Expression and human chromosomal localization to 17q25 of the growth-regulated gene encoding the mitochondrial...

Mitochondrial activity requires the expression of nuclear genes, whose products are part of multiproteic complexes leading to ATP production and delivery. We recently characterized a growth-activated mRNA encoding the human mitochondrial ribosomal MRPL12 protein, which is thought to act as a translational regulator of mitochondrial mRNAs. We show here that MRPL12 mRNA expression is enhanced in growth-stimulated cells as a result of transcriptional activation, a feature lost in transformed cell lines. MRPL12 mRNA is highly expressed in the colon, in which a reduction in mitochondrial activity was shown to be associated with tumor formation. The human MRPL12 protein is encoded by a unique gene located on chromosome 17 (q25-qter). As no predisposition to colon cancer linked to this chromosomal region was hitherto reported, the MRPL12 gene might be involved in the process of differentiation of colonic epithelial cells.