Alleviating transcript insufficiency caused by Friedreich's ataxia triplet repeats.
Expanded GAA.TTC trinucleotide repeats in intron 1 of the frataxin gene cause Friedreich's ataxia (FRDA) by reducing frataxin mRNA levels. Insufficient frataxin, a nuclear encoded mitochondrial protein, leads to the progressive neurodegeneration and cardiomyopathy characteristic of FRDA. Previously we demonstrated that long GAA.TTC tracts impede transcription elongation in vitro and provided evidence that the impediment results from an intramolecular purine.purine.pyrimidine DNA triplex formed behind an advancing RNA polymerase. Our model predicts that inhibiting formation of this triplex during transcription will increase successful elongation through GAA.TTC tracts. Here we show that this is the case. Oligodeoxyribonucleotides designed to block particular types of triplex formation provide specific and concentration-dependent increases in full-length transcript. In principle, therapeutic agents that selectively interfere with triplex formation could alleviate the frataxin transcript insufficiency caused by pathogenic FRDA alleles.
Grabczyk
E
E
Section on Genomic Structure and Function, Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA. grabczyk@helix.nih.gov
Usdin
K
K
D000483:Alleles; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D005621:Friedreich Ataxia / Q000235:genetics*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D033862:Iron-Binding Proteins; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D010957:Plasmids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D013698:Templates, Genetic; D013816:Thermodynamics; D014158:Transcription, Genetic / Q000235:genetics*; D018911:Trinucleotide Repeats / Q000235:genetics*; D000096923:Frataxin
D004247:DNA; D004278:DNA, Superhelical; D012321:DNA-Directed RNA Polymerases; D033862:Iron-Binding Proteins; D009838:Oligodeoxyribonucleotides; D017853:Phosphotransferases (Alcohol Group Acceptor); D012333:RNA, Messenger; D000096923:Frataxin; C051802:triplex DNA