Role of kinesin2 in neurite outgrowth
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Kinesin 2 is microtubule-dependent (+)-end-directed molecular motor known to be involved in directional transport in neurons and neuronal development (Takeda, Yamazaki et al. 2000; Hirokawa and Takemuda 2005). Kinesin 2 is in fact a heterotrimeric protein complex which consists of two different motor subunits that form heterodimer and third non-motor accessory subunit called kinesin associated protein KAP3 (Cole and Scholey 1995). Motor subunits, namely KIF3A, KIF3B and KIF3C, combine to form at least two distinct complexes, KIF3A-KIF3B and KIF3A-KIF3C (KIF3A is capable of interacting with either KIF3B or KIF3C, while KIF3B and KIF3C do not interact with each other) (Muresan, Abramson et al. 1998). KIF3A and KIF3B are widely expressed throughout all the tissues while KIF3C is preferentially expressed in the nervous tissues (Muresan, Abramson et al. 1998).

scheme

Schematic drawing illustrating kinesin 2 complex. KIF3A and KIF3C (yellow and orange) form heterodimer and kinesin superfamily-associated protein 3 (KAP3; green) associates at the C terminal end.

In this screen we have tested effect of overexpression of two subunits of kinesin 2 complex:

Overexpression of KIF3C had no effect on neurite length or neurite number but it is localized in the tip of the growing neurites. Time-lapse microscopy revealed that the protein accumulates very early at the sites of neurite initiation - before any visible neurite outgrowth occurred. This result may support the role of KIF3C in very early events in neurite outgrowth like neurite initiation. Click the link and see the effect of KIF3C (kinesin 2 motor subunit) overexpression on neurite outgrowth.

Overexpression of KAP3 blocked neurite outgrowth. Click the link and see the effect of KAP3 (kinesin 2 non-motor subunit) overexpression on neurite outgrowth.