During Drosophila oogenesis, two different isoforms of Squid (Sqd)– a heterogeneous nuclear ribonucleoprotein (hnRNP) – regulate the localisation and translation of gurken (grk) mRNA, whose restriction to the dorsal anterior region of the oocyte is crucial for establishing the dorsoventral axis. On , Goodrich and colleagues investigate the mechanism by which Sqd regulates grkexpression. They show that another hnRNP, Hrb27C, together with the protein Ovarian tumour (Otu), interacts with Sqd to localise grk mRNA. Unexpectedly, hrb27C, sqd and otu mutants also have defective nurse-cell polytene chromosome dispersion. Normally, the visible polytene chromosomes of nurse cells disperse during early oogenesis, possibly to facilitate rapid ribosome synthesis. The researchers go on to propose a model in which Sqd, Hrb27C and Otu function in a single RNP complex that spatially and temporally regulates different RNA targets in different cell types.
