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J. R. Leheste, B. H. Hallas, G. Torres; SIRT1 Activation Affects the Transmission of Photoperiodic Information by Melatonin. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3235.
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© ARVO (1962-2015); The Authors (2016-present)
The mammalian protein deacetylase SIRT1 (Sirtuin1) is a key factor involved in cellular health and longevity. SIRT1 function can be efficiently activated by a calorie restriction (CR) diet or the CR mimetic resveratrol. SIRT1 is known to modify the function of protein targets ranging from transcription factors to histones of the nucleosome. We recently identified endogenous DNA targets of SIRT1 with function in the central nervous system (CNS). The gene encoding the membrane-bound G protein-coupled receptor 50 (GPR50) is of particular interest because of its ability to heterodimerize with the melatonin receptor 1 (MT1), causing inhibition of receptor function. Disturbances in melatonin signaling are implicated in mood disorders, such as seasonal affective and bipolar disorder. Our project investigates the effect of resveratrol-dependent SIRT1 activation on gpr50 gene expression and the consequences for photoperiodic melatonin signaling.
Resveratrol is used to activate SIRT1 in human HEK-293 cells (50mM, 48hours) and mature Sprague-Dawley rats (1g/kg food, 29 days). Quantitative PCR (QPCR), measuring sirt1 and gpr50 expression, is performed with cDNA generated from HEK-293 cells or rat frontal cortex. As control, gpr50 expression is modified in HEK-293 cells by either overexpression or RNA interference (RNAi). Phospholipase C (PLC) activity is used to determine the impact of resveratrol-dependent SIRT1 activation, GPR50 overexpression, or RNAi on melatonin-dependent signal transduction through MT1.
Following activation through resveratrol, the expression of sirt1 increases approximately 2.5-fold in HEK-293 cells and remains unchanged in rat frontal cortex. At the same time, gpr50 expression increases about 5-fold in HEK-293 cells and 2-fold in rat frontal cortex. Expression of gpr50 further correlates with PLC activity in HEK-293 cells.
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