Evidence of tissue-specific, post-transcriptional regulation of NRE-2 expression

Mitochondrial respiratory function requires the expression of genes both from the mitochondrial and nuclear genomes. Nuclear respiratory factor 2 (NRF-2) is a transcription factor required for the expression of several nuclear-encoded mitochondrial proteins, including the specific mitochondrial transcription factor Tfam. This makes NRF-2 a likely candidate to coordinate expression of mitochondrial components. NRF-2 is a multisubunit complex of which the a subunit binds DNA and the beta subunit enhances this binding, respectively. We have analysed in vivo the expression patterns of NRF-2 subunits both at the mRNA and protein level, in three rat tissues, Liver, testis and brain. In contrast with Tfam or the 'housekeeping' beta -actin expressions in which a parallel gradient was observed, no correlation was found between NRF-2 mRNAs and proteins levels, thus suggesting post-transcriptional regulation. (C) 2000 Societe francaise de biochimie et biologie moleculaire / Editions scientifiques et medicales Elsevier SAS.