Mouse specific up regulation of Ccnb1 expression by miR 199a 5p in keratinocyte
MicroRNA (miRNA) are a class of single stranded, small non coding RNA that regulate various biological processes, including skin and hair cycle regulation, by modulating the expression of specific genes at the post transcriptional level. Recently, several studies reported that miRNA directly or indirectly up regulate target genes. Previously, we performed microarray analysis to identify the target genes of miR 199a 5p in a mouse skin keratinocyte cell line and detected more than 200 genes whose expression was significantly increased by miR 199a 5p overexpression 1.5 fold) In this study, we further investigated these genes and found that cyclin B1 (Ccnb1) expression was positively regulated by miR 199a 5p in keratinocyte. Moreover, Ccnb1 expression was inversely correlated with miR 199a 5p expression during the mouse hair cycle. Cell cycle analysis showed that the proportion of cells in S phase was slightly increased, while the proportion of cells in G2/M phase decreased by miR 199 5p. Using luciferase assay, we found that the 3' untranslated region of Ccnb1 was a direct target of miR 199a 5p. We also found that the regulation of Ccnb1 expression by miR 199a 5p is mouse specific. CCNB1 expression was not affected in the human and monkey cell lines. These results provide a new relationship between Ccnb1 and miR 199a 5p in both mouse keratinocyte and miRNA biology.
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