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The Journal of Neuroscience, September 6, 2006, 26(36):9153-9161; doi:10.1523/JNEUROSCI.1384-06.2006

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Development/Plasticity/Repair
Photic Regulation of Arylalkylamine N-Acetyltransferase Binding to 14-3-3 Proteins in Retinal Photoreceptor Cells

Nikita Pozdeyev,¹ Carla Taylor,¹ Rashidul Haque,¹ Shyam S. Chaurasia,¹ Amy Visser,¹ Aamera Thazyeen,¹ Yuhong Du,¹ Haian Fu,¹ Joan Weller,³ David C. Klein,³ and P. Michael Iuvone^1,2

¹Departments of Pharmacology and ²Ophthalmology, Emory University School of Medicine, Atlanta, Georgia 30322, and ³Laboratory of Neuroendocrinology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480

Correspondence should be addressed to P. Michael Iuvone, Department of Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322. Email: miuvone{at}pharm.emory.edu

14-3-3 proteins are a ubiquitous, highly conserved family of chaperone proteins involved in signal transduction, regulation of cell cycle, intracellular trafficking/targeting, cytoskeletal structure, and transcription. Although 14-3-3 proteins are among the most abundant proteins in the CNS, very little is known about their functional roles in the vertebrate retina. In the present study, we demonstrated that photoreceptors express 14-3-3 protein(s) and identified a 14-3-3 binding partner in photoreceptor cells, the melatonin-synthesizing enzyme arylalkylamine N-acetyltransferase (AANAT). Importantly, our data demonstrate that the binding of 14-3-3 to AANAT is regulated by light, with dramatic functional consequences. During the night in darkness, retinal AANAT is phosphorylated and forms a complex with 14-3-3 proteins with an apparent molecular weight of 90 kDa. Phosphorylation of AANAT facilitates the binding of enzyme to 14-3-3 proteins. Within the complex, AANAT is catalytically activated and protected from dephosphorylation and degradation. Light disrupts the AANAT/14-3-3 complex, leading to catalytic inactivation, dephosphorylation, and proteolytic degradation of the enzyme. In the presence of the proteasome inhibitor, lactacystin, light results in the formation of a high molecular weight complex (>150 kDa), which may represent an intermediate in the AANAT degradation process. These findings provide new insight into the roles of 14-3-3 proteins in photoreceptor cells and to the mechanisms controlling melatonin synthesis in the vertebrate retina.

Key words: arylalkylamine-N-acetyltransferase; melatonin; 14-3-3 proteins; retina; photoreceptors; phosphorylation; light

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Received Dec. 8, 2005; revised July 31, 2006; accepted Aug. 1, 2006.

Correspondence should be addressed to P. Michael Iuvone, Department of Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322. Email: miuvone{at}pharm.emory.edu

This article has been cited by other articles:

				D. C. Klein Arylalkylamine N-Acetyltransferase: "the Timezyme" J. Biol. Chem., February 16, 2007; 282(7): 4233 - 4237. [Abstract] [Full Text] [PDF]

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