Genes coding for metal induced synthesis of RNA sequences are differentially amplified and regulated in mammalian cells. [CHO cells]
Three variant cell lines were isolated which survive cadmium (Cd/sup + +/) concentrations 10 to 200 fold greater than that which kills parental Chinese hamster cells (line CHO). Cadmium treatment of the variants induces the synthesis of a highly abundant poly A/sup +/ RNA class which directs the synthesis of metallothionein in a cell-free translation system. Hybridization of cDNA complementary to these inducible, highly abundant RNA sequences (cDNA/sub a/) with RNA from variant cells showed that: (1) the induced abundant class has a total complexity of approx. 2000 NT; (2) CD/sup + +/ induction increases the cellular concentration of these sequences approx. 2000 fold above preinduction levels in each of the variants; and (3) most, if not all, of these sequences are expressed constitutively in uninduced cells. Cadmium induction of sensitive CHO cells increases the cellular concentration of only a subset of the sequences inducible in resistant cells and then only to a level 100 fold higher than in uninduced cells. Only approx. 50% of the sequences are constitutively expressed at measurable levels in uninduced CHO cells. Hybridization of cDNA/sub a/ with genomic DNA from the three resistant variants showed that genes coding for the induction of specific RNA sequences are amplified approx. 10 fold in Cd/sup r/20F4 cells, approx. 4 fold in Cd/sup r/30F9 cells, and unamplified in Cd/sup r/2C10 cells relative to CHO. While sensitive CHO cells can tolerate only 0.2 ..mu..M Cd/sup + +/, Cd/sup r/30F9, Cd/sup r/20F4, and Cd/sup r/2C10 cells are resistant to 40 ..mu..M, 26 ..mu..M, and 2 ..mu..M Cd/sup + +/ respectively. Thus, gene amplification alone cannot be responsible for the observed resistance of the variant cell lines.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6566639
- Report Number(s):
- LA-UR-81-859; CONF-810350-1
- Resource Relation:
- Conference: ICN-UCLA symposium on molecular and cellular biology, Keystone, CO, USSR, 15 Mar 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
RNA
CADMIUM COMPOUNDS
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CATIONS
CELL CULTURES
DNA
GENES
HAMSTERS
HYBRIDIZATION
METALLOTHIONEIN
ANIMALS
CHARGED PARTICLES
IONS
MAMMALS
METALLOPROTEINS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RODENTS
SYNTHESIS
VERTEBRATES
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)
550400 - Genetics
550100 - Behavioral Biology