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Shambhu Varma, Svitlana Kovtun; Protective Effect of Caffeine Against High Sugar Induced Transcription of Micro-RNAs and Consequent Gene Silencing. A Study Using Galactosemic Mice Lenses. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2963.
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Previous studies have shown that caffeine prevents the formation of cataracts induced by a high galactose diet and consequent oxidative stress. The objective of this study was to investigate if this protective effect is reflected in the attenuation of the transcription of microRNAs known to induce apoptosis and cell death by gene silencing.
Young CD-1 mice were fed either a normal lab diet or the diet containing 25% galactose without or with1% caffeine. One week later, the animals were sacrificed, lenses isolated and promptly processed for RNA isolation and subsequent preparation of cDNAs by reverse transcriptase reaction. miR specific cDNAs were then quantified by PCR in a 96 well microRNA specific cassette using an ABI7900HT PCR machine.
As expected from previous studies, the lenses were positive for all the 84 miRs corresponding to the microRNA probes present in the cassette wells. However, the transcription of at least 19 miRs were significantly up regulated in galactosemic lenses as compared to that in the normal. The most significant elevations with fold values significantly greater than 2 with respect to normal were in the cases of miR-199, miR-16, miR-126, miR-124, miR-9, miR-872, miR-126, miR-196, miR-182, miR-295,miR-218,miR-385 and miR-374, most of them known to be pro-apoptotic. Such elevations were inhibited significantly by incorporating caffeine in the galactose diet. This has been demonstrated for the first time.
Since aberrant up regulation of microRNAs is well known to cause silencing of various genes and consequent deactivation of protein translation, and since caffeine has been found to down regulate such aberration, it is concluded that the beneficial effect of caffeine against cataract formation induced by sugars could be attributed to its ability to suppress up regulation in the transcription of toxic miRs and consequent gene silencing.
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