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Ribosomal RNA large subunit methyltransferase J (RrmJ), an Escherichia coli heat shock protein, is responsible for 2′-O-ribose methylation in 23S rRNA. In mammals, three close homologs of RrmJ have been identified and have been designated as FTSJ1, FTSJ2 and FTSJ3; however, little is known about these genes. In this study, we characterized the mammalian FTSJ2, which was the most related protein to RrmJ in a phylogenetic analysis that had similar amino acid sequence features and tertiary protein structures of RrmJ. FTSJ2 was first identified in this study as a nucleus encoded mitochondrial protein that preserves the heat shock protein character in mammals in which the mRNA expressions was increased in porcine lung tissues and A549 cells after heat shock treatment. In addition, a recent study in non-small cell lung cancer (NSCLC) suggested that the FTSJ2 gene is located in a novel oncogenic locus. However, our results demonstrate that the expression of FTSJ2 mRNA was decreased in the more invasive subline (CL1-5) of the lung adenocarcinoma cells (CL1) compared with the less invasive subline (CL1-0), and overexpression of FTSJ2 resulted in the inhibition of cell invasion and migration in the rhabdomyosarcoma cell (TE671). In conclusion, our findings indicate that mammalian FTSJ2 is a mitochondrial ortholog of E. coli RrmJ and conserves the heat shock protein properties. Moreover, FTSJ2 possesses suppressive effects on the invasion and migration of cancer cells.

The E. coli heat shock protein which is called ribosomal RNA large subunit methyltransferase J (RrmJ) responsible for the 2’-O-ribose methylation of A-loop U2552 in the 23S rRNA. This gene is highly conserved from Prokaryota to Eukaryota. In human, three closed homologues of RrmJ have been identified and designated as FTSJ1, FTSJ2 and FTSJ3. In this study, we characterized mammalian FTSJ2 from the amino acid sequences alignment to the mitochondrial localization, and suggested the similar function to RrmJ. The RT-PCR results showed that there were much lower FTSJ2 mRNA expression in eight hepatoma cell lines (HepG2, Hep3B, HHCM, Huh7, 22T, 59T, SK-Hep1, PLC/PRF/5) and one medulloblastoma cell line (Te671), compared with the expression level in normal liver tissue. Subsequently, after the medulloblastoma cells were transfected with FTSJ2 overexpression vector, the FTSJ2-overexpressed Te671 cells (FTSJ2/Te671) showed the inhibition effects of cell migration and invasion in vitro. In addition, this also caused the rearrangement of F-action in FTSJ2/Te671 detected by immunofluorescence. However, recent study showed that FTSJ2 may involve in tumourigenesis, and FTSJ2 gene was activated in non-small cell lung cancer. Thus, we proposed that FTSJ2 may play different roles in different tissues during tumourigenesis through the catalysis of ribosomal RNA methylation in mitochondria. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3877. doi:10.1158/1538-7445.AM2011-3877