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Author Notes:

Address correspondence to: P. Michael Iuvone, Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia 30322. Fax: 404-778-2231, miuvone@emory.edu (miuvone); rhaque@emory.edu (rhaque)

Present Address S.C.: Translational Clinical Research Lab, Singapore Eye Research Institute, Singapore.

Subjects:

Research Funding:

The research was supported by NIH grants R01EY004864 (PMI), P30EY006360 (PMI), funds from the Intramural Research Program of the Eunice Shriver Kennedy National Institute of Child Health and Human Development (DCK), and an unrestricted departmental grant from Research to Prevent Blindness (RPB). PMI is a recipient of the Senior Scientific Investigator Award from RPB. NWS is supported by the BBSRC UK (G18273).

Keywords:

  • CRE
  • AP1
  • cAMP
  • CREB
  • circadian rhythm
  • arylalkylamine N-acetyltransferase
  • Aanat
  • gene regulation
  • retina
  • melatonin
  • JunD
  • cFos

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

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Journal Title:

Journal of Neurochemistry

Volume:

Volume 119, Number 1

Publisher:

, Pages 6-17

Type of Work:

Article | Post-print: After Peer Review

Abstract:

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 4kb of 5′-flanking region and the first exon of Aanat. Forskolin treatment stimulated luciferase activity driven by the ~4kb 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 (CLS). Electrophoretic mobility shift assays (EMSA), 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 CLS and TTATT8 elements in the 484 bp proximal promoter interact to mediate cAMP-dependent transcriptional regulation of Aanat.

Copyright information:

© 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry

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