EVIDENCE FOR A LOCALIZATION SIGNAL IN THE 3'-UNTRANSLATED REGION FROMVIMENTIN MESSENGER-RNA

There is increasing evidence that some mRNAs are localised in eukaryot ic somatic cells, but it is unclear what proportion of mRNAs are local ised and whether this sorting involves 3'-untranslated sequences. The presence of a localisation signal within the 3'-untranslated region of vimentin mRNA was investigated by studying mRNA distribution in fibro blasts transfected with beta-globin and hybrid globin-vimentin gene co nstructs. In cells transfected with constructs containing either a fra gment of the rabbit beta-globin gene containing both coding sequences and 3'untranslated region or the beta-globin coding sequences alone in situ hybridisation showed that beta-globin mRNA was distributed throu ghout the cytoplasm without any evident localisation. In contrast, in cells transfected with globin coding sequences linked to the vimentin 3'-untranslated region there was a strong perinuclear localisation of the hybrid mRNA. The results show that loss of its endogenous 3'-untra nslated region does not affect distribution of beta-globin mRNA wherea s the vimentin 3'-untranslated region causes an altered localisation o f beta-globin mRNA. We conclude that the vimentin 3'-untranslated regi on contains a localisation signal which can direct reporter sequences to the perinuclear cytoplasm. (C) 1997 Elsevier Science Ltd.