Porcine granulosa cells do not express transforming growth factor-beta 2 (TGF-beta 2) messenger ribonucleic acid: molecular basis for their inability to produce TGF-beta activity comparable to that of rat granulosa cells

The Macaque Ovary, with Special Reference to the Cynomolgus Macaque (Macaca fascicularis)

Concerning functional and morphological aspects, the ovary of the cynomolgus macaque is representative for the conditions in higher primates like humans and is therefore of major relevance in toxicological research. Against this background, a comprehensive overview about the cynomolgus macaque ovary is given from its embryonic appearance, throughout the adolescent and adult development until old age. The overview includes morphologic characteristics, a description of the different cell types, comparisons between the expression of selected receptors, and some details on hormonal effects if considered necessary for understanding the unit of ovarian morphology and function. The close correlation of hormones and morphological characteristics of the ovary and of the other reproductive organs is emphasized by several schematic drawings and images. Special emphasis is also laid on the comparison to the human organism indicating the similarity of both species and hence underlining the importance of the cynomolgus macaque as a model in toxicological research.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. Martina Zöller and Eberhard Buse are employed by Covance Inc. Eric Van Esch is employed by Schering-Plough. No other competing interests were declared.

The role of proteins of the transforming growth factor-beta superfamily in the intraovarian regulation of follicular development

Ovarian follicular development occurs in a hierarchical manner with each follicle having a unique biochemical composition at any moment in time. It has long been understood that a precise coordination between the growth and maturation of the oocyte and adjacent follicular cells (i.e. somatic cells) is essential in order to produce an oocyte that is fully competent to undergo fertilization and embryo development. In addition to the critical endocrine signalling pathways between the hypothalamus, pituitary and ovary, it is now evident that the oocyte itself is important in influencing the microenvironment of the developing follicle by regulating, via paracrine and autocrine mechanisms, its own maturation as well as somatic cell proliferation, differentiation and ovulation rate. Several of the key oocyte-derived regulating factors are members of the transforming growth factor-beta (TGF-beta) superfamily and to date the best understood are growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and BMP6. Significant species differences appear to exist in the relative importance of these growth factors and much remains to be elucidated about their roles in the human ovary. More information on the roles of these factors during ovarian follicular development is likely to advance new therapeutic applications for management of fertility as well as our understanding of how better to assess oocyte quality.

The role of transforming growth factor-beta (TGF-beta) during ovarian follicular development in sheep

BACKGROUND

Recently, several members of the transforming growth factor-beta (TGF-beta) superfamily have been shown to be essential for regulating the growth and differentiation of ovarian follicles and thus fertility.

METHODS

Ovaries of neonatal and adult sheep were examined for expression of the TGF-betas 1-3 and their receptors (RI and RII) by in situ hybridization using ovine cDNAs. The effects of TGF-beta 1 and 2 on proliferation and differentiation of ovine granulosa cells in vitro were also studied.

RESULTS

The expression patterns of TGF-beta 1 and 2 were similar in that both mRNAs were first observed in thecal cells of type 3 (small pre-antral) follicles. Expression of both mRNAs continued to be observed in the theca of larger follicles and was also present in cells within the stroma and associated with the vascular system of the ovary. There was no evidence for expression in granulosa cells or oocytes. Expression of TGF-beta 3 mRNA was limited to cells associated with the vascular system within the ovary. TGFbetaRI mRNA was observed in oocytes from the type 1 (primordial) to type 5 (antral) stages of follicular growth and granulosa and thecal cells expressed this mRNA at the type 3 (small pre-antral) and subsequent stages of development. The TGFbetaRI signal was also observed in the ovarian stroma and vascular cells. In ovarian follicles, mRNA encoding TGFbetaRII was restricted to thecal cells of type 3 (small pre-antral) and larger follicles. In addition, expression was also observed in some cells of the surface epithelium and in some stromal cells. In granulosa cells cultured for 6 days, both TGF-beta 1 and 2 decreased, in a dose dependent manner, both the amount of DNA and concentration of progesterone.

CONCLUSION

In summary, mRNA encoding both TGF-beta 1 and 2 were synthesized by ovarian theca, stroma and cells of the vascular system whereas TGF-beta 3 mRNA was synthesized by vascular cells. Luteinizing granulosa cells also responded to both TGF-beta 1 and beta 2 in vitro. These findings in sheep are consistent with TGF-beta potentially being an important autocrine regulator of thecal cell function and possibly a paracrine regulator of ovarian cell function at various development stages.

Transforming growth factor-beta isoform expression during bovine ovarian antral follicle development

Transforming growth factor-beta (TGF-beta) isoforms are important paracrine and autocrine signaling molecules for the regulation of ovarian follicle growth and physiology. Effective communication between the epithelial granulosa cells, the mesenchymal theca cells, and the oocyte is vital for ovarian function and reproductive success. The expression, localization, and regulation of TGF-beta isoforms in the developing bovine follicle was examined using both immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (RT-PCR) procedures. TGF-beta1 protein was found to be present in the granulosa cells of early pre-antral, early antral, and 1-2 mm follicles. Interestingly, there was no visible staining of granulosa cells of 3-5 or 5-10 mm follicles. There was also no TGF-beta1 staining of theca cells. TGF-beta2 and TGF-beta3 staining were present in the granulosa and theca cells of all follicle stages examined. The levels of TGF-beta mRNA expression in granulosa and theca cells from antral follicles was measured using quantitative RT-PCR. For each isoform mRNA expression levels did not change in different sized antral follicles. TGF-beta3 mRNA levels were much higher than those of TGF-beta1 and TGF-beta2 in both granulosa and theca. Expression levels were higher in theca than in granulosa for TGF-beta2 and TGF-beta3. FSH was found to decrease TGF-beta1 mRNA expression in granulosa cells, but had no effect on TGF-beta2 and TGF-beta3. Bovine ovarian follicles were found to have a unique pattern of TGF-beta isoform expression and regulation when compared to other species (i.e., rodent, pig, quail, and human). The similarities and differences between the various species is discussed to help elucidate common functions of TGF-beta in the ovary. In summary, observations demonstrate that as antral follicles develop, TGF-beta3 is the most abundant TGF-beta isoform and TGF-beta1 protein levels decline in large follicles. Granulosa cell TGF-beta1 expression was decreased by FSH and this correlated with reduced levels in large antral follicles. TGF-betas involved in antral follicular growth and development appear to act as paracrine/autocrine signaling molecules having a species-specific pattern of expression.

The spontaneously hypertensive rat as a model of human cardiovascular disease: evidence of exacerbated cardiopulmonary injury and oxidative stress from inhaled emission particulate matter

Cardiovascular disease is considered a probable risk factor of particulate matter (PM)-related mortality and morbidity. It was hypothesized that rats with hereditary systemic hypertension and underlying cardiac disease would be more susceptible than healthy normotensive rats to pulmonary injury from inhaled residual oil fly ash (ROFA) PM. Eight spontaneously hypertensive (SH) and eight normotensive Wistar-Kyoto (WKY) rats (12-13 weeks old) were implanted with radiotelemetry transmitters on Day -10 for measurement of electrocardiographic (ECG) waveforms. These and other nonimplanted rats were exposed to filtered air or ROFA (containing leachable toxic levels of metals) on Day 0 by nose-only inhalation (ROFA, 15 mg/m(3) x 6 h/day x 3 days). ECGs were monitored during both exposure and nonexposure periods. At 0 or 18 h post-ROFA exposure, rats were assessed for airway hyperreactivity, pulmonary and cardiac histological lesions, bronchoalveolar lavage fluid (BALF) markers of lung injury, oxidative stress, and cytokine gene expression. Comparisons were made in two areas: (1) underlying cardiopulmonary complications of control SH rats in comparison to control WKY rats; and (2) ROFA-induced cardiopulmonary injury/inflammation and oxidative burden. With respect to the first area, control air-exposed SH rats had higher lung and left ventricular weights when compared to age-matched WKY rats. SH rats had hyporeactive airways to acetylcholine challenge. Lung histology revealed the presence of activated macrophages, neutrophils, and hemorrhage in control SHrats. Consistently, levels of BALF protein, macrophages, neutrophils, and red blood cells were also higher in SH rats. Thiobarbituric acid-reactive material in the BALF of air-exposed SH rats was significantly higher than that of WKY rats. Lung inflammation and lesions were mirrored in the higher basal levels of pulmonary cytokine mRNA expression. Cardiomyopathy and monocytic cell infiltration were apparent in the left ventricle of SH rats, along with increased cytokine expression. ECG demonstrated a depressed ST segment area in SH rats. With regard to the second area of comparison (ROFA-exposed rats), pulmonary histology indicated a slightly exacerbated pulmonary lesions including inflammatory response to ROFA in SH rats compared to WKY rats and ROFA-induced increases in BALF protein and albumin were significantly higher in SH rats than in WKY rats. In addition, ROFA caused an increase in BALF red blood cells in SH rats, indicating increased hemorrhage in the alveolar parenchyma. The number of alveolar macrophages increased more dramatically in SH rats following ROFA exposure, whereas neutrophils increased similarly in both strains. Despite greater pulmonary injury in SH rats, ROFA-induced increases in BALF GSH, ascorbate, and uric acid were attenuated when compared to WKY rats. ROFA inhalation exposure was associated with similar increases in pulmonary mRNA expression of IL-6, cellular fibronectin, and glucose-6-phosphate dehydrogenase (relative to that of beta-actin) in both rat strains. The expression of MIP-2 was increased in WKY but attenuated in SH rats. Thus, SH rats have underlying cardiac and pulmonary complications. When exposed to ROFA, SH rats exhibited exacerbated pulmonary injury, an attenuated antioxidant response, and acute depression in ST segment area of ECG, which is consistent with a greater susceptibility to adverse health effects of fugitive combustion PM. This study shows that the SH rat is a potentially useful model of genetically determined susceptibility with pulmonary and cardiovascular complications.

Osteoarthritis-like changes in the murine knee joint resulting from intra-articular transforming growth factor-beta injections

OBJECTIVE

To examine the impact of prolonged TGF-beta exposure on cartilage and ligamentous joint structures in vivo, to investigate involvement of TGF-beta in osteoarthritis pathology.

METHODS

TGF-beta was injected into murine knee joints once or repeatedly, whereafter articular cartilage proteoglycan (PG) synthesis and content, and histological changes in knee joints were studied over a 2-month period.

RESULTS

A single injection of TGF-beta stimulated patellar cartilage PG synthesis for 3 weeks and PG content for 2 weeks. Triple TGF-beta injections prolonged the increase in PG content to 3 weeks. Patellar cartilage showed no histological abnormalities at 1 and 2 months after the last injection. In contrast, 2 months after triple TGF-beta injections the superficial layer of tibial cartilage still had an increased proteoglycan content, while severe PG depletion was found in deeper layers of the posterior part of the lateral tibia in particular. Eventually, lesions occurred at the level of the tide-mark, exactly the site where cartilage is torn off in experimental and spontaneous osteoarthritis in mice. Additionally, multiple TGF-beta injections induced formation of chondroid structures along the margins of articular cartilage. These chondroid structures were transformed into osteophytes via endochondral ossification. Formation of chondroid tissue was also observed in collateral ligaments.

CONCLUSION

Multiple intra-articular injections of TGF-beta induce changes in articular cartilage and surrounding tissues that have strong resemblance to features of experimental and spontaneous osteoarthritis in mice, suggesting a role for TGF-beta in the OA process.

The effect of transforming growth factor-beta on steroidogenesis and expression of key steroidogenic enzymes with a human ovarian thecal-like tumor cell model

OBJECTIVE

Our purpose was to determine the effects of transforming growth factor-beta on steroidogenesis and regulation of steroidogenic enzyme expression by use of a human ovarian thecal-like tumor cell culture system.

STUDY DESIGN

Human ovarian thecal-like tumor cells were treated in serum-free medium in the presence or absence of forskolin and transforming growth factor-beta 1. The accumulation of progesterone and androstenedione in the culture medium was evaluated by radioimmunoassay. The effects of forskolin with or without transforming growth factor-beta 1 on the enzymatic activity of P450c17 and 3 beta HSD, the expression of immunodetectable P450c17 protein, and the expression of messenger ribonucleic acid for P450scc, P450c17, and 3 beta HSD were determined.

RESULTS

Basal steroid secretion, steroidogenic enzyme activity, enzyme protein, and messenger ribonucleic acid expression were not affected by transforming growth factor-beta 1 alone. Forskolin treatment significantly stimulated steroid production and the enzymatic activity of P450c17 and 3 beta HSD up to 10-fold above basal levels. However, transforming growth factor-beta 1 inhibited forskolin-stimulated androstenedione production to near basal levels and increased progesterone 1.4- to 2-fold while suppressing P450c17 enzyme activity to near basal levels, but it did not affect 3 beta HSD activity. Forskolin-stimulated immunodetectable P450c17 alpha protein was markedly inhibited by transforming growth factor-beta 1. In addition, transforming growth factor-beta 1 markedly inhibited the forskolin-stimulation of P450c17 messenger ribonucleic acid, while not significantly altering P450scc or 3 beta HSD messenger ribonucleic acid expression.

CONCLUSION

Forskolin stimulated human ovarian thecal-like tumor cell steroidogenesis, P450c17 and 3 beta HSD activity, immunodetectable P450c17, and messenger ribonucleic acid content for P450scc, P450c17, and 3 beta HSD. Transforming growth factor-beta 1 inhibited forskolin stimulation of androstenedione production through the inhibition of P450c17 expression.

Latent transforming growth factor-beta is present in the extracellular matrix of embryonic hearts in situ

Transforming growth factor-beta (TGF-beta) is an important regulator of development. In vitro, TGF-beta is secreted in a latent, inactive form and can be activated by pH extremes, chaotropic agents, or cell-surface proteases. However, there is little evidence for the existence of latent TGF-beta in vivo. In this study, we determined whether (1) cultured embryonic cardiac segments secrete latent or active TGF-beta, (2) binding of TGF-beta antibody to TGF-beta was conformation-dependent (i.e., active vs. latent), and (3) immunostaining of embryonic hearts changed after exposure to activating conditions. Only latent TGF-beta 3 (acid activatable) was detected in conditioned medium of stage 14-16 chick cardiac segments as measured by a growth inhibition bioassay. No growth-inhibitory activity was present in nonacidified control medium. When blotted onto a membrane, only transiently acidified conditioned medium bound TGF-beta antibody. These data showed that cardiac segments secrete latent TGF-beta which binds with antibody if activated. To determine if antibody binding to tissue sections required exposure to TGF-beta-activating conditions, stage 14-16 embryos were fixed and sectioned under conditions that maximally retained extracellular matrix (ECM). Under these conditions, immunostaining was found in the myocardium but not in the endocardium or cardiac ECM. Limited immunostaining was found in other areas of the embryo and was always cell-associated. In addition to the above staining, when tissue sections were exposed to TGF-beta activating conditions, immunopositive staining was present within most of the embryonic ECM including the cardiac ECM. All immunostaining was blocked by preabsorption with TGF-beta 3 protein. These data suggest that active TGF-beta has a very limited distribution while latent TGF-beta is more abundant in embryonic ECM. Therefore, in vivo activation of TGF-beta may play an important role in mediating the expression of TGF-beta function during development.

Transforming growth factor-beta 1 in reproduction and development

Expression patterns of TGF-beta s during embryogenesis and in adult reproductive organs, as well as the activities of these molecules in in vitro assays of biological processes relating to reproduction and development, have suggested that TGF-beta s may play a role in both reproductive function and embryonic development. To investigate the function of TGF-beta 1 in vivo, the murine TGF-beta 1 gene was disrupted by gene targeting, and animals that lacked TGF-beta 1 activity were generated. Homozygous mutant animals were obtained which exhibited a multifocal inflammatory disease. However, the observed numbers of homozygous mutant offspring were less than expected, suggesting the occurrence of some type of prenatal lethality. This paper reviews the proposed role of the TGF-beta s in reproductive and developmental processes and discusses observations obtained from the TGF-beta 1 gene-targeting experiments as they relate to these processes.