Effects of dynein on microtubule mechanics and centrosome positioning

Abstract

When microtubules are severed by laser ablation, newly created minus ends increase in curvature, but they straighten when dynein is inhibited. It is found that cytoplasmic dynein generates tension and friction along microtubule lengths and that these forces govern the dynamics of centrosome centering.

Centrosome Centering and Decentering by Microtubule Network Rearrangement

“…Here we focused on conditions in which MTs can be longer than the cell diameter, which is the case for adult mammalian cells in interphase (Wu et al, 2011), rather than the more usually studied large mitotic cells in embryos (Kimura and Onami, 2007;Wühr et al, 2010;Minc et al, 2011). Under these conditions, several parameters could regulate the symmetry of MT network architecture, independently of external cues or preexisting asymmetries in boundary conditions such as local capture, stabilization, or mechanical forces.…”

“…Alex Mogilner New York University MT explicitly and solve the system correctly (Pinot et al, 2009;Maly and Maly, 2010;Wu et al, 2011).…”

“…Because dynein inhibition has been shown to induce centrosome decentering (Burakov et al, 2003;Wu et al, 2011), we assumed that dynein-associated forces contributed to center the centrosome, that is, that dynein molecules are anchored in the cytoplasm rather than at the cell cortex. We first wanted to know whether a centrosome could spontaneously move off center in the absence of asymmetric cues.…”

End-on microtubule-dynein interactions and pulling-based positioning of microtubule organizing centers

“…The in vitro reconstitution of MTOC positioning in microfabricated chambers has allowed us to reveal a simple reliable mechanism for pulling-based centering that is different from mechanisms that have been proposed before. [36][37][38] In cells, it remains to be confirmed how dominant this mechanism is in different cases. However, the slipping of MT ends along the cortex has been observed in living cells 37,49,50 (see, Fig.…”

“…5 In many systems, these pulling forces arise from dynein at the cortex, 3,10,12,35 although there are also cases where dynein seems distributed along the length of the MTs throughout the cytoplasm. 5,6,[36][37][38] Focusing here on the situation where pulling forces are only generated at the cortex, one can ask how pulling forces affect positioning processes. It has been argued that the abundant presence of pulling force generators at the cortex might lead to a net de-centering force.…”