REGULATION OF POLARIZED GOLGI OUTPOST FORMATION

A CACERES

Conferencia; Reunión Anual Sociedad de Biología de Córdoba (Conferencia S. Taleisnik); 2013

Sociedad de Biología de Córdoba

The neuronal Golgi apparatus (GA) localizes to the perinuclear region and also extends into dendrites as tubulo-vesicular structures designated as Golgi outposts (GOPs). Current evidence suggests that GOPs shape dendritic morphology by functioning as sites of acentrosomal microtubule nucleation and as platforms for the local delivery of synaptic receptors. However, the crucial question of how GOPs are generated remains unanswered. Two possible scenarios have been proposed, one involving fragmentation of the somatic GA followed by transport into dendrites and other one involving local de novo production from dendritic ER. Using live cell imaging and confocal microscopy of cultured hippocampal neurons we now show that GOPs destined to major ?apical? dendrites are generated from the somatic Golgi by a sequence of events involving: 1) tubulation of a Golgi stack; 2) tubule elongation and deployment into the dendrite; 3) tubule fission; and 4) condensation of the fissioned tubule. Suppression of LIMK1, PKD1, or BARs induces Golgi deployment/tubulation without fission selectively reducing the number of GOPs in the major dendrite; interestingly, LPA treatment of cultured neurons stimulates GOPs formation in the main dendrite, an effect dependent on RhoA, ROCK, LIMK1, SSH1, PKD1 and dynamin. Finally, using synchronous release of ectopic glycosyltransferases from the ER to follow transport to their final destination in the GA we show that GOPs formation in minor dendrites is a local, dynamin-independent phenomenon. Supported by grants from ANPCyT.