Asymmetric localizations of LIN-17/Fz and MIG-5/Dsh are involved in the asymmetric B cell division in C. elegans

LIN-44/Wnt and LIN-17/Frizzled (Fz) function in a planar cell polarity (PCP)-like pathway to regulate the asymmetric B cell division in Caenorhabditis elegans. We observed asymmetric localization of LIN-17/Frizzled (Fz) and MIG-5/Dishevelled (Dsh) during the B cell division. LIN-17∷GFP was asymmetrically localized within the B cell prior to and after the B cell division and correlated with B cell polarity. Asymmetric localization of LIN-17∷GFP was dependent upon LIN-44/Wnt and MIG-5/Dsh function. The LIN-17 transmembrane domain and a portion of the cysteine-rich domain (CRD) were required for LIN-17 function and asymmetric distribution to the B cell daughters, while the conserved KTXXXW motif was only required for function. MIG-5∷GFP was also asymmetrically localized within the B cell prior to and after the B cell division in a LIN-17- and LIN-44-dependent manner. Functions of the MIG-5 DEP, PDZ and DIX domains were also conserved. Thus, a novel PCP-like pathway, in which LIN-17 and MIG-5 are asymmetrically localized, is involved in the regulation of B cell polarity.