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Biomedical subjects

I Kola

Publications and source records attributed to I Kola.

At least 91 records · Page 5Linked to original sources
PubMed1995

Cu/Zn-superoxide dismutase and glutathione peroxidase during aging.

During oxidative metabolism harmful reactive oxygen species (ROS) are generated. These species are neutralized by antioxidant enzymes. Firstly, superoxide dismutase (Sod) converts superoxide radicals (.O2-) to hydrogen peroxide (H2O2). Thereafter catalase (Cat) and glutathione peroxidase (Gpx) independently convert this to water. An imbalance in the ratio of Sod to Gpx and Cat results in the accumulation of H2O2 which may participate in the Fenton reaction, resulting in the formation of noxious hydroxyl radicals. These ROS are highly reactive and cause damage to macromolecules such as DNA, protein and lipids. We propose that it is the balance in the activity of the Sod to Gpx plus Cat ratio (Sod/(Gpx plus Cat)) that is an important determinant of cellular aging. This is based on our observation that an altered Cu/Zn-superoxide dismutase (Sod1)/(Gpx1 plus Cat) ratio exists in the brain of aging mice and that this correlates with increased lipid damage. Conversely, aging liver and kidney have an unaffected Sod1/(Gpx1 plus Cat) ratio and lipid damage is not increased with aging. We also examine the Sod1 to Gpx1 ratio in Down syndrome tissue and show that all organs have an altered ratio. This may contribute to the premature aging seen in these individuals. We show that binding of a p50/p65 complex to an NF-kappa B consensus sequence is enhanced by H2O2 treatment in NIH3T3 cells. Thus an altered Sod1/(Gpx1 plus Cat) ratio may also affect gene expression by altering the binding and/or availability of transcription factors to DNA.

Aging↗
PubMed1994

A gene on human chromosome 21 located in the region 21q22.2 to 21q22.3 encodes a factor necessary for signal transduction and antiviral response to type I interferons.

The type I interferons (IFNs) are a family of multifunctional cytokines which includes the 15 IFN alpha subtypes and IFN beta. These IFNs compete for binding to cell surface receptors. However, murine cells transfected with a cDNA for a human IFN alpha receptor (IFNAR) developed an antiviral response only to human IFN alpha B, but not to human IFN alpha 2 nor -beta(1). In this study we show, using a panel of CHO-human chromosome 21 hybrid cell lines which all express IFNAR, that only those containing the region 21q22.2 to 21q22.3 transduce signals for IFN responses. Two such hybrid cell lines responded to IFNs alpha 2, -alpha B and -beta by induction of 2'-5' oligoadenylate synthetase and resistance to viral infection. Other hybrid cell lines, that lacked the region 21q22.2-3, failed to transduce signals as above; even though they expressed IFNAR and bound human IFN alpha 2, -alpha B, and -beta. These data demonstrate that a gene(s) located in the region 21q22.2-3 encodes a factor(s) which is necessary for signaling but does not influence ligand binding. This factor is not the cofactor required for IFN gamma signaling which is located in the region 21p to 21q22.1(2).

2',5'-Oligoadenylate Synthetase↗
PubMed1994

Pdha-2: a model for studying transcriptional regulation in early spermatocytes.

Precise temporal and tissue-specific expression of genes during spermatocyte differentiation is crucial for the formation of functional spermatozoa. However, the mechanisms that regulate gene expression during spermatogenesis are poorly understood. One testis-specific gene, Pdha-2, is beginning to emerge as a potentially important model for the study of these events. This review focuses on our current understanding of the expression and regulation of Pdha-2 during spermatogenesis.

Animals↗
PubMed1994

Regulation of gene expression by transcription factors Ets-1 and Ets-2.

The ETS family of transcription factors have a DNA-binding domain in common that binds a core GGA(A/T) DNA sequence. A large number of proteins have now been identified that contain an ETS DNA-binding domain (see review by Wasylyk et al., 1993). Ets-1 was first described as the cellular homolog of v-ets. which is translated as a 135-kDa gag-myb-ets fusion protein from the replication-deficient retrovirus E26 in chickens. Ets-2 was subsequently described as a closely related protein that contains the highly conserved ETS DNA-binding domain. This paper considers the manner by which the two closely related genes, Ets-1 and Ets-2, apparently play distinct roles in embryo development and in the immune system of adult mice. Although both Ets-1 and Ets-2 transform fibroblasts (Seth et al., 1989), the temporal and tissue-specific expression patterns suggest that these two proteins play distinct biological roles and consequently transactivate different downstream cellular target genes.

Amino Acid Sequence↗
PubMed1994

Role of interferons in the regulation of cell proliferation, differentiation, and development.

There now appears to be evidence to support the view that the type I IFNs are naturally produced negative regulators of growth that also modify cell differentiation. Consistent with this, it appears that the ability to produce and respond to IFN is suppressed in early embryonic development when cell proliferation and differentiation are essential. In the later stages of fetal development, IFN production is de-repressed, and cells show increased sensitivity to IFN, which may be important in regulating cell proliferation and/or differentiation processes or the interaction between fetal and maternal tissues. Interestingly, the IFN system can also be suppressed in disease states such as the development of tumours or in the establishment of a (chronic) viral infection. Therefore, understanding the developmental regulation of the IFN system may be important to understanding and controlling the IFN system in disease. More extensive studies of the developmental stage and tissue-specific expression of type I IFNs and their receptors are necessary, as well as more direct in vivo experiments to further elucidate the role of the IFN system in reproduction and development.

Animals↗
PubMed1994

Decreased natural killer cell activity in endometriosis patients: relationship to disease pathogenesis.

A number of reports have measured NK cell activity in patients with endometriosis with varied results. Therefore we have examined the NK activity of PBL from 44 gynecological patients undergoing laparoscopy. This analysis has demonstrated a significant reduction in NK activity only in more severe stages of endometriosis (stages III and IV) relative to patients with milder disease and controls. These data indicate that decreased NK activity is unlikely to be a primary etiological factor in the development of endometriosis but may indicate that decreased NK activity is related to the development of the more frequent and/or larger lesions characteristic of severe endometriosis. These data could indicate potential for immunotherapy of patients with advanced endometriosis by the upregulation of NK activity in vivo.

Cytotoxicity Tests, Immunologic↗
PubMed1994

Mouse testis Pdha-2 promoter upstream sequences confer tissue-and temporal-specific activity in transgenic mice.

Spermatogenesis is a complex process requiring the coordinate expression of a number of testis-specific genes. One of these, Pdha-2, codes for the murine testis-specific isoform of the E1 alpha subunit of the pyruvate dehydrogenase complex. To elucidate the mechanisms regulating its expression in vivo, we have begun to investigate the Pdha-2 promoter in transgenic mice. In this paper, a construct containing 3.0 kb of promoter and upstream sequences is reported to be sufficient for directing the testis-specific expression of a CAT reporter gene in mice harbouring the transgene. Similarly to the endogenous Pdha-2, the CAT gene is expressed in testis in a stage-specific manner. However, the 3.0-kb Pdha-2 promoter is not active in somatic tissue suggesting that repressor elements may be present within these sequences.

3T3 Cells↗
PubMed1994

Expression of copper/zinc superoxide dismutase and glutathione peroxidase in organs of developing mouse embryos, fetuses, and neonates.

The rise in antioxidant enzyme activity in the lungs of late-gestation fetuses is thought to be caused by the preparation of the pulmonary antioxidant system for birth. However, recent data have shown that such a rise also occurs in the livers of late-gestation fetuses. Consequently, this surge cannot solely be ascribed to the preparation of the pulmonary antioxidant system for birth. In this study we examine the expression of copper/zinc superoxide dismutase (Sod1) and glutathione peroxidase (Gpx1) in various organs of late-gestational mouse fetuses. Furthermore, we compare the expression of these genes in organs of fetuses, neonates, and adult mice. These studies were carried out to investigate whether the change in mRNA levels for these two genes is related to a developmental change in oxidant stress. Our data demonstrate that an increase in both Sod1 and Gpx1 mRNA occurs in lungs and livers of late-gestational mouse fetuses. The brain demonstrates an increase in Sod1 expression at or around the time of birth, the kidney shows an elevation in Gpx1 mRNA levels, and the heart fails to demonstrate a surge in both Sod1 and Gpx1 mRNA levels. Our data show that the liver is the organ with the highest levels of Sod1 and Gpx1 mRNA in embryos and neonates (immediately after birth). In the adult, the liver has the highest levels of Sod1 mRNA and the spleen the highest level of Gpx1 mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Temporal and tissue-specific interactions involving novel transcription factors and the proximal promoter of the mouse Pdha-2 gene.

We have determined by deletion analysis that the most proximal region of the Pdha-2 promoter between nucleotide position -187 to +22 harbors a transcriptionally active core. This "core" promoter directs high levels of CAT (chloramphenicol acetyltransferase) reporter gene transcription in HeLa cells. DNase I footprinting of the proximal promoter revealed four regions of protection. One of these contains the consensus sequence for the Sp1 binding site and another the ATF/CREB binding site. The cis-sequences of the remaining two protected regions (designated MEP-2 and MEP-3; Mouse E1 alpha Promoter site) show no apparent consensus homology with cis-elements of other known transcription factors. Results of electrophoretic mobility shift assays confirm that the ATF/CREB and MEP binding sites interact in a characteristic and specific manner with factors present in nuclei of both testis and somatic tissue. The factor which recognizes the MEP-3 motif appears to be ubiquitous, whereas the MEP-2-protein complexes were tissue-specific. Interestingly, formation of a complex involving MEP-2 and a putative testis-specific binding factor (tau-MEP-2BF) is first observed in the testis of 2-week-old mice, this correlates with the expression of Pdha-2. In contrast, the formation of complexes between the MEP-2 binding site and a somatic variant of MEP-2BF (sigma-MEP-2BF) decreases in the testis as spermatogenesis proceeds. Our results suggest that 1) the MEP-2 binding factors are temporally regulated during spermatogenesis, and 2) interactions involving these factors with the MEP-2 cis-element may be important for modulating Pdha-2 expression.

Aging↗
PubMed1993

The Ets1 transcription factor is widely expressed during murine embryo development and is associated with mesodermal cells involved in morphogenetic processes such as organ formation.

The Ets family of genes encodes a class of transcription factors. Ets1 is predominantly expressed in the lymphoid organs of neonatal and adult mice, whereas Ets2 is expressed in every organ examined. In this study, we investigate the expression of Ets1 and Ets2 during murine embryonic development. Our data show that Ets1 expression increases in embryos after implantation and during organogenesis such that it is expressed in all the organs of day-15 embryos studied. In later fetal stages, Ets1 expression is predominant in the lymphoid tissues, brain, and organs that are undergoing branching morphogenesis (e.g., lung) but is dramatically reduced in other organs such as the stomach and intestine. In neonatal development, Ets1 is expressed only in the lymphoid organs and brain. In situ hybridization analysis demonstrates that expression of Ets1 occurs in mesenchymal cells of developing organs, in the nervous system, and in forming bone. Furthermore, expression of Ets1 is upregulated in P19 cells induced to differentiate into mesoderm-like cells. Ets2, on the other hand, is expressed in differentiated and undifferentiated P19 and F9 cells and in all organs of embryonic, neonatal, and adult mice studied. These data suggest that Ets1 plays an important role in mesodermal cells associated with morphogenetic processes such as organ formation and tissue modeling, whereas Ets2 plays a more fundamental role in cells.

Animals↗
PubMed1992

C-ets-1 protooncogene expression alters the growth properties of immortalized rat fibroblasts.

Ets family genes have been cloned and characterized from a variety of species ranging from human to Drosophila. The ets proteins encode transcription factors that activate transcription via specific binding to GGAA core sequence present in various promoter/enhancers. To investigate the role of ets protooncogene expression on the growth properties of rat embryo fibroblasts (REF), we constructed and introduced ets expression vectors into primary, as well as immortalized REF cells. The transfected cells contained multiple copies of the vector DNA, and the Northern blot analysis demonstrated overexpression of the c-ets-1-specific mRNA. Although the expression of the ets genes was unable to immortalize primary rat embryo fibroblasts, the expression of ets-1 in REF-1 cells enabled their growth in serum-free medium and effected tumorigenic activity in nude mice.

Animals↗
PubMed1992

Cu/Zn superoxide dismutase mRNA and enzyme activity, and susceptibility to lipid peroxidation, increases with aging in murine brains.

To protect against reactive oxygen species, prokaryotic and eukaryotic cells have developed an antioxidant defence mechanism where O2- is converted to H2O2 by superoxide dismutase (Sod), and in a second step, H2O2 is converted to H2O by catalase (Cat) and/or glutathione peroxidase (Gpx). If Sod levels are increased without a concomitant Gpx increase, then the intermediate H2O2 accumulates. This intermediate could undergo the Fenton's reaction, generating hydroxyl radicals which may lead to lipid peroxidation in cells. In this study, we investigate the expression of Sod1, Gpx1 and susceptibility to lipid peroxidation during the aging process in mouse brains. We demonstrate that the mRNA levels and enzyme activity of Sod1 are higher in brains from adult mice compared to neonatal mice. Furthermore, we show that a linear increase in Sod1 mRNA and enzyme activity occurs with aging (1-100 weeks). On the contrary, we find that the mRNA and enzyme activity for Gpx1 does not increase with aging in mouse brains. In addition, our results demonstrate that the susceptibility of murine brains to lipid peroxidation increases with aging. The data in this study are consistent with the notion that reactive oxygen species may contribute to the aging process in mammalian brains. These results are discussed in relation to the normal aging process in mammals, and to the premature aging and mental retardation in Down syndrome.

Aging↗
PubMed1992

The evolution of human chromosome 21: evidence from in situ hybridization in marsupials and a monotreme.

We have mapped five human chromosome 21 (HSA 21) markers in marsupials and a monotreme, two major groups of mammals that diverged from eutherians 130-150 and 150-170 million years before present (MYrBP), respectively. We have found that these genes map to two distinct autosomal sites, one containing SOD1/CBR/BCEI and the other containing ETS2/INFAR, in the marsupials Macropus eugenii and Sminthopsis macroura (which belong to orders that diverged 40-80 MYrBP), as well as in the monotreme Ornithorhynchus anatinus (the platypus). Since marsupials and monotremes diverged independently from eutherians, these data suggest that HSA 21 genes were originally located in two separate autosomal blocks. In another Sminthopsis species, SOD1 is linked to TRF (a marker on HSA 3q), suggesting that the ancestral SOD1/CBR/BCEI region also included HSA 3 markers. We suggest that these blocks became fused early in the eutherian evolution to form a HSA 3/21 chromosome, which has remained intact in artiodactyls, but has been independently disrupted in both the primate and rodent lineages.

Animals↗
PubMed1992

The incidence of chromosomal aneuploidy in stimulated and unstimulated (natural) uninseminated human oocytes.

The incidence of chromosomal aneuploidy in human oocytes is higher than for various animal species. Since this estimate for aneuploidies is based on data obtained from in-vitro fertilization (IVF) patients, it is possible that superovulation could be contributing to this phenomenon. In this study we determine the incidence of chromosomal aneuploidy in nonstimulated uninseminated human oocytes donated by IVF patients. Furthermore, we compare this incidence of aneuploidy to that obtained after superovulation using two different protocols for induction of multiple follicular growth. The rate of aneuploidy in non-stimulated oocytes was 20% (4/20). This is not significantly different from the rate of aneuploidy in oocytes obtained after superovulation with clomiphene/human menopausal gonadotrophin (HMG)/(HCG) (15/43 = 35%, chi 2 = 1.11; P > 0.20), buserelin-flare (8/25 = 32%; chi 2 = 0.32; P > 0.05), and the rate of aneuploidy in the total number of superovulated oocytes (23/68 = 34%; chi 2 = 82; P < 0.30). Furthermore, the incidence of chromosome aneuploidy in non-stimulated uninseminated oocytes (20%) was well within the range and not significantly different from that reported in the literature for both superovulated uninseminated oocytes (range, 21-57%; total aneuploidy rate, 67/216 = 31%; P < 0.30) and superovulated inseminated oocytes (range, 3-56%; total aneuploidy, 339/1480 = 23%; P < 0.95). Consequently, the data provide evidence that superovulation protocols used in IVF may not be responsible for the higher rate of aneuploidy in human oocytes. These results are discussed in relation to hypotheses on the occurrence of meiotic non-disjunction.

Adult↗
PubMed1992

Localization of four human chromosome 21 genes--SOD1, ETS2, IFNAR, and CBR--to two different chromosomes in the marsupial species Macropus eugenii.

We have mapped the chromosomal location of four genes previously assigned to human chromosome 21--Cu/Zn superoxide dismutase (SOD1), the protooncogene ETS2, the interferon alpha/beta receptor gene (IFNAR), and the carbonyl reductase gene (CBR)--in the tammar, Macropus eugenii. The genes are localized on two separate autosomes: SOD1 and CBR map to chromosome 7 and ETS2 and IFNAR map to chromosome 3 or 4. These results provide the first example of asynteny between SOD1/CBR and ETS2/IFNAR in a mammalian species. The results suggest that either this synteny group has been disrupted in the marsupial lineage, or, alternatively, the genes located on human chromosome 21 may have been joined after the marsupials diverged from the eutherian mammals some 130-150 million years ago.

Alcohol Oxidoreductases↗
PubMed1991

Centrioles in the beginning of human development.

We demonstrate the presence of centrioles in fertilized human oocytes at syngamy. Single or double centrioles within centrosomes were detected by transmission electron microscopy at one pole of the first cleavage spindle in normal and dispermic embryos (25-26 hr after insemination). Sperm centrioles were also closely associated with the male pronucleus (16-20 hr after insemination) in pronuclear stage embryos. A tripolar spindle derived from a tripronuclear embryo is also demonstrated with two centrioles at one pole. The data provide evidence that human centrioles, as those in most other animals, and unlike the mouse, are paternally derived, thus supporting Boveri's classical theory. Furthermore, this study provides insights to the proposed mechanisms of aberrant cleavage patterns of dispermic human embryos.

Blastocyst↗
PubMed1991

Thermolability of mouse oocytes is due to the lack of expression and/or inducibility of Hsp70.

Eukaryotic and prokaryotic cells have been shown to respond to physical and chemical stress by the induction of proteins called heat shock proteins. Heat shock protein 70 (Hsp70), is the most ubiquitous of these proteins. Although heat shock proteins are generally thought to protect cells from physiologically stressful stimuli, it cannot be assumed that this is so, because several cases exist in which thermotolerance is acquired without the production of heat shock proteins, and in several other cases the hyperproduction of these heat shock proteins does not produce thermotolerance. In this study we show that unfertilized mouse oocytes are sensitive to elevated temperatures, and that the synthesis of Hsp70 cannot be induced in these oocytes. Furthermore, our data demonstrate that the expression of Hsp70 in mouse oocytes is sufficient for the acquisition of thermotolerance. Mouse oocytes were injected with mRNA for Hsp70, and the viability of these oocytes was determined after heating. The number of viable oocytes was significantly higher in the group injected with Hsp70 mRNA and then heated compared with oocytes injected with Hsp70 antisense mRNA and sham-injected controls treated in an identical manner. No significant differences in the number of viable oocytes were found between the group that had been injected with Hsp70 mRNA, heated, and then allowed to recover for 3 hr and the group maintained at 37 degrees C throughout.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗