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Natàlia Vilà, Pablo Zoroquiain, Shawn C Maloney, Ana Beatriz Toledo Dias, Emilia Antecka, Miguel N Burnier; SIRTUINS ARE DIFFERENTIALLY EXPRESSED IN DISTINCT RETINAL LAYERS. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1853.
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© ARVO (1962-2015); The Authors (2016-present)
While recent studies have indicated a role for Sirtuins (SIRT) in biological processes, including metabolic diseases, cancer, diabetes and aging, the exact nature of SIRT functions has not been elucidated. Moreover, their function and expression in normal ocular tissues remain unknown. The aim of this study is to evaluate the expression of all sirtuin proteins (SIRT1-7) in normal human retinas.
Twenty-three formalin-fixed, paraffin-embedded normal donor eyes (mean age = 72+/- 21.7 years), were evaluated in this study. Immunohistochemistry was performed on serial sections of all eyes with antibodies against each of the seven individual sirtuins (SIRT1-7). Staining was graded semi-quantitatively in the macula area and peripheral retina based on the intensity (negative=0, weak=1, strong=2) and extent (negative=0, staining ≤50% of cells=1, staining >50% of cells=2). A combined score was calculated to describe the expression for each sirtuin using the following equation: 2 x expression x intensity. Results were expressed in the following manner: 0 to 2=negative, 3 to 4= weak expression, ≥5 = strong expression.
All sirtuins were expressed in all of the studied retinas; however, the staining score differed for each sirtuin across the various retinal layers assessed. The retinal pigment epithelium (RPE) expressed SIRT-4, 6 and 7. SIRT-6 was strongly positive only in the macula, and both SIRT-4 and -7 were also strongly positive in the macula and peripheral retina. The inner nuclear layer (INL) weakly expressed SIRT-3 throughout the retina. The outer nuclear layer (ONL) was the sole structure that was negative for all sirtuins. No significant differences were found between macular and peripheral retina in the same layer, except for SIRT-6 in RPE, which was strongly expressed in the macula while negative in the peripheral retina (p<0.05).
Our data provides an overview of the expression of sirtuins in normal human retinas. SIRT-3 was the only sirtuin protein found in the inner nuclear layer, while no sirtuins were expressed in the outer nuclear layer of the retina. These results serve as a foundation for further research into the roles of sirtuins in normal and diseased retina.
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