Unlike any other cell in the body, neurons must communicate over distances spanning almost the size of an organism. Although rapid information flow is carried by electrical signals, long distance transport is essential to support three core functions: input integration, action potential propagation and synaptic transmission. Fast axonal transport constitutes the backbone of long-distance communication in neurons, functionally connecting distal areas with the soma and vice versa. In spite of its relevance for neuronal development, maintenance and survival, characterisation of the mechanisms controlling the targeting of specific ligands, such as growth factors and their receptors, to specific axonal transport routes remains in its infancy. A comprehensive understanding of long-range axonal transport in neurons is critical for a better understanding of neuronal function and to unveil the causes of neurodegenerative disorders.
The Molecular Neuropathobology laboratory has pioneered the functional analysis of axonal retrograde transport and its association with neurodegenerative diseases. Recently, we have performed a proteomic approach, which has allowed the characterisation of several components of long-range axonal retrograde carriers in motor neurons. However, many factors still remain poorly characterised or unknown.
The aim of this project is to build a functional map of retrograde axonal transport carriers in different neurons and follow their maturation. This approach aims to uncover both general and specific mechanisms of retrograde axonal transport, which may explain the selective sensitivity of certain neurons to specific axonal transport defects. Our laboratory has optimised a strategy for the characterisation of retrograde transport carriers containing neurotrophin receptors based on paramagnetic iron oxide nanoparticles coupled with linear ion trap Fourier transformed mass spectroscopy, which yielded 216 unique hits, including motors, novel cargo proteins, ion channels and transporters. These preliminary results demonstrate the feasibility of our approach to create a physical map of axonal signalling endosomes and the need for a systematic analysis to discover novel factors associated with this compartment.
In this project, the applicant will purify and map retrograde axonal transport carriers from different times after internalisation in motor neurons (MN) and dorsal root ganglia (DRG0 neurons. The kinetics of endosome maturation will be quantitatively assessed using quantitative mass-spec. We will use nanobeads derivatised with the binding fragment of tetanus toxin, nerve growth factor (NGF) or with an antibody directed against the neurotrophin receptor p75NTR to study the composition of wild type axonal carriers and compare it with those isolated from MN and DRG of mouse models of neurodegeneration. This approach will allow us to uncover new components of signalling endosomes and understand how impairments in axonal transport of these organelles is affected in different neurodegenerative conditions.
Application Deadline:
30 April 2011
Contact:
Giampietro Schiavo,
giampietro.schiavo@cancer.org.uk
