Aberrant Placental Villus Expression of miR-486-3p and miR-3074-5p in Recurrent Miscarriage Patients and Uterine Expression of These MicroRNAs during Early Pregnancy in Mice.

MicroRNAs (miRNAs) are critical regulators of gene expression; they have emerged as new players in the pathophysiology of reproductive disorders such as preeclampsia and recurrent miscarriage (RM). In this study, miRNA expression profiles were determined by deep sequencing analysis in placental villi obtained from women with RM and with gestational age-matched normal pregnancy (NP). A total of 69 miRNAs were found to be aberrantly expressed in RM. Five of these human (Homo sapiens) miRNAs (hsa-miRNAs), including hsa-miR-3074-5p, -486-3p, -1269b, -6765-3p and -144-3p, were validated by qRT-PCR in 12 RM and 10 NP placental villi. Hsa-miR-3074-5p expression was significantly higher, while hsa-miR-486-3p expression was significantly lower, in RM compared to NP. Subsequently, the expression of mouse (Mus musculus) miR-486-3p (mmu-miR-486-3p) and mmu-miR-3074-5p, which are identical to hsa-miR-486-3p and hsa-miR-3074-5p, respectively, were examined by qRT-PCR in the uterus during early pregnancy. Mmu-miR-486-3p expression was significantly increased during the peri-implantation period, and the levels were significantly higher at implantation than at non-implantation sites. In contrast, the expression of mmu-miR-3074-5p was markedly decreased at implantation compared to non-implantation sites. These data suggest that miR-486-3p and miR-3074-5p may be involved in embryo implantation and that their aberrant expression is associated with RM. Larger studies are warranted to follow up this pilot study.