Sobczak Krzysztof, Krzyzosiak Wlodzimierz J
Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
J Biol Chem. 2004 Oct 1;279(40):41563-72. doi: 10.1074/jbc.M405130200. Epub 2004 Jul 29.
The expanded CAG repeat in the coding sequence of the spinocerebellar ataxia type 1 (SCA1) gene is responsible for SCA1, one of the hereditary human neurodegenerative diseases. In the normal SCA1 alleles usually 1-3 CAT triplets break the continuity of the CAG repeat tracts. Here we show what is the structural role of the CAU interruptions in the SCA1 transcripts. Depending on their number and localization within the repeat tract the interruptions either enlarge the terminal loop of the hairpin formed by the repeats, nucleate the internal loops in its stem structure, or force the repeats to fold into two smaller hairpins. Thus, the interruptions destabilize the CAG repeat hairpin, which is likely to decrease its ability to participate in the putative RNA pathogenesis mechanism driven by the long CAG repeat hairpins.
脊髓小脑共济失调1型(SCA1)基因编码序列中CAG重复序列的扩增是导致SCA1的原因,SCA1是一种人类遗传性神经退行性疾病。在正常的SCA1等位基因中,通常有1 - 3个CAT三联体打断CAG重复序列的连续性。在这里,我们展示了CAU中断在SCA1转录本中的结构作用。根据它们在重复序列中的数量和定位,这些中断要么扩大由重复序列形成的发夹的末端环,在其茎结构中形成内部环的核心,要么迫使重复序列折叠成两个较小的发夹。因此,这些中断使CAG重复发夹不稳定,这可能会降低其参与由长CAG重复发夹驱动的假定RNA致病机制的能力。