Laboratoire Dynamique de la Compartimentation Cellulaire, CNRS UPR2355/IFR87, Institut des Sciences du Végétal, Centre de Recherche de Gif (FRC3115), 91198, Gif-sur-Yvette Cedex, France.
Plant J. 2011 Mar;65(6):958-71. doi: 10.1111/j.1365-313X.2011.04481.x. Epub 2011 Feb 18.
Sphingolipids play an essential role in the functioning of the secretory pathway in eukaryotic organisms. Their importance in the functional organization of plant cells has not been studied in any detail before. The sphingolipid synthesis inhibitor fumonisin B1 (FB1), a mycotoxin acting as a specific inhibitor of ceramide synthase, was tested for its effects on cell growth, cell polarity, cell shape, cell cycle and on the ultrastructure of BY2 cells. We used cell lines expressing different GFP-tagged markers for plant cell compartments, as well as a Golgi marker fused to the photoconvertible protein Kaede. Light and electron microscopy, combined with flow cytometry, were applied to analyse the morphodynamics and architecture of compartments of the secretory pathway. The results indicate that FB1 treatment had severe effects on cell growth and cell shape, and induced a delay in cell division processes. The cell changes were accompanied by the formation of the endoplasmic reticulum (ER)-derived tubular aggregates (FB1-induced compartments), together with an inhibition of cargo transport from the ER to the Golgi apparatus. A change in polar localization of the auxin transporter PIN1 was also observed, but endocytic processes were little affected. Electron microscopy studies confirmed that molecular FB1 targets were distinct from brefeldin A (BFA) targets. We propose that the reported effects of inhibition of ceramide biosynthesis reflect the importance of sphingolipids during cell growth and establishment of cell polarity in higher plant cells, notably through their contribution to the functional organization of the ER or its differentiation into distinct compartments.
鞘脂类在真核生物分泌途径的功能中起着至关重要的作用。它们在植物细胞功能组织中的重要性以前没有被详细研究过。鞘脂合成抑制剂腐马菌素 B1（FB1）是一种真菌毒素，作为神经酰胺合酶的特异性抑制剂，其对细胞生长、细胞极性、细胞形状、细胞周期以及 BY2 细胞超微结构的影响已被测试。我们使用表达不同 GFP 标记物的细胞系来标记植物细胞区室，以及与光可转换蛋白 Kaede 融合的高尔基体标记物。光镜和电子显微镜结合流式细胞术被应用于分析分泌途径区室的形态动力学和结构。结果表明，FB1 处理对细胞生长和细胞形状有严重影响，并诱导细胞分裂过程延迟。细胞变化伴随着内质网（ER）衍生的管状聚集物的形成（FB1 诱导的区室），同时抑制了从 ER 到高尔基体的货物运输。还观察到生长素转运蛋白 PIN1 的极性定位发生变化，但内吞过程受影响较小。电子显微镜研究证实，分子 FB1 的靶标与布雷菲德菌素 A（BFA）的靶标不同。我们提出，抑制神经酰胺生物合成的报道影响反映了鞘脂类在高等植物细胞生长和建立细胞极性中的重要性，特别是通过它们对 ER 功能组织或其分化为不同区室的贡献。
