Anthony J. Zeleznik

Vascular permeability factor and vascular endothelial growth factor in ovarian hyperstimulation syndrome: a preliminary report *

Objective To determine whether serum levels of vascular permeability factor (VPF) are elevated in patients with ovarian hyperstimulation syndrome (OHSS) and to determine if luteinizing granulosa cells may be a source of VPF. Design Prospective observational study. Setting University IVF and GIFT program. Patients Eight consecutive IVF and GIFT patients at high risk for OHSS. Main Outcome Measures Vascular permeability factor concentration in serum and follicular fluid. Results Serum VPF was significantly higher (15.2 ± 4.0 pM; mean ± SEM) on day +14 in the group who developed severe OHSS compared with those who did not. Follicular fluid VPF (171.5 ± 18.5 pM) was approximately 100-fold greater than serum (1.7 ± 1.3 pM) or peritoneal fluid (2.5 ± 1.3 pM) 36 hours after hCG administration. Conclusion Vascular permeability factor is elevated in patients with severe OHSS and the ovary may be a source of VPF secretion.

Follicle-stimulating hormone/cAMP regulation of aromatase gene expression requires β-catenin

Estrogens profoundly influence the physiology and pathology of reproductive and other tissues. Consequently, emphasis has been placed on delineating the mechanisms underlying regulation of estrogen levels. Circulating levels of estradiol in women are controlled by follicle-stimulating hormone (FSH), which regulates transcription of the aromatase gene (CYP19A1) in ovarian granulosa cells. Previous studies have focused on two downstream effectors of the FSH signal, cAMP and the orphan nuclear receptor steroidogenic factor-1 (NR5A1). In this report, we present evidence for β-catenin (CTNNB1) as an essential transcriptional regulator of CYP19A1. FSH induction of select steroidogenic enzyme mRNAs, including Cyp19a1, is enhanced by β-catenin. Additionally, β-catenin is present in transcription complexes assembled on the endogenous gonad-specific CYP19A1 promoter, as evidenced by chromatin immunoprecipitation assays. Transient expression and RNAi studies demonstrate that FSH- and cAMP-dependent regulation of this promoter is sensitive to alterations in the level of β-catenin. The stimulatory effect of β-catenin is mediated through functional interactions with steroidogenic factor-1 that involve four acidic residues within its ligand-binding domain, mutation of which attenuates FSH/cAMP-induced Cyp19a1 mRNA accumulation. Together, these data demonstrate that β-catenin is essential for FSH/cAMP-regulated gene expression in the ovary, identifying a central and previously unappreciated role for β-catenin in estrogen biosynthesis, and a potential broader role in other aspects of follicular maturation.

Delivery of a Cyclic Adenosine 3′,5′-Monophosphate Response Element-Binding Protein (CREB) Mutant to Seminiferous Tubules Results in Impaired Spermatogenesis1

FSH binding to Sertoli cells is required for optimal production of sperm in mammals. The cAMP response element-binding protein (CREB) is a major mediator of FSH-induced changes in gene expression. To determine whether CREB is required for spermatogenesis, an adenovirus encoding a phosphorylation-defective CREB mutant (AdCREBm1) was used to inhibit CREB activity in Sertoli cells. Addition of AdCREBm1 to primary rat Sertoli cell cultures completely abolished induction of the CREB-regulated c-fos gene. Injection of an adenovirus encoding ss-galactosidase into the rat testis seminiferous tubules in vivo demonstrated that predominately Sertoli cells were infected by adenovirus. AdCREBm1-directed expression of CREBm1 in seminiferous tubules did not affect Sertoli cell viability, but resulted in the apoptosis of meiotic spermatocyte germ cells within 4 days of adenovirus injection into seminiferous tubules. Disrupted spermatogenesis, defined by at least a 75% reduction of round spermatids, was observed in 42 +/- 5.8% of seminiferous tubules 14 days after AdCREBm1 infection, whereas using this criteria, testes injected with a control adenovirus did not display disrupted spermatogenesis. These data demonstrate that AdCREBm1 causes apoptosis and elimination of germ cells and suggest that CREB is required to produce a Sertoli cell-derived factor that is critical for germ cell survival.FSH binding to Sertoli cells is required for optimal production of sperm in mammals. The cAMP response element-binding protein (CREB) is a major mediator of FSH-induced changes in gene expression. To determine whether CREB is required for spermatogenesis, an adenovirus encoding a phosphorylation-defective CREB mutant (AdCREBm1) was used to inhibit CREB activity in Sertoli cells. Addition of AdCREBm1 to primary rat Sertoli cell cultures completely abolished induction of the CREB-regulated c-fos gene. Injection of an adenovirus encoding ss-galactosidase into the rat testis seminiferous tubules in vivo demonstrated that predominately Sertoli cells were infected by adenovirus. AdCREBm1-directed expression of CREBm1 in seminiferous tubules did not affect Sertoli cell viability, but resulted in the apoptosis of meiotic spermatocyte germ cells within 4 days of adenovirus injection into seminiferous tubules. Disrupted spermatogenesis, defined by at least a 75% reduction of round spermatids, was observed in 42 +/- 5.8% of seminiferous tubules 14 days after AdCREBm1 infection, whereas using this criteria, testes injected with a control adenovirus did not display disrupted spermatogenesis. These data demonstrate that AdCREBm1 causes apoptosis and elimination of germ cells and suggest that CREB is required to produce a Sertoli cell-derived factor that is critical for germ cell survival.

The physiology of follicle selection

During the follicular phase of the primate menstrual cycle, a single follicle usually matures to the preovulatory stage and releases its oocyte for fertilization and the potential establishment of pregnancy. In assisted reproductive technology procedures, it is desirable to override the natural process of follicle selection to produce many oocytes that are capable of being fertilized and undergoing normal embryo development. The goal of this chapter is to summarize the current views regarding the natural process of follicle selection in primates and to discuss how this process may be amplified to produce a greater number of oocytes.

FSH and FOXO1 regulate genes in the sterol/steroid and lipid biosynthetic pathways in granulosa cells.

The forkhead box transcription factor FOXO1 is highly expressed in granulosa cells of growing follicles but is down-regulated by FSH in culture or by LH-induced luteinization in vivo. To analyze the function of FOXO1, we infected rat and mouse granulosa cells with adenoviral vectors expressing two FOXO1 mutants: a gain-of-function mutant FOXOA3 that has two serine residues and one threonine residue mutated to alanines rendering this protein constitutively active and nuclear and FOXOA3-mutant DNA-binding domain (mDBD) in which the DBD is mutated. The infected cells were then treated with vehicle or FSH for specific time intervals. Infection of the granulosa cells was highly efficient, caused only minimal apoptosis, and maintained FOXO1 protein at levels of the endogenous protein observed in cells before exposure to FSH. RNA was prepared from control and adenoviral infected cells exposed to vehicle or FSH for 12 and 24 h. Affymetrix microarray and database analyses identified, and real time RT-PCR verified, that genes within the lipid, sterol, and steroidogenic biosynthetic pathways (Hmgcs1, Hmgcr, Mvk, Sqle, Lss, Cyp51, Tm7sf2, Dhcr24 and Star, Cyp11a1, and Cyp19), including two key transcriptional regulators Srebf1 and Srebf2 of cholesterol biosynthesis and steroidogenesis (Nr5a1, Nr5a2), were major targets induced by FSH and suppressed by FOXOA3 and FOXOA3-mDBD in the cultured granulosa cells. By contrast, FOXOA3 and FOXOA3-mDBD induced expression of Cyp27a1 mRNA that encodes an enzyme involved in cholesterol catabolism to oxysterols. The genes up-regulated by FSH in cultured granulosa cells were also induced in granulosa cells of preovulatory follicles and corpora lutea collected from immature mice primed with FSH (equine choriogonadotropin) and LH (human choriogonadotropin), respectively. Conversely, Foxo1 and Cyp27a1 mRNAs were reduced by these same treatments. Collectively, these data provide novel evidence that FOXO1 may play a key role in granulosa cells to modulate lipid and sterol biosynthesis, thereby preventing elevated steroidogenesis during early stages of follicle development.

Follicle Selection in Primates: “Many Are Called but Few Are Chosen”

Abstract During the follicular phase of humans and most nonhuman primates, a single preovulatory follicle usually matures each menstrual cycle. The observation that numerous preovulatory follicles may be stimulated to mature when exogenous gonadotropins are administered indicates that there must be a precise and highly reproducible mechanism by which only one of the many follicles capable of ovulating actually does so. The goal of this review is to summarize past and current research which indicates that follicle selection in primates is the result of an exquisitely sensitive interplay between gonadotropin secretion by the pituitary gland, steroid production by the ovary, and maturation-dependent alterations of the ovarys responsiveness to gonadotropins.

Elements involved in the regulation of the StAR gene.

The steroidogenic acute regulatory protein (StAR) mediates the transfer of cholesterol from the outer to the inner mitochondrial membrane, the regulated step in steroidogenesis. A most interesting facet of this protein is the manner in which its expression is acutely regulated. In this regard, a number of studies have concentrated on the search for consensus cis regulatory elements within its promoter, and, more importantly, on whether these elements are involved in its expression. This short review will summarize some of the findings that have been reported concerning the nature of how the expression of this gene is regulated.

Convergence of 3′,5′-Cyclic Adenosine 5′-Monophosphate/Protein Kinase A and Glycogen Synthase Kinase-3β/β-Catenin Signaling in Corpus Luteum Progesterone Synthesis

Progesterone secretion by the steroidogenic cells of the corpus luteum (CL) is essential for reproduction. Progesterone synthesis is under the control of LH, but the exact mechanism of this regulation is unknown. It is established that LH stimulates the LH receptor/choriogonadotropin receptor, a G-protein coupled receptor, to increase cAMP and activate cAMP-dependent protein kinase A (PKA). In the present study, we tested the hypothesis that cAMP/PKA-dependent regulation of the Wnt pathway components glycogen synthase kinase (GSK)-3beta and beta-catenin contributes to LH-dependent steroidogenesis in luteal cells. We observed that LH via a cAMP/PKA-dependent mechanism stimulated the phosphorylation of GSK3beta at N-terminal Ser9 causing its inactivation and resulted in the accumulation of beta-catenin. Overexpression of N-terminal truncated beta-catenin (Delta90 beta-catenin), which lacks the phosphorylation sites responsible for its destruction, significantly augmented LH-stimulated progesterone secretion. In contrast, overexpression of a constitutively active mutant of GSK3beta (GSK-S9A) reduced beta-catenin levels and inhibited LH-stimulated steroidogenesis. Chromatin immunoprecipitation assays demonstrated the association of beta-catenin with the proximal promoter of the StAR gene, a gene that expresses the steroidogenic acute regulatory protein, which is a cholesterol transport protein that controls a rate-limiting step in steroidogenesis. Collectively these data suggest that cAMP/PKA regulation of GSK3beta/beta-catenin signaling may contribute to the acute increase in progesterone production in response to LH.

Sperm recovery and survival: two tests that predict in vitro fertilization outcome

OBJECTIVES To determine if human sperm recovery during swim-up and sperm survival after 24 hours, as obtained from a screening semen specimen, are predictive of subsequent IVF and clinical pregnancy rates (PRs) and to determine if these techniques can identify men with normal semen analysis parameters and poor IVF success. DESIGN Historical prospective study. SETTING All semen evaluations and IVF cycles were performed at the University of Pittsburgh, Magee-Womens Hospital, Pittsburgh, Pennsylvania. PATIENTS, PARTICIPANTS Couples undergoing IVF at Magee-Womens Hospital from August 1988 through June 1993. INTERVENTIONS A screening semen analysis and swim-up procedure were performed on all couples undergoing IVF. The number of spermatozoa recovered after swim-up and the percentage of motile spermatozoa present after a 24-hour incubation were recorded. MAIN OUTCOME MEASURES Fertilization and PRs were compared according to the parameters obtained from routine semen analysis, the number of spermatozoa obtained with swim-up, and the percentage of motile spermatozoa at 24 hours. RESULTS Using chi2 or Fishers exact test, fertilization rates were significantly different according to the number of spermatozoa recovered after swim-up (< or = 2.0 and > 2.0 x 10(6) spermatozoa recovered, 48.3% versus 71.4%) as were PRs (16.9% versus 29.8%). Similarly, the percentage of motile spermatozoa present at 24 hours (< or = 20% and > 20%) discriminated between fertilization rates (45.9% versus 65.8%) and PRs (16.4% versus 36.5%). Among a subset of men with normal semen analyses and total motile sperm counts > or = 40 x 10(6), the results from swim-up and survival discriminated between men with high and low fertilization and PRs. Receiver operating characteristic analysis revealed that swim-up results better discriminated between pregnant and nonpregnant IVF patients than sperm motility, but that the percentage of motile spermatozoa present at 24 hours was no better in this regard than sperm motility. CONCLUSIONS The number of spermatozoa recovered after swim-up and the percentage of spermatozoa that maintain their motility after 24 hours were both helpful in assessing IVF and PRs and may be helpful in altering physicians to a subset of men having normal semen analysis parameters yet poor IVF success.

Randomized, prospective trial of leuprolide acetate and conventional superovulation in first cycles of in vitro fertilization and gamete intrafallopian transfer.

Ovarian stimulation after pituitary suppression with gonadotropin-releasing hormone agonists (GnRH-a) has been effective in women who have exhibited a poor response to conventional superovulation strategies. Their effectiveness in unselected women undergoing their first cycle of in vitro fertilization or gamete intrafallopian transfer, however, remains to be established. To address this question, we randomized 114 women to one of two treatment protocols. Protocol 1 consisted of 100 mg of clomiphene citrate on days 5 to 9, followed by 150 IU human menopausal gonadotropin (hMG) beginning on day 9. Protocol 2 consisted of daily GnRH-a beginning in the midluteal phase. Stimulation with 150 IU hMG commenced after pituitary down regulation and ovarian suppression were achieved. Human menopausal gonadotropin was continued in both protocols until adequate follicular development and serum estradiol concentrations were obtained. Protocol 2 patients reached egg retrieval significantly more often (87%) than Protocol 1 patients (61%), but the mean number of mature eggs retrieved and the pregnancy rate per retrieval were not significantly different between the two groups.