Evidence for the involvement of LIMK1, PKD1 and BARS in Golgi outpost formation

JAUSORO I; QUASSOLLO G; WOJNACKI J; GASTALDI L; MARZOLO MP; CONDE C; CÁCERES A

Congreso; 5th ISN Special Conference; 2012

In neurons, the Golgi apparatus localizes to the perinuclear region; it also extends into dendrites as discrete tubulo-vesicular organelles designated as Golgi outposts (GOps). Interestingly, NMDAR are sorted at the ER from AMPAR, bypassing the somatic Golgi and merging instead with GOps, raising the possibility that the latter may serve as secretory platforms for local delivery of synaptic receptors. Disruption of the dynein/dynactin complex reduces the number of GOps and dendritic branches, suggesting a direct relationship between their abundance and dendritic complexity. However, the crucial question of how GOps are generated remains unanswered. Two possible scenarios have been proposed, one involving fragmentation of the somatic Golgi followed by transport of remnant membranes into dendrites; the other involving local de novo production from dendritic ER. Live cell imaging with spinning disk confocal microscopy of cultured hippocampal neurons reveals that GOps are generated from the somatic Golgi by a sequence of events involving: (i) tubulation of a Golgi cisterna; (ii) elongation and penetration within a dendrite (deployment); (iii) tubule fission; and (iv) condensation of the fissioned tubule. Suppression of LIMK1, PKD1 or BARs reduce the number of GOps and induce Golgi deployment/tubulation without fission; by contrast, ectopic expression of these proteins or LPA treatment or reelin stimulate Golgi outpost formation, an effect dependent on RhoA-ROCK, dynamin and cortactin. Supported by ANPCyT and CONICET.