Department of Biomedical Genetics, University of Rochester, Rochester, NY, 14642, USA.
Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14642, USA.
Sci Rep. 2017 Jul 12;7(1):5164. doi: 10.1038/s41598-017-05498-4.
Hematopoietic ontogeny is characterized by distinct primitive and definitive erythroid lineages. Definitive erythroblasts mature and enucleate extravascularly and form a unique membrane skeleton, composed of spectrin, 4.1R-complex, and ankyrinR-complex components, to survive the vicissitudes of the adult circulation. However, little is known about the formation and composition of the membrane skeleton in primitive erythroblasts, which progressively mature while circulating in the embryonic bloodstream. We found that primary primitive erythroblasts express the major membrane skeleton genes present in similarly staged definitive erythroblasts, suggesting that the composition and formation of this membrane network is conserved in maturing primitive and definitive erythroblasts despite their respective intravascular and extravascular locations. Membrane deformability and stability of primitive erythroblasts, assayed by microfluidic studies and fluorescence imaged microdeformation, respectively, significantly increase prior to enucleation. These functional changes coincide with protein 4.1 R isoform switching and protein 4.1R-null primitive erythroblasts fail to establish normal membrane stability and deformability. We conclude that maturing primitive erythroblasts initially navigate the embryonic vasculature prior to establishing a deformable cytoskeleton, which is ultimately formed prior to enucleation. Formation of an erythroid-specific, protein 4.1R-dependent membrane skeleton is an important feature not only of definitive, but also of primitive, erythropoiesis in mammals.
造血发生的特点是存在明显的原始和定型红细胞谱系。定型红细胞在血管外成熟并去核，形成独特的膜骨架，由血影蛋白、4.1R 复合物和锚蛋白 R 复合物组成，以适应成人循环的变化。然而，对于原始红细胞中膜骨架的形成和组成知之甚少，原始红细胞在胚胎血流中循环时逐渐成熟。我们发现初级原始红细胞表达与同样阶段的定型红细胞中存在的主要膜骨架基因，这表明尽管它们位于血管内和血管外，这种膜网络的组成和形成在成熟的原始和定型红细胞中是保守的。通过微流控研究和荧光成像微变形分别检测到原始红细胞的膜变形性和稳定性，在去核之前显著增加。这些功能变化与蛋白 4.1R 同工型转换一致，蛋白 4.1R 缺失的原始红细胞无法建立正常的膜稳定性和变形性。我们得出结论，成熟的原始红细胞在建立可变形细胞骨架之前，首先在胚胎脉管系统中导航，该骨架最终在去核之前形成。形成红细胞特异性、蛋白 4.1R 依赖性膜骨架不仅是哺乳动物定型红细胞生成的一个重要特征，也是原始红细胞生成的一个重要特征。
