Amplification of the metallothionein-I gene in cadmium-resistant mouse cells.
Friend leukemia cells resistant to cadmium toxicity were selected. More than 70% of total cysteine incorporation in these cells was into the metal-binding protein, metallothionein. We used cDNA and genomic DNA clones containing the metallothionein-I gene to measure the concentration of its mRNA, the rate of gene transcription, and the number of genes. On a per cell basis, optimally induced, cadmium-resistant cells have a 14-fold more metallothionein-I mRNA, a 6-fold higher rate of metallothionein-I gene transcription, and 6-fold more metallothionein-I genes than do nonresistant cells. Metaphase spreads revealed that the resistant cells are nearly tetraploid and contain, on the average, three very small chromosomes that are absent from non-resistant Friend cells.
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004351:Drug Resistance; D005622:Friend murine leukemia virus; D005784:Gene Amplification; D007942:Leukemia, Experimental; D008667:Metalloproteins / Q000235:genetics*; D008668:Metallothionein / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D014158:Transcription, Genetic
D008667:Metalloproteins; D002104:Cadmium; D008668:Metallothionein