Structural and functional analysis of the mouse mdr1b gene promoter

D. Cohen, R. L. Piekarz, S. I.H. Hsu, R. A. DePinho, N. Carrasco, S. B. Horwitz

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Abstract

The overproduction of P-glycoprotein, an integral membrane protein thought to function as a drug efflux pump, is the hallmark of the multidrug resistance phenotype. In murine multidrug resistant J774.2 cell lines, distinct mdr genes, mdr1a and mdr1b, encode unique P-glycoprotein isoforms. To examine the transcriptional regulation of the mdr1b gene, its promoter was isolated and characterized. The transcription initiation site was mapped by primer extension, and the 5'-flanking region was sequenced. Several potential regulatory elements were identified in this region. A transient expression vector was constructed by fusion of 540 base pairs of 5'-flanking sequence and part of the first untranslated exon to the chloramphenicol acetyltransferase (CAT) gene. When transfected into monkey kidney COS-1, rat pituitary GH3 or T47D human breast cells, the mdr1b 5'-flanking sequences were capable of driving CAT expression. Transient transfection studies using deletion subclones of the mdr1b-CAT construct were done to locate potential cis-acting sequences. The studies indicate the presence of cis-acting elements in the 5'-flanking region of the mdr1b gene. The implications of these findings for expression and regulation of the mdr1b gene are discussed.

Original languageEnglish (US)
Pages (from-to)2239-2244
Number of pages6
JournalJournal of Biological Chemistry
Volume266
Issue number4
Publication statusPublished - Aug 6 1991

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Cohen, D., Piekarz, R. L., Hsu, S. I. H., DePinho, R. A., Carrasco, N., & Horwitz, S. B. (1991). Structural and functional analysis of the mouse mdr1b gene promoter. Journal of Biological Chemistry, 266(4), 2239-2244.