[Radial-organized microtubules provide maintenance of the cell shape and more effective intercellular transport than in the case of free microtubules].
Microtubules take part in very different cell processes including cell polarization and migration, intercellular transport and some others. Therefore the microtubules spatial organization is crucial for normal cell behaviour. Fibroblasts have radial microtubule array consisting of microtubules running from the centrosome. This microtubule array includes two components: (1) centrosomal microtubules with their minus ends attached to the centrosome and with their plus ends radiating to the cell periphery and (2) free microtubules with the ends non-attached to the centrosome. Distinction in the dynamic properties, intercellular organization and structure of centrosome-attached and free microtubules allow us to assume that their functions in the cell are also different. In order to investigate centrosome-attached and free microtubules functions we used the cytoplasts--experimentally denucleated cellular fragments and under certain condition lacking of the centrosome as well--which contain only free microtubules. Centrosome-containing cytoplasts do not differ significantly in the form, general morphology and the size from the intact cells. At the same time centrosome-lacking cytoplasts keep extremely thinned out network of microtubules located in the central area of the cytoplast. These cytoplasts lose the original cell shape usual for fibroblasts and get rough, with protrusions, lamella; the internal architecture of the cytoplasm and organoids arrangement is also broken. Saltatory movements in the centrosome-containing cytoplasts are similar to those in the intact cells, and saltatory movements in centrosome-lacking cytoplasts show half the speed and smaller distances compared with intact cells. Besides, the saltatory movements of granules in the centrosome-lacking cytoplasts occur mainly in the central regions of the cytoplasts and they are less ordered than in the intact cells and in the cytoplasts kept the centrosome. We believe that radial organization of the microtubules provide effective transport and dynamical interactions of microtubules plus ends with cortical structures of the cell, which are sufficient for maintenance of typical fibroblast-like shape, whereas disorganized free microtubules by themselves cannot keep up the shape and intercellular organization characteristic of fibroblasts.
Chernobel'skaia
O A
OA
Alieva
I B
IB
Vorob'ev
I A
IA
D000818:Animals; D001692:Biological Transport; D048430:Cell Shape; D018385:Centrosome / Q000378:metabolism / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D003594:Cytoplasmic Granules / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure*; D014709:Vero Cells