| Summary: | 博士 === 國立陽明大學 === 臨床醫學研究所 === 100 === Silent information regulator T1 (SirT1), a member of the sirtuin family, is a NAD-dependent histone deacetylase and an essential cellular mediator for longevity. We firstly investigate the SirT1 mRNA expression in retinal stem cells from rats and human eyes of different ages. SirT1 expression was significantly decreased in in vivo aged eyes, associated with poor self-renewal abilities. The expression of SirT1 on oxidative stress-induced damage was significantly decreased, negatively correlated with the level of intracellular reactive oxygen species (ROS) production. Importantly, the anti-oxidant effects of resveratrol in hydrogen peroxide-treated retinal stem cells were significantly abolished by knockdown of SirT1 expression (sh-SirT1). SirT1 expression provides a feasible sensor in assessing self-renewal and aging process in
retinal stem cells.
In addition, both SirT1 and Oct4 (SirT1/Oct4) expression was decreased in an age-dependent manner in retina and retinal pigment epithelium cells (RPEs) with aged-related macular degeneration. To investigate the possible rescuing role of SirT1/Oct4, polyurethane-short branch polyethylenimine (PU-PEI) was used to co-overexpress SirT1/Oct4 on aged RPEs (aRPEs) or light-injured rat retinas.
SirT1/Oct4 overexpression increased the expressions of several progenitor-related genes and the sphere-formation ability of aRPE cells. Microarray analysis further suggested that the gene expression profile of SirT1/Oct4-overexpressing aRPE cells was similar to that of retinal progenitor-related transcriptome. Moreover, SirT1/Oct4 overexpression enhanced antioxidant enzyme activities, which was accompanied by a decrease in intracellular ROS production and hydrogen peroxide-induced oxidative stress. Importantly, PU-PEI-mediated SirT1/Oct4 gene transfer rescued retinal cell loss and improved electroretinographic responses in light-injured rat retinas. In summary, these data suggest that PU-PEI-mediated delivery of SirT1/Oct4 reprograms aRPEs into a more primitive state and results in cytoprotection by regulating the antioxidative capabilities of these cells. All these data indicated that SirT1 play a novel role in assessing retinal stem cell self-renewal and regulating the anti-oxidative capability of aRPE cells.
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