The SNAREs SNAP23, VAMP4 and syntaxin6 are necessary for the establishment of neuronal polarity

GRASSI DIEGO, QUIROGA SANTIAGO

Huerta Grande

Congreso; XXVII Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2012

Sociedad Argentina de Investigación en Neurociencias (SAN)

Two different types of regulated exocytosis have been described in bothneurons and non neuronal cells: i) Regulated secretory exocytosis to releasespecific products that are segregated in the organelle lumen (e.g.neurotransmiters) and ii) Regulated exocytosis for non secretory purposes .Results from our laboratory demonstrated that the latter phenomenon isinvolved in the regulation of plasmalemmal precursor vesicles (PPVs)exocytosis during initial axonal outgrowth and is essential for the establishmentof neuronal polarity. This process requires activation of the small GTPase TC10and the exocyst complex by the IGF-1 receptor pathway. We have extensiveknowledge about the regulatory components involved in synaptic vesicleexocytosis but little is known about the regulation of PPVs fusion with theplasmalemma. The experiments shown here were designed to identify theSNAREs involved in PPVs fusion and the establishment of neuronal polarity.Our results showed that SNAP23, VAMP4 and syntaxin6 are expressed early indifferentiating neurons and exhibit a polarized distribution at the young axon.Loss of function experiments demonstrated that the expression of these threeproteins is necessary for the establishment of neuronal polarity. We are nowconducting experiments to obtain direct evidence about the role of SNAP23,VAMP4 and syntaxin6 in the regulation of PPVs fusion in differentiatingneurons.