Melatonin synthesis in retina: cAMP-dependent transcriptional regulation of chicken arylalkylamine N-acetyltransferase (Aanat) by a CRE-like sequence (CLS) and a TTATT repeat motif in the proximal promoter
| Autor: | Haque, Rashidul, Chong, Nelson W., Ali, Fatima, Chaurasia, Shyam S., Sengupta, Trisha, Chun, Eugene, Howell, Jennifer C., Klein, David C., Iuvone, P. Michael |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Cell Nucleus
Chromatin Immunoprecipitation 5' Flanking Region Proto-Oncogene Proteins c-jun Electrophoretic Mobility Shift Assay Chick Embryo Transfection Arylalkylamine N-Acetyltransferase Article Gene Expression Regulation Enzymologic Retina Cyclic AMP Mutagenesis Site-Directed Animals RNA Small Interfering Cyclic AMP Response Element-Binding Protein Luciferases Promoter Regions Genetic Proto-Oncogene Proteins c-fos Cells Cultured DNA Primers Melatonin Repetitive Sequences Nucleic Acid |
| Popis: | Arylalkylamine N-acetyltransferase (AANAT) is the key regulatory enzyme controlling the daily rhythm of melatonin biosynthesis. In chicken retinal photoreceptor cells, Aanat transcription and AANAT activity are regulated in part by cAMP-dependent mechanisms. The purpose of this study was to identify regulatory elements within the chicken Aanat promoter responsible for cAMP-dependent induction. Photoreceptor-enriched retinal cell cultures were transfected with a luciferase reporter construct containing up to 4 kb of 5'-flanking region and the first exon of Aanat. Forskolin treatment stimulated luciferase activity driven by the ∼4 kb promoter construct and by all 5'-deletion constructs except the smallest, Aanat (-217 to +120)luc. Maximal basal and forskolin-stimulated expression levels were generated by the Aanat (-484 to +120)luc construct. This construct lacks a canonical cyclic AMP-response element (CRE), but contains two other potentially important elements in its sequence: an eight times TTATT repeat (TTATT₈) and a CRE-like sequence. Electrophoretic mobility shift assays, luciferase reporter assays, chromatin immunoprecipitation, and siRNA experiments provide evidence that these elements bind c-Fos, JunD, and CREB to enhance basal and forskolin-stimulated Aanat transcription. We propose that the CRE-like sequence and TTATT₈ elements in the 484 bp proximal promoter interact to mediate cAMP-dependent transcriptional regulation of Aanat. |
| Databáze: | OpenAIRE |
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