TRANSCRIPTIONAL REGULATION OF THE VIMENTIN-ENCODING GENE IN MOUSE MYELOID-LEUKEMIA M1 CELLS

To investigate the regulatory mechanisms controlling expression of the vimentin-encoding gene (Vim) during mouse myeloid leukemia M1 cell di fferentiation, mouse Vim was cloned and the transcriptional activity o f its 5' promoter region was analysed by chloramphenicol acetyltransfe rase (CAT) assay. Analyses of various deletion mutants revealed that a 188-bp fragment of the proximal Vim promoter (pVim) was sufficient fo r effective transcription in M1 cells. This 188-bp sequence is highly conserved between mouse, hamster and human. Further deletion analyses revealed that a minimum promoter element (-44 to +26) is essential for basic promoter function and could respond to cell differentiation. De tailed analyses of mutant and chimeric pVim constructs defined a CCAAT box at -89 to -84 to be an essential positive regulatory element. A G + C-rich element between the CCAAT and TATA boxes was found to act as a strong negative regulatory element in Vim transcription.