The biological effects of estrogens are largely mediated through estrogen receptors (ERs), which belong to the nuclear receptor gene family of transcription factors. ER-alpha 36 has been recently identified as a new variant of ER alpha, but its expression and roles in female reproduction system remain unknown. Immunocytochemistry and confocal microscopy were employed to observe ER-alpha 36 distribution in mouse ovary during postnatal development and in oocyte during meiotic maturation. ER-alpha 36 was consistently present in the nuclei of oocytes regardless of follicular growth stage and mouse age until germinal vesicle breakdown (GVBD). Its immunosignal was smeared in granulosa cells. However, the ER-alpha 36 signal is up-regulated and found in cytoplasm with little or no nuclear staining during corpus luteum development. ER-alpha 36 was also found in theca cells. We showed by Western blot that ER-alpha 36 was expressed in mouse oocytes at various maturation stages. When the function of nuclear ER-alpha 36 was blocked by microinjecting anti-ER-alpha 36 specific antibody into the germinal vesicle (GV) of mouse oocytes, the first polar body emission occurred earlier in a higher proportion of oocytes compared to the control. These results suggest that ER-alpha 36 may play critical roles in mouse ovarian folliculogenesis and oocyte development.

KeyWords: BETA ER-BETA; CORPUS-LUTEUM; DIFFERENTIAL EXPRESSION; PROTEIN-SYNTHESIS; KNOCKOUT MOUSE; MESSENGER-RNA; SEX REVERSAL; MICE; LOCALIZATION; PITUITARY

This research result was published by HISTOCHEMISTRY AND CELL BIOLOGY

Xu BZ, Lin SL, Li M, Zhu JQ, Li S, Ouyang YC, Chen DY, Sun QY. Changes in estrogen receptor-alpha variant (ER-alpha 36) expression during mouse ovary development and oocyte meiotic maturation. HISTOCHEMISTRY AND CELL BIOLOGY. 2009, 131(3): 347-354.