Solexa sequencing of novel and differentially expressed microRNAs in maternal placenta of Holstein cattle with retained fetal membranes

Abstract

MicroRNAs (miRNAs) can post-transcriptionally regulate gene expression and play an important role in the development and function of organs and cells in cattle. This study identified novel and differentially expressed miRNAs in the maternal placenta of Holstein cattle with retained fetal membranes (6 cows for each group). The study found 4,596,223 reads that matched the bovine genome in the normal maternal placenta library (5,930,853 reads in total), and found that a total of 4,270,190 reads were present in the retained fetal membrane maternal placenta library (5,367,946 reads in total). In the present study, 36 novel bovine miRNAs were identified in the normal and retained fetal membrane library and 33 novel miRNAs in the maternal placenta libraries. It was discovered that 69 known miRNAs were significantly differentially expressed between the two samples (P<0.05), with 33 up-regulated retained fetal membranes and 36 down-regulated maternal placenta miRNAs. Real-time quantitative PCR analysis was used to verify known miRNAs. Notably, six miRNAs (down-regulated: bta-miR-423-5p, bta-miR-181a, bta-miR-185; up-regulated: bta-miR-411a, bta-miR-31, bta-miR-424-5p) were significantly highly expressed and exceeded 1.2-fold change. These known miRNAs may be important for retained fetal membranes in cattle. Possible causes of the fetal membrane retention were discussed with a bioinformatic analysis of the differentially expressed miRNAs.