HASUWA Hidetoshi , Assistant Professor and OKABE Masaru , Professor Emeritus at the Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, demonstrated that members of the miRNA family, miR-200b and miR-429, in the pituitary play an essential role in triggering ovulation. They showed that mice lacking these miRNA become sterile. They went on to clarify the mechanism behind this phenomenon. That is, normally, these miRNAs reduce the production of the transcription factor ZEB1 and increase the secretion of luteinzing hormone (LH) necessary for ovulation, the starting point for reproduction and of great importance in the maintenance of a species. They demonstrated that ovulation does not function without the role played by miRNA. Their findings clarified the relationship between miRNA and hormone secretion, adding a new viewpoint to ovulation disorder, one of the causes of infertility.
Abstract

Ovulation in the mouse and other mammals is controlled by hormones secreted by the hypothalamo-pituitary-ovarian axis. We describe anovulation and infertility in female mice lacking the microRNAs miR-200b and miR-429. Both miRNAs are strongly expressed in the pituitary gland, where they suppress expression of the transcriptional repressor ZEB1. Eliminating these miRNAs, in turn, inhibits luteinizing hormone (LH) synthesis by repressing transcription of its beta subunit gene, which leads to lowered serum LH concentration, an impaired LH surge, and failure to ovulate. Our results reveal roles for miR-200b and miR-429, and their target the Zeb1 gene, in the regulation of mammalian reproduction. Thus, the hypothalamo-pituitary-ovarian axis was shown to require miR-200b and miR-429 to support ovulation.

Related links :

• Genome Information Research Center, Research Institute for Microbial Diseases
• Department of Experimental Genome Research