Cell-cell signalling, microtubule organization and RNA localization: is PKA a link?

Specification of the anterior-posterior axis of the Drosophila embryo is brought about by the asymmetric localization of specific maternally expressed RNAs and proteins within the oocyte. While many of these localized molecules have been identified and progress has been made towards understanding their functions, how the localization process is instigated remains unclear. A recent paper reports that protein kinase A (PKA) activity is essential for many of these RNA localizations and for the correct polarization of the microtubule cytoskeleton. These and other results support a model for anterior-posterior axis establishment which involves intercellular signalling between the oocyte and certain neighbouring somatic cells.