title: Protective effect of caffeine against high sugar-induced transcription of microRNAs and consequent gene silencing: a study using lenses of galactosemic mice.
abstract: OBJECTIVE
  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 (miRNAs) known to induce apoptosis and cell death by gene silencing.
  
  
  METHODS
  Young CD-1 mice were fed either a normal laboratory diet or a diet containing 25% galactose with or without 1% caffeine. One week later, the animals were euthanized, and the lenses isolated and promptly processed for RNA isolation and subsequent preparation of cDNAs by reverse transcriptase reaction. Mature miRNA (miR)-specific cDNAs were then quantified with PCR in a 96-well microRNA-specific cassette using an ABI7900HT PCR machine.
  
  
  RESULTS
  As expected from previous studies, the lenses were positive for all 84 miRs corresponding to the miRNA probes present in the cassette wells. However, the levels of at least 19 miRs were significantly elevated in galactosemic lenses compared to those in the normal lenses. The majority are proapoptotic. Such elevation was inhibited by caffeine. This has been demonstrated for the first time.
  
  
  CONCLUSIONS
  Since aberrant elevation of miRNAs silences various genes and consequently deactivates protein translation, and since caffeine downregulates such aberration, the beneficial effect of caffeine could be attributed to its ability to suppress elevation of toxic miRs and consequent gene silencing.
authors: Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA. svarm001@umaryland.edu
authors: Shambhu D
authors: SD
authors: Varma
authors: Svitlana
authors: S
authors: Kovtun
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002386:Cataract / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control; D004195:Disease Models, Animal; D005690:Galactose / Q000494:pharmacology; D005693:Galactosemias / Q000150:complications* / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing / Q000187:drug effects*; D006801:Humans; D007908:Lens, Crystalline / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D035683:MicroRNAs; D002110:Caffeine; D005690:Galactose