- The role of Dynein-dependent retrograde axonal transport in sensory and motor neurons
Neurons are highly polarized cells with an elongated axon that extends far away from the cell body. In order to maintain neuronal homeostasis, neurons rely extensively on axonal transport of membranous organelles and other molecular complexes. Axonal transport plays a central role in the establishment of neuronal polarity, axonal growth and stabilization and synapses formation, allowing for precise spatio-temporal activation and modulation of numerous molecular cascades. Anterograde and retrograde axonal transport (Figure 1) is supported by various molecular motors, such as kinesins and dyneins, and a complex microtubule network. Cytoplasmic dynein is the main retrograde molecular motor and is constructed around the heavy chain, which is the force-generating subunit and is composed of a motor and a tail domain. The former is responsible for motility generation while the latter acts as a platform for the association of other subunits, such as the intermediate, light-intermediate and light chains, which collectively mediate the direct and indirect binding/association of cargos. Roadblock 1 (DYNLRB1) is one of the 3 light chain families and was presumed to be an accessory subunit for specific cargoes. Recent work demonstrated that DYNLRB1 depletion in proprioceptive neurons significantly impairs retrograde axonal transport and consequently compromises neuronal survival (Terenzio et al., 2020). This observation suggests that DYNLRB1 is an essential subunit for dynein-mediated transport.
We investigate the role of DYNLRB1 in axonal retrograde transport. To this extent we utilize a fusion construct of DYNLRB1 and a promiscuous biotinylating enzyme to selectively label DYNLRB1’s interactors with dynein and identify them by mass spectrometry (Figure 2). We will then proceed characterizing the most promising candidates in vitro and in vivo and their potential implication in the genesis of neurological disorders.