Leven R M, Nachmias V T
Exp Cell Res. 1984 Jun;152(2):476-85. doi: 10.1016/0014-4827(84)90649-9.
Cultured megakaryocytes, isolated from guinea pig bone marrow, were treated with buffer or adenosine diphosphate (ADP) (10 microM) on plain or coated glass surfaces. Control cells were rounded and non-adherent. The nucleotide induced the cells to spread to several times the initial diameter, and to become flattened and markedly adherent to the substratum. 'Cytoskeletons' were examined by transmission electron microscopy (TEM). Those from unspread cells contained only rare microfilaments and no filament bundles; those from spread cells contained large numbers of microfilaments in nets and many filament bundles, which were largely oriented circumferentially. Interference reflection microscopy demonstrated that the spread cells were attached to the substratum in arc-shaped regions, which corresponded to arcs containing alpha-actinin as seen by specific immunofluorescence of the same cells. However, other arcs of alpha-actinin staining did not correspond to arcs of tight attachment. We conclude that fibrous arcs, which appear to assemble as part of the spreading process, play a role in what are probably transient surface attachment sites. A survey of observations of spreading in other cell types suggests that similar arcs are more widespread than has been realized.
从豚鼠骨髓中分离出的培养巨核细胞，在普通或包被的玻璃表面上用缓冲液或二磷酸腺苷（ADP）（10微摩尔）处理。对照细胞呈圆形且不贴壁。核苷酸诱导细胞伸展至初始直径的数倍，变得扁平并显著贴附于基质。通过透射电子显微镜（TEM）检查“细胞骨架”。未伸展细胞的细胞骨架仅含有稀少的微丝且无丝束；伸展细胞的细胞骨架含有大量呈网状的微丝和许多丝束，这些丝束大多沿圆周方向排列。干涉反射显微镜显示，伸展细胞在弧形区域与基质附着，这些区域与通过相同细胞的特异性免疫荧光观察到的含有α - 辅肌动蛋白的弧形区域相对应。然而，α - 辅肌动蛋白染色的其他弧形区域与紧密附着的弧形区域并不对应。我们得出结论，似乎作为伸展过程一部分组装而成的纤维弧形结构，在可能是短暂的表面附着位点中发挥作用。对其他细胞类型伸展观察结果的调查表明，类似的弧形结构比人们所意识到的更为普遍。
