Malate dehydrogenase is negatively regulated by miR-1 in Trichomonas vaginalis.

MicroRNAs are highly conserved small noncoding RNAs that can suppress protein translation through complementary binding to target mRNAs. We used a novel approach to identify miRNA targets in the protist Trichomonas vaginalis by comparing the levels of differentially expressed proteins and genes in the trophozoite and amoeboid stages. We observed that the T. vaginalis malate dehydrogenase (Tv_MDH) gene was upregulated 20-fold in the amoeboid stage, but the protein level was reduced by 4.5-fold. Bioinformatics analysis revealed that the Tv_MDH mRNA contains putative target sites of the miR-1 family. The expression level of endogenous tva-miR-1 in the amoeboid stage was 50-fold higher than in the trophozoite stage. Transfection of trophozoites with tva-miR-1 mimics reduced Tv_MDH protein expression by 60%. Based on these experimental data, we conclude that Tv_MDH is negatively regulated by tva-miR-1. The results of this study demonstrate that a combination of proteomic and transcriptomic approaches is a powerful tool for identifying miRNA targets.