GPR-1/2 support unequal division

Polarity is set early on—even single cell stage embryos already know their front from back. Recent research by the laboratory of Pierre Gönczy (Swiss Institute for Experimental Cancer Research, Lausanne, Switzerland) is identifying how this polarity is translated into differences in cell behavior.

Polarity in worm embryos, which is set by the PAR proteins, produces an unequal first mitotic division, and thus a small posterior and large anterior blastomere. A previous screen by Gönczy identified two proteins, GPR-1 and GPR-2, necessary for this unequal division. Although direct interactions between PARs and GPR-1/2 have not been demonstrated, Kelly Colombo, Gönczy, and colleagues now demonstrate an asymmetric GPR-1/2 distribution that depends on PAR proteins. Higher levels of GPR-1/2 in the posterior are proposed to activate two Gα subunits. The group...