Association of nucleus and centrosome: magnet or velcro?

A structural link between cell's nucleus and centrosome was proposed years ago. Such a link was suggested to maintain nucleus-centrosome axis, determine polarity of interphase cells and ensure spindle assembly in mitotic cells. The idea of structural link is supported by the facts that centrosomes are usually located in close proximity to the nuclei and remain attached to the nuclei in mildly homogenated cells. However, juxtaposed location can result rather from the tendency of both organelles to occupy central position in cell than from the existence of a specific structural link. Moreover, the nucleus was shown to be transported towards the centrosome along microtubules by dynein bound to nuclear envelope; inhibition of dynein results in the increase of nucleus-centrosome distance. The interaction of both organelles is disturbed in response to actin depolymerisation, although the exact role of actin filaments in this process remains unknown. The link between the nucleus and the centrosome can support simultaneous migration of nuclei and centrosomes in large cells and in syncytia, but its existence in interphase fibroblast-like and epithelia-like cells was not confirmed yet. Further studies include direct visualisation of a specific link between centrosome and nucleus and elucidation of actin role in its formation.