Par3 and Dynein Associate to Regulate Local Microtubule Dynamics and Centrosome Orientation during Migration

Abstract

Summary Background Centrosome orientation toward the leading edge of migrating cells depends on dynein and microtubules (MTs) and as well on a number of signaling factors at the leading edge. However, centrosomes are maintained at the cell center during orientation in fibroblasts suggesting that factors working at sites other than the leading edge may also be involved. Results In a search for factors that function with dynein in centrosome orientation, we found that the polarity protein Par3 associated with dynein and that knockdown of Par3 inhibited centrosome orientation by disrupting the position of the centrosome at the cell center, the same phenotype as that observed with dynein inhibition. Par3 associated with dynein through its N-terminal dimerization and PDZ1 domains, and interacted specifically with dynein light intermediate chain 2 (LIC2). siRNA knockdown of LIC2, but not LIC1, or overexpression of LIC2 or the N-terminal domain of Par3, also inhibited centrosome orientation by disrupting centrosome position. Par3 specifically localized to cell-cell contacts in wound-edge fibroblasts where it overlapped with MT ends and dynein puncta in a LIC2 dependent fashion. Live imaging showed that MTs exhibited increased pausing at cell-cell contacts compared to the leading edge and that this elevated pausing was dependent on Par3 and LIC2. Conclusion Par3 associates with dynein and contributes to the local regulation of MT dynamics at cell-cell contacts and proper positioning of the centrosome at the cell center. We propose that Par3 acts as a cortical factor that tethers MTs through its association with LIC2-dynein.

Lamin A variants that cause striated muscle disease are defective in anchoring transmembrane actin-associated nuclear lines for nuclear movement

“…S2A). Depletion of lamin A/C from NIH 3T3 fibroblasts also reduced cell migration velocity compared with control NIH 3T3 fibroblasts (22,27) (Fig. S2B).…”

“…In this system, the serum factor lysophosphatidic acid (LPA) activates Cdc42-dependent pathways that trigger actin and myosin II-dependent rearward nu-clear movement (away from the leading edge) and microtubuleand dynein-dependent maintenance of the centrosome at the cell center (20)(21)(22). The combined effect of these two processes is the reorientation of the centrosome to a position between the nucleus and the leading edge.…”

“…The effects of the FPLD variants on centrosome position are likely indirect because centrosome positioning involves dyneindependent microtubule tethering at the cell cortex (22). We therefore focused on the immotile nuclear phenotype caused by EDMD and DCM LMNA variants.…”

Common themes in centriole and centrosome movements

“…Studies on centrosome reorientation in migrating 214 fibroblasts suggest that the centrosome might remain relatively central while the nucleus 215 moves rearwards [20]. Centrosome position is maintained by dynein-mediated cortical 216 tethering of microtubules [62]; however, it is unclear whether centrosome rotation drives 217 nuclear movement or vice versa. 218…”

Coordinate Control of Host Centrosome Position, Organelle Distribution, and Migratory Response by Toxoplasma gondii via Host mTORC2

“…The orientation of the centrosome and Golgi is susceptible to regulation in mammalian cells, for example during directional responses to migratory stimuli (11)(12)(13). A potential mechanism, then, of parasite-mediated reorganization is the mimicry of host signals that govern the polarization response, resulting in a stable, intrinsically polarized state.…”