The polarized transport of Syntaxin 6 mediated by KIF5C is essential for the exocytosis of IGF-1 receptor and the establishment of neuronal polarity

OKSDATH, M.; QUIROGA, S.

Mar del Plata

Congreso; XXX Congreso de la Sociedad Argentina de Investigaciones en Neurociencias (SAN); 2015

SAN

The formation of a polarized neuron, containing one long axon and several branchingdendrites, requires the action of two interrelated processes, specification of the axon andaxonal elongation. Regarding the regulation of initial axonal outgrowth, a particularly earlyevent that occurs in neurons that have not yet exhibited a discernible axon (stage 2 ofdifferentiation) is the segregation of activatable IGF-1 receptors (IGF-1r) in a single neurite(Sosa et al., 2006)). This event is critical for the outgrowth of the future axon. In order tobecome activatable, the IGF-1r needs to be inserted to the neuron plasmmalema. This occursby exocytotic incorporation of vesicles containing IGF-1r with the participation of the exocistcomplex (Dupraz et al., 2009) and the SNAREs proteins VAMP4, Syntaxin 6 and SNAP23 (Grassi et al., 2015). Besides polarization of the IGF-1r, two early polarity events are known: i) The accumulation of stable microtubules at one neurite (the future axon-Witte et al., 2008), and ii)The preferential transport to one neurite of the microtubular motor KIF5C (Jacobson et al.,2006) which shows a preference to interact with axonal (stable) over dendritic microtubules.Our results show that these three early polarity events described above are interdependentphenomena necessary for the regulation of initial axonal outgrowth, essential for theestablishment of neuronal polarity