Communication between intracellular membrane trafficking and the cytoskeleton is important for regulating many biological processes. The detailed interactions between these two networks are not well understood. RAB-11 is enriched in recycling endosomes and the trans-Golgi network, where it regulates membrane recycling back to the plasma membrane. In C. elegans, in
rab-11 RNAi embryos cytokinesis fails to complete as reported (Skop et al, 2001), and we find that embryos also show a series of spindle alignment defects, including failure of P0 spindle rotation and dramatic anaphase spindle movements. The regulators for wild-type anaphase spindle movement, such as PAR-2, PAR-3, GPR-1/2, and dynactin still function to modulate this dramatic movement in
rab-11 RNAi embryos. This exaggerated movement resembles the phenotype of
zyg-8 mutant embryos (Gonczy et al, 2001). Unlike in
zyg-8 mutants, the length of astral microtubules in the anaphase spindle is normal in
rab-11 RNAi embryos, but is greatly reduced during metaphase. Preliminary results indicate that this violent anaphase spindle movement can be phenocopied by shortening the metaphase astral microtubules by Nocodazole in wild-type embryos. RAB-11::GFP appears to localize to ER and Golgi. In addition, ER and Golgi morphology are affected by
rab-11 RNAi. Our results suggest that the endomembrane system has a role in regulating microtubule length during metaphase to ensure proper spindle alignment in C. elegans early embryos.