3-nitrotyrosine shortens axons of a non-dopaminergic neuron by inhibiting mitochondrial motility

Abstract 3-nitrotyrosine (3-NT), a byproduct of oxidative/nitrosative stress, is implicated in age-related neurodegenerative disorders. Existing literature indicates that free 3-NT becomes integrated into the carboxy-terminal domain of α-tubulin through the tyrosination/detyrosination cycle. Independently of this integration, 3-NT has been linked to the cell death of dopaminergic neurons. Given the critical role of tyrosination/detyrosination in governing axonal morphology and function, the substitution of tyrosine with 3-NT in this process may potentially disrupt axonal homeostasis, although this aspect remains underexplored. In this study, we examined the impact of 3-NT on the axons of cerebellar granule neurons, representing non-dopaminergic neurons. Our observations revealed axonal shortening, which correlated with the incorporation of 3-NT into α-tubulin. Importantly, this axonal effect was observed prior to the onset of cellular death. Furthermore, 3-NT was found to diminish mitochondrial motility within the axon, resulting in a subsequent reduction in mitochondrial membrane potential. The suppression of syntaphilin, a protein responsible for anchoring mitochondria to microtubules, reversed the 3-NT-induced decrease in mitochondrial motility, consequently restoring axonal elongation. These findings underscore the inhibitory role of 3-NT in axonal elongation by impeding mitochondrial movement, implying its potential involvement in axonal dysfunction within non-dopaminergic neurons. Competing Interest Statement The authors have declared no competing interest. Data availability Data will be made available on request. Abbreviations - CGN - cerebellar granule neuron - DA - dopaminergic - DIV - days in vitro - DMEM - dulbecco’s modified eagle’s medium - MMP - mitochondrial membrane potential - 3-NT - 3-nitrotyrosin - PBS - phosphate-buffered saline - SDS - sodium dodecyl sulfate - Snph - syntaphilin - TMRM - tetramethylrhodamine methyl ester - Ttl - tubulin tyrosine ligase