Cd2+, Mn2+ and Zn2+ induced synthesis of nuclear RNA in the livers of normal and adrenalectomized rats

Weser, Ulrich; Hübner, L.

doi:10.1016/0014-5793(70)80445-8

Cited by 20 publications

(5 citation statements)

References 29 publications

(4 reference statements)

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“…3), the yield of mRNA from polyribosomal RNA (Table 1) varied consistently with the percentage of metallothionein-mRNA activity measured. It should be noted that zinc administration results in a general increase in RNA polymerase activity (Weser & Hubner, 1970). Therefore zinc-induced synthesis of other mRNA species may also have contributed to the difference noted in recovery and efficiency of translation of mRNA pools between zinc-treated and control rats.…”

Section: Discussionmentioning

confidence: 99%

Induction of rat liver metallothionein mRNA and its distribution between free and membrane-bound polyribosomes

Shapiro¹,

Cousins²

1980

Biochemical Journal

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Total, membrane-bound and free polyribosomes were purified from livers of Zn2+-treated and control rats. Polyadenylated RNA was separated from the polyribosomal RNA extracts by oligo(dT)--cellulose chromatography and translated in a wheat-germ cell-free translation system. Newly synthesized 35S-labelled metallothionein was isolated from the other [35S]methionine-labelled translation products by activated-thiol--Sepharose 4B chromatography. The purity of the 35S-labelled metallothionein product was substantiated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Zinc administration resulted in an elevation of metallothionein mRNA activity to 11% of the total polyribosomal mRNA activity. The vast majority of biologically active metallothionein mRNA was localized in the free polyribosomal pool, at least 94% and 97% in control and zinc-treated rats respectively. The increase in the percentage of polyribosomal mRNA coding for metallothionein after zinc administration was 3-fold, whether measured directly in total polyribosomal mRNA or as a combination derived from membrane-bound and free polyribosomal mRNA. These data indicate that the induction of metallothionein mRNA by zinc involves only free polyribosomes and suggest that the function of metallothionein is limited to intracellular processes.

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Section: Discussionmentioning

confidence: 99%

Induction of rat liver metallothionein mRNA and its distribution between free and membrane-bound polyribosomes

Shapiro¹,

Cousins²

1980

Biochemical Journal

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“…For further details see [31,32]. -, absorbance CD spectra of proteins with respect to the disulphide chromophore is particularly critical because of different contributions of P and M helical conformations of the C-S-S-C grouping.…”

Section: Interpretation Of Circular-dichroism Datamentioning

confidence: 99%

Characterization of Cd, Zn‐Thionein (Metallothionein) Isolated from Rat and Chicken Liver

Weser

Rupp

Donay

et al. 1973

European Journal of Biochemistry

201

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The preparation of pure metallothionein from Cd-pretreated rats and chicken was performed using short-time treatment with chloroformlethano1 followed by ion-exchange and gel chromatography. The protein contained 7 g-atoms metal ions per 12000 g protein. The Zn to Cd ratio was 1 :2.4 f 0.1. The Cd, Zn-thionein remained homogeneous during Sephadex G-25, 6-50 and 6-75 gel filtration, during polyacrylamide disc-gel electrophoresis and in the analytical ultracentrifuge. The high content of cysteine residues (approx. one-third of the total residues) was consistent with the cysteine content of metallothionein isolated from human or equine tissues. The Cd, Znthionein was of considerable temperature stability. The physicochemical properties were examined by ultraviolet spectroscopy, circular dichroism (CD) measurements and X-ray photoelectron spectroscopy. The millimolar absorption coefficient of the native protein was a t 250nm ~2543 = 80.6 mM-1-cm-1. Virtually no aromatic amino acids were present. The E~~~ value of the apoprotein prepared by metal displacement using HC1 was E~~~ = 13.2 mM-1 * cm-l. When the ultraviolet spectrum of the apoprotein was recorded a t p H 6.6 a distinct peak was detectable at 255 nm (eZ5,, = 18.7 m M-1. om-l). The existence of inter-or intramolecular disulphide formation was confumed by CD measurements employing the polyethyleneglycol esters of di-tert-butyloxycarbonyl-L-cystine and tert-butyloxycarbonyl-L-cysteine as model aompounds for high-molecularweight and water-soluble cysteine compounds, respectively.From CD data it was concluded that Cd, Zn-thionein exists mainly as a random-coil peptide.Some indication of the binding of Cd and Zn in the native protein with eS-R moieties was obtained from ultraviolet data. Final proof of the exclusive coordination of these metal ions with cysteine sulphur was successful using both circular dichroism measurements and especially X-ray photoelectron spectroscopy. The last method proved most convenient for determining the binding energies of the core electrons of Cd (Cd 3d,,= = 411.0 eV and Cd 3d,ll = 404.4 eV), Zn (2 pal, =1021.0 eV) and S (2p = 161.7 eV). The corresponding binding energies for S in the cystine complexes with Zn2+ and Cd2+ were 163.0 eV and 162.8 eV, respectively.Sixteen years ago Margoshes andVallee were able to demonstrate the simultaneous presence of Cd, Zn and even Hg in a protein isolated from kidney cortex sulphur-containing amino acids, it was suggested the protein be named metallothionein. At the moment the discussion regarding the biochemical function of metallothionein is still going on. One important action would appear rather attractive : the decontamination of biological systems from harmful mercury and cadmium ions. This hypothesis has been supported by the observation of a rapid rise of metallothinein synthesis following the oral or intraperiotoneal administration of cadmium to rabbits [5,6], rats [7 to 91 and chicken [10,11].Although our knowledge of metauothionein is quite established, there is still considerable work ...

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“…Cherian and Goyer (25) have also noted the failure to develop successfully in vitro systems to study the biosynthesis of metallothionein. Thus, to date, in vitro translation experiments have not confirmed the in vivo effects of cadmium on RNA metabolism (18,24,26,27), and in particular the stimulated synthesis of messenger RNA's following cadmium exposure (24). The detailed mechanisms which regulate cadmium-thionein synthesis are unknown at the present time; however, it is clear that in rat liver (1) they involve controls at the transcriptional level, (2) these controls are responsive to the levels of nonspecifically bound cadmium in the cell, (3) synthesis of thionein decreases as the cytoplasmic levels of this protein sequester intracellular cadmium.…”

Section: Cell-free Homologous Polysomal System For Cd-thionein Inductionmentioning

confidence: 99%

Cadmium, an effector in the synthesis of thionein.

Bryan¹,

Hidalgo²,

Koppa³

et al. 1979

Environ Health Perspect

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Cadmium can elicit the synthesis of thionein in liver cells independent of tissue-organ interactions. The metal diffuses across the plasma membrane and is partitioned between subcellular components in a time dependent manner such that thionein synthesis responds to levels of nonspecifically and specifically bound cytoplasmic metal. Cadmium appears to function at the transcriptional level, and the metal may act to increase the pool of specific m-RNA's.

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Cd²⁺, Mn²⁺ and Zn²⁺ induced synthesis of nuclear RNA in the livers of normal and adrenalectomized rats

Cited by 20 publications

References 29 publications

Induction of rat liver metallothionein mRNA and its distribution between free and membrane-bound polyribosomes

Induction of rat liver metallothionein mRNA and its distribution between free and membrane-bound polyribosomes

Characterization of Cd, Zn‐Thionein (Metallothionein) Isolated from Rat and Chicken Liver

Cadmium, an effector in the synthesis of thionein.

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