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Irreversible incorporation of L-dopa into the C-terminus of α-tubulin inhibits binding of molecular motor KIF5B to microtubules and alters mitochondrial traffic along the axon

Zorgniotti et al. Neurobiol Dis. 2021

L-dopa is the most effective drug used to date for management of Parkinson’s disease symptoms. Unfortunately, long-term administration of L-dopa often results in development of motor disorders, including dyskinesias. Despite extensive research on L-dopa-induced dyskinesia, its pathogenesis remains poorly understood. We demonstrated previously that L-dopa can be post-translationally incorporated into the C-terminus of α-tubulin in living cells. In the present study, we investigated the effect of the presence of L-dopa-tubulin-enriched microtubules on mitochondrial traffic mediated by molecular motor KIF5B. Using biochemical approaches in combination with experiments on neuronal cell lines and mouse hippocampal primary cultures, we demonstrated that L-dopa incorporation into tubulin is irreversible. Transport of mitochondria along the axon was altered after L-dopa treatment of cells. In L-dopa-treated cells, mitochondria had reduced ability to reach the distal segment of the axon, spent more time in pause, and showed reduced velocity of anterograde movement. KIF5B motor, a member of the kinesin family involved in mitochondrial transport in neurons, showed reduced affinity for Dopa-tubulin-containing microtubules. Our findings, taken together, suggest that tyrosination state of tubulin (and microtubules) is altered by L-dopa incorporation into tubulin; the gradual increase in amount of altered microtubules affects microtubule functioning, impairs mitochondrial traffic and distribution, and this could be relevant in Parkinson’s disease patients chronically treated with L-dopa.

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Authors: Zorgniotti A, And Ditamo, Arce CA, CG arm

Article: Irreversible incorporation of L-dopa into the C-terminus of α-tubulin inhibits binding of molecular motor KIF5B to microtubules and alters mitochondrial traffic along the axon. Zorgniotti A, And Ditamo, Arce CA, Bisig CG.Neurobiol Dis. 2021 Jan;147:105164. doi: 10.1016/j.nbd.2020.105164. Epub 2020 Nov 7.PMID: 33171229