Expression of Flotilin-2 and Acrosome Biogenesis Are Regulated by MiR-124 during Spermatogenesis

MicroRNAs (miRNAs) are a class of short non-coding RNA molecules, which diversely regulate gene expression in organisms. Although the regulatory role of these small RNA molecules has been recently explored in animal spermatogenesis, the role of miR-124 in male germ cells is poorly defined. In our previous study, flotillin-2 was investigated as a novel Golgi-related protein involved in sperm acrosome biogenesis. The current study was designed to analyze the contribution of miR-124 in the regulation of flotillin-2 expression during mouse acrosome biogenesis. Luciferase assays revealed the target effects of miR-124 on flotillin-2 expression. Following intratesticular injection of miR-124 in 3-week-old male mice, quantitative real-time RT-PCR and western blot analysis were employed to confirm the function of miR-124 in regulating flotillin-2 after 48 hours. Sperm abnormalities were assessed 3 weeks later by ordinary optical microscopy, the acrosome abnormalities were also assessed by PNA staining and transmission electron microscopy. The results showed the proportion of sperm acrosome abnormalities was significantly higher than that of the control group. The expression of flotillin-2 and caveolin-1 was significantly downregulated during acrosome biogenesis. These results indicated that miR-124 could potentially play a role in caveolin-independent vesicle trafficking and modulation of flotillin-2 expression in mouse acrosome biogenesis.