TY - JOUR
T1 - Translation of the FMR1 mRNA is not influenced by AGG interruptions
AU - Ludwig, Anna L.
AU - Raske, Christopher
AU - Tassone, Flora
AU - Garcia-Arocena, Dolores
AU - Hershey, John W.
AU - Hagerman, Paul J
PY - 2009/9/14
Y1 - 2009/9/14
N2 - The fragile X mental retardation 1 (FMR1) gene contains a CGG-repeat element within its 5′ untranslated region (5′UTR) which, for alleles with more than ∼40 repeats, increasingly affects both transcription (up-regulation) and translation (inhibition) of the repeat-containing RNA with increasing CGG-repeat length. Translational inhibition is thought to be due to impaired ribosomal scanning through the CGG-repeat region, which is postulated to form highly stable secondary/tertiary structure. One striking difference between alleles in the premutation range (55-200 CGG repeats) and those in the normal range (<∼40 repeats) is the reduced number/absence of 'expansion stabilizing' AGG interruptions in the larger alleles. Such interruptions, which generally occur every 9-11 repeats in normal alleles, are thought to disrupt the extended CGG-repeat hairpin structure, thus facilitating translational initiation. To test this hypothesis, we have measured the translational efficiency of CGG-repeat mRNAs with 0-2 AGG interruptions, both in vitro (rabbit reticulocyte lysates) and in cell culture (HEK-293 cells). We demonstrate that the AGG interruptions have no detectable influence on translational efficiency in either a cell-free system or cell culture, indicating that any AGG-repeat-induced alterations in secondary/tertiary structure, if present, do not involve the rate-limiting step(s) in translational initiation.
AB - The fragile X mental retardation 1 (FMR1) gene contains a CGG-repeat element within its 5′ untranslated region (5′UTR) which, for alleles with more than ∼40 repeats, increasingly affects both transcription (up-regulation) and translation (inhibition) of the repeat-containing RNA with increasing CGG-repeat length. Translational inhibition is thought to be due to impaired ribosomal scanning through the CGG-repeat region, which is postulated to form highly stable secondary/tertiary structure. One striking difference between alleles in the premutation range (55-200 CGG repeats) and those in the normal range (<∼40 repeats) is the reduced number/absence of 'expansion stabilizing' AGG interruptions in the larger alleles. Such interruptions, which generally occur every 9-11 repeats in normal alleles, are thought to disrupt the extended CGG-repeat hairpin structure, thus facilitating translational initiation. To test this hypothesis, we have measured the translational efficiency of CGG-repeat mRNAs with 0-2 AGG interruptions, both in vitro (rabbit reticulocyte lysates) and in cell culture (HEK-293 cells). We demonstrate that the AGG interruptions have no detectable influence on translational efficiency in either a cell-free system or cell culture, indicating that any AGG-repeat-induced alterations in secondary/tertiary structure, if present, do not involve the rate-limiting step(s) in translational initiation.
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U2 - 10.1093/nar/gkp713
DO - 10.1093/nar/gkp713
M3 - Article
C2 - 19752155
AN - SCOPUS:73349116887
VL - 37
SP - 6896
EP - 6904
JO - Nucleic Acids Research
JF - Nucleic Acids Research
SN - 0305-1048
IS - 20
M1 - gkp713
ER -