A transcriptional enhancer of the glutamine synthetase gene that is selective for retinal Müller glial cells.
This article demonstrates that the chicken glutamine synthetase (GS) promoter contains cis-acting elements that direct transcription to retinal Müller glial cells. The transient assay system developed to identify these elements involved electroporation of intact retinal tissue with GS-beta-galactosidase fusion genes followed by preparation of primary cultures and histochemical assay of cells expressing beta-galactosidase. Plasmids containing beta-galactosidase under transcriptional control by two different viral promoters are expressed primarily in neuronal cells after transfection of intact embryonic d 12 retina. In sharp contrast, expression is primarily in Müller glia after transfection with a GS-beta-galactosidase fusion gene. Although GS is glucocorticoid inducible, steroid hormone is not required to achieve Müller cell-selective expression of the GS-beta-galactosidase fusion gene. Deletion studies indicate that multiple cis-acting elements located between nucleotides-436 and -61 relative to the GS transcription start site contribute to produce Müller cell selectivity. Moreover, these upstream elements enhance expression of a heterologous promoter in Müller cells not neurons. These results indicate that an enhancer located between 61 and 436 nucleotides upstream of the transcription start site contributes to Müller cell-selective expression of the GS gene in the retina.
Li
Y C
YC
Division of Pharmacology, College of Pharmacy, Ohio State University, Columbus 43210, USA.
Beard
D
D
Hayes
S
S
Young
A P
AP
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured / Q000201:enzymology; D002645:Chickens; D018274:Electroporation; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D017930:Genes, Reporter; D005816:Genetic Complementation Test; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012160:Retina / Q000166:cytology*; D014158:Transcription, Genetic / Q000235:genetics; D014760:Viral Fusion Proteins / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics
D014760:Viral Fusion Proteins; D001616:beta-Galactosidase; D005974:Glutamate-Ammonia Ligase