IDENTIFICATION OF A FUNCTIONAL PROMOTER ELEMENT IN THE 5'-FLANKING REGION OF THE RAT CMG1 TIS11B GENE/

The cMG1 gene was originally identified as a mitogen-stimulated primar y response gene. However, in contrast to genes such as c-fos and TIS11 , cMG1 is also expressed at significant levels before and after the tr ansient elevation induced by agonists. We have sequenced a 1.3 kb rat genomic cMG1 clone, which includes 931 bp upstream of the transcriptio n start site identified by primer-extension analysis. A 1033 bp fragme nt, including this 5'-flanking sequence, directed the expression of th e reporter gene chloramphenicol acetyltransferase (CAT) in transfected NIH-3T3 cells. Progressive 5'-to-3' deletion indicated that an elemen t located between -138 and -114 was responsible for most of this basal CAT expression. DNA mobility-shift assays showed that the sequence be tween -143 and -105 contained binding sites for cellular proteins, the principal complexes involving nucleotides between -119 and - 105. We conclude that these complexes may represent the transcription factor-D NA element interactions that determine basal cMG1 expression.