The SNAREs SNAP23, VAMP4 and Syntaxin6 are necessary for the establishment of neuronal polarity

DIEGO GRASSI; SANTIAGO QUIROGA

Puerto Varas

Congreso; XXVII annual meeting of Chilean Society for Cell Biology; 2013

Sociedad Chilena de Biología Celular

Two different types of regulated exocytosis are known in neurons: well-studiedsecretory exocytosis (for release of synaptic vesicles) and non-secretory exocytosis(for enlargement of the plasma membrane). The last one is essential for neuriteoutgrowth and is sustained by the exocytosis of specific vesicles, namedplasmalemmal precursor vesicles (PPVs). However, targeting mechanisms for PPVsto developing axon are barely understood. Previous results of our lab indicate thatTC10 and exo70 (two components of exocyst complex) are necessary for tetheringof PPVs and addition of new membrane, allowing axon elongation stimulated byIGF-1. But the SNARE proteins involved in docking and fusion of PPVs remains, sofar, unidentified. The present study attempts to elucidate the SNARE proteinsimplicated in these steps and VAMP4, SNAP23 and Syntaxin6 were spotted ascandidates. Data obtained showed that these SNAREs acquire polarizeddistribution in early stages of axonal development and, besides, are required forpreferential insertion of IGF-1 receptor in plasma membrane of developing axon.Others SNAREs involved in axonal elongation like VAMP7, SNAP25 and Syntaxin1seems are not essential in regulation of initial axonal outgrowth and, therefore, notnecessary for the establishment of neuronal polarity.