α-Tubulin Tyrosination and CLIP-170 Phosphorylation Regulate the Initiation of Dynein-Driven Transport in Neurons

Abstract

Summary Motor-cargo recruitment to microtubules is often the rate-limiting step of intracellular transport, and defects in this recruitment can cause neurodegenerative disease. Here, we use in vitro reconstitution assays with single molecule resolution, live-cell transport assays in primary neurons, computational image analysis and computer simulations to investigate the factors regulating retrograde transport initiation in the distal axon. We find that phosphorylation of the cytoskeletal-organelle linker protein CLIP-170 and post-translational modifications of the microtubule track combine to precisely control the initiation of retrograde transport. Computer simulations of organelle dynamics in the distal axon indicate that while CLIP-170 primarily regulates the time to microtubule encounter, the tyrosination state of the microtubule lattice regulates the likelihood of binding. These mechanisms interact to control transport initiation in the axon in a manner sensitive to the specialized cytoskeletal architecture of the neuron.

Self-propelling vesicles define glycolysis as the minimal energy machinery for neuronal transport

“…The use of native purified vesicles on polymerized MTs unequivocally demonstrates that the embedded glycolytic machinery is sufficient to propel vesicles along MTs without any other sources of energy. The velocity of the movement and the distance travelled on MTs, although much slower than those observed in vivo , were consistent with those observed previously in similar experiments2336373839. This is, to our knowledge, the first demonstration of an autonomous motile system for vesicles.…”

The tubulin code at a glance

“…Tyrosination also has a strong effect on the processivity of dynein in complex with dynactin and BicD2 (McKenney et al, 2016). Moreover, the tyrosination status of MTs controls the interaction with some plus-end tracking proteins, such as the cytoplasmic linker protein 170 (CLIP170; encoded by CLIP1) (Bieling et al, 2008;Nirschl et al, 2016;Peris et al, 2006).…”

Combinatorial regulation of the balance between dynein microtubule end accumulation and initiation of directed motility

“…Dynactin‐dependent plus‐end localisation of dynein has been demonstrated to be involved in the control of transport initiation in distal neurites (Moughamian et al , 2013; Nirschl et al , 2016). In non‐polarised cells, the role of dynactin in transport initiation is, however, not so well understood (Kim et al , 2007; Dixit et al , 2008).…”