Intracellular mechanisms regulating cell survival in ovarian follicles

Regulation of Follicular Development in Chickens: WIF1 Modulates Granulosa Cell Proliferation and Progesterone Synthesis via Wnt/β-Catenin Signaling Pathway

Proliferation, apoptosis, and steroid hormone secretion by granulosa cells (GCs) and theca cells (TCs) are essential for maintaining the fate of chicken follicles. Our previous study showed that the Wnt inhibitor factor 1 (WIF1) plays a role in follicle selection. However, the significance of WIF1 in GC- and TC-associated follicular development was not explicitly investigated. This study found that WIF1 expression was strongly downregulated during follicle selection (p < 0.05) and was significantly higher in GCs than in TCs (p < 0.05). WIF1 inhibits proliferation and promotes apoptosis in GCs. Additionally, it promotes progesterone secretion in prehierarchal GCs (pre-GCs, 1.16 ± 0.05 ng/mg vs. 1.58 ng/mg ± 0.12, p < 0.05) and hierarchal GCs (hie-GCs, 395.00 ng/mg ± 34.73 vs. 527.77 ng/mg ± 27.19, p < 0.05) with the participation of the follicle-stimulating hormone (FSH). WIF1 affected canonical Wnt pathways and phosphorylated β-catenin expression in GCs. Furthermore, 604 upregulated differentially expressed genes (DEGs) and 360 downregulated DEGs in WIF1-overexpressed GCs were found through RNA-seq analysis (criteria: |log2⁡(FoldChange)| > 1 and p_adj < 0.05). Cytokine-cytokine receptor interaction and the steroid hormone biosynthesis pathway were identified. In addition, the transcript of estrogen receptor 2 (ESR2) increased significantly (log2⁡(FoldChange) = 1.27, p_adj < 0.05). Furthermore, we found that WIF1 regulated progesterone synthesis by upregulating ESR2 expression in GCs. Additionally, WIF1 suppressed proliferation and promoted apoptosis in TCs. Taken together, these results reveal that WIF1 stimulates follicle development by promoting GC differentiation and progesterone synthesis, which provides an insight into the molecular mechanism of follicle selection and egg-laying performance in poultry.

A glance into the roles of microRNAs (exosomal and non-exosomal) in polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrine disorder in women of reproductive age. The clinical symptoms include hyperandrogenism, chronic anovulation, and multiple ovarian cysts. PCOS is strongly associated with obesity and insulin resistance. MicroRNAs (miRNAs) are a group of short non-coding RNAs that play a role in the post-transcriptional regulation of gene expression and translational inhibition. They play a vital role in the regulation of multiple metabolic and hormonal processes as well as in oocyte maturation and folliculogenesis in the female reproductive system. miRNAs can be used as diagnostic biomarkers or therapeutic targets because of their stability. The encapsulation of miRNAs in extracellular vesicles or exosomes contributes to their stability. Exosomes are constantly secreted by many cells and size of about 30 to 150 nm. Enveloping miRNAs exosomes can release them for cellular communication. The induced transfer of miRNAs by exosomes is a novel process of genetic exchange between cells. Many studies have shown that along with non-exosomal miRNAs, different types of exosomal miRNAs derived from the serum and follicular fluid can play an essential role in PCOS pathogenesis. These miRNAs are involved in follicular development and various functions in granulosa cells, apoptosis, cell proliferation, and follicular atresia. The present study aimed to comprehensively review the evidence on miRNAs and their affected pathways under both non-exosomal and exosomal circumstances, primarily focusing on the pathogenesis of PCOS.

Transcriptome-wide m6A methylation profiling of Wuhua yellow-feathered chicken ovary revealed regulatory pathways underlying sexual maturation and low egg-laying performance

RNA N6-melthyladenosine (m6A) can play an important role in regulation of various biological processes. Chicken ovary development is closely related to egg laying performance, which is a process primarily controlled by complex gene regulations. In this study, transcriptome-wide m6A methylation of the Wuhua yellow-feathered chicken ovaries before and after sexual maturation was profiled to identify the potential molecular mechanisms underlying chicken ovary development. The results indicated that m6A levels of mRNAs were altered dramatically during sexual maturity. A total of 1,476 differential m6A peaks were found between these two stages with 662 significantly upregulated methylation peaks and 814 downregulated methylation peaks after sexual maturation. A positive correlation was observed between the m6A peaks and gene expression levels, indicating that m6A may play an important role in regulation of chicken ovary development. Functional enrichment analysis indicated that apoptosis related pathways could be the key molecular regulatory pathway underlying the poor reproductive performance of Wuhua yellow-feathered chicken. Overall, the various pathways and corresponding candidate genes identified here could be useful to facilitate molecular design breeding for improving egg production performance in Chinese local chicken breed, and it might also contribute to the genetic resource protection of valuable avian species.

Quantitative lipidomic analysis of chicken egg yolk during its formation

BACKGROUND

The accumulation of lipids in egg yolk during its formation represents a knowledge gap between food science and animal science research to which researchers in either field have not paid sufficient attention. Therefore, the egg yolk samples during different periods of formation (yellow follicle, YF; small hierarchical follicles, SF; and the largest hierarchical follicle, LF) were prepared, and their fatty acid compositions and lipidomes were quantitatively compared.

RESULTS

The fatty acid profiles and lipidomes of egg yolks at the three stages of formation were significantly different. The relative content of oleic acid and palmitic acid were increased, but that of the main polyunsaturated fatty acids (linoleic acid, linolenic acid and docosahexaenoic acid) was decreased in the SF period to the LF period. Among the 786 lipid molecular species identified, 150 and 46 differentially abundant lipids (DALs) were identified in the pairwise comparison of YF/SF (early stage of egg yolk formation) and SF/LF (late stage of egg yolk formation), respectively. Triglycerides and diglycerides, represented by TG(14:0/18:1/20:1) and DG(18:1/18:1/0:0), were decreased, whereas free fatty acids (especially free unsaturated fatty acids) were greatly increased during yolk formation. The changes in phospholipids were complex; the relative abundance of phosphatidylcholine [represented by PC(18:0/22:5)] decreased, whereas phosphatidylethanolamine [represented by PE(18:0/18:0)] increased. In addition, the relative abundance of lysophosphatidylcholine [represented by LPC(18:1/0:0)] was increased during egg yolk formation.

CONCLUSION

The transport and accumulation of lipids into the egg yolk is dynamically adjusted during its formation, and the transport and timing of different lipid molecular species are different. © 2022 Society of Chemical Industry.

The Diverse Roles of 17β-Estradiol in Non-Gonadal Tissues and Its Consequential Impact on Reproduction in Laying and Broiler Breeder Hens

Estradiol-17β (E2) has long been studied as the primary estrogen involved in sexual maturation of hens. Due to the oviparous nature of avian species, ovarian production of E2 has been indicated as the key steroid responsible for activating the formation of the eggshell and internal egg components in hens. This involves the integration and coordination between ovarian follicular development, liver metabolism and bone physiology to produce the follicle, yolk and albumen, and shell, respectively. However, the ability of E2 to be synthesized by non-gonadal tissues such as the skin, heart, muscle, liver, brain, adipose tissue, pancreas, and adrenal glands demonstrates the capability of this hormone to influence a variety of physiological processes. Thus, in this review, we intend to re-establish the role of E2 within these tissues and identify direct and indirect integration between the control of reproduction, metabolism, and bone physiology. Specifically, the sources of E2 and its activity in these tissues via the estrogen receptors (ERα, ERβ, GPR30) is described. This is followed by an update on the role of E2 during sexual differentiation of the embryo and maturation of the hen. We then also consider the implications of the recent discovery of additional E2 elevations during an extended laying cycle. Next, the specific roles of E2 in yolk formation and skeletal development are outlined. Finally, the consequences of altered E2 production in mature hens and the associated disorders are discussed. While these areas of study have been previously independently considered, this comprehensive review intends to highlight the critical roles played by E2 to alter and coordinate physiological processes in preparation for the laying cycle.

Quantitative proteomic analyses during formation of chicken egg yolk

A quantitative comparison of the proteomes during different periods of the formation of egg yolk, from yellow follicles (YF), small hierarchical follicles (9-12 mm, SF), and the largest hierarchical follicle (LF), was performed. The abundance of major egg yolk proteins (apolipoprotein B and vitellogenins) changed significantly during the yolk formation, and several protein hydrolases and isomerases, which may be related to the processing of egg yolk proteins, also varied significantly. The binding proteins for three vitamins (retinol, riboflavin, and vitamin D) and cholesterol were all most abundant in the LF period, suggesting that these nutrients were transported mainly at the final period of the egg yolk formation. Immunoglobulins decreased and complement proteins increased as formation progressed, indicating the dynamic nature of the egg yolk immune system. These results are helpful for understanding the nutrient composition, the formation of assembly structure, the preservation and processing properties of egg yolk.

Histomorphology and gene expression profiles during early ovarian folliculogenesis in duck and goose

In contrast to the later stages of follicle development, little is known about the characteristics and mechanisms associated with early folliculogenesis in avian species. The objectives of the present study were to examine and compare the histomorphological and molecular changes of primordial, primary, and secondary follicles from duck and goose ovaries during the first 6 post-hatching week. Morphological analysis showed that the length and width of both duck and goose ovaries increased steadily during weeks 1 to 5 but increased acutely at week 6, whereas a greater increment was observed in the ovarian length of ducks than that of geese during weeks 4 to 5. Furthermore, smaller diameters of the 3 categories of follicles were observed in ducks than those in geese at the first appearance, but they reached a similar size at week 6. More importantly, secondary follicles were found in the ovaries of ducks 1 wk earlier than in those of geese. These results indicated a more rapid growth rate for ovarian follicles in ducks than in geese during early post-hatching development. At the molecular level, it was found that the mRNAs encoding follicle stimulating hormone receptor (FSHR), anti-Müllerian hormone (AMH), B-cell leukemia/lymphoma 2, and cysteine-dependent aspartate specific protease 3 (CASPASE3) were ubiquitously expressed in all ovarian follicles of ducks and geese with different expression profiles in each follicular category during the first 6 post-hatching week. Notably, transcript levels of FSHR, AMH, and CASPASE3 changed differently between ducks and geese during weeks 5 to 6, which was postulated to be one of the mechanisms inducing more rapid growth of ovarian follicles in ducks rather than in geese. In conclusion, our results revealed, for the first time, differences in early folliculogenesis, including the rate of growth of each follicular category and the timing of transition of primary to secondary follicles, between ducks and geese, and these differences could result from different expression profiles of FSHR, AMH, and CASPASE3 during early post-hatching development.

Transcriptomic Analysis of circRNAs and mRNAs Reveals a Complex Regulatory Network That Participate in Follicular Development in Chickens

Follicular development plays a key role in poultry reproduction, affecting clutch traits and thus egg production. Follicular growth is determined by granulosa cells (GCs), theca cells (TCs), and oocyte at the transcription, translation, and secretion levels. With the development of bioinformatic and experimental techniques, non-coding RNAs have been shown to participate in many life events. In this study, we investigated the transcriptomes of GCs and TCs in three different physiological stages: small yellow follicle (SYF), smallest hierarchical follicle (F6), and largest hierarchical follicle (F1) stages. A differential expression (DE) analysis, weighted gene co-expression network analysis (WGCNA), and bioinformatic analyses were performed. A total of 18,016 novel circular RNAs (circRNAs) were detected in GCs and TCs, 8127 of which were abundantly expressed in both cell types. and more circRNAs were differentially expressed between GCs and TCs than mRNAs. Enrichment analysis showed that the DE transcripts were mainly involved in cell growth, proliferation, differentiation, and apoptosis. In the WGCNA analysis, we identified six specific modules that were related to the different cell types in different stages of development. A series of central hub genes, including MAPK1, CITED4, SOD2, STC1, MOS, GDF9, MDH1, CAPN2, and novel_circ0004730, were incorporated into a Cytoscape network. Notably, using both DE analysis and WGCNA, ESR1 was identified as a key gene during follicular development. Our results provide valuable information on the circRNAs involved in follicle development and identify potential genes for further research to determine their roles in the regulation of different biological processes during follicle growth.

Variations in the Expression Pattern of HSP27 and MSK1 Genes During the Development of Prehierarchical Follicles in the Zi Geese (Anser Cygnoides)

The p38MAPKs (mitogen-activated protein kinases) signaling contributes a pivotal role in mammalian ovarian follicular development; however, the knowledge regarding their expression in geese remains unresolved. The objective of the current study was to determine the spatio-temporal expression of heat shock protein 27 (HSP27) and mitogen- and stress-activated protein kinase 1 (MSK1) genes in the prehierarchical follicles during geese ovarian development. The prehierarchical follicles samples were harvested from 35- to 37-week-old healthy laying geese. HSP27 and MSK1 relative expression in various sized prehierachical follicles was detected by real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting. Follicular wall localization of HSP27 and MSK1 was examined by using immunohistochemistry. Our results at mRNA level indicated that HSP27 was highly expressed in middle white follicles whereas MSK1 was predominantly expressed in small white follicles. The western blotting results for HSP27 and MSK1 were inconsistent with the RT-qPCR results in various stages of prehierachical follicular development but noticeably, HSP27 proteins were still expressed more in middle white follicles while MSK1 proteins were more abundant in primary follicles. At different stages of prehierarchical development, immunodetections in the granulosa and theca cells revealed that HSP27 was intensively localized in middle white follicles while strong detections of MSK1 were observed in large white follicles. These results indicate HSP27 and MSK1 might be associated to the key regulators of folliculogenesis in geese.

In vitro effects of PNP and PNMC on apoptosis and proliferation in the hen ovarian stroma and prehierarchal follicles

This study aimed to examine the mRNA expression, activity, and immunolocalisation of apoptosis/proliferation regulating factors following in vitro exposure of the stroma, white (WFs), and yellowish (YFs) follicles of the chicken ovary to 4-nitrophenol (PNP) or 3-methyl-4-nitrophenol (PNMC). PNMC increased the mRNA expression of caspase-3, -8, Apaf-1, and cytochrome c in the ovarian stroma. The activity of caspase-3, -8, and -9 decreased in WFs in both nitrophenol-treated groups. PNP reduced the number of caspase-3-positive cells in the stromal connective tissue (CT) and the theca interna and externa layers of WFs. In the stroma, the proliferating index decreased in the wall of primary follicles in both nitrophenol-treated groups, however, in the CT, the effect of PNMC was opposite. In the theca interna of WFs, PNP diminished the proliferating index. These results suggest that nitrophenols might impact the development of chicken ovarian follicles by affecting cell death and proliferation.

Bmp4 inhibits goose granulosa cell apoptosis via PI3K/AKT/Caspase-9 signaling pathway

Bone morphogenetic protein 4 (BMP4) has an important role in regulating cellular proliferation, differentiation and apoptosis. It, however, is still unclear as to the mechanisms by which BMP4 regulates the apoptosis of granulosa cells (GCs) in geese. In the present study, there was cloning of the full-length coding sequence of goose BMP4 gene, which consisted of 1212 nucleotides encoding 403 amino acids. Its deduced amino acid sequence comprised one signal peptide, one TGFβ pro-peptide and one mature peptide domain. Results from conducting the quantitative real-time PCR (qPCR) indicated the relative abundances of BMP4 mRNA in geese GCs increased gradually from the relative abundances in pre-hierarchical follicles that were 4 to 6 mm in diameter to that in the fifth largest (F5) follicle and then relative abundances of BMP4 mRNA decreased with further development as the largest (F1) follicle. Results from use of the TUNEL assay indicated that overexpression of the goose BMP4 gene suppressed GC apoptosis and this was confirmed when relative abundances of the CAD, Caspase-9 and Caspase-3 proteins were determined using western blotting. In addition, overexpression of the BMP4 gene induced phosphorylation of AKT, which was inhibited with use of the PI3K inhibitor, LY294002. Co-transfection of BMP4 and LY294002 resulted in increased relative abundances of Caspase-9 and CAD proteins but had no effect on that of Caspase-3. Taken together, these results suggested that expression of the BMP4 gene resulted in a reduction in Caspase-9 protein leading to inhibition of GC apoptosis via the PI3K/AKT signaling pathway in geese.

Expression and Mutation Analyses of Fas, FLIP and Bcl-2 in Granulosa Cell Tumor of Ovary

Aims and background

Mounting evidence indicates that evasion of apoptosis contributes to tumor pathogenesis. Although both Fas and Bcl-2 are crucial in apoptosis of normal ovarian cells, their roles in ovarian tumors, especially stromal tumors, are largely unknown. The aim of this study was to explore mutation of the Fas gene and expression of the apoptosis-related proteins Fas, FLICE-like inhibitory protein (FLIP) and Bcl-2 in granulosa cell tumor (GCT) of the ovary.

Methods

We analyzed the expression of Fas, FLIP and Bcl-2 in 20 GCT tissues by immunohistochemistry. We also analyzed somatic mutations of the Fas gene in the same GCT tissues by polymerase chain reaction and single-strand conformation polymorphism assay.

Results

Expression of Fas was evident in 12 GCTs (60%), but the remaining 8 GCTs showed no or markedly decreased Fas immunostaining. Expression of FLIP was identified in 30% of the GCT samples and expression of Bcl-2 in 75%. All GCTs with positive Fas expression (n = 12) showed either FLIP or Bcl-2 expression. The GCTs were found to carry no somatic Fas mutations.

Conclusions

Our data show that alterations of the apoptosis-related proteins Fas, FLIP and Bcl-2 are common in GCT, and suggest that expression of FLIP and Bcl-2 and loss of Fas expression might play role in the pathogenesis of GCT, possibly by inhibiting apoptosis.

Histology of the Ovary of the Laying Hen (Gallus domesticus)

The laying hen (Gallus domesticus) is a robust animal model for epithelial ovarian cancer. The use of animal models is critical in identifying early disease markers and developing and testing chemotherapies. We describe the microscopic characteristics of the normally functioning laying hen ovary and proximal oviduct to establish baselines from which lesions associated with ovarian cancer can be more readily identified. Ovaries and oviducts were collected from 18-month-old laying hens (n = 18) and fixed in 10% neutral buffered formalin. Hematoxylin- and eosin-stained sections were examined by light microscopy. Both post-ovulatory follicular regression and atresia of small follicles produce remnant clusters of vacuolated cells with no histological evidence that scar tissue persists. Infiltrates of heterophils are associated with atresia of small follicles, a relationship not previously documented in laying hen ovaries. Because these tissues can be mistaken for cancerous lesions, we present a detailed histological description of remnant Wolffian tissues in the laying hen ovary. Immunohistochemical staining for pancytokeratin produced a positive response in ovarian surface epithelium and staining for vimentin produced a positive response in granulosa cells of follicles. Epithelial cells lining glands of the remnant epoöphoron had a positive response to both pancytokeratin and vimentin, a result also observed in women.

Immunohistochemical, morphological and histometrical analyses of follicular development in Astyanax bimaculatus (Teleostei: Characidae) exposed to an organochlorine insecticide

Thiodan^® is an organochlorine insecticide used in agriculture that can reach aquatic ecosystems where it can affect fish reproduction. This research aimed to evaluate follicular development and the expression of integrin β1, collagen type IV and caspase 3 by morphological, histometrical and immunohistochemical analyses of Astyanax bimaculatus exposed to Thiodan^®. Treatments included three sublethal concentrations of Thiodan^® (1.15, 2.30, and 5.60μgL^-1) for 96h and a control without the insecticide. Mature females with ovaries in advanced follicular development were chosen for study (average weight: 11.52 ± 2.0g; average total length: 9.12 ± 0.64cm). The follicles of A. bimaculatus exhibited normal morphology, while the diameters of secondary follicles showed an increase (P< 0.05) in all concentrations when compared to the control group; a characteristic of follicles undergoing the initial stages of intoxication. Immunohistochemical analysis revealed secondary follicles with greater expression of integrin β1 and collagen type IV in cytoplasm of follicular cells than in the primary follicles in all treatments and in the control. Immunolocalization of caspase 3 was detected in follicular cells during secondary development in all tested concentrations of Thiodan^® and the control. These analyses demonstrate positive immunolocalization throughout the course of follicular development, even in fish exposed to varying concentrations of Thiodan^® for 96h, demonstrating that follicular cells retain their physiological integrity.

Expression of cocaine- and amphetamine-regulated transcript (CART) in hen ovary

Background

Cocaine- and amphetamine-regulated transcript (CART), discovered initially by via differential display RT-PCR analysis of brains of rats administered cocaine, is expressed mainly in central nervous system or neuronal origin cells, and is involved in a wide range of behaviors, such as regulation of food intake, energy homeostasis, and reproduction. The hens egg-laying rate mainly depends on the developmental status of follicles, expression of CART have not been identified from hen follicles, the regulatory mechanisms of CART biological activities are still unknown. The objective of this study was to characterize the mRNA expression of CART in hen follicular granulosa cells and determine CART peptide localization and regulatory role during follicular development.

Methods

Small white follicles (1–2 mm in diameter) were treated for RNA isolation; Small white follicles (1–2 mm in diameter) and large white follicles (4–6 mm in diameter) were treated for immunohistochemical localization and large white follicles (4–6 mm in diameter), small yellow follicles (6–8 mm in diameter), large yellow follicles (9–12 mm in diameter), mature follicles (F5, F4, F3, F2, F1, >12 mm in diameter) were treated for RNA isolation and Real time PCR.

Results

The results showed that full length of the CDS of hen CART was 336 bp encoding a 111 amino acid polypeptide. In the hen ovary, CART peptide was primarily localized to the theca layer, but not all, the oocyte and granulosa layer, with diffused, weaker staining than relative to the theca cell layer. Further, amount of CART mRNA was more (P < 0.05) in granulosa cells of 6–8 mm follicles compared with that in granulosa cells of other follicles. However, CART mRNA amount was greater in theca cells of 4–6 mm follicles relative to follicles of other sizes (P < 0.05).

Conclusions

Results suggest that CART could play a potential role in developmental regulation of chicken follicles.

Time course effect of lipopolysaccharide on Toll-like receptors expression and steroidogenesis in the Chinese goose ovary

The ovary of Chinese goose is easily infected by microorganisms because of the mating behaviour in water, which causes decreased laying performance. This study investigated the time course effect of lipopolysaccharide (LPS) on the steroidogenesis and mRNA expression of Toll-like receptors (TLRs), a class of key pattern recognition receptor, in the breeding goose ovary. The laying geese were treated intravenously with LPS for 0, 6, 12, 24 and 36 h, and all birds were slaughtered approximately 8 h after oviposition. The expression levels of TLRs in the white and yellowish follicles, and granulosa and theca layers of hierarchical follicles were examined by real-time PCR. All 10 members of avian TLR family were differentially expressed among the different follicular tissues. Moreover, at 24 and 36 h after LPS treatment, the hierarchical follicle morphological structure was altered, but the expression levels of TLRs were still higher than the control. Furthermore, during LPS treatment period, the expression pattern of TLRs 2A and 4 genes was similar to that of TLR15 in the white follicles, TLRs 1B, 5 and 15 in the yellowish follicles, TLRs 7 and 15 in the granulosa layer, and TLRs 1A, 2B, 3, 7 and 15 in the theca layer, which had a negative correlation with the kinetics of plasma P4 and E2 concentrations. In conclusion, the mechanism by which pathogen infection inhibited goose follicular growth and further decreased egg production may involve a gradually enhanced inflammatory response and reduced endocrine function. This may be due to stimulated TLRs in the ovary.

Regulatory Mechanisms Underlying the Expression of Prolactin Receptor in Chicken Granulosa Cells

Prolactin (PRL) has both pro- and anti-gonadal roles in the regulation of avian ovarian functions through its interaction with the receptor (PRLR). However, neither the pattern of expression of PRLR nor its regulatory mechanisms during follicle development have been clearly defined. The objective of the present study was to investigate mechanisms of PRLR expression in chicken granulosa cells. Levels of PRLR transcript were highest in the stroma and walls of follicles < 2 mm in diameter and progressively declined with the maturation of follicles. In preovulatory follicles, PRLR was expressed at higher levels in granulosa than theca layers. FSH exerted the greatest stimulatory effect on PRLR and StAR expression in cultured granulosa cells of the 6–8 mm follicles but this effect declined as follicles matured to F1. In contrast, LH did not alter the expression of PRLR in granulosa cells of all follicular classes but increased levels of StAR in F2 and F1 granulosa cells. Both non-glycosylated- (NG-) and glycosylated- (G-) PRL upregulated basal PRLR expression in granulosa cells of the 6–8 mm, F3 or F1 follicles but had little effect in F2 follicles. Furthermore, FSH-stimulated PRLR expression was reduced by the addition of either isoform of PRL especially in F2 granulosa cells. These results indicate that PRLR is differentially distributed and regulated by FSH or PRL variants independently or in combination in the follicular hierarchy. By using activators and inhibitors, we further demonstrated that multiple signaling pathways, including PKA, PKC, PI3K, mTOR and AMPK, are not only directly involved in, but they can also converge to modulate ERK2 activity to regulate FSH-mediated PRLR and StAR expression in undifferentiated granulosa cells. These data provide new insights into the regulatory mechanisms controlling the expression of PRLR in granulosa cells.

Expression and regulation of prolactin-like protein messenger RNA in undifferentiated chicken granulosa cells

Prolactin-like protein (PRL-L; LOC417800) is a homolog of PRL in non-mammalian vertebrates and can act as a functional ligand of PRL receptor (PRLR). Despite its widespread expression in extrapituitary tissues, mechanisms of regulation of PRL-L in the chicken ovary remain unknown. In this study, we first examined PRL-L expression in chicken ovarian developing follicles. PRL-L transcript levels were highest (P<0.05) in follicular walls of <2mm follicles and progressively declined during follicle maturation. Undifferentiated granulosa cells of 6-8mm follicles had higher (P<0.05) PRL-L mRNA levels than differentiated granulosa cells of F3, F2 or F1 follicles. In cultured undifferentiated granulosa cells, levels of PRL-L transcript were increased (P<0.05) by follicle stimulating hormone (FSH) treatment while were not altered by the addition of luteinizing hormone (LH). In addition, 10ng/ml non-glycosylated (NG-) and 1ng/ml glycosylated (G-) PRL increased (P<0.05) but at higher levels (100 or 1000ng/ml) both showed no effects on PRL-L expression. Furthermore, 100ng/ml NG-PRL enhanced (P<0.05) FSH-induced PRL-L expression, whereas the effects of G-PRL were not significant. These results suggest that PRL-L mRNA is differentially expressed in the follicular hierarchy and its high abundance in undifferentiated granulosa cells is under the regulation of FSH or PRL variants independently or in combination. Moreover, in undifferentiated granulosa cells we also provide evidence for a positive role for PKA, PKC and PI3K signaling while a negative role for ERK2 in mediating FSH stimulation of PRL-L transcription.

Exposure to triptolide affects follicle development in NIH mice

Triptolide (TPL) is a main active compound isolated from Tripterygium wilfordii Hook f. Despite its positive therapeutic effect, the female reproductive toxicity of TPL is still the bottleneck of clinical application. The study was designed to investigate the adverse effects on mice ovary and underlying mechanism of TPL. Adult female NIH mice were treated with two therapeutic doses of TPL (25 and 50 μg/kg/d) for 50 days, respectively. Mice estrous cycle was detected by vaginal cytology method. Half mice from each group were selected randomly to perform superovulation. Quality and quantity of ovulated eggs were evaluated. Other mice from each group were executed for morphological study. Ovarian histological sections were stained by H&E staining for ovarian pathologic detection and follicular counts. Apoptotic granulosa cell (GC) was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Endoplasmic reticulum (ER) stress-related proteins and antiapoptotic X-linked inhibitor of apoptosis protein (XIAP) were detected by immunohistochemical method. Two doses of TPL resulted in estrous cycle disorder and follicles in development reservoir impairment. Quality and quantity of mice ovulated eggs significantly decreased after TPL treatment. Ovarian pathologic examination revealed TPL-induced TUNEL-positive GCs increase and ER stress–related proteins (78-kDa glucose-regulated protein, p-protein kinase-like endoplasmic reticulum kinase, p-eukaryotic initiation factor 2α, and CCAAT/enhancer binding protein homologous protein) expression upregulation. Meanwhile, the expression of antiapoptosis protein XIAP in mice ovary was obviously inhibited by TPL. Our results may demonstrate that therapeutic doses of TPL can injure ovary function, but there is no difference between high-dose and low-dose groups. GCs apoptosis by ER stress pathway and antiapoptotic function impairment may partly mediate TPL-induced ovary toxicity.

Menoprogen, a TCM Herbal Formula for Menopause, Increases Endogenous E2 in an Aged Rat Model of Menopause by Reducing Ovarian Granulosa Cell Apoptosis

The effect of Menoprogen (MPG) on ovarian granulosa cell (GC) apoptosis was investigated in vitro and in vivo in an aged rat model of menopause. Intragastric administration of Menoprogen or estradiol valerate to 14-month-old senile female rats for eight weeks increased plasma E₂ levels, as well as the weight of both ovarian and uterine tissues. Flow cytometric (FCM) analysis of isolated GCs from MPG-treated aged rats showed reductions in the G₀/G₁ ratio and apoptotic peaks. Isolated GCs also exhibited an increase in cell size and the number of cytoplastic organelles and intracellular gap junctions, the reappearance of secretory granules, and a lack of apoptotic bodies as determined by TEM. Results from a TdT-mediated dUTP nick end-labeling (TUNEL) assay revealed a reduction in TUNEL-positive GCs after MPG treatment. Immunohistochemical analysis showed a downregulation of proapoptotic Bax proteins and an upregulation of antiapoptotic Bcl-2 proteins. The addition of MPG-medicated serum to the media of cultured GCs also reduced cadmium chloride-induced apoptosis and downregulated caspase-3 protein expression. This work demonstrates that Menoprogen inhibits GC apoptosis in aged female rats and thereby increases E₂ production. This represents a novel mechanism of action for this herbal medicine in the treatment of menopausal symptoms.

Dynamic Changes in the Follicular Transcriptome and Promoter DNA Methylation Pattern of Steroidogenic Genes in Chicken Follicles throughout the Ovulation Cycle

The molecular mechanisms associated with follicle maturation and ovulation are not well defined in avian species. In this study, we used RNA-seq to study the gene expression profiles of the chicken follicles from different developmental stages (pre-hierarchical, pre-ovulatory and post-ovulatory). Transcriptomic analysis revealed a total of 1,277 and 2,310 genes were differentially expressed when follicles progressed through the pre-hierarchical to hierarchical and pre-ovulatory to post-ovulatory transitions, respectively. The differentially expressed genes (DEG) were involved in signaling pathways such as adherens junction, apoptosis and steroid biosynthesis. We further investigated the transcriptional regulation of follicular steroidogenesis by examining the follicle-specific methylation profiles of Star (steroidogenic acute regulatory protein), Cyp11a1 (cytochrome P450, family 11, subfamily a, polypeptide 1) and Hsd3b (hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1), genes encoding the key enzymes for progesterone synthesis. The varied patterns of DNA methylation in proximal promoters of Star and Cyp11a1but not Hsd3b in different follicles could play a major role in controlling gene expression as well as follicular steroidogenic activity. Finally, the promoter-reporter analysis suggests that TGF-β could be involved in the regulation of Hsd3b expression during ovulation. Together, current data not only provide novel insights into the molecular mechanisms of follicular physiology in chicken follicles, but also present the first evidence of epigenetic regulation of ovarian steroidogenesis in avian species.

Molecular aspects of bovine cystic ovarian disease pathogenesis

Cystic ovarian disease (COD) is one of the main causes of reproductive failure in cattle and causes severe economic loss to the dairy farm industry because it increases both days open in the post partum period and replacement rates due to infertility. This disease is the consequence of the failure of a mature follicle to ovulate at the time of ovulation in the estrous cycle. This review examines the evidence for the role of altered steroid and gonadotropin signaling systems and the proliferation/apoptosis balance in the ovary with cystic structures. This evidence suggests that changes in the expression of ovarian molecular components associated with these cellular mechanisms could play a fundamental role in the pathogenesis of COD. The evidence also shows that gonadotropin receptor expression in bovine cystic follicles is altered, which suggests that changes in the signaling system of gonadotropins could play a fundamental role in the pathogenesis of conditions characterized by altered ovulation, such as COD. Ovaries from animals with COD exhibit a disrupted steroid receptor pattern with modifications in the expression of coregulatory proteins. These changes in the pathways of endocrine action would trigger the changes in proliferation and apoptosis underlying the aberrant persistence of follicular cysts.

Free Spanish abstract: A Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/149/6/R251/suppl/DC1.

Salmonella Enteritidis infection slows steroidogenesis and impedes cell growth in hen granulosa cells

Infection by Salmonella Enteritidis (SE) causes decreased egg production in laying hens. Immunoresponse, steroidogenesis, and cell proliferation by chicken granulosa cells (cGCs) are of particular interest because these changes are involved in follicular growth, atresia, and ovulation. To elucidate the possible mechanisms underlying these changes, transcriptional alterations in cGCs at distinct stages of follicular maturity were studied. Luteinizing hormone (LH)-and follicle-stimulating hormone (FSH) were applied to the cGCs isolated from hierarchical and prehierarchical follicles, respectively, to imitate the effects of gonadotropin during in vitro SE infection. Results showed that the expression of Toll-like receptor 15 was dependent on the follicular maturity, with mature cells having a more significant and progressively stronger immunoresponse. Attenuated responses to LH and FSH as well as retardant steroidogenesis due to down-regulated LH receptor, FSH receptor, and the P450 side-chain cleavage system were observed and may have led to delayed hierarchical follicular growth. Deteriorated cell viability of prehierarchical follicles may occur, as the proliferation of stimulator heparin-binding epidermal growth factor was reduced significantly. Furthermore, the infection led to a higher probability of cGCs from the smaller follicles undergoing apoptosis than those from F1 follicles. Collectively, the data provide evidence of a tendency toward pathogen elimination in F1 follicles by induction of a strong immune response and cell apoptosis in smaller follicles to avoid bacterial transovarian infection. It is our speculation that slowed steroidogenesis and impeded follicular growth may play essential roles in decreased ovulation rate as well as further decreased egg production during SE infection.

Ovarian follicle selection and granulosa cell differentiation

The reproductive strategy for avian species that produce a sequence (or clutch) of eggs is dependent upon the maintenance of a small cohort of viable, undifferentiated (prehierarchal) follicles. It is from this cohort that a single follicle is selected on an approximate daily basis to initiate rapid growth and final differentiation before ovulation. This review describes a working model in which follicles within this prehierarchal cohort are maintained in an undifferentiated state by inhibitory cell signaling until the time of selection. Ultimately, follicle selection represents a process in which a single undifferentiated follicle per day is predicted to escape such inhibitory mechanisms to begin rapid growth and final maturation before ovulation. Several processes initiated within the granulosa cell layer at selection are dependent upon G protein-coupled receptors signaling via cyclic adenosine monophosphate (cAMP), and several critical processes are described herein. Finally, reference is made to several practical outcomes that can result from understanding the process of selection, including applications within the poultry industry. Proximal factors and processes that mediate follicle selection can either extend or decrease the length of the laying sequence, and thus directly influence overall egg production. In particular, any aberration that results in the selection of more than one follicle per day will result in decreased egg production. More generally, in wild birds these processes are modified by prevailing environmental conditions and by social interactions to influence clutch size. The elucidation of cellular processes that regulate follicle selection can assist in the development of assisted reproductive technologies for application in threatened and endangered avian species.

The effects of isotretinoin on the ovarian reserve of females with acne

There are some side effects of isotretinoin in many organs. However, a study investigating the effects of isotretinoin on the human ovarian reserve has not been reported previously. The study was conducted to investigate possible effects of isotretinoin on ovarian reserve. Serum anti-Müllerian hormone (AMH) levels were measured at the beginning and at the end of isotretinoin treatment in 22 patients with acne and in 22 women without. The mean AMH level before treatment was 5.77 ng/mL in the study group and 3.79 ng/mL in the control group (p = 0.008). Following treatment, the mean AMH level was 4.69 ng/mL in the study group. This mean AMH level after treatment was statistically lower than the AMH level before treatment (p = 0.012). There was no significant difference between the mean AMH level at the end of treatment and that of the control group (p = 0.20). The high level of pre-treatment AMH levels could be an evidence of hyperandrogenism in women with acne, even if they are not identified as having polycystic ovary syndrome (PCOS) or hyperandrogenism. Decrease in AMH levels following exposure to isotretinoin may suggest that it has a detrimental effect on the ovaries.

Gene Expression During Early Folliculogenesis in Goats Using Microarray Analysis

Understanding of gene expression and metabolic, biological and physiological pathways in ovarian follicular development can have a significant impact on the dynamics of follicular atresia or survival. In fact, some oocyte loss occurs during the transition from secondary to early tertiary follicles. This study aimed to understand, by microarray analysis, the temporal changes in transcriptional profiles of secondary and early antral (tertiary) follicles in caprine ovaries. Ovarian follicles were microdissected and pooled to extract total RNA. The RNA was cross hybridized with the bovine array. Among 23,987 bovine genes, a total of 14,323 genes were hybridized with goat mRNAs while 9,664 genes were not. Of all the hybridized genes, 2,466 were stage-specific, up- and down-regulated in the transition from secondary to early tertiary follicles. Gene expression profiles showed that three major metabolic pathways (lipid metabolism, cell death, and hematological system) were significantly differentiated between the two follicle stages. In conclusion, this study has identified important genes and pathways which may potentially be involved in the transition from secondary to early tertiary follicles in goats.

Ovarian dysfunction and gene-expressed characteristics of female mice caused by long-term exposure to titanium dioxide nanoparticles

Although numerous studies have described the accumulation of titanium dioxide nanoparticles (TiO(2) NPs) in the liver, kidneys, lung, spleen, and brain, and the corresponding damage, it is unclear whether or not TiO(2) NPs can be translocated to the ovary and cause ovarian injury, thus impairing fertility. In the current study, ovarian injury and gene-expressed characteristics in female mice induced by intragastric administration of TiO(2) NPs (10mg/kg) for 90 consecutive days were investigated. Our findings indicated that TiO(2) NPs can accumulate in the ovary and result in ovarian damage, cause an imbalance of mineral element distribution and sex hormones, decrease fertility or the pregnancy rate and oxidative stress in mice. Microarray analysis showed that in ovaries from mice treated with TiO(2) NPs compared to controls, 223 genes of known function were up-regulated, while 65 ovarian genes were down-regulated. The increased expression of Cyp17a1 following TiO(2) NPs treatment suggested that the increase in estradiol biosynthesis may be a consequence of increased TiO(2) NPs. In addition, the elevated expression of Akr1c18 implied that progesterone metabolism was accelerated, thus causing a decrease in the progesterone concentration. Taken together, the apparent regulation of key ovarian genes supports the hypothesis that TiO(2) NPs directly affects ovarian function.

Developmental programming: impact of prenatal testosterone excess on ovarian cell proliferation and apoptotic factors in sheep

Prenatal testosterone (T) excess leads to reproductive dysfunctions in sheep, which include increased ovarian follicular recruitment and persistence. To test the hypothesis that follicular disruptions in T sheep stem from changes in the developmental ontogeny of ovarian proliferation and apoptotic factors, pregnant Suffolk sheep were injected twice weekly with T propionate or dihydrotestosterone propionate (DHT; a nonaromatizable androgen) from Days 30 to 90 of gestation. Changes in developmental expression of proliferating cell nuclear antigen (PCNA), BCL2, BAX, activated CASP3, and FAS/FASLG were determined at Fetal Days 90 and 140, 22 wk, 10 mo, and 21 mo of age by immunocytochemisty. Prenatal T treatment induced changes in expression of proliferative and apoptotic markers in a follicle-, age-, and steroid-specific manner. Changes in BAX were evident only during fetal life and PCNA, BCL2, and CASP3 only postnatally. Prenatal T and not DHT increased PCNA and decreased BCL2 in granulosa/theca cells of antral follicles at 10 and 21 mo but decreased CASP3 in granulosa/theca cells of antral follicles at 22 wk (prepubertal) and 10 and 21 mo. Both treatments decreased BAX immunostaining in granulosa cells of Fetal Day 90 primordial/primary follicles. Neither treatment affected FAS expression at any developmental time point in any follicular compartment. Effects on BAX appear to be programmed by androgenic actions and PCNA, BCL2, and CASP3 by estrogenic actions of T. Overall, the findings demonstrate that fetal exposure to excess T disrupts the ovarian proliferation/apoptosis balance, thus providing a basis for the follicular disruptions evidenced in these females.

Follicular populations, recruitment and atresia in the ovaries of different strains of mice

Follicular atresia is a key event in the selection of the ovulatory follicles and occurs during all developmental stages. The aims of the study were to evaluate the follicular population as well as the rates of follicular recruitment and atresia in different strains of mice. Ovaries were obtained from four strains of mice: G1/ Swiss, G2/ F1 Swiss×C57BL/6, G3/ inbred strain C57BL/6, and G4/ F1 C57BL/6×Swiss. All mice used in the study were 60 days old. Ovaries collected from the mice were fixed and processed for histological analysis. The G2 ovaries were also used to examine immunolocalization of active caspase-3. The pimordial follicle population was smaller in G3 mice than in G1, G2 and G4 groups (7 565±1 845 vs. 17 180±3 159, 14 785±3 319 and 13 325±2 685, respectively; p<0.05). The rate of follicular recruitment in G3, however, was higher than in the other groups (29.2% vs. 18.2%, 17.3% and 13.0% in G1, G2 and G4, respectively; p<0.05), resulting in a similar (p>0.05) number of antral follicles among groups. The small follicular pool in G3 mice was also associated with a lower rate of follicular atresia (11.4% vs. 17.2%, 16.7% and 13.6% for G3, G1, G2 and G4, respectively; p<0.05). The number of follicles stained with active caspase-3 was higher (p<0.05) during the final stage of preantral folliculogenesis than in other stages of follicular development suggesting that apoptosis in mice occurs earlier in comparison to large animals. Thus, it was concluded that differences in follicle reservoir among mice strains are compensated by an increased rate of follicular recruitment and a decreased rate of follicular atresia; and atresia occurs in mice mainly at the end of the preantral stage of folliculogenesis.

Disruption of the salmon reproductive endocrine axis through prolonged nutritional stress: changes in circulating hormone levels and transcripts for ovarian genes involved in steroidogenesis and apoptosis

Mechanisms regulating the normal progression of ovarian follicular growth versus onset of atresia in fishes are poorly understood. To gain a better understanding of these processes, we exposed immature female coho salmon (Oncorhynchus kisutch) to prolonged fasting to induce follicular atresia and monitored body growth, development of the ovarian follicles, changes in reproductive hormones, and transcripts for ovarian genes. Prolonged fasting reduced body and ovary weight and increased the appearance of atretic follicles relative to normally fed controls. Endocrine analyses showed that fasting reduced plasma insulin-like growth factor 1 (IGF1), estradiol-17β (E2), and pituitary, but not plasma, levels of follicle-stimulating hormone (FSH). Transcripts for ovarian fsh receptor (fshr) and steroidogenesis-related genes, such as steroidogenic acute regulatory protein (star), 3β-hydroxysteroid dehydrogenase (hsd3b), and P450 aromatase (cyp19a1a) were significantly lower in fasted fish. Ovarian expression of apoptosis-related genes, such as Fas-associated death domain (fadd), caspase 8 (casp8), caspase 3 (casp3), and caspase 9 (casp9) were significantly elevated in fasted fish compared to fed fish, indicating that apoptosis is involved in the process of atresia in this species. Interestingly, some genes such as fadd, casp8, casp3, and hsd3b, were differentially expressed prior to increases in the number of atretic follicles and reductions in hormone levels induced by fasting, and may therefore have potential as early indicators of atresia. Together these results suggest that prolonged nutritional stress may disrupt the reproductive system and induce follicular atresia in part via reductions in ovarian IGF and FSH signaling, and downstream effects on steroidogenesis-related genes and E2 production.

Progestin signaling through mPRα in Atlantic croaker granulosa/theca cell cocultures and its involvement in progestin inhibition of apoptosis

Although there is substantial evidence that membrane progestin receptors (mPRs) perform a critical physiological role in meiotic maturation of fish oocytes, it is unknown whether they are also intermediaries in progestin signaling in the surrounding follicular cells. Here, we show that mPRα protein is located on the plasma membranes of both granulosa and theca cells (G/T cells) isolated from Atlantic croaker ovaries and is associated with the presence of a single high affinity, limited capacity, pertussis toxin-sensitive, specific progestin [17,20β,21-trihydroxy-4-pregnen-3-one (20β-S)] membrane binding site with the characteristics of mPRα. Treatment of G/T cells with 20β-S caused rapid G protein activation and a transient, pertussis toxin-sensitive, decrease in cAMP levels, whereas the selective nuclear progesterone receptor agonist, R5020, did not cause G protein activation, consistent with previous reports on mPRα signaling. 20β-S treatment decreased serum starvation-induced cell death in both G/T cells and in seatrout mPRα-transfected MDA-MB-231 cells, whereas R5020 was ineffective. Moreover, a selective mPRα agonist, 10-ethenyl-19-norprogesterone, mimicked the protective action of 20β-S against cell death, which was lost upon knockdown of mPRα protein but not after progesterone receptor knockdown, further demonstrating an involvement of mPRα. Signaling molecules involved in inhibition of apoptosis, Erk and serine-threonine kinase, were activated in G/T cells by 20β-S, which suggests a potential mechanism for mPRα inhibition of apoptosis. This is the first study to demonstrate endogenous mPR signaling in the ovarian follicle and to suggest a novel physiological role for mPRα in mediating the antiapoptotic actions of progestins in ovarian follicle cells.

Primary ovarian insufficiency

Primary ovarian insufficiency is a subclass of ovarian dysfunction in which the cause is within the ovary. In most cases, an unknown mechanism leads to premature exhaustion of the resting pool of primordial follicles. Primary ovarian insufficiency might also result from genetic defects, chemotherapy, radiotherapy, or surgery. The main symptom is absence of regular menstrual cycles, and the diagnosis is confirmed by detection of raised follicle-stimulating hormone and declined oestradiol concentrations in the serum, suggesting a primary ovarian defect. The disorder usually leads to sterility, and has a large effect on reproductive health when it arises at a young age. Fertility-preservation options can be offered to some patients with cancer and those at risk of early menopause, such as those with familial cases of primary ovarian insufficiency. Long-term deprivation of oestrogen has serious implications for female health in general; and for bone density, cardiovascular and neurological systems, wellbeing, and sexual health in particular.

Transcriptional effects of progesterone receptor antagonist in rat granulosa cells

Progesterone, acting via the nuclear progesterone receptor (PGR), reduces apoptosis in periovulatory granulosa cells, and is a likely mediator of the anti-atretic actions of LH. The underlying mechanisms, however, have not been clearly defined. In this study, we sought to identify progesterone-mediated transcriptional changes involved in apoptosis regulation. Granulosa cells from immature, gonadotropin-primed female rats were treated in vitro with 100 nM of the PGR antagonist Org 31710. Transcriptional effects were analyzed after 5 and 22 h of incubation using microarrays, and the expression of 85 genes was subsequently measured by quantitative PCR. Follow-up experiments focused on genes related to the functional group "apoptosis". We have identified novel, early gene targets of PGR that may be involved in the control of apoptosis and other biologically significant functions in periovulatory granulosa cells. This study expands our knowledge of events that occur during the processes of ovulation and luteinization.

Oocyte-granulosa-theca cell interactions during preantral follicular development

The preantral-early antral follicle transition is the penultimate stage of follicular development in terms of gonadotropin dependence and follicle destiny (growth versus atresia). Follicular growth during this period is tightly regulated by oocyte-granulosa-theca cell interactions. Formation of the theca cell layer is a key event that occurs during this transitional stage. Granulosal factor(s) stimulates the recruitment of theca cells from cortical stromal cells, while oocyte-derived growth differentiation factor-9 (GDF-9) is involved in the differentiation of theca cells during this early stage of follicular development. The preantral to early antral transition is most susceptible to follicular atresia. GDF-9 promotes follicular survival and growth during transition from preantral stage to early antral stage by suppressing granulosa cell apoptosis and follicular atresia. GDF-9 also enhances preantral follicle growth by up-regulating theca cell androgen production. Thecal factor(s) promotes granulosa cell proliferation and suppress granulosa cell apoptosis. Understanding the intraovarian mechanisms in the regulation of follicular growth and atresia during this stage may be of clinical significance in the selection of the best quality germ cells for assisted reproduction. In addition, since certain ovarian dysfunctions, such as polycystic ovarian syndrome and gonadotropin poor-responsiveness, are consequences of dysregulated follicle growth at this transitional stage, understanding the molecular and cellular mechanisms in the control of follicular development during the preantral-early antral transition may provide important insight into the pathophysiology and rational treatment of these conditions.

An imbalance between apoptosis and proliferation contributes to follicular persistence in polycystic ovaries in rats

BACKGROUND

Cystic ovarian disease is an important cause of infertility that affects bovine, ovine, caprine and porcine species and even human beings. Alterations in the ovarian micro-environment of females with follicular cysts could alter the normal processes of proliferation and programmed cell death in ovarian cells. Thus, our objective was to evaluate apoptosis and proliferation in ovarian cystic follicles in rats in order to investigate the cause of cystic follicle formation and persistence.

METHODS

We compared the number of in situ apoptotic cells by TUNEL assay, expression of active caspase-3 and members of Bcl-2 family by immunohistochemistry; and cell proliferation by the expression of the proliferation markers: PCNA and Ki-67.

RESULTS

The proliferation index was low in granulosa of tertiary and cystic follicles of light exposed rats when compared with tertiary follicles of control animals, while in theca interna only cystic follicles presented low proliferation index when compared with tertiary follicles (p < 0.05). The granulosa of cysts exhibited a similar cell DNA fragmentation to early atretic follicles. In the granulosa and theca interna, active caspase-3 shown similar immunostaining levels in tertiary and cystic follicles (p < 0.05). The granulosa cells presented high expression of Bcl-2, Bcl-xL and Bcl-w in the tertiary and cystic follicles with diminishing intensity in the atretic follicles, except with Bcl-w where the intensity was maintained in the atretic follicles (p < 0.05). The expression of Bax was weak in the healthy and cystic follicles. In the theca interna, Bcl-2 expression was the same as the pattern found in the granulosa; no differences were found between tertiary and cystic follicles from both groups for Bcl-xL and Bcl-w. The expression of Bax in this layer was higher in the tertiary follicles of the treated animals (p < 0.05) while the values for cystic follicles were similar to those in the tertiary follicles of controls. The theca externa showed low expression of the pro and anti-apoptotic proteins.

CONCLUSION

These results show that the combination of weak proliferation indices and low apoptosis observed in follicular cysts, could explain the cause of the slow growth of cystic follicles and the maintenance of a static condition without degeneration, which leads to their persistence. These alterations may be due to structural and functional modifications that take place in these cells and could be related to hormonal changes in animals with this condition.

Parental effects in ecology and evolution: mechanisms, processes and implications

As is the case with any metaphor, parental effects mean different things to different biologists--from developmental induction of novel phenotypic variation to an evolved adaptation, and from epigenetic transference of essential developmental resources to a stage of inheritance and ecological succession. Such a diversity of perspectives illustrates the composite nature of parental effects that, depending on the stage of their expression and whether they are considered a pattern or a process, combine the elements of developmental induction, homeostasis, natural selection, epigenetic inheritance and historical persistence. Here, we suggest that by emphasizing the complexity of causes and influences in developmental systems and by making explicit the links between development, natural selection and inheritance, the study of parental effects enables deeper understanding of developmental dynamics of life cycles and provides a unique opportunity to explicitly integrate development and evolution. We highlight these perspectives by placing parental effects in a wider evolutionary framework and suggest that far from being only an evolved static outcome of natural selection, a distinct channel of transmission between parents and offspring, or a statistical abstraction, parental effects on development enable evolution by natural selection by reliably transferring developmental resources needed to reconstruct, maintain and modify genetically inherited components of the phenotype. The view of parental effects as an essential and dynamic part of an evolutionary continuum unifies mechanisms behind the origination, modification and historical persistence of organismal form and function, and thus brings us closer to a more realistic understanding of life's complexity and diversity.

Signaling pathways involved in the effect of follicle-stimulating hormone on chick embryo testis cell proliferation

The aim of the present study was to evaluate the signaling pathways involved in the follicle-stimulating hormone (FSH) regulated mitogenic activity. For this purpose, 18-d-old chick embryo testis cells were dissociated and cultured for 60 h on polycarbonate membranes. The culture medium was Dulbecco modified Eagle's medium with or without high pure human FSH (hFSH), human recombinant FSH, or different regulators of tyrosine kinase activity as herbimycin A and genistein, or serine/threonine kinases [cyclic adenosine monophosphate (cAMP)-dependent protein serine kinase and protein kinase C] as cAMP, phorbol myristate, and forskolin. In some experiments the regulators were added simultaneously with hFSH. The [3H]-thymidine incorporation was used as an indicator of DNA synthesis. In addition, fragments of chick embryo testis were cultured in the presence or absence of FSH or herbimycin A, and 5-bromo-2'-deoxy-uridine was added to identify the proliferating cell subpopulations. The effect of hFSH on [3H]-thymidine incorporation began at 24 h, and the increment was significant at 36 and 60 h of culture. The hFSH as well as human recombinant FSH significantly stimulated [3H]-thymidine incorporation to testicular cells. The 5-bromo-2'-deoxy-uridine technique showed a high signal in pericordonal and interstitial cells of the hFSH-treated groups, confirming the results obtained using [3H]-thymidine uptake. The treatment with the tyrosine kinase inhibitor herbimycin A increased the [3H]-thymidine uptake, but genistein did not. Regulators of PKA such as cAMP and forskolin, as well as PKC regulators and the phorbol ester phorbol myristate, did not influence cell proliferation. In summary, an inhibitor of tyrosine kinase, herbimycin A, induced per se an increment in chick embryo testis cell proliferation, a fact that strongly suggests that tyrosine kinase signaling pathway functions by inhibiting the proliferation of these cells. On the other hand, the cAMP-PKA pathway had no significant role during the embryonic stage of chick embryo testis. Our results also showed that the effect of FSH on chick embryo cell proliferation occurs mainly in pericordonal and interstitial testis cells.

Mitochondria As A Target For Early Detection and Diagnosis of Cancer

Mitochondrial dysfunction and mutations in mitochondrial DNA (mtDNA) have been frequently reported in cancer, neurodegenerative diseases, diabetes, and aging syndromes. The mitochondrion genome (16.5 Kb) codes only for a small fraction (estimated to be 1%) of the proteins housed within this organelle. The other proteins are encoded by the nuclear DNA (nDNA) and transported into the mitochondria. The identification of mitochondrial proteins that are aberrantly expressed in cancer cells and other diseases is now possible through recent developments in proteomic and bioinformatic technologies. These developments set the stage for a comprehensive organelle-based proteomic approach for the identification of new markers for the early detection, risk assessment, and diagnosis of cancer, and other diseases and for the identification of new targets for therapeutic prevention and intervention.