The nervous system governs vital functions as well as complex behaviours enabling animals to interact with their environment. The mature nervous system is composed of billions of neurons that are interconnected according to a highly precise map (i.e. the connectome). Fine-tuned regulation of these connections is crucial for the accurate functioning of the network. Neuronal connectivity is established during development by linked processes of axon specification, outgrowth/navigation, synapse formation and pruning of exuberant connections and undergoes limited remodelling in the mature central nervous system [1], [2]. Consequently, ectopic, exuberant or imprecise connections can lead to major neurodevelopmental disorders [3], [4], [5], [6]. A crucial step in the assembly of neuronal circuits lies in the ability of axons to accurately navigate towards their appropriate targets, which can be located over very long distances (i.e. more than one metre). During their road trip in the developing embryo, the distal tips of growing axons (i.e. the growth cones) undergo cycles of growth, pausing, turning or retraction behaviours, which are dictated by a myriad of physical, mechanical and chemical cues present in their extracellular environment. Different classes of chemical cues are encountered by the growth cone along its journey, such as permissive (e.g. Netrin-1) or adhesive molecules (e.g. CAMs), extra-cellular matrix components (e.g. laminin), anti-adhesive substrate-bound cues (e.g. Slits) and diffusible chemotropic cues (e.g. Semaphorins, morphogens, neurotrophic factors), which will elicit growth cone attraction or repulsion [2], [7], [8]. Importantly, several studies have demonstrated that the response of attraction versus repulsion is not due to the intrinsic property of a particular cue. Rather, it is due to the specific growth cone receptors and downstream effectors engaged, including cytoskeleton-associated proteins [9], [10].

While the repertoire of guidance cues and associated receptors wiring the nervous system has mostly been identified, the intracellular pathways that modulate axon responsiveness to guidance signals are far from being deciphered. Notably, how guidance signals are integrated and translated into the cytoskeleton remodelling that underlies growth cone mechanical behaviours remains largely unknown. Pioneer studies aiming at linking guidance signals to the cytoskeleton remodelling first focused on the actin cytoskeleton [11], [12]. Since then, several cues have been shown to drive growth cone attraction, repulsion or collapse through RhoGTPase-mediated actin remodelling [for review, see [13], [14], [15]]. By contrast, molecular links between guidance signals and the MT cytoskeleton have remained largely unstudied until recently. This is mostly due to the fact that unlike F-actin, MTs have only recently emerged as key driving forces and direct targets of guidance cues in axon pathfinding and pruning [16], [17]. Indeed, several MT-interacting proteins have been identified as decisive players in these developmental processes in vitro and/or in vivo [18], [19], [20], [21], [22], [23], [24], [25], [26], [27]. Furthermore, tubulin isoforms and posttranslational modifications have lately come out as key regulators of MT functions in the axon navigation processes influencing MT properties as well as the activity/MT binding affinity of MT-interacting proteins [28], [29], [30], [31]. This review summarises the main experiments that have established MT remodelling as a key driving force in axon guidance and pruning and provides a detailed overview of the molecular mechanisms that tune MT properties and functionalities to steer developing axons or prune exuberant connections.