The planar cell polarity (PCP) pathway, one of the Wnt signaling pathways, is involved in the coordination of orientation of cell polarity or organizing convergent extension for correct morphogenesis. In Drosophila wing cells, it is known that Van Gogh is asymmetrically localized to the proximal cortex, while Frizzled (Fz) and Dishevelled (Dsh) are localized to the distal cortex. During asymmetric divisions in C. elegans, although Fz and Dsh are asymmetrically localize to the posterior cortex as in the PCP pathway, asymmetric division is controlled by the Wnt/b-catenin asymmetry pathway that involves asymmetric localization of WRM-1/b-catenin to the anterior cortex. The involvement of VANG-1, the sole homolog of Van Gogh, in asymmetric divisions has not been clearly demonstrated. To examine whether VANG-1 is involved in asymmetric divisions in C. elegans, we analyzed the phenotypes of
vang-1 mutants in seam cells. Seam cells V1-V6 are positioned on each lateral side of the animals and repeatedly undergo self-renewing asymmetric divisions in each larval stage to produce anterior daughter cells that fuse with the hypodermal syncytium called
hyp7 and posterior daughter cells that remain as seam cells. In
vang-1 single mutants, we found that asymmetric divisions were abnormal at the L2 stage when each seam cell divides twice; a first proliferative division and a second self-renewing asymmetric division. In
vang-1 mutants, polarity of the second division tended to be reversed specifically in the anterior (Vn.pa) but not in the posterior (Vn.pp) daughters of the first division. At the L1 stage, although seam cell polarity was normal in
vang-1 single mutant, we found that
vang-1 genetically interacted with Wnts. The polarity of seam cells is redundantly controlled by four Wnts (
lin-44,
cwn-1,
egl-20 and
cwn-2) (Yamamoto et al 2011). Although, in triple Wnts (
lin-44,
cwn-1 and
egl-20) mutants, polarity of V4 and V6 are almost normal, further mutation of
vang-1 disrupted, polarity of these cells but not V1 or V2. These results suggest that
vang-1 is needed for the long-range signaling of
cwn-2 that is expressed anterior to the V cells. We will further study genetic interactions between
vang-1 and Wnt genes.