Date Published: November 13, 2009
Publisher: Public Library of Science
Author(s): Takuya Kobayashi, Takashi Murayama, Anja-Katrin Bielinsky. http://doi.org/10.1371/journal.pone.0007827
Abstract: Cytoplasmic dynein complex is a large multi-subunit microtubule (MT)-associated molecular motor involved in various cellular functions including organelle positioning, vesicle transport and cell division. However, regulatory mechanism of the cell-cycle dependent distribution of dynein has not fully been understood.
Partial Text: Cytoplasmic dynein is a microtubule (MT) minus end-directed molecular motor and plays an important role in many cellular functions including organelle positioning, vesicle transport, and cell division . Cytoplasmic dynein forms a huge multisubunit protein complex (∼1.5 MDa) composed of two identical heavy chains, two 74-kDa intermediate chains (IC74), four light intermediate chains (LICs), and up to three light chain dimers (LC8, TcTex-1, and Roadblock) , . The heavy chain which is a member of the AAA ATPase protein superfamily carries a motor activity , and the other subunits comprising the cargo binding domain may play a regulatory role for intracellular transport .
In this study, we have visualized cytoplasmic dynein with mfGFP-tagged IC74 in living HeLa cells. We found that behavior of cytoplasmic dynein dramatically changes in a cell-cycle dependent manner (Fig. 8). In interphase, dynein distributes as spot-like foci which might carry the cargos or as comet-like foci which are colocalized with EB1 on the growing MTs. In late-interphase, dynein is concentrated in the centrosome and the radial MT array. In prophase, localization at the daughter centrosomes and radial MT arrays is remarkable. In prometaphase to metaphase, dynein is localized at spindle MTs where it frequently moves from spindle poles toward chromosomes and cortex. Possible kinetochore and cortical dyneins are also seen. In anaphase to telophase, spindle-associated dynein decreases, whereas cytosolic dynein increases. These findings correspond to the previous reports of localization of dynein by immunostaining of dynein subunits with fixed cells , , , , , , .