Ciana Annarita, Achilli Cesare, Gaur Anjali, Minetti Giampaolo
Cell Physiol Biochem. 2017;42(3):1127-1138. doi: 10.1159/000478768. Epub 2017 Jun 30.
BACKGROUND/AIMS: A high surface-to-volume ratio and a spectrin membrane-skeleton (MS) confer to the mammalian red blood cells (RBCs) their characteristic deformability, mechanical strength and structural stability. During their 120 days of circulatory life in humans, RBCs decrease in size, while remaining biconcave disks, owing to a coordinated decrease in membrane surface area and cell water. It is generally believed that part of the membrane is lost with the shedding of spectrin-free vesicles of the same type that can be obtained in vitro by different treatments. If this were true, an excess of MS would arise in old RBCs, with respect to the lipid bilayer. Aim of this paper was to investigate this aspect.
Quantification of spectrin by electrophoretic methods was carried out in RBCs of different age.
Spectrin decreases, on a per cell basis, with RBC ageing. On the other hand, the membrane raft protein marker flotillin-2, while decreasing in the membrane of old cells, was found to be strongly depleted in the membrane of in vitro-induced vesicles.
Part of the membrane-skeleton is probably lost together with part of the lipid bilayer in a balanced way. These findings point to a mechanism for the in vivo release of membrane that is different from that which is known to occur in vitro.
背景/目的：高表面积与体积比以及血影蛋白膜骨架（MS）赋予哺乳动物红细胞（RBC）其特有的可变形性、机械强度和结构稳定性。在人类循环寿命的120天里，红细胞尺寸减小，同时由于膜表面积和细胞内水分的协同减少，仍保持双凹圆盘状。一般认为，部分膜会随着无血影蛋白囊泡的脱落而丢失，这种囊泡可通过不同处理在体外获得。如果真是这样，相对于脂质双层，衰老红细胞中会出现过量的MS。本文旨在研究这一方面。
采用电泳方法对不同年龄红细胞中的血影蛋白进行定量分析。
血影蛋白含量随红细胞衰老而逐细胞减少。另一方面，膜筏蛋白标记物flotillin-2在衰老细胞的膜中减少，而在体外诱导囊泡的膜中被发现严重缺失。
膜骨架的一部分可能与脂质双层的一部分以平衡的方式一起丢失。这些发现指出了一种体内膜释放机制，该机制与已知的体外发生机制不同。
