11S regulator has an influence on degradation of polyQ containing protein by proteasomeстатьяТезисы
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Дата последнего поиска статьи во внешних источниках: 15 января 2019 г.
Аннотация:DOI:10.1111/febs.12340
# SW04.S19–65
Proteasome functions in every eukaryotic cell, degrading most of
the irregular or nonviable cellular proteins. Turning off proteasome
leads to disastrous consequences, and finally to cell death.
The polyglutamine (polyQ) repeat diseases are inherited neurodegenerative
disorders attributed to elongation of polyQ fragments
(from 6–35 to 36–306 glutamine residues) in certain proteins.
These abnormal proteins form aggregates and become insoluble,
resulting in cytoplasmic or nuclear protein inclusions in some
brain regions. Analysis of inclusions reveals presence of mutant
proteins, and also of ubiquitin and components of 26S proteasome
(20S core, 19S and 11S regulatory particles). It is assumed
that proteasomal degradation system attempts to digest abnormal
misfolded proteins, but fails to cut within polyQ regions or does
it with low efficiency. Then proteasome may become clogged and
inactivated by these long aggregated polyQ sequences. The aim
of our study was to investigate the effect of the 11S regulator on
proteasomal degradation of polyQ-containing protein, namely
huntingtin (htt). 20S, 26S proteasome and 11S regulator were isolated
from mice brains. Homogenates were subjected to stepwise
salt fractionation with subsequent purification by different chromatographic
methods (gel filtration and anion exchange chromatography).
Isolated proteins were characterized by molecular
weight using gel-filtration and Western-blot. The dependency of
20S proteasome peptidase activity on concentration of 11S regulator
was examined. Kinetic constants of proteasome hydrolysis
of three peptide substrates (Suc-LLVY-AMC, Z-LLE-AMC and
Ac-RLR-AMC) were studied in presence of 11S regulator. HEK
cells were transfected by vector containing 15Q or 138Q htt gene
(generous gift of Prof. E.V. Kaznacheeva, St.-Petersburgh) and
cell lysates were subjected to hydrolysis by 20S proteasome with
or without 11S regulator. Reactions were followed by Westernblot
(anti-htt antibodies were kindly provided by Vladimir A. Vigont).
Our data suggest a possible acceleration of proteasomal
degradation of htt in the presence of the 11S regulator.