De. Handy et H. Gavras, EVIDENCE FOR CELL-SPECIFIC REGULATION OF TRANSCRIPTION OF THE RAT ALPHA(2A)-ADRENERGIC RECEPTOR GENE, Hypertension, 27(4), 1996, pp. 1018-1024
We investigated the transcriptional activity of the -131 to -92 region
of the rat alpha(2A)-adrenergic receptor gene. In HT29 cells, this re
gion has a positive effect on transcription, whereas in RINm5F cells,
this region has a negative effect on transcription. The -131 to -92 re
gion has a GC box (GGGGCGG) surrounded by overlapping GGAGG repeats. T
o analyze nuclear factor binding to this region, we made a series of s
equence substitutions in the GGAGG repeats, the GC box, or botti regio
ns. Gel mobility shift assays indicated that most of the nuclear facto
r complexes formed between the wild-type -131/-92 sequence and either
HT29 or RINm5F extracts were specific for Sp1 or related proteins that
recognize a GC box. Mutation of either the GGAGG repeats or the GC bo
x did not eliminate the binding of Spl or related nuclear factors, sug
gesting that both the GGAGG repeats and the GC box could bind Sp1-rela
ted factors. Mutation of both these sites eliminated the binding of Sp
1-related factors. In the absence of Sp1 binding sites, this region ha
d a negative effect on transcription in HT29 and a positive effect on
transcription in RINm5F cells. These data support the notion that Sp1
and/or a related factor may control both positive and negative gene ex
pression and suggest that the -131/-92 region may be involved in regul
ating tissue-specific levels of alpha(2A)-adrenergic receptor gene exp
ression.