Alcohol consumption is a well-established risk factor for hormone-dependent breast cancer. In vitro studies performed to understand the mechanisms by which ethanol acts on breast cancer cells have ...shown that this compound stimulates both proliferation and migration. In the present study, we show by gelatin zymography that, when exposed to ethanol, MCF-7 human breast cancer cells display a higher amount of active metalloproteinases (MMP) 2 and 9 in their culture medium. This increase is somewhat higher than those observed in the case of 17beta-estradiol (E2) exposure. As expected, anti-estrogen ICI 182,780 inhibits the E2-induced overexpression of a well-known estrogen responsive gene, the progesterone receptor, in MCF-7 cells. ICI 182,780 also inhibits the E2-induced increase in MMP-2 and -9 secretion. Nevertheless, in the case of ethanol exposure, this ER ant-agonist was only efficient on MMP-9 secretion. In addition, although MMP-9 transcription was not sensitive to E2 or ethanol, MMP-2 transcription was stimulated in MCF-7 cells exposed to ethanol. Collectively, these results give new insights into the effects of alcohol on breast cancer cell migration, which are not due solely to an estrogen-like activity of alcohol.
Bundles of paired helical filaments (PHF) accumulate in the pyramidal neurons that degenerate during Alzheimer's disease. This neurofibrillary degeneration is highly correlated with clinical signs of ...dementia. During the degenerating process, Tau proteins, which are the major antigenic components of PHF, are abnormally phosphorylated and two pathological isoforms named Tau 64 and 69 are expressed. We have studied their immunoblot distribution in the cortical gray and white matter from different regions of normal and Alzheimer brains, to determine if the degenerating process preferentially affects the somatodendritic or the axonal domain. Two categories of antibodies were used. The first category consisted of anti-human native Tau, anti-Tau proteins from different vertebrates, anti-PHF, monoclonal antibody Alz-50 and an anti-C terminal repeated region of Tau. In control brains, these antibodies strongly detected normal Tau proteins in the gray matter while Tau immunodetection was weak in the white matter. In Alzheimer brain cortices, each antibody detected Tau 64 and 69 in gray matter extracts but not at all in white matter extracts. The second category of anti-Tau consisted of the anti-PHF saturated with normal brain protein extracts. This antiserum only probed the abnormally phosphorylated Tau proteins. It detected Tau 64 and 69 exclusively in the cortical gray matter of Alzheimer brains. Moreover, a 55-kDa Tau protein was also immunolabelled, which might be an intermediary form between normal Tau and Tau 64 and 69. Our results demonstrate that Tau proteins are normal and major components of the somatodendritic domain and that Tau pathology, reflected by the presence of Tau 64 and 69, affects preferentially this domain during Alzheimer's disease.
Abstract In the amphibian Pleurodeles waltl , estradiol treatment of genetically male larvae (ZZ) induces male-to-female sex reversal whereas heat treatment of genetically female larvae (ZW) inhibits ...estradiol synthesis and leads to female-to-male sex reversal. No data are available on estrogen receptors in this species. In the present study, we have isolated a unique full-length pw ERα cDNA and its 5′-flanking region whose promoter activity was confirmed by transfection assays. RT-PCR studies performed in adult animals using ERα-specific primers, revealed that pw ERα mRNA was present mainly in reproductive tissues: gonads, fat body and oviduct. Pw ERα transcript was also detected in liver, suggesting its implication in vitellogenesis control as in numerous oviparous species. The level of pw ERα transcripts was also studied during gonad differentiation by quantitative real-time PCR. At stage 5430d pw ERα expression in gonads of ZW larvae was significantly higher than in ZZ ones. This sex-specific discrimination was confirmed when gonad–mesonephros–interrenal complexes (GMI), taken at the same stage, were subjected to whole mount in situ hybridization. In comparison, the female-enriched expression of P450 aromatase, which was studied as a control of ovary differentiation, was observed earlier (stage 54). In ZW larvae reared at 32 °C, a condition leading to sex reversal, pw ERα mRNA level at stage 5430d was lower than in control females. Taken together, these results showing a female-enriched and thermosensitive expression of pw ERα suggest an important role for this receptor in gonad differentiation of the urodele amphibian Pleurodeles waltl.
In vertebrates, sex is determined essentially by two means, genetic factors located on sex chromosomes and epigenetic factors such as temperature experienced by the individual during development. ...Steroids, especially estrogens, are clearly involved in gonadal differentiation in non-mammalian vertebrates. In this regard, the expression of the estrogen-producing enzyme, aromatase, has been shown to be temperature-sensitive in species where temperature can reverse sex differentiation, especially in our model, the amphibian Pleurodeles waltl. We investigated here the regulation of aromatase expression in the brain during sex differentiation in Pleurodeles. We first isolated a brain isoform of aromatase mRNA which differs in its 5' untranslated region from the isoform previously isolated from adult gonads. In adult Pleurodeles, the brain isoform is mainly expressed in brain tissue while the other isoform is gonad specific. Thus, regulation of aromatase expression in P. waltl could occur by alternative splicing of non-coding exon 1 as previously described in mammals. We then investigated aromatase expression in the brain of male and female larvae and found no differences with regard to sex. Measures of aromatase activity in the brain also showed no differences between sexes at larval stages whereas activity markedly increases in the ovary concomitant with the start of gonadal differentiation. These results support the hypothesis that aromatase could be a target of a temperature-sensitive sex-reversing effect in the gonads but not in the brain.
Magneto-optical (MO) studies have been carried out on superconducting thin films. In this paper, we give the features that determine the signal to noise ratio of the imaging system and optimize the ...image contrast. The flux distribution of vortices in thin films are given, which determines the requirements to satisfy for vortex visualization using a MO layer. Images of partial flux penetration through the slit of a DC SQUID are presented. Flux focusing efficiency can be deduced from these Images.
Neuronal death is a process which may be either physiological or pathological. Apoptosis and necrosis are two of these processes which are particularly studied. However, in neurodegenerative ...disorders, some neurons escape to these types of death and “agonize” in a process referred to as neurofibrillary degeneration. Neurofibrillary degeneration is characterized by the intraneuronal aggregation of abnormally phosphorylated microtubule-associated Tau proteins. A number of studies have reported a reactivation of the cell cycle in the neurofibrillary degeneration process. This reactivation of the cell cycle is reminiscent of the initiation of apoptosis in post-mitotic cells where G1/S markers including cyclin D1 and cdk4/6, are commonly found. However, in neurons exhibiting neurofibrillary degeneration, both G1/S and G2/M markers are found suggesting that they do not follow the classical apoptosis and an aberrant cell cycle occurs. This aberrant response leading to neurofibrillary degeneration may be triggered by the sequential combination of three partners: the complex Cdk5/p25 induces both apoptosis and the “abnormal mitotic Tau phosphorylation”. These mitotic epitopes may allow for the nuclear depletion of Pin1. This latter may be responsible for escaping classical apoptosis in a subset of neurons. Since neurofibrillary degeneration is likely to be a third way to die, molecular mechanisms leading to changes in Tau phosphorylation including activation of kinases such as cdk5 or other regulators such as Pin1 could be important drug targets as they are possibly involved in early stages of neurodegeneration.
In Alzheimer's disease, neurofibrillary degeneration results from the aggregation of abnormally phosphorylated Tau proteins into filaments and it may be related to the reactivation of mitotic ...mechanisms. In order to investigate the link between Tau phosphorylation and mitosis, Xenopus laevis oocytes in which most of the M‐phase regulators have been discovered were used as a cell model. The human Tau isoform htau412 (2+3–10+) was microinjected into prophase I oocytes that were then stimulated by progesterone that activate cyclin‐dependent kinase pathways. Hyperphosphorylation of the Tau isoform, which is characterized by a decrease of its electrophoretic mobility and its labelling by a number of phosphorylation‐dependent antibodies, was observed at the time of germinal vesicle breakdown. Surprisingly, Tau immunoreactivity, considered as typical of Alzheimer's pathology (AT100 and phospho‐Ser422), was observed in meiosis II. Because meiosis II is considered as a mitosis‐like phase, we investigated if our observation was also relevant to a neurone‐like model. Abnormal Tau phosphorylation was detected in mitotic human neuroblastoma SY5Y cells overexpressing Tau. Regarding AT100‐immunoreactivity and phospho‐Ser422, we suggest that phosphatase 2A inhibition and a phosphorylation combination of mitotic kinases may lead to this Alzheimer‐type phosphorylation. Our results not only demonstrate the involvement of mitotic kinases in Alzheimer‐type Tau phosphorylation but also indicate that Xenopus oocyte could be a useful model to identify the kinases involved in this process.
It was suggested that increased Cu-Zn superoxide dismutase (SOD-1) might be involved in the various biological abnormalities found in Down's syndrome (DS) such as premature aging and Alzheimer-type ...neurological lesions. As a model system for testing this hypothesis we have developed two strains of transgenic mice carrying only one copy of the human SOD-1 gene. In the first strain (TG1), no expression has been found by northern blot analysis. The second strain (TG2) exhibited human SOD-1 mRNA and increased SOD-1 activity in the brain (1.93 fold), in the heart (1.69 fold), thymus (1.49 fold) and to a lesser extent in muscle (1.25 fold), liver (1.19 fold), kidney (1.18 fold), spleen (1.35 fold), lung (1.26 fold) and erythrocytes (1.09 fold). In this strain, increased SOD-1 activity in the brain did not induce modifications in the seleno-dependent glutathione peroxidase, glutathione reductase and glutathione S-transferase activities. In brain homogenates, we have focused our studies on Tau proteins which are known to be the major antigenic components of paired helical filaments (PHF), both in DS and Alzheimer's disease. Our results suggested that, in our experimental conditions, the overexpression of SOD-1 did not induce the modifications of Tau proteins similar to those seen during neurofibrillary degeneration.
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