Tissue-specific expression of two mRNA species transcribed from a single vimentin gene.

We have isolated chicken cDNA and genomic clones for the intermediate filament subunit vimentin and show that the gene for this protein, which exists in a single copy in the haploid chicken genome, is transcribed into two mature mRNA species with approximate lengths of 2.0 and 2.3 kb. We have found cell-specific regulation in the expression of these two mRNAs; whereas both mRNA species are present in muscle cells, fibroblasts, spinal cord and lens, erythroid cells from 10- and 15-day-old chicken embryos express predominantly the lower molecular weight RNA. The difference between these two mRNAs is due to different lengths of their 3' untranslated regions, suggesting that the cell-specific regulation of their expression occurs either by specific termination of transcription or by differential post-transcriptional processing of the 3' untranslated region. Additionally, a remarkable induction (40- to 50-fold) in the abundance of the vimentin mRNA is observed in erythroid cells as chicken development proceeds from 4 to 15 days, which suggests that the level of expression of vimentin during erythroid development is regulated at the transcriptional level.