title: Predicting microRNA targets in time-series microarray experiments via functional data analysis.
abstract: BACKGROUND
  MicroRNA (miRNA) target prediction is an important component in understanding gene regulation. One approach is computational: searching nucleotide sequences for miRNA complementary base pairing. An alternative approach explored in this paper is the use of gene expression profiles from time-series microarray experiments to aid in miRNA target prediction. This requires distinguishing genuine targets from genes that are secondarily down-regulated as part of the same regulatory module. We use a functional data analytic (FDA) approach, FDA being a subfield of statistics that extends standard multivariate techniques to datasets with predictor and/or response variables that are functional.
  
  
  RESULTS
  In a miR-124 transfection experiment spanning 120 hours, for genes with measurably down-regulated mRNA, exploratory functional data analysis showed differences in expression profiles over time between directly and indirectly down-regulated genes, such as response latency and biphasic response for direct miRNA targets. For prediction, an FDA approach was shown to effectively classify direct miR-124 targets from time-series microarray data (accuracy 88%; AUC 0.96), providing better performance than multivariate approaches.
  
  
  CONCLUSIONS
  Exploratory FDA analysis can reveal interesting aspects of dynamic microarray miRNA studies. Predictive FDA models can be applied where computational miRNA target predictors fail or are unreliable, e.g. when there is a lack of evolutionary conservation, and can provide posterior probabilities to provide additional confirmatory evidence to validate candidate miRNA targets computationally predicted using sequence information. This approach would be applicable to the investigation of other miRNAs and suggests that dynamic microarray studies at a higher time resolution could reveal further details on miRNA regulation.
authors.affiliation: The Bioinformatics Centre, Department of Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen N, Denmark. bparker@binf.ku.dk
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Parker
authors.forename: Jiayu
authors.initials: J
authors.lastname: Wen
mesh_terms: D019295:Computational Biology / Q000379:methods; D020869:Gene Expression Profiling / Q000706:statistics & numerical data; D035683:MicroRNAs / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods* / Q000706:statistics & numerical data; D025341:Principal Component Analysis; D017423:Sequence Analysis, RNA / Q000706:statistics & numerical data; D013223:Statistics as Topic; D014162:Transfection
chemical_list: D035683:MicroRNAs