Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity
Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity
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DOI：
10.1182/blood-2003-03-0928
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发表时间：
2004-03-01
期刊：
影响因子：
20.3
通讯作者：
Chasis, JA
中科院分区：
文献类型：
--
作者：
Lee, JCM;Gimm, JA;Chasis, JA
在成红细胞去核过程中，被质膜包围的细胞核与成红细胞胞质分离。该过程的一个关键方面是将成红细胞质膜组分分选为网织红细胞和排出的细胞核。虽然它是已知的，细胞骨架元件肌动蛋白和血影蛋白分区网织红细胞，很少被了解的分子机制，质膜蛋白分选。我们选择血型糖蛋白A（GPA）作为模型整合蛋白质开始研究蛋白质分选机制。使用免疫荧光显微镜和蛋白质印迹法，我们发现，GPA排序主要为网织红细胞。我们推测骨架连接的程度可能控制跨膜蛋白的分选模式。为了探讨这一假设，我们量化的程度GPA协会的细胞骨架在成红细胞，年轻的网织红细胞，和成熟的红细胞使用荧光成像微变形（FIMD），并观察到GPA经历了戏剧性的重组在终末分化。我们发现，与成熟细胞相比，成红细胞和年轻网织红细胞中的GPA与膜细胞骨架的直接或间接联系更多。我们的结论是，骨骼蛋白协会可以调节蛋白质分选去核过程中。此外，我们认为，在早期的调查结果中观察到的网织红细胞膜的刚性增强，至少部分地，从GPA与血影蛋白为基础的骨架的连接性增加。(C)2004年，美国血液学会。
During erythroblast enucleation, nuclei surrounded by plasma membrane separate from erythroblast cytoplasm. A key aspect of this process is sorting of erythroblast plasma membrane components to reticulocytes and expelled nuclei. Although it is known that cytoskeletal elements actin and spectrin partition to reticulocytes, little is understood about molecular mechanisms governing plasma membrane protein sorting. We chose glycophorin A (GPA) as a model integral protein to begin investigating protein-sorting mechanisms. Using immunofluorescence microscopy and Western blotting we found that GPA sorted predominantly to reticulocytes. We hypothesized that the degree of skeletal linkage might control the sorting pattern of transmembrane proteins. To explore this hypothesis, we quantified the extent of GPA association to the cytoskeleton in erythroblasts, young reticulocytes, and mature erythrocytes using fluorescence imaged microdeformation (FIMD) and observed that GPA underwent dramatic reorganization during terminal differentiation. We discovered that GPA was more connected to the membrane cytoskeleton, either directly or indirectly, in erythroblasts and young reticulocytes than in mature cells. We conclude that skeletal protein association can regulate protein sorting during enucleation. Further, we suggest that the enhanced rigidity of reticulocyte membranes observed in earlier investigations results, at least in part, from increased connectivity of GPA with the spectrin-based skeleton. (C) 2004 by The American Society of Hematology.