ZNF471 modulates EMT and functions as methylation regulated tumor suppressor with diagnostic and prognostic significance in cervical cancer

Cell Biology and Toxicology - Cervical cancer (CC) is a leading cause of cancer-related death among women in developing countries. However, the underlying mechanisms and molecular targets for...     

Semen Abnormalities,Sperm DNA Damage and Global Hypermethylation in Health Workers Occupationally Exposed to Ionizing Radiation

Background

Cytogenetic studies have demonstrated that low levels of chronic radiation exposure can potentially increase the frequency of chromosomal aberrations and aneuploidy in somatic cells. Epidemiological studies have shown that health workers occupationally exposed to ionizing radiation bear an increased risk of hematological malignancies.

Objectives

To find the influence of occupational radiation exposure on semen characteristics, including genetic and epigenetic integrity of spermatozoa in a chronically exposed population.

Methods

This cross sectional study included 134 male volunteers of which 83 were occupationally exposed to ionizing radiation and 51 were non-exposed control subjects. Semen characteristics, sperm DNA fragmentation, aneuploidy and incidence of global hypermethylation in the spermatozoa were determined and compared between the non-exposed and the exposed group.

Results

Direct comparison of the semen characteristics between the non-exposed and the exposed population revealed significant differences in motility characteristics, viability, and morphological abnormalities (P<0.05–0.0001). Although, the level of sperm DNA fragmentation was significantly higher in the exposed group as compared to the non-exposed group (P<0.05–0.0001), the incidence of sperm aneuploidy was not statistically different between the two groups. However, a significant number of hypermethylated spermatozoa were observed in the exposed group in comparison to non-exposed group (P<0.05).

Conclusions

We provide the first evidence on the detrimental effects of occupational radiation exposure on functional, genetic and epigenetic integrity of sperm in health workers. However, further studies are required to confirm the potential detrimental effects of ionizing radiation in these subjects.     

Correlation between riboflavin carrier protein induction and its mRNA activity in estrogen stimulated chicken liver and oviduct

Poly A enriched RNA from either liver or oviduct of estradiol-17β treated immature chicks supported [³H]-leucine incorporation into immunoprecipitable riboflavin carrier protein in a dose-dependent manner when translated in the rabbit reticulocyte lysate system. Primary translation product of riboflavin carrier protein had a molecular weight of 38,000 which on incubation with a stripped hepatic microsomal preparation was processed to a product with a size comparable to native riboflavin carrier protein. Poly A enriched RNA from both the liver and the oviduct of estrogen-treated birds stimulated [³H]-leucine incorporation into riboflavin carrier protein and this was 2–3 fold higher during secondary stimulationvis-a-vis primary stimulation with the steroid. Poly A enriched RNA from the liver of progesteronetreated birds during secondary stimulation did not support riboflavin carrier protein synthesis. In contrast, poly A enriched RNA from the oviduct of the birds treated with progesterone during secondary (but not primary) stimulation did exhibit riboflavin carrier protein-mRNA activity which was comparable to that stimulated by estradiol-17β     

Mechanism of foetal wastage following immunoneutralization of riboflavin carrier protein in the pregnant rat: disturbances in flavin coenzyme levels

Immunoneutralization of maternal RCP results in a greater than 90% decrease in the content and the incorporation of [2-14C]riboflavin into embryonic FAD as well as a percentage redistribution of both embryonic FMN and riboflavin. This is unaccompanied by any discernible changes in flavin distribution pattern in the maternal liver. Embryonic alpha-glycerophosphate dehydrogenase and NADPH-cytochrome c reductase register significant decreases in activities in the RCP antiserum-treated rats. These alterations readily explain the arrest of foetal growth culminating in pregnancy termination in the antiserum-treated animals.     

Hormonal modulation of reproduction-specific thiamin carrier protein in the rat

The hormonal modulation of thiamin carrier protein in the plasma and uterine luminal secretion during the normal reproductive phases of the animal (estrous cycle and pregnancy) as well as during experimental estrogenisation was investigated in the rat using a specific and sensitive homologous radioimmunoassay procedure developed for this purpose. Following a single injection of estrogen to immature male rats, thiamin carrier protein rapidly accumulated in plasma attaining peak concentration at 48 h and declining thereafter. A 1.5-fold amplification of the inductive response was observed on secondary stimulation with the hormone. The magnitude of the response exhibited a clear dependency on the dose of the steroid hormone, whereas the time at which peak levels of thiamin carrier protein production was remained unaltered in the concentration range of the steroid tested. The inductive effect of estrogen was severely curtailed by the antiestrogens,viz., En- and Zu-clomiphene citrates, while progesterone was incapable of either modulating the estrogen-induced response or eliciting an induction by itself. Cycloheximide drastically blocked the response to estrogen. Evidence for the ability of uterus to serve as yet another independent site of thiamin carrier protein synthesis was obtained byin vitro incorporation of radioactive amino acids into immunoprecipitable thiamin carrier protein in the tissue explants of estrogenised female rats. The levels of thiamin carrier protein in uterine luminal fluid measured during estrous cycle, pregnancy and experimental estrogenisation exhibited remarkable similarity to the plasma thiamin carrier protein profiles.     

The interaction of riboflavin with a protein isolated from hen's egg white: a spectrofluorimetric study.

The interaction of riboflavin with a protein isolated from egg white has been studied spectrofluorimetrically at different pH values. In 0.1 M phosphate buffer pH 7.0; 1:1 complex formation occurs with the association constant Ka = 7.7-10(7) M-1. In the presence of 0.033% sodium dodecyl sulphate, the complex dissociated with a rate constant of 4-10(-2) sec-1 at 29 degrees C. The binding was sensitive to pH and to the antibodies produced against the protein. On lowering the pH from 7 to 4 the binding affinity decreased approximately 100-fold and below pH 4, the binding could not be detected at all. These data, together with those obtained by measuring the fluorescence intensities of riboflavin in presence of N-bromosuccinimide oxidized- and disulphide reduced apoprotein, suggest that carboxyl functions, 1-2 tryptophan residues and 2-3 disulphide bridges are essential for binding. The emission spectra of the protein under different conditions upon excitation at 280 and 295 nm were analyzed to calculate the quantum yield (Q) and the efficiency of energy transfer (e) from tyrosine to tryptophan residues. From these data it was concluded that the energy transfer did not occur with equal efficiency under all conditions and that the tryptophan residues responsible for the riboflavin binding are more accessible to N-bromosuccinimide oxidation than others.     

Early pregnancy termination in rats immunized with denatured chicken riboflavin carrier protein.

Immunoneutralization of the maternal riboflavin carrier protein in the pregnant rat with antibodies to chicken egg vitamin carrier has earlier been shown to terminate their pregnancies. In order to understand the nature of the epitopic conformations capable of eliciting antibodies bioneutralizing the endogenous riboflavin carrier protein in the pregnant rat, we compared pregnancy progression in the fertile rodents following active immunization with either the native, SDS-denatured, reduced-carboxymethylated or SDS-treated reduced carboxymethylated avian egg white riboflavin carrier protein. The data revealed that despite the total antibody titers being higher in the animals immunized with the native protein, the antibodies elicited against the denatured avian vitamin carrier exhibited relatively better potencies to bioneutralize the endogenous maternal protein as evidenced by higher rates of early fetal resorption.     

Partial purification and properties of a transamidinase from Lathyrus sativus seedlings. Involvement in homoarginine metabolism and amine interconversions.

A transamidinase was purified 463-fold from Lathyrus sativus seedlings by affinity chromatography on homoarginine--Sepharose. The enzyme exhibited a wide substrate specificity, and catalysed the reversible transfer of the amidino groups from donors such as arginine, homoarginine and canavanine to acceptors such as lysine, putrescine, agmatine, cadaverine and hydroxylamine. The enzyme could not be detected in the seeds, and attained the highest specific activity in the embryo axis on day 10 after seed germination. Its thiol nature was established by strong inhibition by several thiol blockers and thiol compounds in the presence of ferricyanide. In the absence of an exogenous acceptor, it exhibited weak hydrolytic activity towards arginine. It had apparent mol.wt. 210000, and exhibited Michaelis--Menten kinetics with Km 3.0 mM for arginine. Ornithine competitively inhibited the enzyme, with Ki 1.0 mM in the arginine--hydroxylamine amidino-transfer reaction. Conversion experiments with labelled compounds suggest that the enzyme is involved in homoarginine catabolism during the development of plant embryo to give rise to important amino acids and amine metabolites. Presumptive evidence is also provided for its involvement in the biosynthesis of the guanidino amino acid during seed development. The natural occurrence of arcain in L. sativus and mediation of its synthesis in vitro from agmatine by the transamidinase are demonstrated.