Abstract
BackgroundThe pathophysiological mechanism of recurrent miscarriage (RM) is unclear. The goals of this study were to determine the role of microRNA-4497 overexpression in placental villus tissues in early RM; To identify the potential target mRNAs of miRNA-4497; And to investigate the microRNA-4497-mediated regulatory mechanisms in placental trophoblasts.MethodsBioinformatics analysis was performed to identify the candidate target genes of miRNA-4497. The protein expression of Sp1 transcription factor (SP1), chemokine (C-X-C motif) receptor 5 (CXCR5) and bone morphogenetic protein 8a (BMP8A) were determined in the villus tissues of the RM and normal groups by Western blotting and immunohistochemistry. Cultured 293T cells were co-transfected with the miRNA-4497 agomir or luciferase reporter vectors containing the wild-type or mutant 3’-UTRs of the target mRNAs to verify the regulatory role of miRNA-4497.ResultsBioinformatics analysis suggested that SP1, CXCR5 and BMP8A mRNAs are potential targets of miRNA-4497. The expression of SP1, CXCR5 and BMP8A proteins in the chorionic villus tissues of RM placentas were significantly decreased compared to those in the normal controls. Moreover, SP1 protein levels were inversely correlated with the levels of miRNA-4497 in the placentas of RM patients and normal controls. The expression of SP1 mRNA and protein were down-regulated in HTR-8/SVneo cells after forced overexpression of the miRNA-4497 agomir. The results of the co-transfection assay showed that mutation of the miRNA-4497-binding sites in the 3’-untranslated region (3’-UTR) of SP1 led to a recovery of luciferase activity upon overexpression of miRNA-4497, suggesting that SP1 could be a direct target of miRNA-4497.ConclusionsAn increased miRNA-4497 level in the placental villus tissues associated with recurrent miscarriage may down-regulate SP1 expression. The negative regulation of SP1 by miRNA-4497 may potentially contribute to the pathogenesis of recurrent miscarriage through promotion of trophoblast apoptosis. These findings provide novel information on the regulation of placental trophoblast apoptosis, and could be useful for the development of new therapeutic strategies for better management of recurrent miscarriage.
Highlights
The pathophysiological mechanism of recurrent miscarriage (RM) is unclear
An increased miRNA-4497 level in the placental villus tissues associated with recurrent miscarriage may down-regulate Sp1 transcription factor (SP1) expression
The negative regulation of SP1 by miRNA-4497 may potentially contribute to the pathogenesis of recurrent miscarriage through promotion of trophoblast apoptosis
Summary
The pathophysiological mechanism of recurrent miscarriage (RM) is unclear. Despite considerable research efforts in the past decades, the pathophysiological mechanism of RM remains largely unclear. MiRNAs participate in the modulation of gene expression by binding to the 3’-untranslated regions (3’-UTRs) of the target mRNAs [3], resulting in changes in mRNA stability and/or suppression of protein translation. Subsequent changes in the protein expression could lead to pathophysiological alterations in the cell structure and function. Since the first identification of microRNA lin-4 in Caenorhabditis elegans, the existence of a large number of miRNAs has been validated in humans. MiRNAs regulate more than a third of human genes involved in a variety of biological processes, such as proliferation, differentiation, apoptosis, metabolism and cell migration and invasion [4]. Aberrant expression of miRNAs may contribute to RM and other reproductive disorders [5]
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