Disease relevance of Dhx9

• Using phage display library screening, we identified an EWS-FLI1 binding peptide containing homology to RHA [1].
• DDX3, a DEAD box RNA helicase, is deregulated in hepatitis virus-associated hepatocellular carcinoma and is involved in cell growth control [2].
• Hepatitis C virus core protein interacts with cellular putative RNA helicase [3].
• X-linked immunodeficient mice spontaneously produce lupus-related anti-RNA helicase A autoantibodies, but are resistant to pristane-induced lupus [4].

High impact information on Dhx9

• We suggest that p68 could be a DNA or RNA helicase in the cell nucleus which is involved in replication, transcription or RNA processing and is required for cell growth [5].
• In this study, a virulence-associated DEAD-box RNA helicase-encoding gene (VAD1) was isolated from a mutant defective in the virulence factor laccase [6].
• Translation of m7G-capped cellular mRNAs is initiated by recruitment of ribosomes to the 5' end of mRNAs via eukaryotic translation initiation factor 4F (eIF4F), a heterotrimeric complex comprised of a cap-binding subunit (eIF4E) and an RNA helicase (eIF4A) bridged by a scaffolding molecule (eIF4G) [7].
• Immunofluorescent confocal microscopy showed that Pdcd4 colocalizes with eIF4A in the cytoplasm. eIF4A is an ATP-dependent RNA helicase needed to unwind 5' mRNA secondary structure [8].
• The carboxyl terminus of RNA helicase A contains a bidirectional nuclear transport domain [9].

Biological context of Dhx9

• Nuclear DNA helicase II (NDH II), alternatively named RNA helicase A (RHA), is an F-actin binding protein that is particularly enriched in the nucleolus of mouse cells [10].
• Furthermore, mouse NDH II redistributed in mitosis in a manner highly correlated with Pol I activity [11].
• Conditions leading to the inhibition of Pol I activity in the interphase decreased the amount of NDH II in the nucleoli that diffused into the nucleoplasm and the cytosol [11].
• Using Southern blot analysis employing a mouse backcross panel, we have assigned the mouse RNA helicase A gene to chromosome 1, mapping near the D1Bir20 locus at MGD position 67 [12].
• In this report, we describe the isolation of a mouse cDNA encoding RNA helicase A. The deduced amino acid sequence derived from mouse RNA helicase A cDNA exhibits 87 and 47% identity to its human and Drosophila homologs, respectively [12].

Anatomical context of Dhx9

• Taken together, these results support the idea that an actin-based filamentous network may anchor NDH II at the nucleolar periphery for pre-ribosomal RNA processing, ribosome assembly, and/or transport [10].
• Here, we show that the nucleolar localization of NDH II of murine 3T3 cells depended on an ongoing rRNA synthesis [10].
• ESFT cell lines and patient tumors highly expressed RHA [1].
• GRTH is transcriptionally up-regulated by gonadotropin, displays ATPase and RNA helicase activities, and participates in germ cell development [13].
• Modulation of T cell development and activation by novel members of the Schlafen (slfn) gene family harbouring an RNA helicase-like motif [14].

Associations of Dhx9 with chemical compounds

• Contrary to the effect of inhibiting rRNA synthesis, treatment of mouse cells with the translation inhibitor cycloheximide did not compromise the nucleolar localization of murine NDH II [11].
• This gene encodes a putative RNA helicase, and its expression is down-regulated when F9 cells are differentiated with retinoic acid and cyclic AMP [15].
• Pups of strains with high avoidance capacity and small IIP-MF projections (RHA rats, DBA/2 and BALB/c mice) were injected with varying doses of thyroxine during the postnatal period [16].
• One of these proteins, nonstructural protein 3 (NS3), has serine protease and NTPase/RNA helicase activity [17].
• In this study, we show that a murine cell line resistant to the novel immunoregulatory drug Leflunomide (Arava) overexpresses a 135-kDa protein that is a putative DEAH-box RNA helicase [18].

Regulatory relationships of Dhx9

• Murine p53 inhibits the function but not the formation of SV40 T antigen hexamers and stimulates T antigen RNA helicase activity [19].

Other interactions of Dhx9

• Depolymerization with gelsolin led to a striking accumulation of NDH II in the nucleoli of MCF-7 cells [10].
• This supports the liklihood that the DNA and RNA helicase activities of T antigen reflect discrete functions. p53 did not significantly affect the ATP-dependent conversion of T antigen monomers to hexamers [19].
• Csm, a cardiac-specific isoform of the RNA helicase Mov10l1, is regulated by Nkx2.5 in embryonic heart [20].
• Germ cell-specific ATP-dependent RNA helicase, the product of the mouse vasa homolog (Mvh), has been shown to play an essential role in the development of the male germ cell [21].
• This TLR-independent induction of IFN-alphabeta after SV infection is replication dependent and mediated by the RNA helicase, retinoic acid-inducible gene-I (RIG-I) and not the related family member, melanoma differentiation-associated gene 5 [22].

Analytical, diagnostic and therapeutic context of Dhx9

• Northern blot and primer extension analyses indicate that, although its level is variable, RNA helicase A appears to be expressed from a single transcription start site in all tissues tested [12].

References