Ovulation is a complex process that is initiated by the lutenizing hormone surge and is controlled by the temporal and spatial expression of specific genes. This review focuses on recent endocrine, biochemical, and genetic information that has been derived largely from the identification of new genes that are expressed in the ovary, and from knowledge gained by the targeted deletion of genes that appear to impact the ovulation process. Two main areas are described in most detail. First, because mutant mouse models indicate that appropriate formation of the cumulus matrix is essential for successful ovulation, genes expressed in the cumulus cells and those that control cumulus expansion are discussed. Second, because mice null for the progesterone receptor fail to ovulate and are ideal models for dissecting the critical events downstream of progesterone receptor, genes expressed in mural granulosa cells that regulate the expression of novel proteases are described.

ADAMTS-1 (a disintegrin and metalloprotease with thrombospondin motifs-1) is a member of the ADAMTS family of metalloproteases which, together with AD-AMTS-4 and ADAMTS-5, has been shown to degrade members of the lectican family of proteoglycans. AD-AMTS-1 mRNA is induced in granulosa cells of periovulatory follicles by the luteinizing hormone surge through a progesterone receptor-dependent mechanism. Female progesterone receptor knockout (PRKO) mice are infertile primarily due to ovulatory failure and lack the normal periovulatory induction of ADAMTS-1 mRNA. We therefore investigated the protein localization and function of ADAMTS-1 in ovulating ovaries. Antibodies against two specific peptide regions, the prodomain and the metalloprotease domain of ADAMTS-1, were generated. Pro-ADAMTS-1 of 110 kDa was identified in mural granulosa cells and appears localized to cytoplasmic secretory vesicles. The mature (85-kDa prodomain truncated) form accumulated in the extracellular matrix of the cumulus oocyte complex (COC) during the process of matrix expansion. Each form of AD-AMTS-1 protein increased >10-fold after the ovulatory luteinizing hormone surge in wild-type but not PRKO mice. Versican is also localized selectively to the ovulating COC matrix and was found to be cleaved yielding a 70-kDa N-terminal fragment immunopositive for the neoepitope DPEAAE generated by ADAMTS-1 and AD-AMTS-4 protease activity. This extracellular processing of versican was reduced in ADAMTS-1-deficient PRKO mouse ovaries. These observations suggest that one function of ADAMTS-1 in ovulation is to cleave versican in the expanded COC matrix and that the anovulatory phenotype of PRKO mice is at least partially due to loss of this function. ADAMTS-11 (a disintegrin and metalloprotease with thrombospondin-like repeats-1) is a multidomain, multifunctional metalloprotease first cloned from a colon carcinoma cell line (1). Subsequently, ADAMTS-1 has been shown to be induced by luteinizing hormone (LH) in periovulatory follicles of mouse (2), rat (3), and mare.2 Expression of ADAMTS-1 is dependent on LH-induced expression of progesterone and progesterone receptor (PR) in granulosa cells (2, 3). Progesterone receptor null (PRKO) mice fail to ovulate but differentiate normally to form corpora lutea that contain entrapped oocytes (2, 4, 5). AD-AMTS-1 null mice also display impaired ovulation with morphologically abnormal ovaries (6). These observations have indicated that ADAMTS-1 may play a key role in the ovulation process.Ovulation in the mammalian ovary occurs in response to the LH surge that activates several extracellular matrix (ECM) remodeling processes. Dissolution of the connective matrix and cellular layers at the follicular apex and ovarian surface are necessary for release of the oocyte. Based on the anovulatory phenotypes of mice with null mutations of cyclooxygenase-2 (COX-2) (7, 8), prostaglandin E 2 receptor (9, 10), and bikunin (11), it is becoming evident that expansion of the matrix surrounding the cumulus cells and oocyte is ess...

Mutations in the androgen receptor (AR) gene cause a range of phenotypic abnormalities of male sexual development. At one end of the spectrum are individuals with complete androgen insensitivity (complete testicular feminization) who exhibit normal breast development and female external genitalia. At the other extreme are individuals with male phenotypes that are characterized by either subtle undervirilization or infertility. Studies in a number of different laboratories have identified mutations of the AR gene in subjects with androgen resistance syndromes. Defects that interrupt the AR open-reading frame have been traced to a number of distinct types of genetic alterations, have been identified in widely separated segments of the AR gene, and are invariably associated with the phenotype of complete androgen insensitivity. By contrast, mutations that cause single amino acid substitutions within the AR are localized to the DNA-or ligand-binding domains of the receptor protein and have been associated with the full range of androgen-resistant phenotypes. Regardless of the nature of the mutation, functional studies and assays of AR abundance suggest that the phenotypic abnormalities that result from mutation of the AR are the result of the impairment of receptor function, decreases in receptor concentration, or both.

Ovulation is a complex process initiated by the preovulatory LH surge, characterized by cumulus oocyte complex (COC) expansion and completed by the release of a mature oocyte. Although many ovarian genes that impact ovulation have been identified, we hypothesized that genes selectively expressed in COCs would be overlooked by approaches using whole ovary or granulosa cell samples. RNA isolated from COCs collected from preovulatory follicles of equine chorionic gonadotropin (CG) primed mice and at selected times after human CG treatment was subjected to microarray analyses and results confirmed by RT-PCR analyses, Western blotting, and immunofluorescent studies. A remarkable number of genes were up-regulated in COCs including Areg, Ereg, and Btc. Several genes selectively expressed in cumulus cells compared with granulosa cells were related to neuronal (Mbp, Tnc, Nts) or immune (Alcam, Pdcd1, Cd34, Cd52, and Cxcr4) cell function. In addition to Sfrp2, other members of the Wnt/Fzd family (Sfrp4, Fdz1 and Fdz2) were expressed in COCs. Thus, there is a cumulus cell-specific, terminal differentiation process. Furthermore, immunofluorescent analyses documented that cumulus cells are highly mitotic for 4-8 h after human CG and then cease dividing in association with reduced levels of Ccnd2 mRNA. Other down-regulated genes included: Cyp19a1, Fshr, Inhb, and the oocyte factors Zp1-3 and Gja4. In summary, the vast number of matrix, neuronal, and especially immune cell-related genes identified by the gene- profiling data of COCs constitutes strong and novel evidence that cumulus cells possess a repertoire of immune functions that could be far greater than simply mediating an inflammatory-like response.