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Mol. Cell. Biol., 05 1996, 2056-2064, Vol 16, No. 5
MK Ray, CY Chen, RJ Schwartz and FJ DeMayo
This report defines the elements between bp -800 and -166 that regulate the
quantitative level of mouse CC10 (mCC10) transcription in the lungs. The
elements in this promoter domain are the response elements for the NKx2.1
homeobox protein, thyroid transcription factor 1 (TTF1). DNase I footprint
analysis identified five binding sites for TTF1 between bp -800 and - 166.
These sites are located at bp -344 to -335, - 282 to -273, -268 to -263,
-258 to -249, and - 199 to - 190. In addition to these enhancer elements,
two TTF1 binding sites were identified in the proximal promoter region (bp
- 166 to + 1), at bp -74 to -69 and -49 to -39. An identical footprint of
the mCC10 promoter region was also observed with another member of the NKx
family, NKx 2.5, the cardiac muscle-specific homeobox protein (CSX).
Deletion and linker-scanner mutational analyses of the TTF1 binding sites
in the mCC10 distal promoter region with transient cotransfection into CV1
cells with either TTF1 or CSX identified the site located between bp - 282
and -273 as the major regulator of CC10 expression, with minor regulation
by sites at bp -344 to -335 and -258 to -249. The importance of the NKx
binding site at bp -282 to -273 was verified in vivo. Transgenic mice
generated with the human growth hormone gene fused to 800 bp of the mCC10
promoter containing a mutation in the TTF1 binding site at bp -282 to -273
showed a reduction in transgene expression equal to that of the mice
generated with only 166 bp of 5'-flanking DNA. This report emphasizes the
importance of TTF1 or related factors as major regulators of pulmonary gene
expression and demonstrates the potential of NKx proteins to bind and
activate heterologous target genes.
Copyright © 1996, American Society for Microbiology
Transcriptional regulation of a mouse Clara cell-specific protein (mCC10) gene by the NKx transcription factor family members thyroid transciption factor 1 and cardiac muscle-specific homeobox protein (CSX)
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
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