The mRNA cap-binding protein eIF4E participates in mRNA translation, masking, nucleocytoplasmic shuttling, and turnover. Multiple isoforms of eIF4E are expressed in metazoans, yet individual roles are unknown. We investigated one C. elegans isoform, IFE-4, which has orthologues in plants and mammals. IFE-4 is present in 48S initiation complexes, indicating that it participates in protein synthesis initiation. IFE-4::GFP was expressed in neurons and muscle from pharynx, vulva, tail, body wall, and spermatheca. Knockout of
ife-4 by RNAi or a null mutation (
ife-4) caused defects in egg-laying, brood size, food sensation, and response to serotonin. mRNAs affected by
ife-4 knockout were determined by DNA microarray analysis of polysomal distribution, which is an indicator of translational efficiency. Polysome shifts, in the absence of total mRNA changes, were observed for only 33 of the 18,967 mRNAs tested. A disproportionate number of these were related to egg laying and were expressed in neurons and/or muscle. Translational regulation of three candidate mRNAs was confirmed by reduced protein levels of DAF-12, EGL-15, and KIN-29. To discover common features among mRNAs affected by
ife-4 knockout, we applied two algorithms, a classical scatter plot and a self-organizing map (SOM), to two heterogeneous datasets. The first dataset contained differences in polysomal distribution between
ife-4 and N2 worms for all mRNAs. The second dataset contained published expression patterns of mRNAs across developmental stages. Genes in the first dataset were partitioned according to changes in polysomal distribution, whereas genes in the second dataset were clustered according to developmental expression pattern. The outputs of the two algorithms were then linked using a two-dimensional color scale. This revealed a correlation between an mRNAs IFE-4-dependent translational efficiency and developmental expression pattern. mRNAs showing the strongest dependence on IFE-4 progressively increased in level from embryos to L4 and then decreased in adults. However, the converse was not true: most mRNAs with this expression pattern were not dependent on IFE-4. Thus, developmental expression pattern is only one of multiple factors (yet to be discovered) determining an mRNAs dependence on IFE-4 for efficient translation. (Supported by NIH Grant GM20818.)