Department of Integrative Biology and Physiology, UCLA, Los Angeles, California 90095; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139; Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138.
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139.
J Biol Chem. 2013 Mar 22;288(12):8610-8618. doi: 10.1074/jbc.M112.441535. Epub 2013 Jan 25.
Neutrophils are characterized by their distinct nuclear shape, which is thought to facilitate the transit of these cells through pore spaces less than one-fifth of their diameter. We used human promyelocytic leukemia (HL-60) cells as a model system to investigate the effect of nuclear shape in whole cell deformability. We probed neutrophil-differentiated HL-60 cells lacking expression of lamin B receptor, which fail to develop lobulated nuclei during granulopoiesis and present an in vitro model for Pelger-Huët anomaly; despite the circular morphology of their nuclei, the cells passed through micron-scale constrictions on similar timescales as scrambled controls. We then investigated the unique nuclear envelope composition of neutrophil-differentiated HL-60 cells, which may also impact their deformability; although lamin A is typically down-regulated during granulopoiesis, we genetically modified HL-60 cells to generate a subpopulation of cells with well defined levels of ectopic lamin A. The lamin A-overexpressing neutrophil-type cells showed similar functional characteristics as the mock controls, but they had an impaired ability to pass through micron-scale constrictions. Our results suggest that levels of lamin A have a marked effect on the ability of neutrophils to passage through micron-scale constrictions, whereas the unusual multilobed shape of the neutrophil nucleus is less essential.
中性粒细胞的特征是其独特的核形状，据认为这有助于这些细胞通过直径小于其直径五分之一的孔隙。我们使用人早幼粒细胞白血病（HL-60）细胞作为模型系统来研究核形状对整个细胞变形性的影响。我们探测了缺乏层粘连蛋白 B 受体表达的中性粒细胞分化的 HL-60 细胞，这些细胞在粒细胞生成过程中不能发育成分叶核，并表现出 Pelger-Huët 异常的体外模型；尽管它们的核呈圆形，但这些细胞在类似的时间尺度内穿过微米级的狭窄区域，与乱序对照相似。然后，我们研究了中性粒细胞分化的 HL-60 细胞独特的核膜组成，这也可能影响其变形性；尽管在粒细胞生成过程中通常下调层粘连蛋白 A，但我们通过基因修饰 HL-60 细胞产生了具有明确异位层粘连蛋白 A 水平的细胞亚群。过表达层粘连蛋白 A 的中性粒细胞样细胞表现出与模拟对照相似的功能特征，但它们通过微米级狭窄区域的能力受损。我们的结果表明，层粘连蛋白 A 的水平对中性粒细胞通过微米级狭窄区域的能力有显著影响，而中性粒细胞核的异常多分叶形状则不那么重要。
