Analysis of microRNA expression in organ of Corti in neonatal and adult rats

ObjectiveTocharacterizemicroRNA(miRNA)expressionprofileinmicrodissectedauditoryepitheliafromtheCorti'sOrganinnewbornandadultrats.MethodsTheTaqManMicroRNAArrayswereusedtoidentifyexpressionofmicroRNAinthenewbornandadultgroups.GOanalysiswasappliedtoanalyzethemainfunctionofthedifferentialexpressiongenesaccordingtotheGeneOntologywhichisthekeyfunctionalclassificationofNCBI.Similarly,PathwayanalysiswasusedtofindoutthesignificantpathwayofthedifferentialgenesaccordingtoKEGG,BiocartaandReatome.ResultsIncreasedexpressionwasseenin16miRNAsinmatureratcomparedtonewbornrats,withincreasedfoldingrangingfrom17to600folds.Expressionlevelsin2miRNAswerereducedinmaturerats,namelyrno-miR-29candrno-miR-29a.Thehigh-enrichmentGOstargetedbyover-expressedmiRNAswerenegativeregulationofepithelialcelldifferentiation,common-partnerSMADproteinphosphorylation,mesenchymal-epithelialcellsignaling,regulationoftransforminggrowthfactorbeta2production,etc.FunctionalanalysisofmiRNAsbyKEGGrevealedthat19signaltransductionpathwayswereupregulatedand14weredownregulated.ConclusionsThedifferenceinmiRNAexpressionpatternsintheorganofCortibetweenneonatalandadultratsmaybecloselyrelatedtomaturationoftheorganofCortiandlossofproliferativecapacityofinnerearhaircells,andTGFβsignalingmayplayanimportantroleinhaircellsregeneration.