-2328. doi: 10.1002/2211-5463.13241. Epub 2021 Jul 19.
Previous studies have indicated that the ability to form cubic membrane (CM), a three-dimensional periodic structure with cubic symmetry, in amoeba (Chaos carolinense) under stress conditions depends on the type of food organism supplied before cell starvation. The significant increase in docosapentaenoic acid (DPA; C22:5n-6) during the starvation period has been reported to induce CM formation and support Chaos cell survival. In this article, we further investigated the lipid profiles of food organisms of the Chaos cells to reveal the key lipid components that might promote CM formation. Our results show that the lipids extracted from cells of the native food organism Paramecium multimicronucleatum are enriched in plasmalogens. More specifically, plasmalogen phosphatidylcholine and plasmalogen phosphatidylethanolamine might be the key lipids that trigger CM formation in Chaos cells under starvation stress conditions. Unexpectedly, CM formation in these cells is not supported when the native food organism was replaced with plasmalogen-deficit Tetrahymena pyriformis cells. Based on a previous lipidomics study on amoeba Chaos and this study on the lipid composition of its food organisms, three key lipids (plasmalogen phosphatidylcholine, plasmalogen phosphatidylethanolamine and diacyl-phosphatidylinositol) were identified and used for liposomal construction. Our in vitro study revealed the potential role of these lipids in a nonlamellar phase transition. The negative staining transmission electron microscopy data of our liposomal constructs support the notion that plasmalogens may curve the membrane, which, in turn, may facilitate membrane fusion and vesicular formation, which is crucial for membrane dynamics and trafficking.
先前的研究表明，在应激条件下，变形虫（大变形虫）形成立方膜（CM）（一种具有立方对称性的三维周期性结构）的能力取决于细胞饥饿前提供的食物生物体的类型。据报道，饥饿期间二十二碳五烯酸（DPA；C22:5n-6）的显著增加会诱导立方膜的形成并支持大变形虫细胞的存活。在本文中，我们进一步研究了大变形虫细胞食物生物体的脂质谱，以揭示可能促进立方膜形成的关键脂质成分。我们的结果表明，从原生食物生物体多小核草履虫的细胞中提取的脂质富含缩醛磷脂。更具体地说，缩醛磷脂酰胆碱和缩醛磷脂酰乙醇胺可能是在饥饿应激条件下触发大变形虫细胞中立方膜形成的关键脂质。出乎意料的是，当原生食物生物体被缺乏缩醛磷脂的梨形四膜虫细胞取代时，这些细胞中不会形成立方膜。基于先前对变形虫大变形虫的脂质组学研究以及对其食物生物体脂质组成的这项研究，确定了三种关键脂质（缩醛磷脂酰胆碱、缩醛磷脂酰乙醇胺和二酰基磷脂酰肌醇）并用于脂质体构建。我们的体外研究揭示了这些脂质在非层状相变中的潜在作用。我们脂质体构建体的负染色透射电子显微镜数据支持了缩醛磷脂可能使膜弯曲的观点，这反过来可能促进膜融合和囊泡形成，这对于膜动力学和运输至关重要。
