Novel genes modulated by FSH in normal and immortalized FSH-responsive cells: new insights into the mechanism of FSH action

Regulation of granulosa and theca cell transcriptomes during ovarian antral follicle development

Coordinated interactions between ovarian granulosa and theca cells are required for female endocrine function and fertility. To elucidate these interactions the regulation of the granulosa and theca cell transcriptomes during bovine antral follicle development were investigated. Granulosa cells and theca cells were isolated from small (<5 mm), medium (5-10 mm), and large (>10 mm) antral bovine follicles. A microarray analysis of 24,000 bovine genes revealed that granulosa cells and theca cells each had gene sets specific to small, medium and large follicle cells. Transcripts regulated (i.e., minimally changed 1.5-fold) during antral follicle development for the granulosa cells involved 446 genes and for theca cells 248 genes. Only 28 regulated genes were common to both granulosa and theca cells. Regulated genes were functionally categorized with a focus on growth factors and cytokines expressed and regulated by the two cell types. Candidate regulatory growth factor proteins mediating both paracrine and autocrine cell-cell interactions include macrophage inflammatory protein (MIP1 beta), teratocarcinoma-derived growth factor 1 (TDGF1), stromal derived growth factor 1 (SDF1; i.e., CXCL12), growth differentiation factor 8 (GDF8), glia maturation factor gamma (GMFG), osteopontin (SPP1), angiopoietin 4 (ANGPT4), and chemokine ligands (CCL 2, 3, 5, and 8). The current study examined granulosa cell and theca cell regulated genes associated with bovine antral follicle development and identified candidate growth factors potentially involved in the regulation of cell-cell interactions required for ovarian function.

Death by a thousand cuts: granzyme pathways of programmed cell death

The granzymes are cell death-inducing enzymes, stored in the cytotoxic granules of cytotoxic T lymphocytes and natural killer cells, that are released during granule exocytosis when a specific virus-infected or transformed target cell is marked for elimination. Recent work suggests that this homologous family of serine esterases can activate at least three distinct pathways of cell death. This redundancy likely evolved to provide protection against pathogens and tumors with diverse strategies for evading cell death. This review discusses what is known about granzyme-mediated pathways of cell death as well as recent studies that implicate granzymes in immune regulation and extracellular proteolytic functions in inflammation.

Identification of differentially expressed markers in human follicular cells associated with competent oocytes

BACKGROUND

The development of an accurate method for selection of high-quality embryos is essential to achieve high pregnancy rates with single embryo transfer in human IVF. The developmental competence of the oocyte is acquired during follicle maturation and strong communication also exists between the follicular cells (FCs) and the oocytes; thus oocyte developmental competence may be determined by markers expressed in the surrounding FCs.

METHODS

From consenting patients (n = 40), FCs were recovered on a per follicle basis by individual follicle puncture. Hybridization analyses using a custom-made complementary DNA microarray containing granulosa/cumulus expressed sequence tags (ESTs) from subtracted libraries and an Affymetrix GeneChip were performed to identify specific genes expressed in follicles leading to a pregnancy. The selected candidate genes were validated by quantitative-PCR (Q-PCR).

RESULTS

Subtractive libraries prepared from pooled samples representing pregnant versus non-pregnant patients produced 1694 ESTs. Hybridization data analysis discriminated 115 genes associated with competent follicles. Selected candidates were confirmed by Q-PCR: 3-beta-hydroxysteroid dehydrogenase 1 (P = 0.0078), Ferredoxin 1 (P = 0.0203), Serine (or cysteine) proteinase inhibitor clade E member 2 (P = 0.0499), Cytochrome P450 aromatase (P = 0.0359) and Cell division cycle 42 (P = 0.0396).

CONCLUSIONS

Microarray technologies are useful to mine the transcriptome of FCs expressed in follicles associated with competent oocytes and could be used to improve embryo selection with the objective of successful single embryo transfer.

Macrophages express granzyme B in the lesion areas of atherosclerosis and rheumatoid arthritis

Granzyme B is a major mediator of the cytotoxic immune response by inducing target cell death when internalized in the presence of perforin. Recently, several studies have focused on another role of granzyme B, which is extracellular matrix (ECM) remodeling through the degradation of ECM proteins. In order to investigate the expression pattern of granzyme B in the lesion areas of atherosclerosis and rheumatoid arthritis, we performed immunohistochemistry and in situ hybridization analyses using human atherosclerotic plaques and the synovial tissues of rheumatoid arthritic- and osteoarthritic-joints. In atherosclerotic plaques, granzyme B was expressed by macrophages in areas such as the boundary regions between media and intima, areas around necrotic cores, and in shoulder regions. In the synovial tissues of rheumatoid arthritic-joints, the expression of granzyme B was strongly observed in the lining layers where the majority of cells are macrophages and also in perivascular areas where macrophages and a small number of lymphocytes were mixed to form diffuse cellular aggregates. Granzyme B-positive cells were not detected in osteoarthritic synovium. Furthermore, the expression of granzyme B has been induced in the human macrophage cell line, THP-1, by ECM proteins or agents which induce macrophage differentiation. These observations indicate that macrophages should be added to the list of cell types that express granzyme B in human inflammatory diseases and that granzyme B may play a role in macrophage functions that are associated with disease progression.

Human mast cells produce and release the cytotoxic lymphocyte associated protease granzyme B upon activation

Mast cells are widely distributed throughout the body and express effector functions in allergic reactions, inflammatory diseases, and host defense. Activation of mast cells results in exocytosis of preformed chemical mediators and leads to novel synthesis and secretion of lipid mediators and cytokines. Here, we show that human mast cells also express and release the cytotoxic lymphocyte-associated protease, granzyme B. Granzyme B was active and localized in cytoplasmic granules, morphologically resembling those present in cytotoxic lymphocytes. Expression and release of granzyme B by mast cell-lines HMC-1 and LAD 2 and by cord blood- and mature skin-derived human mast cells depended on the mode of activation of these cells. In mast cell lines and cord blood-derived mast cells, granzyme B expression was mainly induced by non-physiological stimuli (A23187/PMA, Compound 48/80) and substance P. In contrast, mature skin-derived mast cells only produced granzyme B upon IgE-dependent stimulation. We conclude that granzyme B is expressed and released by human mast cells upon physiologic stimulation. This suggests a role for granzyme B as a novel mediator in mast cell biology.

Meta-analysis of several gene lists for distinct types of cancer: a simple way to reveal common prognostic markers

Background

Although prognostic biomarkers specific for particular cancers have been discovered, microarray analysis of gene expression profiles, supported by integrative analysis algorithms, helps to identify common factors in molecular oncology. Similarities of Ordered Gene Lists (SOGL) is a recently proposed approach to meta-analysis suitable for identifying features shared by two data sets. Here we extend the idea of SOGL to the detection of significant prognostic marker genes from microarrays of multiple data sets. Three data sets for leukemia and the other six for different solid tumors are used to demonstrate our method, using established statistical techniques.

Results

We describe a set of significantly similar ordered gene lists, representing outcome comparisons for distinct types of cancer. This kind of similarity could improve the diagnostic accuracies of individual studies when SOGL is incorporated into the support vector machine algorithm. In particular, we investigate the similarities among three ordered gene lists pertaining to mesothelioma survival, prostate recurrence and glioma survival. The similarity-driving genes are related to the outcomes of patients with lung cancer with a hazard ratio of 4.47 (p = 0.035). Many of these genes are involved in breakdown of EMC proteins regulating angiogenesis, and may be used for further research on prognostic markers and molecular targets of gene therapy for cancers.

Conclusion

The proposed method and its application show the potential of such meta-analyses in clinical studies of gene expression profiles.

FSH signaling pathways in immature granulosa cells that regulate target gene expression: branching out from protein kinase A

Follicle-stimulating hormone (FSH) is necessary and sufficient to induce maturation of ovarian follicles to a mature, preovulatory phenotype in the intact animal, resulting in the generation of mature eggs and production of estrogen. FSH accomplishes these actions by inducing a complex pattern of gene expression in target granulosa cells that is regulated by input from many different signaling cascades, including those for the extracellular regulated kinases (ERKs), p38 mitogen-activated protein kinases (MAPKs), and phosphatidylinositol-3 kinase (PI3K). The upstream kinase that appears to be responsible for initiating all of the signaling that regulates gene expression in these epithelial cells is protein kinase A (PKA). PKA not only signals to directly phosphorylate transcription factors like cAMP response element binding protein and to promote chromatin remodeling by phosphorylating histone H3, this versatile kinase also enhances the activity of the p38 MAPK, ERK, and PI3K pathways. Additionally, accumulating evidence suggests that activation of a single signaling cascade downstream of PKA is not sufficient to activate target gene expression. Rather, cross-talk between and among signaling cascades is required. We will review the signaling cascades activated by FSH in granulosa cells and how these cascades contribute to the regulation of select target gene expression.

Cloning and partial characterization of Entamoeba histolytica PTPases

Reversible protein tyrosine phosphorylation is an essential signal transduction mechanism that regulates cell growth, differentiation, mobility, metabolism, and survival. Two genes coding for protein tyrosine phophatases, designed EhPTPA and EhPTPB, were cloned from Entamoeba histolytica. EhPTPA and EhPTPB proteins showed amino acid sequence identity of 37%, both EhPTPases showed similarity with Dictyostelium discoideum and vertebrate trasmembranal PTPases. mRNA levels of EhPTPA gene are up-regulated in trophozoites recovered after 96h of liver abscess development in the hamster model. EhPTPA protein expressed as a glutathione S-transferase fusion protein (GST::EhPTPA) showed enzymatic activity with p-nitrophenylphosphate as a substrate and was inhibited by PTPase inhibitors vanadate and molybdate. GST::EhPTPA protein selectively dephosphorylates a 130kDa phosphotyrosine-containing protein in trophozoite cell lysates. EhPTPA gene codifies for a 43kDa native protein. Up-regulation of EhPTPA expression suggests that EhPTPA may play an important role in the adaptive response of trophozoites during amoebic liver abscess development.

Transcriptome analysis of FSH and FSH variant stimulation in granulosa cells from IVM patients reveals novel regulated genes

FSH is crucial for oocyte maturation and fertility and is the main component in infertility treatment in assisted reproduction. The granulosa cells expressing the FSH receptor interact with the oocyte and provide nourishing substrates controlling the oocyte maturation. Thus, transcriptome analysis of granulosa cells stimulated by FSH is of major importance in understanding the communication between oocytes and granulosa cells. In this study, gene expression profiles were assessed in human granulosa cells from normal cycling in vitro maturation (IVM) patients using oligonucleotide gene chips. Granulosa cells were stimulated for 2 h with either FSH or a previously generated glycosylated FSH variant (FSH1208) that exhibited increased in vivo activity because of prolonged half-life. The analysis identified 74 significantly FSH/FSH1208 regulated genes. Amongst these were well known FSH regulated genes as well as genes not previously described to be important in the FSH signalling pathway. These novel FSH regulated genes include transcription factors [cAMP responsive element modulator (CREM)/inducible cAMP early repressors (ICER), GATA 6, ZFN 361, Bcl11a, CITED1 and TCF 8] and other regulatory proteins and enzymes (IGF-BP3, syntaxin and PCK1) possibly important for oocyte/granulosa cell interaction and function. Array data were validated for 13 genes by northern blots or RT-PCR. Furthermore, no significant differences in gene regulation were detected between the two FSH analogs. This work uncovers novel data important for understanding the folliculogenesis. Furthermore, the results suggest that FSH1208 has a gene expression profile like FSH and thus, in the light of known prolonged in vivo activity, might be a candidate for improved infertility treatment.

Extracellular granzymes: current perspectives

Granzyme A (GrA) and granzyme B (GrB) play key roles in the induction of target cell death induced by cytotoxic lymphocytes. Whilst these roles have been extensively studied, it is becoming apparent that both granzymes also possess extracellular activities. Soluble granzymes are found extracellularly in normal plasma and are elevated in a number of diseases, ranging from viral and bacterial infections to autoimmune diseases. Here, we discuss the current knowledge of extracellular granzyme substrates, inhibitors and functions; and the pathological consequences of extracellular granzymes in disease. In addition, we provide new evidence for the role of glycosaminoglycan-binding sites of granzymes in extracellular matrix remodeling.

Regulation of protein tyrosine phosphatase 4a1, B-cell translocation gene 2, nuclear receptor subfamily 4a1 and diacylglycerol O-acyltransferase 1 by follicle stimulating hormone in the rat ovary

Ovarian response to follicle stimulating hormone (FSH) and luteinising hormone (LH) leads to the formation of a mature follicle that is eventually ovulated. FSH and LH are essential for this process because they direct changes in somatic cells associated with folliculogenesis by regulating the expression of multiple genes. We hypothesised that genes induced by FSH in rat Sertoli cells would also show hormonal regulation during rat folliculogenesis. The objective of this study was to determine the expression patterns of diacylglycerol O-acyltransferase 1 (Dgat1), nuclear receptor subfamily 4a1 (Nr4a1), an anti-proliferative gene (Btg2) and a protein tyrosine phosphatase (Ptp4a1) in the ovaries of pregnant mare serum gonadotrophin (PMSG)-treated and human chorionic gonadotrophin (hCG)-treated rats. Expression of Dgat1, Nr4a1 and Ptp4a1 was induced in ovaries 4 h post PMSG treatment. When rats were treated with hCG, Dgat1, Nr4a1 and Ptp4a1 expression was induced by 12 h. Expression of Nr4a1 protein increases 12–24 h after induction of gene expression. Nr4a1 protein was observed in the granulosa, theca and luteal cells post PMSG and hCG treatment. These findings should increase our knowledge of mechanisms regulating folliculogenesis and luteinisation and demonstrate the diverse proteins that are important in ovarian function.

Differential expression of genes coding for EGF-like factors and ADAMTS1 following gonadotropin stimulation in normal and transformed human granulosa cells

We have demonstrated previously that the synthesis of epiregulin and amphiregulin, of the EGF-like growth factor family, is stimulated by luteinizing hormone in human follicular (granulosa) cells obtained from in vitro fertilization program. In the present work, we demonstrate that H89, a PKA inhibitor, attenuated the expression of these growth factors both in the mRNA and the protein levels, suggesting PKA involvement in this signaling pathway. SV40-transformed human granulosa cells showed higher basal levels of epiregulin and amphiregulin than normal cells, which were still elevated following cAMP stimulation by Forskolin. Cleavage by a disintegrin and metalloproteinases (ADAMs) is essential for activation of these growth factors, allowing their interaction with EGF receptor. Expression of ADAMTS1 and ADAM12 was downregulated by cAMP in normal, but not in SV40-transformed cells, suggesting that in normal cells epiregulin and amphiregulin activity is downregulated by a feedback mechanism that may be lost in SV40-transformed cells and their loss of downregulation may be involved in the development of ovarian tumors.

Thrombin impairs alveolar fluid clearance by promoting endocytosis of Na+,K+-ATPase

Coagulation is an emerging area of interest in the pathogenesis and treatment of acute lung injury. Concentrations of the edemagenic coagulation protease thrombin are elevated in plasma and lavage fluids from afflicted patients. We explored the impact of thrombin on the formation and resolution of alveolar edema. Intravascularly applied thrombin inhibited active transepithelial 22Na transport in intact rabbit lungs, suppressing alveolar fluid clearance. Epithelial permeability was unaffected, whereas endothelial permeability was increased. In A549 human lung epithelial cells and in mouse primary alveolar type II cells, thrombin blocked ouabain-sensitive Na+,K+-ATPase-mediated 86Rb+ uptake, without altering amiloride-sensitive sodium currents. Furthermore, thrombin downregulated cell-surface expression of Na+,K+-ATPase, but not ENaC alpha and beta subunits. The endocytosis inhibitor phalloidin oleate blocked all thrombin-induced effects on sodium transport activity. Similarly, diphenyleneiodonium chloride, an inhibitor of reactive oxygen radical production, as well as a protein kinase C-zeta inhibitor, prevented these thrombin-induced effects. Thus, thrombin signaling via reactive oxygen species and protein kinase C-zeta promotes Na+,K+-ATPase endocytosis, resulting in loss of function. We propose here a dual role for thrombin in mediating disturbances to fluid balance in the lung: thrombin concomitantly provokes edema formation by increasing endothelial permeability, and inhibits alveolar edema resolution by blocking Na+,K+-ATPase function.

Extracellular matrix remodeling by human granzyme B via cleavage of vitronectin, fibronectin, and laminin

Human granzyme B (GrB) released from cytotoxic lymphocytes plays a key role in the induction of target cell apoptosis when internalized in the presence of perforin. Here we demonstrate that GrB also possesses a potent extracellular matrix remodeling activity. Both native and recombinant GrB caused detachment of immortalized and transformed cell lines, primary endothelial cells, and chondrocytes. Cell detachment by GrB induced endothelial cell death (anoikis). GrB also inhibited tumor cell spreading, migration, and invasion in vitro. Investigation into the underlying mechanism revealed that GrB efficiently cleaves three proteins involved in extracellular matrix structure and function: vitronectin, fibronectin, and laminin. In vitronectin, GrB cleaves after an Arg-Lys-Asp (RGD) motif, which is part of the integrin-binding site found in matrix proteins. We propose that targeting of the integrin-extracellular matrix interface by GrB may allow perforin-independent killing of target cells via anoikis, restrict motility of tumor cells, facilitate lymphocyte migration, or directly reduce virus infectivity. It may also contribute to tissue destruction in diseases in which extracellular GrB is evident, such as rheumatoid arthritis and atherosclerosis.

Drug development for ovarian hyper-stimulation and anti-cancer treatment: blocking of gonadotropin signaling for epiregulin and amphiregulin biosynthesis

Gonadotropins play a crucial role in ovarian homeostasis and fertilization through the activation of the cAMP cascade. However, gonadotropin hyper-stimulation may be associated with higher risk for ovarian cancer development. It has been suggested, that high gonadotropin levels in peritoneal and ovarian cystic fluids of patients suffering from benign ovarian cysts, may lead to malignancy. Moreover, we have recently discovered that gonadotropin stimulation can activate the MAPK cascade in target cells. Using DNA microarray technology and RNA from human granulosa cells, we discovered that stimulation with saturating doses of gonadotropins dramatically elevates activity of genes coding for epiregulin and amphiregulin. These gene products can bind and activate the EGF receptor and ERBB4, which are associated with the development of various cancers such as ovarian, breast endometrial and other non-gynecological malignancies. Gonadotropin receptors are expressed not only in the gonads, but also in non-gonadal tissues and in cancer cells. The discovery that gonadotropins activate certain mitogenic signal transduction pathways, may serve as a guide for novel anti-cancer therapy by (1) specific interference at the receptor level to block the gonadotropic response, or arresting the receptor expression and (2) blocking downstream mitogenic signals generated by these hormones, like attenuation of the expression of epiregulin and amphiregulin that belong to the EGF family, using anti-sense and/or SiRNA techniques targeted to suppress their expression. Moreover, since amphiregulin and epiregulin act as mediators of luteinizing hormone (LH) action in the mammalian ovulatory follicles, regulation of the expression of these factors may open new possibilities in treatment of ovarian malfunction implicated with ovarian hyper-stimulation.

Follicle-stimulating hormone activation of hypoxia-inducible factor-1 by the phosphatidylinositol 3-kinase/AKT/Ras homolog enriched in brain (Rheb)/mammalian target of rapamycin (mTOR) pathway is necessary for induction of select protein markers of follicular differentiation

We sought to elucidate the role of AKT in follicle-stimulating hormone (FSH)-mediated granulosa cell (GC) differentiation. Our results define a signaling pathway in GCs whereby the inactivating phosphorylation of tuberin downstream of phosphatidylinositol (PI) 3-kinase/AKT activity leads to Rheb (Ras homolog enriched in brain) and subsequent mTOR (mammalian target of rapamycin) activation. mTOR then stimulates translation by phosphorylating p70 S6 kinase and, consequently, the 40 S ribosomal protein S6. Activation of this pathway is required for FSH-mediated induction of several follicular differentiation markers, including luteinizing-hormone receptor (LHR), inhibin-alpha, microtubule-associated protein 2D, and the PKA type IIbeta regulatory subunit. FSH also promotes activation of the transcription factor hypoxia-inducible factor-1 (HIF-1). FSH-stimulated HIF-1 activity is inhibited by the PI 3-kinase inhibitor LY294002, the Rheb inhibitor FTI-277 (farnesyltransferase inhibitor-277), and the mTOR inhibitor rapamycin. Finally, we find that the FSH-mediated up-regulation of reporter activities for LHR, inhibin-alpha, and vascular endothelial growth factor is dependent upon HIF-1 activity, because a dominant negative form of HIF-1alpha interferes with the up-regulation of these genes. These results show that FSH enhances HIF-1 activity downstream of the PI 3-kinase/AKT/Rheb/mTOR pathway in GCs and that HIF-1 activity is necessary for FSH to induce multiple follicular differentiation markers.

Steroidogenesis and apoptosis in the mammalian ovary

Ovarian cell death is an essential process for the homeostasis of ovarian function in human and other mammalian species. It ensures the selection of the dominant follicle and the demise of excess follicles. In turn, this process minimizes the possibility of multiple embryo development during pregnancy and assures the development of few, but healthy embryos. Degeneration of the old corpora lutea in each estrous/menstrual cycle by programmed cell death is essential to maintain the normal cyclicity of ovarian steroidogenesis. Although there are multiple pathways that can determine cell death or survival, crosstalk among endocrine, paracrine and autocrine factors, as well as among protooncogenes, tumor suppressor genes, survival genes and death genes, plays an important role in determining the fate of ovarian somatic and germ cells. The establishment of immortalized rat and human steroidogenic granulosa cell lines and the investigation of pure populations of primary granulosa cells allows systematic studies of the mechanisms that control steroidogenesis and apoptosis in granulosa cells. We have discovered that during initial stages of granulosa cell apoptosis progesterone production does not decrease. In contrast, we found that it is elevated up to 24h following the onset of the apoptotic stimuli exerted by starvation, cAMP, p53 or TNF-alpha stimulation, before total cell collapse. These observations raise the possibility for an alternative unique apoptotic pathway, one not involving mitochondrial Cyt C release associated with the destruction of mitochondrial structure and steroidogenic function. Using mRNA from apoptotic cells and affymetrix DNA microarray technology we discovered that granzyme B, a protease that normally resides in T cytotoxic lymphocytes and natural killer cells of the immune system is expressed and activated in granulosa cells. Thus, the apoptotic signals could bypass mitochondrial signals for apoptosis, which can preserve their steroidogenic activity until complete cell destruction. This unique apoptotic pathway assures cyclicity of estradiol and progesterone release in the estrous/menstruous cycle even during the initial stages of apoptosis.

Alternative pathways of ovarian apoptosis: death for life

Ovarian cell death is an essential process for the homeostasis of ovarian function in human and other mammalian species. It ensures the selection of the dominant follicle and the demise of excess follicles. In turn, this process minimizes the possibility of multiple embryo development during pregnancy and assures the development of few, but healthy embryos. Degeneration of the old corpora lutea in each estrus/menstrual cycle by programmed cell death is essential for maintaining the normal cyclicity of ovarian steroidogenesis. Although there are multiple pathways that can determine cell death or survival, crosstalk among endocrine, paracrine and autocrine factors, as well as among protooncogenes, tumor suppressor genes, survival genes and death genes, play an important role in determining the fate of ovarian somatic and germ cells. The establishment of immortalized rat and human steroidogenic granulosa cell lines and the investigation of pure populations of primary granulosa cells allows for systematic studies of the mechanisms that control steroidogenesis and apoptosis of granulosa cells. We have discovered that during initial stages of granulosa cell apoptosis progesterone production does not decrease. In contrast, we found that it is elevated for up to 24hr following the onset of the apoptotic stimuli exerted by starvation, cAMP, p53 or tumor necrosis factor alpha stimulation, before total cell collapse. These observations raise the possibility for an alternative unique apoptotic pathway, one that does not involve mitochondrial cytochrome C release associated with the destruction of mitochondrial structure and steroidogenic function. Using mRNA from apoptotic cells and Affymetrix DNA microarray we discovered that Granzyme B, a protease that normally resides in T cytotoxic lymphocytes and natural killer cells of the immune system is expressed and activated in granulosa cells, thereby allowing the apoptotic signals to bypass mitochondrial signals for apoptosis, which can preserve their steroidogenic activity until complete cell destruction. This unique apoptotic pathway assures the cyclicity of estradiol and progesterone release in the estrus/menstrus cycle even during the initial stage of apoptosis.