Expression and human chromosomal localization to 17q25 of the growth-regulated gene encoding the mitochondrial ribosomal protein MRPL12.

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.