A novel growth differentiation factor-9 (GDF-9) related factor is co-expressed with GDF-9 in mouse oocytes during folliculogenesis.

Growth differentiation factor-9 (GDF-9) is a transforming growth factor-b (TGF-b) family member which is expressed in the oocytes in mouse ovaries (McGrath, S.A., Esquela, A.F., Lee, S.J., 1995. Oocyte-specific expression of growth/differentiation factor-9. Mol. Endocrinol. 9, 131-136). GDF-9 is indispensable for normal folliculogenesis since female mice deficient for the GDF-9 gene are infertile due to an arrest of follicular growth at the primary follicle stage (Dong, J., Albertini, D.F., Nishimori, K., Kumar, T.R. , Lu, N., Matzuk, M.M., 1996. Growth differentiation factor-9 is required during early ovarian folliculogenesis. Nature 383, 531-535). We searched the GenBank Expressed Sequence Tag (EST) database with the mouse GDF-9 cDNA sequence, and identified from a mouse 2-cell embryo library an EST cDNA that encodes a putative member of the TGF-b superfamily, and named it as GDF-9B. Northern blot hybridization analyses of mouse ovaries revealed a single transcript of approximately 4.0 kilobases (kb) for GDF-9B and of 2.0 kb for GDF-9. We cloned by reverse transcription-polymerase chain reaction from mouse ovarian RNA a partial 821-base pair GDF-9B cDNA that spans the sequence encoding the putative mature region of GDF-9B. The COOH-terminal region of GDF-9B appears to be 53% homologous to GDF-9. Moreover, like GDF-9, GDF-9B lacks the cysteine residue needed for the covalent dimerization of several TGF-b family members. Using in situ hybridization analysis, we demonstrate that GDF-9B and GDF-9 mRNAs are co-localized in the oocyte. We also show that GDF-9B and GDF-9 genes are co-ordinately expressed during follicular development.

Regulation of prostaglandin F2 alpha receptor expression in cultured human granulosa-luteal cells.

PGF2 alpha is a metabolite of arachidonic acid that triggers regression of the corpus luteum. Recent animal studies have indicated that PGF2 alpha (FP) receptor messenger ribonucleic acid (mRNA) is expressed in the corpus luteum. To understand the regulation of the FP receptor in the ovary we have cloned a partial complementary DNA (cDNA) sequence of the FP receptor from human granulosa cells obtained from women undergoing in vitro fertilization. The sequence of this cDNA is identical to the previously reported FP receptor sequences obtained from human uterine and placental cDNA libraries. Low levels of the FP receptor mRNA were observed in freshly isolated granulosa cells or in cultured granulosa-luteal (GL) cells, as detected by reverse transcriptase-PCR. hCG and 8-bromo-cAMP increased the steady state levels of the FP receptor mRNAs after incubation for 24-48 h, as detected by Northern blot hybridization. The stimulatory effect of hCG was concentration and culture stage dependent. Further, hCG and 8-bromo-cAMP increased binding of radiolabeled PGF2 alpha to intact GL cells. In contrast, phorbol 12-myristate 13-acetate inhibited basal as well as hCG- and 8-bromo-cAMP-induced FP receptor mRNA expression and binding of the radiolabeled ligand. In summary, hCG, 8-bromo-cAMP, and phorbol 12-myristate 13-acetate modulate the expression of the FP receptor in human GL cells, which may represent a mechanism to regulate the responsiveness of the ovary to PGF2 alpha.

Identification of ovarian granulosa cells as a novel site of expression for bone morphogenetic protein-3 (BMP-3/osteogenin) and regulation of BMP-3 messenger ribonucleic acids by chorionic gonadotropin in cultured human granulosa-luteal cells.

Bone morphogenetic proteins (BMP) belong structurally to the transforming growth factor-beta superfamily comprising several growth and differentiation factors such as inhibin, activin, and Müllerian inhibitory factor that regulate ovarian function. We studied here the potential expression of BMP-2, -3, and -4 messenger RNAs (mRNAs) in isolated human granulosa cells obtained at oocyte retrieval for in vitro fertilization. Freshly isolated granulosa cells were found to express BMP-3 (also known as osteogenin) mRNAs but not those of BMP-2 or -4. The BMP-3 transcripts were detected with RT-PCR amplification followed by Southern blot hybridization, as well as by Northern and dot blot hybridization analyses. To investigate whether BMP-3 mRNAs are hormonally regulated, cultures of human granulosa-luteal (GL) cells were treated with different concentrations of purified human chorionic gonadotropin (hCG) at varying stages of culture. hCG decreased BMP-3 mRNA levels from the first day of the culture up to day 5. Time-dependence studies showed that a clear decrease in BMP-3 mRNA levels was evident at 24 h after hCG treatment, and that the effect of hCG was concentration dependent with 3 ng/mL hCG decreasing significantly (P < 0.05) BMP-3 mRNA levels. Furthermore, the cAMP analog, 8-bromo-cAMP (8-Br-cAMP), which activates protein kinase-A, and 12-0-tetradecanoylphorbol 13-acetate, an activator of protein kinase-C, both markedly decreased BMP-3 mRNA levels in an 8-h treatment. We conclude that: 1) BMP-3 mRNAs are expressed in human granulosa cells; 2) their steady state levels are hormonally regulated in cultured human GL cells as evidenced by the ability of hCG to markedly decrease BMP-3 transcript levels; and (3) that activation of both protein kinase-A-and protein kinase-C-mediated signaling pathways also results in a decrease in BMP-3 mRNA levels in GL cells. We suggest that BMP-3, like several other members of the transforming growth factor-beta superfamily, is a potential local regulator of female gonadal function.

Human growth differentiation factor 9 (GDF-9) and its novel homolog GDF-9B are expressed in oocytes during early folliculogenesis.

Growth differentiation factor 9 (GDF-9) is a transforming growth factor-beta family member that is required for normal folliculogenesis in female mice, but its role as a regulator of human fertility is still unclear. We determined here by in situ hybridization and immunohistochemical analyses the localization of the GDF-9 messenger ribonucleic acid (mRNA) and protein during human folliculogenesis. The GDF-9 transcripts were not detected in primordial follicles, but they are abundantly expressed in primary follicles in frozen sections of ovarian cortical tissue material obtained at laparoscopic surgery. We raised antipeptide antibodies against GDF-9 and showed by immunohistochemical studies on paraffin sections of whole human ovaries that the GDF-9 protein is most abundantly expressed in primary follicles. We recently demonstrated that a novel GDF-9-related factor, GDF-9B, is coexpressed with GDF-9 during murine folliculogenesis. We now isolated human GDF-9B complementary DNA and genomic clones and report the unusually restricted expression pattern of human GDF-9B. The human GDF-9B transcript can be detected only in the gonads by RT-PCR analysis, and in situ hybridization studies indicate that it is not expressed in small primary follicles but, rather, in the oocytes of late primary follicles. Functional studies using the Xenopus laeuis embryo model indicate that unlike the transforming growth factor-beta family members activin and bone morphogenetic protein-4, neither GDF-9 nor GDF-9B affects mesoderm induction, suggesting that they may use signaling pathways distinct from those well defined for activin and bone morphogenetic protein-4. We conclude that 1) both GDF-9 mRNA and protein are abundantly expressed in oocytes of primary follicles in human ovary, suggesting that the GDF-9 transcript is translated at this early stage of folliculogenesis; 2) human GDF-9B is specifically expressed in gonads at low levels; and 3) the expression of GDF-9 mRNA begins slightly earlier than that of GDF-9B in the human oocytes during follicular development. Our results are consistent with the suggestion that GDF-9 and GDF-9B may regulate human folliculogenesis in a manner specific to the ovary.

Localization of growth differentiation factor-9 (GDF-9) mRNA and protein in rat ovaries and cDNA cloning of rat GDF-9 and its novel homolog GDF-9B.

Although targeted gene disruption of GDF-9, an oocyte derived growth factor, leads to an arrest of folliculogenesis and causes infertility in female mice, little is known on the expression of GDF-9 protein in the ovary. We show that GDF-9 protein is expressed in rat oocytes during folliculogenesis from the early primary follicle stage onwards but the most intensive immunostaining was seen in primary and preantral follicles. Northern blot analyses of the ontogeny of GDF-9 gene expression in postnatal rat ovaries showed that the GDF-9 transcript levels are clearly increased on the second postnatal day concomitant with the appearance of primary follicles. Interestingly, Northern blot and in situ hybridization analyses indicate a similar expression pattern for GDF-9B, the rat ortholog of a mouse GDF-9 like factor for which we recently reported the partial amino acid sequence. The polypeptide sequences deduced from isolated ovarian cDNAs indicate that the rat GDF-9 prepropeptide is 440 amino acids (aa) in length and the putative mature peptide is 135 aa whereas rat GDF-9B is 391 aa long and the mature region is 125 aa. We conclude that (1) the GDF-9 protein is highly expressed in the oocytes of primary follicles of rat ovaries suggesting that it plays a role mainly in early folliculogenesis and that (2) the full-length polypeptide sequence of GDF-9B suggests that this novel TGF-beta family member is likely to be a secreted growth factor that may regulate folliculogenesis at similar developmental stages as GDF-9.

Molecular cloning and analysis of the yeast flocculation gene FLO1.

The DNA sequence of the flocculation gene FLO1 of Saccharomyces cerevisiae, which is located on chromosome I (Watari et al., 1989) was determined. The sequence contains a large open reading frame (ORF) of 2586 bp and codes for a protein of 862 amino acids. However, further study (genomic Southern and polymerase chain reaction analyses) indicated that the gene we cloned was not the intact FLO1 gene but a form with an approximately 2 kb deletion in the ORF region. The intact FLO1 gene was then cloned and its nucleotide sequence determined. The sequence revealed that the ORF of the intact gene is composed of 4611 bp which code for a protein of 1537 amino acids. A remarkable feature of the putative Flo1 protein is that it contains four families of repeated sequences composed of 18, 2, 3 and 3 repeats and that it has a large number of serines and threonines. In the deleted FLO1 form, a large part of these repeated sequences was missing. The N- and C-terminal regions are hydrophobic and both contain a potential membrane-spanning region, suggesting that the Flo1 protein is an integral membrane protein and a cell wall component.

Immunoaffinity purification of baculovirus-expressed rubella virus E1 for diagnostic purposes.

Three monoclonal antibodies, termed 4E10, 1E11:10, and 2D9:1, were generated against rubella virus. Immunoblot analysis with purified authentic rubella virus or recombinant baculovirus-expressed rubella virus structural proteins E1, E2, and C demonstrated that they were directed against the E1 envelope glycoprotein of the rubella virus particle. By using the yeast Ty virus-like particle system, it was possible to map the binding site of 1E11:10 within amino acids 236 to 286 of the E1 protein and the binding sites of 2D9:1 and 4E10 outside this region. Immunoaffinity purification with these monoclonal antibodies made it evident that they are useful for obtaining large quantities of pure baculovirus-expressed rubella virus envelope protein E1. The diagnostic potential of this immunoaffinity-purified recombinant rubella virus E1 protein compared with that of authentic rubella virus is demonstrated.