Alterations in ribonucleic acid synthesis by chromium (III).

The effect of Cr(III) on in vitro RNA synthesis directed by DNA and chromatin isolated from mouse liver was investigated in comparison with other inorganic metals. At 1 mM, CrCl3 significantly stimulated RNA synthesis when incubated with DNA or chromatin prior to the addition of Escherichia coli RNA polymerase, while other metals inhibited it. This stimulation by Cr(III) was caused even at 1 muM CrCl3 on either DNA- or chromatin- directed RNA synthesis. The Cr(III)-complexes of DNA and chromatin also showed significantly enhanced template activities. On the other hand, when RNA polymerase was preincubated with Cr(III), a remarkable inhibition was observed in RNA synthesis directed by both DNA and chromatin. In isolated mouse liver nuclei with endogenous RNA polymerases, Cr(III) stimulated Mg2+-activated RNA synthesis but not Mn2r-(NH4)2SO4-activated synthesis. These results suggest that Cr(III) may alter or regulate gene expressions in mammals.