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D.–A.M. Pillers, B. Malmin, J. Pang; Promoter of Retinal Dystrophin Dp260 Includes Glucocorticoid Response Elements and in vitro Expression Can Be Manipulated By Steroids . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3075.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Dystrophin is the product of the DMD (Duchenne muscular dystrophy) gene. Several isoforms of dystrophin have been identified, including Dp260, the retinal isoform. Dp260 plays a role in normal retinal electrophysiology. We sought to identify any regulatory elements within the Dp260 promoter that could be used to manipulate its expression. Methods: A human genomic fragment from a cosmid clone containing the first exon of Dp260 was characterized, and a fragment was subcloned in a pGL2 luciferase reporter vector that was transfected into cell lines Y79 (retinoblastoma), HeLa, COS–7, and C2 (myoblast) for assays of transcription and pharmacologic intervention. Results: Sequence analysis using the TESS (Transcription Element Search System) identified a glucocorticoid response element (GRE). Exposure of transfected cell lines to methylprednisolone resulted in upregulation of activity as demonstrated by relative luciferase activity: Y79 (2 fold), HeLa (6 fold) and C2 (6 fold). COS–7 transfects showed no effect after steroid exposure, as expected for this GR defective cell line. Conclusions: The retinal dystrophin Dp260 promoter includes a GRE which when exposed to steroids in vitro leads to upregulation of Dp260 transcription. Use of the GRE is a novel finding for a gene expressed in retina and a novel finding for dystrophins. In clinical studies, steroidal agents have been associated with improvement in muscle disease in some DMD individuals. The impact of such treatment on retinal function and electrophysiology merits investigation.
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