FUNCTIONAL-ANALYSIS OF CHICKEN VIMENTIN DISTAL PROMOTER REGIONS IN CULTURED LENS CELLS

Synthesis of the cytoskeletal intermediate filament protein vimentin ( Vim) in the lens is unexpected due to the mesenchymal preference of Vi m-encoding gene (Vim) expression and the epithelial origin of the lens . Previous studies indicated that chicken Vim gene expression in cultu red lens cells is regulated by both positive- and negative-acting sequ ence elements within the first -767 nucleotides (nt) of its promoter. Here, we demonstrate the existence of additional upstream chicken Vim promoter elements which function in transfected lens cells. Sequences within the nt -1360/ -1156 region repressed promoter activity in trans fected lens cells to levels lower than that observed for the previousl y defined more proximal repressor elements. The -1612/-1360 region act ivated promoter activity to levels similar to those observed for the s trongest previously defined proximal promoter. The nt sequence analysi s of the upstream promoter region revealed the presence of multiple co nsensus repressor and activator transcription-factor-binding sites. Se veral of these sites have been implicated for lens expression of enzym e-crystallin-encoding genes (cry), suggesting that Vim expression may share features with the cry genes for recruitment and high-level expre ssion in the lens.