Expression and localisation of thioredoxin in mouse reproductive tissues during the oestrous cycle

Expression pattern of new genes regulating female sex differentiation and in vitro maturational status of oocytes in pigs

The processes underlying maturation of mammalian oocytes are considered crucial for the oocytes ability to undergo monospermic fertilization. The same factors of influence are suggested to impact the development of sex associated characteristics, allowing sex differentiation to progress during embryonic growth. The primary aim of the study was to analyze the gene ontology groups involved in regulation of porcine oocytes' response to endogenous stimuli. The results obtained would indicate potential genes influencing sex differentiation. Additionally, they could help to determine new genetic markers, expression profile of which is substantially regulated during porcine oocytes' in vitro maturation. To achieve that, porcine oocytes were collected for analysis before and after in vitro maturation. Pigs were used as they are a readily available model that presents significant similarity to humans in terms of physiology and anatomy. Microarray analysis of oocytes, before and after in vitro maturation was performed and later validated by RT-qPCR. We have particularly detected and analyzed genes belonging to gene ontology groups associated with hormonal stimulation during maturation of the oocytes, that exhibited significant change in expression (fold change ≥ |2|; p < 0.05) namely "Female sex differentiation" (CCND2, MMP14, VEGFA, FST, INHBA, NR5A1), "Response to endogenous stimulus" (INSR, ESR1, CCND2, TXNIP, TACR3, MMP14, FOS, AR, EGR2, IGFBP7, TGFBR3, BTG2, PLD1, PHIP, UBE2B) and "Response to estrogen stimulus" (INSR, ESR1, CCND2, IHH, TXNIP, TACR3, MMP14). Some of them were characteristic for just one of the described ontologies, while some belonged into multiple ontological terms. The genes were analyzed, with their relation to the processes of interest explained. Overall, the study provides us with a range of genes that might serve as molecular markers of in vitro maturation associated processes of the oocytes. This knowledge might serve as a reference for further studies and, after further validation, as a potentially useful knowledge in assessment of the oocytes during assisted reproduction processes.

Molecular Mechanisms Responsible for Increased Vulnerability of the Ageing Oocyte to Oxidative Damage

In their midthirties, women experience a decline in fertility, coupled to a pronounced increase in the risk of aneuploidy, miscarriage, and birth defects. Although the aetiology of such pathologies are complex, a causative relationship between the age-related decline in oocyte quality and oxidative stress (OS) is now well established. What remains less certain are the molecular mechanisms governing the increased vulnerability of the aged oocyte to oxidative damage. In this review, we explore the reduced capacity of the ageing oocyte to mitigate macromolecular damage arising from oxidative insults and highlight the dramatic consequences for oocyte quality and female fertility. Indeed, while oocytes are typically endowed with a comprehensive suite of molecular mechanisms to moderate oxidative damage and thus ensure the fidelity of the germline, there is increasing recognition that the efficacy of such protective mechanisms undergoes an age-related decline. For instance, impaired reactive oxygen species metabolism, decreased DNA repair, reduced sensitivity of the spindle assembly checkpoint, and decreased capacity for protein repair and degradation collectively render the aged oocyte acutely vulnerable to OS and limits their capacity to recover from exposure to such insults. We also highlight the inadequacies of our current armoury of assisted reproductive technologies to combat age-related female infertility, emphasising the need for further research into mechanisms underpinning the functional deterioration of the ageing oocyte.

Regulation of the bovine oviductal fluid proteome

Our objective was to investigate the regulation of the proteome in the bovine oviductal fluid according to the stage of the oestrous cycle, to the side relative to ovulation and to local concentrations of steroid hormones. Luminal fluid samples from both oviducts were collected at four stages of the oestrous cycle: pre-ovulatory (Pre-ov), post-ovulatory (Post-ov), and mid- and late luteal phases from adult cyclic cows (18–25 cows/stage). The proteomes were assessed by nanoLC–MS/MS and quantified by label-free method. Totally, 482 proteins were identified including a limited number of proteins specific to one stage or one side. Proportions of differentially abundant proteins fluctuated from 10 to 24% between sides at one stage and from 4 to 20% among stages in a given side of ovulation. In oviductal fluids ipsilateral to ovulation, Annexin A1 was the most abundant protein at Pre-ov compared with Post-ov while numerous heat shock proteins were more abundant at Post-ov compared with Pre-ov. Among differentially abundant proteins, seven tended to be correlated with intra-oviductal concentrations of progesterone. A wide range of biological processes was evidenced for differentially abundant proteins, of which metabolic and cellular processes were predominant. This work identifies numerous new candidate proteins potentially interacting with the oocyte, spermatozoa and embryo to modulate fertilization and early embryo development.

Dietary-Induced Chronic Hypothyroidism Negatively Affects Rat Follicular Development and Ovulation Rate and Is Associated with Oxidative Stress

The long-term effects of chronic hypothyroidism on ovarian follicular development in adulthood are not well known. Using a rat model of chronic diet-induced hypothyroidism initiated in the fetal period, we investigated the effects of prolonged reduced plasma thyroid hormone concentrations on the ovarian follicular reserve and ovulation rate in prepubertal (12-day-old) and adult (64-day-old and 120-day-old) rats. Besides, antioxidant gene expression, mitochondrial density and the occurrence of oxidative stress were analyzed. Our results show that continuous hypothyroidism results in lower preantral and antral follicle numbers in adulthood, accompanied by a higher percentage of atretic follicles, when compared to euthyroid age-matched controls. Not surprisingly, ovulation rate was lower in the hypothyroid rats. At the age of 120 days, the mRNA and protein content of superoxide dismutase 1 (SOD1) were significantly increased while catalase (CAT) mRNA and protein content was significantly decreased, suggesting a disturbed antioxidant defense capacity of ovarian cells in the hypothyroid animals. This was supported by a significant reduction in the expression of peroxiredoxin 3 ( ITALIC! Prdx3), thioredoxin reductase 1 ( ITALIC! Txnrd1), and uncoupling protein 2 ( ITALIC! Ucp2) and a downward trend in glutathione peroxidase 3 ( ITALIC! Gpx3) and glutathione S-transferase mu 2 ( ITALIC! Gstm2) expression. These changes in gene expression were likely responsible for the increased immunostaining of the oxidative stress marker 4-hydroxynonenal. Together these results suggest that chronic hypothyroidism initiated in the fetal/neonatal period results in a decreased ovulation rate associated with a disturbance of the antioxidant defense system in the ovary.

Oxidative damage increases and antioxidant gene expression decreases with aging in the mouse ovary

Oxidative stress has been implicated in various aspects of aging, but the role of oxidative stress in ovarian aging remains unclear. Our previous studies have shown that the initiation of apoptotic cell death in ovarian follicles and granulosa cells by various stimuli is initiated by increased reactive oxygen species. Herein, we tested the hypothesis that ovarian antioxidant defenses decrease and oxidative damage increases with age in mice. Healthy, wild-type C57BL/6 female mice aged 2, 6, 9, or 12 mo from the National Institute on Aging Aged Rodent Colony were killed on the morning of metestrus. Quantitative real-time RT-PCR was used to measure ovarian mRNA levels of antioxidant genes. Immunostaining using antibodies directed against 4-hydroxynonenal (4-HNE), nitrotyrosine (NTY), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was used to localize oxidative lipid, protein, and DNA damage, respectively, within the ovaries. TUNEL was used to localize apoptosis. Ovarian expression of glutathione peroxidase 1 (Gpx1) increased and expression of glutaredoxin 1 (Glrx1), glutathione S-transferase mu 2 (Gstm2), peroxiredoxin 3 (Prdx3), and thioredoxin 2 (Txn2) decreased in a statistically significant manner with age. Statistically significant increases in 4-HNE, NTY, and 8-OHdG immunostaining in ovarian interstitial cells and follicles were observed with increasing age. Our data suggest that the decrease in mRNA expression of mitochondrial antioxidants Prdx3 and Txn2 as well as cytosolic antioxidants Glrx1 and Gstm2 may be involved in age-related ovarian oxidative damage to lipid, protein, DNA, and other cellular components vital for maintaining ovarian function and fertility.

Thioredoxin and thioredoxin reductase influence estrogen receptor alpha-mediated gene expression in human breast cancer cells

Accumulation of reactive oxygen species (ROS) in cells damages resident proteins, lipids, and DNA. In order to overcome the oxidative stress that occurs with ROS accumulation, cells must balance free radical production with an increase in the level of antioxidant enzymes that convert free radicals to less harmful species. We identified two antioxidant enzymes, thioredoxin (Trx) and Trx reductase (TrxR), in a complex associated with the DNA-bound estrogen receptor alpha (ERalpha). Western analysis and immunocytochemistry were used to demonstrate that Trx and TrxR are expressed in the cytoplasm and in the nuclei of MCF-7 human breast cancer cells. More importantly, endogenously expressed ERalpha, Trx, and TrxR interact and ERalpha and TrxR associate with the native, estrogen-responsive pS2 and progesterone receptor genes in MCF-7 cells. RNA interference assays demonstrated that Trx and TrxR differentially influence estrogen-responsive gene expression and that together, 17beta-estradiol, Trx, and TrxR alter hydrogen peroxide (H(2)O(2)) levels in MCF-7 cells. Our findings suggest that Trx and TrxR are multifunctional proteins that, in addition to modulating H(2)O(2) levels and transcription factor activity, aid ERalpha in regulating the expression of estrogen-responsive genes in target cells.

Thioredoxin and related molecules--from biology to health and disease

Thioredoxin and glutaredoxin systems in mammalian cells utilize thiol and selenol groups to maintain a reducing intracellular redox state acting as antioxidants and reducing agents in redox signaling with oxidizing reactive oxygen species. During the last decade, the functional roles of thioredoxin in particular have continued to expand, also including novel functions such as a secreted growth factor or a chemokine for immune cells. The role of thioredoxin and glutaredoxin in antioxidant defense and the role of thioredoxin in controlling recruitment of inflammatory cells offer potential use in clinical therapy. The fundamental differences between bacterial and mammalian thioredoxin reductases offer new principles for treatment of infections. Clinical drugs already in use target the active site selenol in thioredoxin reductases, inducing cell death in tumor cells. Thioredoxin and binding proteins (ASK1 and TBP2) appear to control apoptosis or metabolic states such as carbohydrate and lipid metabolism related to diseases such as diabetes and atherosclerosis.

Insulin-like growth factor-I (IGF-I) and thioredoxin are differentially expressed along the reproductive tract of the ewe during the oestrous cycle and after ovariectomy

Insulin-like growth factor-I (IGF-I) and thioredoxin are regulated by gonadal steroids in the female reproductive tract of many species. Oestradiol regulates IGF-I and thioredoxin mRNA levels in the reproductive tract of prepubertal lambs. The physiological status (different endocrine environment) may affect the sensitivity of the reproductive tract to oestradiol and progesterone. We studied the effects of different endocrine milieus (late-follicular and luteal phases of the oestrous cycle, and ovariectomy before or after puberty) on the expression of IGF-I, thioredoxin, oestrogen receptor α (ERα) and progesterone receptor (PR) in sheep. The mRNA levels were determined by a solution hybridisation technique. In the uterus the levels of ERα, PR and thioredoxin mRNA were higher in the late-follicular phase group than in the other three groups, and IGF-I mRNA was high during both the late-follicular and the luteal phases. In the cervix only PR mRNA was significantly higher in the ewes in the late-follicular phase than in the other groups. In the oviducts the levels of thioredoxin and ERα mRNA were highest in the ovariectomised adult ewes, and thioredoxin mRNA was higher than the levels found in the ewes in the late-follicular phase. The IGF-I mRNA levels in the oviduct did not differ between any of the groups. The transcripts of IGF-I, thioredoxin, ERα and PR, varied according to the physiological status and also along the female reproductive tract, suggesting that the regulation of the mRNA levels of these factors by the steroid environment is tissue specific.

Koncentrationen av insulin-like growth factor-I (IGF-I) och thioredoxin regleras hos många arter i honors reproduktionsorgan av könssteroider. Sålunda reglerar östradiol IGF-I och thioredoxin mRNA i reproduktionsorganen hos prepubertala lamm. Djurets fysiologiska status (dvs den endokrina miljön) kan påverka känsligheten hos reproduktionsorganen för östradiol och progesteron. Vi studerade effekterna av olika endokrina miljöer (sen follikelfas och lutealfas i östruscykeln, samt ovariektomi före och efter puberteten) på uttrycket av IGF-I, thioredoxin, östrogenreceptor α (ERα) och progesteronreceptorn (PR) hos får. Lösningshybridisering användes för att bestämma mRNA nivåerna. I livmodern var mRNA koncentrationen för ERα, PR och thioredoxin högre i sen follikelfas än i de andra tre grupperna och IGF-I mRNA nivån var hög både under sen follikelfas och i lutealfas. PR mRNA i cervix var signifikant högre hos tackorna under sen follikelfas än i de andra grupperna. I äggledarna var mRNA nivåerna av thioredoxin och ERα högst i de djur som ovariektomerats som vuxna, och thioredoxin mRNA var högre än hos tackorna under sen follikelfas. Det förelåg ingen skillnad vad gäller IGF-I mRNA nivåerna i äggledaren mellan någon av grupperna. IGF-I, thioredoxin, ERα och PR mRNA nivåerna varierade beroende på fysiologisk status och morfologisk lokalisation i reproduktionsorganen. Detta tyder på att steroidhormonernas reglering av dessa faktorers mRNA uttryck också är vävnadsspecifik.

Rat endometrial Vdup1 expression: changes related to sensitization for the decidual cell reaction and hormonal control

During implantation in rodents, attachment and invasion of embryonic trophoblast is accompanied by decidualization of the adjacent endometrial stroma. Decidualization can be initiated only when the endometrium is receptive, and this occurs for a short period in pregnancy. The molecular mechanisms underlying this phenomenon remain unclear. In the current study, using differential display and northern blot analysis, we found that steady-state levels of mRNA for vitamin D3upregulated protein 1 (Vdup1) were significantly higher in ‘refractory’ and ‘delayed’ endometrium compared with ‘receptive’ endometrium or endometrium undergoing artificially induced decidualization. Conversely, thioredoxin (Txn), a ubiquitously expressed cellular redox regulator known to promote growth and proliferation, was found to have elevated transcript levels within the decidualizing endometrium. VDUP1 has previously been shown to bind TXN and inhibit its action. In an inverse, but cooperative, relationship, these molecules have been implicated in regulating cell growth and proliferation in a number of tissues and during transformation to cancer. TheVdup1mRNA is localized to the uterine stroma in the nonreceptive endometrium, the site of increasedTxnmRNA levels during decidualization. In addition,Vdup1mRNA levels are inversely regulated by progesterone and estrogen; prolonged progesterone exposure stimulates an increase inVdup1mRNA levels whereas estrogen decreasesVdup1transcript levels. Together, these results suggest a novel mechanism by which suppression of the decidual response in the nonreceptive endometrium may occur.