Regulation of Cd/sup 2 +//Zn/sup 2 +/-stimulated metallothionein synthesis during induction, deinduction, and superinduction

Journal Article · Tue Jan 01 04:00:00 EST 1980 · Biochemistry; (United States)

OSTI ID:6153027

Hildebrand, C E; Enger, M D

Metallothioneins (MTs) are low-molecular-weight, thiol-rich, metal-binding proteins which are synthesized in animal tissues or in cultured cells in response to Cd/sup 2 +/ or Zn/sup 2 +/ exposure. We have examined regulation of MT synthesis in a Cd/sup 2/--resistant (Cd/sup r/) Chinese hamster cell which is proficient in induction of MT synthesis following exposure to either Cd/sup 2 +/ or Zn/sup 2 +/. The Cd/sup r/ cell MTs are cysteine rich and leucine deficient, bind Zn/sup 2 +/ and Cd/sup 2 +/ with high affinity, and are synthesized only during exposure of the cells to Cd/sup 2 +/ or to excess Zn/sup 2 +/. Induction of MT synthesis is inhibited by 5 ..mu..g/mL actinomycin D (AM), indicating that RNA synthesis is required for induction. MT synthesis also is dependent upon the continued exposure to inducing metal since withdrawal of inducer at the time of maximal MT synthesis results in a deinduction of MT synthesis with a half-time of 2 to 3 h. Analyses of induction and deinduction kinetics, together with the results of RNA synthesis inhibitor studies, suggest that indication of MT synthesis is regulated primarily at the level of transcription of thionein mRNA. Finally, the existence of the AM-mediated superinduction of MT synthesis, a phenomenon originally observed in steroid-mediated induction of specific hepatic enzymes, suggests that similar regulatory mechanisms may operate in these quite different inducible systems.

• OSTI ID: 6153027
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 19:25; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ACTINOMYCIN
ANIMAL CELLS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CADMIUM 109
CADMIUM CHLORIDES
CADMIUM COMPOUNDS
CADMIUM HALIDES
CADMIUM ISOTOPES
CATIONS
CHARGED PARTICLES
CHEMICAL ACTIVATION
CHLORIDES
CHLORINE COMPOUNDS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
EVEN-ODD NUCLEI
FIBROBLASTS
HALIDES
HALOGEN COMPOUNDS
HAMSTERS
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
MUTANTS
NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
RODENTS
SOMATIC CELLS
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
VERTEBRATES
YEARS LIVING RADIOISOTOPES
ZINC CHLORIDES
ZINC COMPOUNDS
ZINC HALIDES