Down-regulation of vimentin gene expression during myogenesis is controlled by a 5'-flanking sequence.

During myogenesis, the intermediate filament proteins vimentin and desmin are differentially expressed. While desmin levels increase dramatically, vimentin mRNA levels decrease substantially. Here, we show that transfected whole- and mini-vimentin-coding genes (Vim) are expressed in fibroblasts (mouse L cells) and down-regulated during muscle cell differentiation in culture. Functional assays with 5'-end Vim::cat constructs demonstrate that this repression is controlled by a 5'-element (nt -321 to -160). This region is distinct from Vim promoter elements (nt -160 to +71) which do not contribute to vimentin's down-regulation during myogenesis.