MiR-145 is upregulated in the retarded preimplantation embryos and modulates cholesterol levels in mice preimplantation embryos through targeting Abca1

BACKGROUND: Preimplantation embryonic lethality is a driver of female infertility. Certain microRNAs (miRNAs) have previously been demonstrated to play important roles in the regulation of embryogenesis. METHODS: Normally developing blastocysts and arrested embryos were collected from patients undergoing intracytoplasmic sperm injection (ICSI), and the expression of specific miRNAs therein was evaluated by qPCR. The overexpression of target molecule miR-145 in early mice embryos was achieved via oocyte microinjection, enabling the subsequent monitoring of how such overexpression impacted embryonic development. Bioinformatics approaches were utilized to identify putative miR-145 target mRNAs, and luciferase reporter assessments were implemented to confirm the ability of miR-145 to regulate Abca1 in HEK293T cells. The functional relationship between miR-145 and Abca1 in the mice’s embryonic development was then confirmed through rescue assays. RESULTS: Abnormally increased miR-145 expression was observed in patients’ arrested embryos, and the exogenous overexpression of this miRNA significantly suppressed mural blastocyst formation. Mechanistically, miR-145 was found to bind to the 3′-untranslated area of the Abca1 mRNA in HK293T cells, thus suppressing its expression and increasing embryonic cholesterol levels. In line with the importance of these cholesterol levels to embryogenesis, the upregulation of Abca1 was sufficient to rescue the observed change in cholesterol levels and the associated retardation of mice embryonic development that occurred in response to the overexpression of miR-145. CONCLUSION: The regulatory dynamics of the miR-145/Abca1 axis play an important role in shaping normal embryonic development.