MicroRNAs (miRNA) are small， non-coding RNAs mediating post-transcriptional regulation of gene expression. miRNAs have recently been implicated in hippocampus-dependent functions such as learning and memory， although the roles of individual miRNAs in these processes remain largely unknown. Here， we achieved stable inhibition using AAV-delivered miRNA sponges of individual， highly expressed and brain-enriched miRNAs; miR-124， miR-9 and miR-34， in hippocampal neurons. Molecular and cognitive studies revealed a role for miR-124 in learning and memory. Inhibition of miR-124 resulted in an enhanced spatial learning and working memory capacity， potentially through altered levels of genes linked to synap... More
MicroRNAs (miRNA) are small， non-coding RNAs mediating post-transcriptional regulation of gene expression. miRNAs have recently been implicated in hippocampus-dependent functions such as learning and memory， although the roles of individual miRNAs in these processes remain largely unknown. Here， we achieved stable inhibition using AAV-delivered miRNA sponges of individual， highly expressed and brain-enriched miRNAs; miR-124， miR-9 and miR-34， in hippocampal neurons. Molecular and cognitive studies revealed a role for miR-124 in learning and memory. Inhibition of miR-124 resulted in an enhanced spatial learning and working memory capacity， potentially through altered levels of genes linked to synaptic plasticity and neuronal transmission. In contrast， inhibition of miR-9 or miR-34 led to a decreased capacity of spatial learning and of reference memory， respectively. On a molecular level， miR-9 inhibition resulted in altered expression of genes related to cell adhesion， endocytosis and cell death， while miR-34 inhibition caused transcriptome changes linked to neuroactive ligand-receptor transduction and cell communication. In summary， this study establishes distinct roles for individual miRNAs in hippocampal function.
