A DOWNSTREAM AP-1 ELEMENT REGULATES IN-VITRO LUNG TRANSCRIPTION FROM THE HUMAN PULMONARY SURFACTANT PROTEIN-B PROMOTER

We have used the human lung surfactant protein B (SP-B) gene as a temp late for in vitro transcription studies, Transcription factors were pr ovided by nuclear extracts from a cultured line of human lung (type II -like) cells, Elements upstream of -50 had essentially no effect on th e efficiency of the SP-B promoter in vitro, However, a deletion of the region from +8 to +8 reduced in vitro transcription by a factor of 10 , The only factor whose binding was detected between +1 and +100 by fo otprinting, and between +12 and +38 by electrophoretic mobility shift analysis (EMSA), was a member of the AP-1 family, Mutation of 4 of 7 b ases of the AP-1 site reduced transcription two-fold and ablated the A P-1 EMSA binding complex observed on the SP-B downstream region (+12 t o +38), Competition with unlabeled AP-1 consensus oligonucleotide abol ished the downstream footprint over the AP-1 site, Thus, the SP-B prom oter is one of a very small class of RNA polymerase II promoters that are strongly dependent in vitro on sequence elements downstream of the transcription start site, and, in this case, the AP-1 consensus eleme nt and surrounding sequences.