MICRORNA PROFILING IN POSTMORTEM BRAIN OF HUMAN ALCOHOLICS

Abstract

MicroRNAs (miRNAs) represent a large class of small single-stranded non-coding RNAs that are thought to regulate diverse functions by post-transcriptional gene silencing. Recently, miRNAs are have been shown to be crucial regulators of gene expression, affecting a wide variety of cellular functions. In brain, miRNAs have been shown to play an important role during development and in regulation of synaptic plasticity, and have been implicated in human brain diseases. In previous studies, we and others have used cDNA and oligonucleotide microarrays to identify and classify genes with altered expression following long-term alcohol consumption; however, the potential role of miRNA regulation of these genes has not been investigated. In the present study, we used miRNA arrays (Ambion+Invitrogen human, mouse, and rat probes) to classify miRNAs with altered expression in postmortem prefrontal cortex following long-term alcohol consumption. miRNAs profiles were obtained from the identical samples (14 well characterized alcoholics and 13 matched controls) that were used in a previous cDNA microarray study (Neuropsychopharm 31, 1574-82, 2006). We found that ~20 miRNAs were significantly up-regulated (p<0.002; 20-45%) in the alcoholic group compared to controls. Interestingly, miRNA down-regulation was not observed at this level of significance. Functional classification of the predicted target genes of the regulated miRNAs demonstrated a large degree of overlap with published mRNA data. For example, genes involved in ubiquitination, apoptosis, cell adhesion, neurogenesis, and neural disease are predicted targets of the regulated miRNAs. In addition, approximately one third of the significantly regulated mRNAs from the previous microarray study were identified as potential targets of the significantly changed miRNAs. miRNAs are key regulators of gene expression but the functions of many human miRNAs are yet to be discovered. This study provides the first analysis of miRNA levels in human alcoholism and raise the possibility that the reduced of expression of brain genes seen in human alcoholism may be due, at least in part, to increased levels of miRNAs. Supported by NIH AA12404.