Phosphatidylserine exposure promotes increased adhesion in Dictyostelium Copine A mutants.
Phosphatidylserine exposure promotes increased adhesion in Dictyostelium Copine A mutants.
复制标题
DOI：
10.1371/journal.pone.0250710
复制
发表时间：
2021
期刊：
影响因子：
3.7
通讯作者：
Damer CK
中科院分区：
文献类型：
--
作者：
Ide AD;Wight EM;Damer CK
磷脂磷脂酰丝氨酸(PS)是许多细胞内蛋白质的关键信号分子和结合伙伴。PS通常存在于细胞膜的内表面，但在一个称为PS暴露的过程中，PS可以反转到外表面。PS暴露在许多细胞功能中都是重要的，然而控制PS暴露的机制还没有得到广泛的研究。铜绿素(CPN)是一类钙依赖的磷脂结合蛋白家族，广泛存在于真核生物中。在有6个Copine基因的Dictyostelius中，CpnA强烈地与PS结合，并在钙升高的情况下从细胞质转移到质膜上。缺乏cpnA基因(cpnA-)的细胞在黏附、趋化、膜转运和胞质分裂等方面存在缺陷。在这项研究中，我们使用流式细胞术和荧光显微镜来显示cpnA-细胞与珠子和细菌的粘附性增加，并且这种粘附性的增加不是由于肌动蛋白细胞骨架或细胞表面蛋白的变化所致。我们发现，cpnA-细胞与PS结合蛋白Annexin V的结合量比亲本细胞高，并且表明未标记的Annexin V降低了cpnA-细胞增加的细胞黏附特性。我们还发现cpnA-细胞对Polybia-MP1更敏感，它与外部PS结合并诱导细胞裂解。总体而言，这表明cpnA-细胞增加了PS暴露，这一特性有助于cpnA-细胞增加细胞黏附。我们认为CpnA在调节质膜脂组成中起作用，可能是PS暴露的负性调节因子。
The phospholipid phosphatidylserine (PS) is a key signaling molecule and binding partner for many intracellular proteins. PS is normally found on the inner surface of the cell membrane, but PS can be flipped to the outer surface in a process called PS exposure. PS exposure is important in many cell functions, yet the mechanisms that control PS exposure have not been extensively studied. Copines (Cpn), found in most eukaryotic organisms, make up a family of calcium-dependent phospholipid binding proteins. In Dictyostelium, which has six copine genes, CpnA strongly binds to PS and translocates from the cytosol to the plasma membrane in response to a rise in calcium. Cells lacking the cpnA gene (cpnA-) have defects in adhesion, chemotaxis, membrane trafficking, and cytokinesis. In this study we used both flow cytometry and fluorescent microscopy to show that cpnA- cells have increased adhesion to beads and bacteria and that the increased adhesion was not due to changes in the actin cytoskeleton or cell surface proteins. We found that cpnA- cells bound higher amounts of Annexin V, a PS binding protein, than parental cells and showed that unlabeled Annexin V reduced the increased cell adhesion property of cpnA- cells. We also found that cpnA- cells were more sensitive to Polybia-MP1, which binds to external PS and induces cell lysis. Overall, this suggests that cpnA- cells have increased PS exposure and this property contributes to the increased cell adhesion of cpnA- cells. We conclude that CpnA has a role in the regulation of plasma membrane lipid composition and may act as a negative regulator of PS exposure.