Localization of ribosomes and translation initiation factors to talin/β3‐integrin‐enriched adhesion complexes in spreading and migrating mammalian cells

Abstract

The spatial localization of translation can facilitate the enrichment of proteins at their sites of function while also ensuring that proteins are expressed in the proximity of their cognate binding partners. Using human embryonic lung fibroblasts and employing confocal imaging and biochemical fractionation techniques, we show that ribosomes, translation initiation factors and specific RNA-binding proteins localize to nascent focal complexes along the distal edge of migrating lamellipodia. 40S ribosomal subunits appear to associate preferentially with beta3 integrin in focal adhesions at the leading edges of spreading cells, with this association strongly augmented by a synergistic effect of cell engagement with a mixture of extracellular matrix proteins. However, both ribosome and initiation factor localizations do not require de novo protein synthesis. Taken together, these findings demonstrate that repression, complex post-transcriptional regulation and modulation of mRNA stability could potentially be taking place along the distal edge of migrating lamellipodia.