Localization of upstream silencer elements involved in the expression of cone transducin alpha-subunit (GNAT2).
Invest Ophthalmol Vis Sci
; 38(1): 196-206, 1997 Jan.
Article
em En
| MEDLINE
| ID: mdl-9008644
ABSTRACT
PURPOSE:
To localize cis-acting elements involved in the expression of the cone-specific G-protein, cone transducin alpha-subunit (GNAT2).METHODS:
In this study, the authors used a genomic clone, HGLG3, to sequence 3139 base pairs of the upstream region of the GNAT2 gene and to localize cis-acting elements involved in the expression of GNAT2. Upstream elements were localized functionally by transfection of chloramphenicol acetyltransferase gene constructs containing nested deletions of this upstream region into WERI-Rb1 cells. Cell specificity of the localized elements was determined by transfection of the HeLa cells. Trans-acting factor-binding sites to functional cis-acting elements were determined by DNasel footprinting. Cell specificity of protein interaction with footprinted regions was tested by electrophoretic mobility shifts with nuclear extracts from WERI-Rb1 and HeLa cells.RESULTS:
Transfection of WERI-Rb1 and HeLa cells revealed the presence of a strong, noncell-specific silencer region between -1130 and -23, a weak, cell-specific promoter between -151 and -10, and a stronger, noncell-specific element between +143 and +167. DNaseI footprinting showed three major footprints (S1, S2, and S3) between -807 and -176, indicating the binding sites for putative negative trans-acting factors. Individual footprinted sequences had similar electrophoretic mobility shifts when they were incubated with nuclear extracts from either WERI-Rb1 or HeLa cells, suggesting that these cells express the same negative factors.CONCLUSIONS:
The expression of the GNAT2 gene is controlled by a strong silencer region, a weak upstream cell-specific promoter, and a strong downstream element. The silencer region interacts with similar proteins from retina- and nonretina-derived cell lines.
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Base de dados:
MEDLINE
Assunto principal:
Transducina
/
Expressão Gênica
/
Elementos Facilitadores Genéticos
/
Células Fotorreceptoras Retinianas Cones
/
Proteínas do Olho
Limite:
Humans
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article