ABSTRACT
Retinoic acid inducible gene I (RIG-I) senses viral RNAs and triggers innate antiviral responses through induction of type I IFNs and inflammatory cytokines. However, whether RIG-I interacts with host cellular RNA remains undetermined. Here we report that Rig-I interacts with multiple cellular mRNAs, especially Nf-κb1. Rig-I is required for NF-κB activity via regulating Nf-κb1 expression at posttranscriptional levels. It interacts with the multiple binding sites within 3'-UTR of Nf-κb1 mRNA. Further analyses reveal that three distinct tandem motifs enriched in the 3'-UTR fragments can be recognized by Rig-I. The 3'-UTR binding with Rig-I plays a critical role in normal translation of Nf-κb1 by recruiting the ribosomal proteins [ribosomal protein L13 (Rpl13) and Rpl8] and rRNAs (18S and 28S). Down-regulation of Rig-I or Rpl13 significantly reduces Nf-κb1 and 3'-UTR-mediated luciferase expression levels. These findings indicate that Rig-I functions as a positive regulator for NF-κB signaling and is involved in multiple biological processes in addition to host antivirus immunity.
Subject(s)
DEAD-box RNA Helicases/metabolism , Gene Expression Regulation/physiology , NF-kappa B/metabolism , RNA, Messenger/metabolism , 3' Untranslated Regions/genetics , Animals , Blotting, Northern , Blotting, Western , DEAD Box Protein 58 , DEAD-box RNA Helicases/genetics , Fluorescent Antibody Technique , Immunoprecipitation , Luciferases , Mice , Mice, Knockout , Microarray Analysis , Molecular Dynamics Simulation , NF-kappa B/genetics , RNA Interference , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction , Ribosomal Proteins/metabolismABSTRACT
Charcot-Marie-Tooth (CMT) disease represents a clinically and genetically heterogeneous group of inherited neuropathies. Here, we report a five-generation family of eight affected individuals with CMT disease type 2, CMT2. Genome-wide linkage analysis showed that the disease phenotype is closely linked to chromosomal region 10p13-14, which spans 5.41 Mb between D10S585 and D10S1477. DNA-sequencing analysis revealed a nonsense mutation, c.1455T>G (p.Tyr485(∗)), in exon 8 of dehydrogenase E1 and transketolase domain-containing 1 (DHTKD1) in all eight affected individuals, but not in other unaffected individuals in this family or in 250 unrelated normal persons. DHTKD1 mRNA expression levels in peripheral blood of affected persons were observed to be half of those in unaffected individuals. In vitro studies have shown that, compared to wild-type mRNA and DHTKD1, mutant mRNA and truncated DHTKD1 are significantly decreased by rapid mRNA decay in transfected cells. Inhibition of nonsense-mediated mRNA decay by UPF1 silencing effectively rescued the decreased levels of mutant mRNA and protein. More importantly, DHTKD1 silencing was found to lead to impaired energy production, evidenced by decreased ATP, total NAD(+) and NADH, and NADH levels. In conclusion, our data demonstrate that the heterozygous nonsense mutation in DHTKD1 is one of CMT2-causative genetic alterations, implicating an important role for DHTKD1 in mitochondrial energy production and neurological development.
