Ksp-cadherin gene promoter. I. Characterization and renal epithelial cell-specific activity

DA Whyte, C Li, RB Thomson, SL Nix… - American Journal …, 1999 - journals.physiology.org
DA Whyte, C Li, RB Thomson, SL Nix, R Zanjani, SL Karp, PS Aronson, P Igarashi
American Journal of Physiology-Renal Physiology, 1999journals.physiology.org
Kidney-specific cadherin (Ksp-cadherin, cadherin 16) is a novel, kidney-specific member of
the cadherin superfamily that is expressed exclusively in the basolateral membrane of renal
tubular epithelial cells. To characterize the Ksp-cadherin gene promoter, a λ bacteriophage
clone containing 3.7 kb of the proximal 5′ flanking region of the mouse Ksp-cadherin gene
was isolated. The transcription initiation site was mapped by RNase protection assays and
5′ rapid amplification of cDNA ends, and a 709-bp intron was identified within the 5 …
Kidney-specific cadherin (Ksp-cadherin, cadherin 16) is a novel, kidney-specific member of the cadherin superfamily that is expressed exclusively in the basolateral membrane of renal tubular epithelial cells. To characterize the Ksp-cadherin gene promoter, a λ bacteriophage clone containing 3.7 kb of the proximal 5′ flanking region of the mouse Ksp-cadherin gene was isolated. The transcription initiation site was mapped by RNase protection assays and 5′ rapid amplification of cDNA ends, and a 709-bp intron was identified within the 5′ untranslated region. The proximal 5′ flanking region was “TATA-less” but contained other consensus promoter elements including an initiator (Inr), GC boxes, and a CAAT box. Potential binding sites were identified for transcription factors that are involved in tissue-specific gene expression including activator protein-2 (AP-2), hepatocyte nuclear factor-3 (HNF-3), basic helix-loop-helix (bHLH) proteins, CCAAT/enhancer-binding protein (C/EBP), and GATA factors. Transfection of luciferase reporter plasmids containing 2.6 kb of the 5′ flanking region markedly increased luciferase activity in renal epithelial cells (MDCK and mIMCD-3) but not in mesenchymal cells (NIH 3T3 and MMR1). Deletion analysis identified an 82-bp region from −31 to −113 that was essential for promoter activity in transfected renal epithelial cells. Electrophoretic mobility-shift assays showed that mIMCD-3 cells contain nuclear proteins that bind to this region of the promoter. Mutational analysis showed that sequences within the HNF-3 consensus site and CAAT box were involved in protein binding and promoter activity. We conclude that the proximal 5′ flanking region of the mouse Ksp-cadherin gene contains an orientation-dependent promoter that is kidney epithelial cell specific. The region of the promoter from −113 to −31 is required for transcriptional activity and contains binding sites for nuclear proteins that are specifically expressed in renal epithelial cells.
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