| Abstract |
The microtubule (MT) cytoskeleton is essential for neuronal morphology, neurite growth, synapse formation and maintenance, as well as regulation of signal transduction. Most cells express multiple isotypes of α- and β-tubulin that can coassemble into MTs. While a variety of signaling pathways regulate MT integrity and homeostasis, little is known about how tubulin isotypes interact in vivo. Here, we report a mechanism in which altered function of a neuronal β-tubulin in Caenorhabditis elegans activates the conserved kinase DLK-1 and its downstream signal transduction, which in turn upregulates expression of an α-tubulin isotype to ensure MT integrity. We find that alteration in the T7 loop of the β-tubulin/BEN-1 causes the formation of BEN-1-enriched islands along MTs in neurites. Combining genome editing with cellular imaging, we identified amino acid residues in α-tubulin/TBA-2 that are necessary for formation of BEN-1 islands. Activation of DLK-1 signaling in ben-1 mutants promotes TBA-2 transcription and protects axon and synapse morphology. These data uncover a positive feedback loop between DLK-1 and regulation of tubulin isotype interaction that maintains neuronal resilience.
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