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MicroRNAs (miRNAs),a class of approximately 22 nucleotide non-coding RNA molecules,negatively regulate the expression of a wide variety of genes,mainly through a direct interaction with the 3-untranslated regions (3-UTRs) of their corresponding mRNA targets.It is estimated that miRNAs regulate up to 60% of all human genes at the post-transcriptional level,implying that miRNAs play pivotal roles in physiological and pathological processes.The regulation of the Schwann cell (SC) response to injurious stimuli by miRNAs remains to be elucidated.Using miRNA microarrays,we identified 17 miRNAs that showed dynamic expression alterations at five early time points following rat sciatic nerve resection.Next,we analyzed the expression pattern of these 17 miRNAs,and integrated their putative targets with differentially expressed mRNAs.The resulting 222 potential targets were mainly involved in cell phenotype modulation,including the immune response,cell death,and cell locomotion.Among the 17 miRNAs,miR-182 expression was up-regulated.The enhanced expression of miR-182 was correlated with nerve injury-induced phenotype modulation of SCs.Further investigation revealed that fibroblast growth factor 9 (FGF9) and neurotrimin (NTM) are two direct targets of miR-182 in SCs,as miR-182 binds to the 3-UTRs of FGF9 and NTM.Silencing FGF9 and NTM recapitulated the inhibitory effect of miR-182 on SC proliferation and migration,whereas enforced knockdown of FGF9 and NTM reversed the miR-182 inhibitors promotion of SC proliferation and migration.Our data indicate that nerve injury inhibits SC proliferation and migration through rapid regulation of miR-182 by targeting FGF9 and NTM,which provides novel insights into the roles of miRNAs in nerve injury and repair.