Loss of Runx3 affects ovulation and estrogen-induced endometrial cell proliferation in female mice

Runx3 is a transcription factor that belongs to the Runx family. We studied the function of Runx3 in the mouse ovary and uterus using the Runx3 knockout (Runx3−/−) mouse. Ovaries were collected from 8‐week‐old wild type (wt) and Runx3−/− mice. Histological studies showed that follicles were present at various developmental stages in the Runx3−/− and wt mouse ovaries. The numbers of primary, preantral and antral follicles in the Runx3−/− mice were significantly less than those in the wt mice while the number of primordial follicles in the Runx3−/− mice was not significantly different from that in the wt mice. Corpora lutea were not detected in the Runx3−/− mouse ovary. Gonadotropin treatment in immature female mice induced ovulation in Runx3−/− mice as well as in wt mice, indicating that ovaries of Runx3−/− mice respond to gonadotropin treatment as those in wt mouse ovaries. This suggests that failure of ovulation is due to dysfunction of regulatory mechanism of gonadotropin secretion. In addition, the uteri of Runx3−/− mice were atrophic, showed thin epithelial layers compared with those of the wt mice, and did not respond to estrogen in terms of DNA replication in endometrial epithelial cells. These results suggest that Runx3 takes part in the regulation of reproductive functions. Mol. Reprod. Dev. 75: 1653–1661, 2008. © 2008 Wiley‐Liss, Inc.