The role of kinesin heavy chain in Drosophila photoreceptor development.

In developing Drosophila photoreceptors a stabilized microtubule structure was discovered and its presence was linked to polarity protein localization defects caused by mutations in the microtubule-severing protein Spastin and the centrosome core protein Centrosomin. It was therefore hypothesized that the microtubules may provide trafficking routes for the polarity proteins during photoreceptor morphogenesis. This study has examined whether kinesin heavy chain (Khc), a subunit of the microtubule-based motor kinesin-1, is essential in polarity protein localization in developing photoreceptors. After finding a strong genetic interaction between crumbs (crb) and khc, loss-of-function and gain-of-function analyses revealed progressive reductions in both the Crb and adherens junction (AJ) domains and an increase in the Crb domain, respectively. Furthermore, the khc mutation also led to similar progressive defects in the stabilized microtubule structures, strongly suggesting that Khc is essential for microtubule structure and Crb localization during distal to proximal rhabdomere elongation in Drosophila pupal photoreceptor development.