Cloning, sequencing, and localization of bovine estrogen receptor-beta within the ovarian follicle

The potential role of estrogen receptor-beta (ER beta) in normal ovarian fo lliculogenesis and in reproductive disorders such as ovarian follicular cys ts has not been well defined. Therefore, we were interested in cloning, seq uencing, and localizing ER beta mRNA and protein within the bovine ovary, B ovine ERP (bER beta) was amplified by reverse transcription-polymerase chai n reaction (RT-PCR), then cloned and sequenced. Results showed that the ope n reading frame of bER beta cDNA spanned 1584 nucleotides encoding a protei n of 527 amino acids, The N-terminal region of bER beta was found to be 80% homologous to human and mouse ERP and 79% homologous to rat ERP. Bovine ER P DNA-binding domain was 100% homologous to human, mouse, and rat ERP seque nces. The C-terminal/ligand-binding domain of bER beta was 89% homologous t o human, 86% homologous to moose, and 88% homologous to rat ER beta, Human and bovine ER beta amino acid sequences are similar in that their coding re gion extended farther 5' than initially reported for the published rat ER b eta sequence. Using in situ hybridization and immunohistochemistry, ERP mRN A and protein, respectively, were demonstrated to be present in granulosa c ells of antral follicles in various stages of follicular growth. These find ings suggest a role for bER beta in ovarian follicular growth and maturatio n.