Pinto, Maria J.Alves, Pedro L.Martins, LuísPedro, Joana R.Ryu, Hyun R.Jeon, Noo LiTaylor, Anne M.Almeida, Ramiro D.2017-01-102017-01-1020161540-8140http://hdl.handle.net/10400.22/9192Differentiation of the presynaptic terminal is a complex and rapid event that normally occurs in spatially specific axonal regions distant from the soma; thus, it is believed to be dependent on intra-axonal mechanisms. However, the full nature of the local events governing presynaptic assembly remains unknown. Herein, we investigated the involvement of the ubiquitin-proteasome system (UPS), the major degradative pathway, in the local modulation of presynaptic differentiation. We found that proteasome inhibition has a synaptogenic effect on isolated axons. In addition, formation of a stable cluster of synaptic vesicles onto a postsynaptic partner occurs in parallel to an on-site decrease in proteasome degradation. Accumulation of ubiquitinated proteins at nascent sites is a local trigger for presynaptic clustering. Finally, proteasome-related ubiquitin chains (K11 and K48) function as signals for the assembly of presynaptic terminals. Collectively, we propose a new axon-intrinsic mechanism for presynaptic assembly through local UPS inhibition. Subsequent on-site accumulation of proteins in their polyubiquitinated state triggers formation of presynapses.engAnimalsAxonsCells, CulturedHippocampusLuminescent ProteinsMicroscopy, FluorescencePolyubiquitinPresynaptic TerminalsProteasome Endopeptidase ComplexProteasome InhibitorsProteolysisRats, WistarRecombinant Fusion ProteinsSignal TransductionSynaptic VesiclesTime FactorsTime-Lapse ImagingTransfectionUbiquitinated ProteinsUbiquitinationCell Differentiationjournal article10.1083/jcb.201509039