Removal of Rab11 endosomes affects spines morphology and dendritic arbor development

SEBASTIÁN OMAR SIRI; QUASSOLLO, GONZALO; CONDE, CECILIA

la serena

Workshop; EMBO WORKSHOP Actualizations in Membrane Trafficking in Health and Disease; 2016

EMBO

A largebody of experimental data over the last 20 years has demonstrated thecrucial role of endosomal trafficduring cell development. The neuronal dendriticarbor development requires a properspatiotemporal distribution of the elements ofthe secretory and endocytic pathways, as well as a dynamic and regulatedcommunication between them.Accordingly, our work has focused on characterizingthe role of recycling endosomes (RE)during the development of the dendritic arborin primary embryonic hippocampalneurons. We first determined the endogenouslocalization of REs in culturedneurons from day in vitro 0 to 21. In the first 8 hours inculture, the neurons exhibited ajuxtanuclear distribution of RE. After 24 hours, theREs change their localization to amore broad distribution throughout the neuritesuntil day 14 they were mainlyconcentrate on the processes tips.The small GTPase Rab11 is enrichedin REs. Utilizing a shRNA-Rab11, we observed ashift in the RE distribution as wellas morphological changes during the development ofthe dendritic arbor. In particular,we detected a shortening of the main neurite and aconcomitant increase in number of dendritic branches. Similarresults werefoundexpressing a dominant negative Rab11 construct in agreement with the centralregulatory role of Rab11 on REdynamics. We quantified the number and morphology ofdendritic spines on mature neurons in culture after decreasing the expression ofRab11.Under this condition, we foundan increased number of thin/filopodia-like spinesas compared with the control withnormal Rab11 levels. These results are in agreementwith recent reports suggesting thatthe endosome positioning is a critical factor in thecontrol of synapse architecture andfunction (Esteves da Silva et al, 2015). Takentogether, our experimental findingssuggest that Rab11 in the recycling endosomes is akey regulator of the dendritic arbordevelopment