Identification of a novel DNA regulatory element in the rabbit surfactant protein B (SP-B) promoter that is a target for ATF/CREB and AP-1 transcription factors

Surfactant protein B (SP-B) is required for the maintenance of biophysical properties and physiological function of pulmonary surfactant. SP-B is expr essed in a cell/tissue-specific manner by the alveolar type II and bronchio lar (Clara) epithelial cells of the lung and is developmentally and hormona lly regulated. We previously identified a minimal promoter region containin g -236/+39 base pairs (bp) of rabbit SP-B gene that is necessary and suffic ient for high level promoter activity in NCl-H441 cells, a cell line with c haracteristics of Clara cells. In this study, we have characterized the fun ctional importance of a novel DNA regulatory element, termed SP-B CRE, with the sequence TGAGGTCA in the SP-B minimal promoter. The SP-B CRE sequence shared homology to cyclic AMP responsive element (CRE) binding sequence and contained an overlapping nuclear receptor element binding half-site. Mutat ion of SP-B CRE into a scrambled sequence reduced promoter activity by grea ter than 70%, whereas mutation into a palindromic consensus CRE increased t he promoter activity by 100%. Electrophoretic mobility shift assay (EMSA) a nd Western immunoblot analysis of affinity purified proteins interacting wi th SP-B CRE showed that it is a target for binding of members of the activa ting transcription factor (ATF)/cyclic AMP response element binding protein (CREB) family of transcription factors, such as CREB, CREM, ATF-1, ATF-2 a s well as c-Jun and TTF-1. Overexpression of CREB, ATF-2 and c-Jun inhibite d SP-B promoter activity in NCl-H441 cells. These data have shown that memb ers of the ATF/CREB family of transcription factors and c-Jun play importan t roles in mediating the transcriptional regulation of the SP-B gene. (C) 2 001 Elsevier Science B.V. All rights reserved.