RER, an evolutionarily conserved sequence upstream of the rhodopsin gene, has enhancer activity.
Previous transgenic mouse experiments localized the mammalian rhodopsin gene promoter to a region just upstream of the mRNA start site, and also suggested the existence of a second more distal regulatory region. A highly conserved 100-base pair (bp) sequence which is homologous to the red and green opsin locus control region is located 1.5-2 kilobases upstream of the rhodopsin gene (depending on the species). In order to test the activity of this 100-bp region, transgenic mice were generated with bovine rhodopsin promoter/lacZ constructs which differed only by the presence or absence of the sequence. Of 11 lines generated, all demonstrated photoreceptor-specific expression of the transgene, but the lines with the putative regulatory region showed significantly higher expression. Additional transgenic lines in which the region was fused to a minimal heterologous promoter did not show transgene expression in the retina. Gel mobility shift and DNase I footprint assays demonstrated that bovine retinal nuclear extracts contain retina-specific as well as ubiquitously expressed factors that interact with the putative regulatory region in a sequence-specific manner. These results indicate that the 100-bp sequence can indeed function in vivo as a rhodopsin enhancer region.
Nie
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Department of Ophthalmology, Wilmer Institute, Baltimore, Maryland.
Chen
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S
Kumar
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R
Zack
D J
DJ
D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002417:Cattle; D017124:Conserved Sequence; D004247:DNA; D018983:DNA Footprinting; D003850:Deoxyribonuclease I / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid; D012160:Retina / Q000378:metabolism; D012243:Rhodopsin / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D004247:DNA; D012243:Rhodopsin; D003850:Deoxyribonuclease I