The interaction between cytoplasmic dynein and dynactin is required for fast axonal transport

Abstract

Fast axonal transport is characterized by the bidirectional, microtubule-based movement of membranous organelles. Cytoplasmic dynein is necessary but not sufficient for retrograde transport directed from the synapse to the cell body. Dynactin is a heteromultimeric protein complex, enriched in neurons, that binds to both microtubules and cytoplasmic dynein. To determine whether dynactin is required for retrograde axonal transport, we examined the effects of anti-dynactin antibodies on organelle transport in extruded axoplasm. Treatment of axoplasm with antibodies to the p150 Glued subunit of dynactin resulted in a significant decrease in the velocity of microtubule-based organelle transport, with many organelles bound along microtubules. We examined the molecular mechanism of the observed inhibition of motility, and we demonstrated that antibodies to p150 Glued disrupted the binding of cytoplasmic dynein to dynactin and also inhibited the association of cytoplasmic dynein with organelles. In contrast, the anti-p150 Glued antibodies had no effect on the binding of dynactin to microtubules nor on cytoplasmic dynein-driven microtubule gliding. These results indicate that the interaction between cytoplasmic dynein and the dynactin complex is required for the axonal transport of membrane-bound vesicles and support the hypothesis that dynactin may function as a link between the organelle, the microtubule, and cytoplasmic dynein during vesicle transport.Neurons possess a striking asymmetric morphology in which elongated axonal processes extend from the cell body. The growth and maintenance of the axon, as well as the movement of materials between the cell body and the distal tip of the axon, rely on the mechanism of axonal transport. The fast bidirectional transport of organelles along the polarized microtubule array of the axon has been well characterized (1-8). Many microtubule-based motors have been identified in neurons, including members of the kinesin superfamily that are implicated in anterograde transport (4, 5) and cytoplasmic dynein, which is required for retrograde transport (6-8).The molecular mechanisms by which these motors are specified for particular types of organelle cargo, as well as the regulation of the interactions between motor proteins, organelles, and microtubules, are largely unknown. A soluble accessory factor, dynactin, was originally isolated via its copurification with cytoplasmic dynein and is one candidate for the activation of cytoplasmic dynein-based organelle motility (reviewed in ref. 9). Dynactin consists of at least seven different polypeptides that cosediment at 20 S (10, 11). These include p150Glued ; the actin-related protein centractin (Arp-1); the ␣ and ␤ subunits of capping protein (CapZ); dynamitin; as well as uncharacterized polypeptides with molecular masses of 62 and 24 kDa (10-17). The largest dynactin polypeptide, p150Glued , is capable of multiple, specific binding interactions. p150Glued binds to the 74-kDa intermediate chain of cytoplasmic dynein via a domain ...

Huntingtin facilitates dynein/dynactin-mediated vesicle transport

“…4C), and the inhibition was bidirectional (Fig. 4D), which is consistent with previous observations of decreased organelle motility with disruption of dynein/ dynactin function (21). The inhibition of vesicular transport along the microtubules by Htt antibodies suggests that Htt facilitates bidirectional vesicle motility.…”

Kif5B and Kifc1 Interact and Are Required for Motility and Fission of Early Endocytic Vesicles in Mouse Liver

“…Second, that plus end motility is increased when minus-end motility is inhibited by incubation of vesicles with antibody to Kifc1 (Figure 8). These data are consistent with the possibility that these motors may be part of a yet to be elucidated protein complex that mediates their coordinate regulation, as has been suggested for vesicle-associated dynein and plus-end kinesins (Brady et al, 1990;Stenoien and Brady, 1997;Waterman-Storer et al, 1997;Ligon et al, 2004). This view is supported in the present study by the finding that Kifc1 and Kif5B can interact with each other as shown by immunoabsorption of native Kif5B by FLAGKifc1 expressed in 293T cells ( Figure 9B).…”

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls

“…Dynactin activates dynein chains to couple organelles to microtubules for fast axonal retrograde transport (Waterman‐Storer et al ., 1997). Suppression of dynein impairs clearance of α‐synuclein aggregates via the autophagosome/lysosome pathway (Li et al ., 2013).…”