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Regulation of metallothionein synthesis in HeLa cells by heavy metals and glucocorticoids

Journal Article · · J. Cell. Physiol.; (United States)
; ;
Metallothioneins (MTs) are low molecular weight, cysteine-rich proteins that bind heavy metals. MT induction occurs in liver in response to either heavy metal (Zn/sup + +/ or Cd/sup + +/) administration or stress. The synthesis of MT can also be induced by either heavy metals or glucocorticoid hormones in HeLa cells cultured in serum-free medium. Induction of MT by zinc is subject to desensitization. In contrast, dexamethasone (dex) induction results in a continued elevation in the rate of MT synthesis. The stability of MT is dependent on the availability of metal; consequently, MT induced by dex is degraded much more rapidly (half-life of 11 to 12 hours) than MT induced by elevated zinc levels (half-life of 36 to 38 hours). Removal of either inducer results in biphasic degradation curves, as apothionein and zinc come into balance. In contrast, deinduction kinetics for MT synthesis following removal of the two inducers (zinc and dex) are the same, with a half-life of two and one-half hours. Inhibition of RNA synthesis blocks deinduction after removal of inducer. Induction of MT occurs in a wide variety of species, from blue-green algae to man. This system should provide an excellent model for the comparative biochemistry of regulation of gene expression.
Research Organization:
Univ. of California, Los Angeles
OSTI ID:
6869045
Journal Information:
J. Cell. Physiol.; (United States), Journal Name: J. Cell. Physiol.; (United States) Vol. 106:1; ISSN JCLLA
Country of Publication:
United States
Language:
English

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Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
BINDING ENERGY
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CADMIUM IONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CORTICOSTEROIDS
DECOMPOSITION
DEXAMETHASONE
ENERGY
GLUCOCORTICOIDS
HALF-LIFE
HELA CELLS
HORMONES
HYDROXY COMPOUNDS
IN VITRO
IONS
KETONES
KINETICS
METABOLISM
METALLOTHIONEIN
MOLECULAR WEIGHT
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PREGNANES
PROTEINS
QUANTITY RATIO
REACTION KINETICS
RNA
SENSITIVITY
STEROID HORMONES
STEROIDS
SYNTHESIS
ZINC IONS