Biology subjects

Comincini, A.

Publications and source records attributed to Comincini, A..

2 recordsLinked to original sources

bioRxiv2026

α-Synuclein and γ-Tubulin Cooperatively Regulate Activity-Evoked Presynaptic Microtubule Nucleation to Gate Dopamine Release

-Synuclein has long been implicated in the regulation of synaptic activity, but the molecular basis that underlies this function has been elusive. Here, we identify a microtubule (MT)-dependent mechanism through which -synuclein regulates synaptic dopamine release. Using live imaging of cultured dopaminergic neurons, we visualize dynamic MTs at individual presynaptic boutons and show that neuronal activity triggers local {gamma}-tubulin-dependent MT nucleation. We find that this nucleation is essential for interbouton synaptic vesicle (SV) transport and for sustained dopamine release during high activity. We further discover that -synuclein acts as a positive regulator of presynaptic MT nucleation by binding directly to {gamma}-tubulin and the /{beta}-tubulin heterodimer. Activity-evoked phosphorylation of -synuclein at serine 129, a modification that accumulates in synucleinopathies and a molecular switch for -synuclein binding to synaptic proteins, occurs in the region of /m tubulin binding and is both necessary and sufficient for MT initiation. Our findings reveal a previously unrecognized, activity-dependent role for -synuclein in the nucleation of axonal MTs that enables on-demand SV interbouton redistribution and dopamine release. This mechanism provides a novel molecular link between -synuclein phosphorylation and MT-dependent modulation of dopamine release, offering insight into how its dysregulation may contribute to dopaminergic synaptic dysfunction, a central feature of synucleinopathies.

cell biology↗

bioRxiv2025

Tubulin autoregulation factors SCAPER and TTC5 recruit γ-tubulin to non-centrosomal MTOCs for neuronal microtubule nucleation and axon regeneration

Neuronal function and survival depend on highly stereotyped non-centrosomal microtubule (MT) arrays. How these arrays form remains poorly understood. Here we identified a role for SCAPER and TTC5, two factors previously implicated in tubulin mRNA autoregulation, in controlling neuronal MT content through {gamma}-tubulin-dependent nucleation. In C. elegans neurons, loss of scpr-1, ttc-5, or both reduced MT numbers to a similar degree as depletion of {gamma}-tubulin, the main MT nucleator. Using conditional single-cell degradation alleles and endogenous tagging, we find that {gamma}-tubulin nucleates MTs in the neuronal cell body from endosomal puncta, and that scpr-1 and ttc-5 are required to recruit {gamma}-tubulin to these structures. SCPR-1 is also instructive, as its overexpression drastically increases {gamma}-tubulin levels and enhances MT density. We propose that these mechanisms are conserved since human SCAPER rescues C. elegans mutants, and SCAPER knockdown in rat hippocampal neurons reduces both {gamma}-tubulin clustering at presynaptic sites and activity-dependent synaptic MT nucleation. Finally, while scpr-1, ttc-5, and{gamma} -tubulin are not required for developmental axon elongation, they are essential for regeneration, where SCPR-1 directs {gamma}-tubulin to the growth cone to facilitate regrowth following injury. These findings reveal mechanisms governing neuronal cytoskeleton assembly and function, and suggest potential crosstalk between tubulin autoregulation and microtubule nucleation.

cell biology↗