Biomedical subjects

Oona Johnstone

Publications and source records attributed to Oona Johnstone.

3 recordsLinked to original sources

PubMed2006

Drosophila RNA binding proteins.

RNA binding proteins are fundamental mediators of gene expression. The use of the model organism Drosophila has helped to elucidate both tissue-specific and ubiquitous functions of RNA binding proteins. These proteins mediate all aspects of the mRNA lifespan including splicing, nucleocytoplasmic transport, localization, stability, translation, and degradation. Most RNA binding proteins fall into several major groups, based on their RNA binding domains. As well, experimental data have revealed several proteins that can bind RNA but lack canonical RNA binding motifs, suggesting the presence of as yet uncharacterized RNA binding domains. Here, we present the major classes of Drosophila RNA binding proteins with special focus on those with functional information.

Amino Acid Sequence↗

PubMed2005

Belle is a Drosophila DEAD-box protein required for viability and in the germ line.

DEAD-box proteins are ATP-dependent RNA helicases that function in various stages of RNA processing and in RNP remodeling. Here, we report identification and characterization of the Drosophila protein Belle (Bel), which belongs to a highly conserved subfamily of DEAD-box proteins including yeast Ded1p, Xenopus An3, mouse PL10, human DDX3/DBX, and human DBY. Mutations in DBY are a frequent cause of male infertility in humans. Bel can substitute in vivo for Ded1p, an essential yeast translation factor, suggesting a requirement for Bel in translation initiation. Consistent with an essential cellular function, strong loss of function mutations in bel are recessive lethal with a larval growth defect phenotype. Hypomorphic bel mutants are male-sterile. Bel is also closely related to the Drosophila DEAD-box protein Vasa (Vas), a germ line-specific translational regulator. We find that Bel and Vas colocalize in nuage and at the oocyte posterior during oogenesis, and that bel function is required for female fertility. However, unlike Vas, Bel is not specifically enriched in embryonic pole cells. We conclude that the DEAD-box protein Bel has evolutionarily conserved roles in fertility and development.

Amino Acid Sequence↗

PubMed2004

Interaction with eIF5B is essential for Vasa function during development.

The DEAD-box RNA helicase Vasa (Vas) is required for germ cell development and function, as well as for embryonic somatic posterior patterning. Vas interacts with the general translation initiation factor eIF5B (cIF2, also known as dIF2), and thus may regulate translation of specific mRNAs. In order to investigate which functions of Vas are related to translational control, we have analyzed the effects of site-directed vas mutations that reduce or eliminate interaction with eIF5B. Reduction in Vas-eIF5B interaction during oogenesis leads to female sterility, with phenotypes similar to a vas null mutation. Accumulation of Gurken (Grk) protein is greatly reduced when Vas-eIF5B interaction is reduced, suggesting that this interaction is crucial for translational regulation of grk. In addition, we show that reduction in Vas-eIF5B interaction virtually abolishes germ cell formation in embryos, while producing a less severe effect on somatic posterior patterning. We conclude that interaction with the general translation factor eIF5B is essential for Vas function during development.

Alleles↗