Evidence for differences in the post-transcriptional regulation of rat metallothionein isoforms

M H Vasconcelos, S C Tam, J H Beattie, J E Hesketh

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    Abstract

    The expression of metallothionein (MT)-1 and -2 mRNAs in rat liver following administration of Cd or Cu was investigated using specific oligonucleotides. The specificity was confirmed using a competitive prehybridization assay. Cd injection caused a biphasic induction of both isoform mRNAs, whereas Cu induced a sustained, monophasic response. Analysis of polyribosomal RNA showed that, after both Cd and Cu treatments, the recruitment of MT-1 mRNA into polyribosomes paralleled the increase in transcription, but the increase of polyribosomal MT-2 mRNA was less than that of total MT-2 mRNA. This indicates that not all the MT-2 mRNA induced was translated, suggesting that there is translational control of MT-2 mRNA expression, but not of MT-1 mRNA. This hypothesis was supported by the observation that, after Cu treatment, the induction of MT-1 protein was induced to the same extent as MT-1 mRNA, whereas the total MT protein (MT-1+MT-2) was increased far less (7-fold) than MT-2 mRNA (30-fold).

    Original languageEnglish
    Pages (from-to)665-671
    Number of pages7
    JournalBiochemical Journal
    Volume315
    Publication statusPublished - 15 Apr 1996

    Keywords

    • MESSENGER-RNA
    • HEPATIC METALLOTHIONEIN
    • LIVER
    • INDUCTION
    • COPPER
    • EXPRESSION
    • INJECTION
    • GENES
    • FETAL
    • ACID

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