A role for RIC-8 (Synembryn) and GOA-1 (G(o)alpha) in regulating a subset of centrosome movements during early embryogenesis in Caenorhabditis elegans

RIG-8 (synembryn) and GOA-1 (G(o)alpha) are key components of a signaling n etwork that regulates neuro-transmitter secretion in Caenorhabditis elegans . Here we show that ric-8 and goa-1 reduction of function mutants exhibit p artial embryonic lethality. Through Nomarski analysis we show that goa-l an d ric-8 mutant embryos exhibit defects in multiple events that involve cent rosomes, including one-cell posterior centrosome rocking, P-1 centrosome fl attening, mitotic spindle alignment, and nuclear migration. In ric-8 reduct ion of function backgrounds, the embryonic lethality, spindle misalignments and delayed nuclear migration are strongly enhanced by a 50% reduction in maternal goa-l gene dosage. Several other microfilament- and microtubule-me diated events, as well as overall embryonic polarity, appear unperturbed in the mutants. In addition, our results suggest that RIG-8 and GOA-1 do not have roles in centrosome replication, ill the diametric movements of daught er centrosomes along the nuclear membrane, or in the extension of microtubu les from centrosomes. Through immunostaining we show that GOA-1 (G(o)alpha) localizes to cell cortices as well as near centrosomes. Our results demons trate that two components of a neuronal signal transduction pathway also pl ay a role in centrosome movements during early embryogenesis.