MicroRNA and 3T3-L1 pre-adipocyte differentiation.

MicroRNAs (miRNAs) have been suggested to play important roles in cell proliferation, apoptosis, and differentiation. In this study, we examined miRNA expression profiles during 3T3-L1 pre-adipocyte differentiation. We constructed miRNA libraries from pre- and post-differentiated 3T3-L1 cells, and identified the expression of 77 previously reported miRNAs and 3 new miRNAs. Next, we investigated the expression levels of 102 miRNAs, including those identified in the libraries, during adipogenesis by Northern blot analysis. Sixty-five miRNAs were detected and the expression of 21 miRNAs was up- or down-regulated during adipogenesis. Intriguingly, changes in the miRNA expression pattern were observed at day 9, when lipid droplets were visible, but not at days 1, 2, or 5 after the induction of differentiation. Antisense inhibition of the up-regulated miRNAs did not affect 3T3-L1 pre-adipocyte differentiation. Although these miRNAs may be involved in modulating adipocyte function, mild down-modulations of the up-regulated miRNAs do not appear to affect 3T3-L1 pre-adipocyte differentiation.