CHARACTERIZATION OF THE PROMOTER REGION OF THE HUMAN TRANSFORMING GROWTH-FACTOR-BETA TYPE-II RECEPTOR GENE

Diminished cellular responsiveness to transforming growth factor-beta (TGF-beta) is frequently correlated with decreased transcription of th e type II receptor for TGF-beta (TGF-beta RII). We have cloned and cha racterized the human TGF-beta RII promoter and, using S1 nuclease mapp ing and 5' rapid amplification of cDNA ends polymerase chain reaction, have identified five alternative transcription start sites within the region -33 to +57. DNA transfection experiments and electrophoretic m obility shift assays have revealed the existence of five distinct regu latory regions including two positive regulatory elements and two nega tive regulatory elements in addition to the core promoter region. The first positive regulatory element (-219 to -172) interacts with two di stinct nuclear protein complexes, at least one of which appears to be a previously unidentified transcription factor. The second positive re gulatory element (+1 to +35) also interacts with two separate protein complexes, both of which appear to be novel transcription factors. Del etion of either positive regulatory element markedly decreased express ion of the target gene, suggesting that both positive regulatory eleme nts are necessary for basal expression levels of TGF-beta RII.