Melatonin synthesis in retina: cAMP-dependent transcriptional regulation of chicken arylalkylamine N-acetyltransferase by a CRE-like sequence and a TTATT repeat motif in the proximal promoter. J Neurochem 2011 Oct;119(1):6-17
Date
07/28/2011Pubmed ID
21790603Pubmed Central ID
PMC3377444DOI
10.1111/j.1471-4159.2011.07397.xScopus ID
2-s2.0-84860416511 (requires institutional sign-in at Scopus site) 22 CitationsAbstract
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.
Author List
Haque R, Chong NW, Ali F, Chaurasia SS, Sengupta T, Chun E, Howell JC, Klein DC, Iuvone PMAuthor
Shyam S. Chaurasia PhD Professor in the Ophthalmology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
5' Flanking RegionAnimals
Arylalkylamine N-Acetyltransferase
Cell Nucleus
Cells, Cultured
Chick Embryo
Chromatin Immunoprecipitation
Cyclic AMP
Cyclic AMP Response Element-Binding Protein
DNA Primers
Electrophoretic Mobility Shift Assay
Gene Expression Regulation, Enzymologic
Luciferases
Melatonin
Mutagenesis, Site-Directed
Promoter Regions, Genetic
Proto-Oncogene Proteins c-fos
Proto-Oncogene Proteins c-jun
RNA, Small Interfering
Repetitive Sequences, Nucleic Acid
Retina
Transfection
