Role of Microtubule Inner Proteins (MIPs) in neuronal microtubule stability – RESIST

Microtubules (MTs) are hollow cylinders able to alternate between growth and shrinkage phases. In neurons, such dynamic MTs co-exist alongside long-lived stable MTs crucial for neuronal functions. Among MT stabilisation mechanisms proposed, Microtubule Inner Proteins (MIPs), located in the MT lumen, confer very high stability on ciliar/flagellar MTs. Strikingly, although MIPs have long been seen inside neuronal MTs, their identity was unknown until we identified MAP6 as a mammalian MIP.
With the overall objective of elucidating the molecular basis of neuronal MT stability, we intend to decipher how neuronal MIPs confer MT stability, and how MIP-containing MTs contribute to neuronal growth and architecture. To achieve this goal, we will work on MAP6, the only known neuronal MIP.
First, we will determine the mechanical properties of MAP6-containing MTs by combining cell-free systems and advanced light microscopy techniques. Second, by combining the use of available and newly developed fluorescent probes with expansion/super-resolution microscopy, we will reveal individual MT in neurons, and chart MAP6-containing MTs within the MT network. Finally, using micro-structured patterns, we will determine how MAP6-containing MTs contribute to neuronal growth and shape, in normal and constrained contexts as well as following axonal de/regeneration.
The work will be performed by 2 teams with long standing experience in the study of cytoskeleton in neurobiology and high expertise in cell biology by combining cell-free cytoskeletal reconstitution, primary neuron cultures, advanced light microscopy techniques, microfluidics and regenerative studies.
Ultimately, the elucidation of some MIP-mediated mechanisms contributing to MT stability will allow the design of innovative drugs specifically targeting stable MTs. These are of interest as the equilibrium between dynamic/stable MTs is impaired in several brain disorders and interferes in the autonomous CNS regenerative processes.