Subtype-Specific Tubulin Post-Translational Modification Profiles Predict Differential Axonal Stability in DRG...

Sensory neurons of the dorsal root ganglia (DRG) comprise a heterogeneous population that transduces diverse somatosensory modalities, including proprioception, mechanosensation, thermosensation, and nociception. Although sensory neuron subtypes differ in function and transcriptional profiles, whether these neurons also differ in axonal microtubule properties remains unclear. Here, we asked whether distinct DRG neuronal subtypes exhibit subtype-specific axonal tubulin post-translational modifications (PTMs), which have been implicated in regulating microtubule structure and function. Using established markers, we resolved five major sensory neuronal subtypes in primary cultures of adult mouse DRG neurons: parvalbumin-positive (PV⁺) proprioceptors, Aβ low-threshold mechanoreceptors (LTMRs), calcitonin gene-related peptide-positive (CGRP⁺) peptidergic nociceptors, isolectin B4-positive (IB4⁺) non-peptidergic nociceptors, and tyrosine hydroxylase-positive (TH⁺) C-LTMRs. Axons exhibited subtype-specific differences in βIII-tubulin content and distinct tubulin PTM signatures, which were validated in vivo. CGRP⁺ and IB4⁺ neurons displayed lower levels of tubulin acetylation and glutamylation compared to PV⁺ neurons and LTMRs in both culture and tissue, and nociceptor neurons showed greater susceptibility to nocodazole-induced microtubule destabilization compared to PV⁺ neurons. Inhibition of histone deacetylase 6 conferred nocodazole resistance to both CGRP⁺ and IB4⁺ neurons. Together, these findings suggest that distinct tubulin PTM signatures contribute to axonal stability and vulnerability across sensory neuron subtypes and support the use of primary adult DRG neuron culture as a tractable platform for biochemical and functional dissection of sensory neuron populations.