Inhibition of polyglutamine protein aggregation and cell death by novel peptides identified by phage display screening.
Proteins with expanded polyglutamine domains cause eight inherited neurodegenerative diseases, including Huntington's, but the molecular mechanism(s) responsible for neuronal degeneration are not yet established. Expanded polyglutamine domain proteins possess properties that distinguish them from the same proteins with shorter glutamine repeats. Unlike proteins with short polyglutamine domains, proteins with expanded polyglutamine domains display unique protein interactions, form intracellular aggregates, and adopt a novel conformation that can be recognized by monoclonal antibodies. Any of these polyglutamine length-dependent properties could be responsible for the pathogenic effects of expanded polyglutamine proteins. To identify peptides that interfere with pathogenic polyglutamine interactions, we screened a combinatorial peptide library expressed on M13 phage pIII protein to identify peptides that preferentially bind pathologic-length polyglutamine domains. We identified six tryptophan-rich peptides that preferentially bind pathologic-length polyglutamine domain proteins. Polyglutamine-binding peptide 1 (QBP1) potently inhibits polyglutamine protein aggregation in an in vitro assay, while a scrambled sequence has no effect on aggregation. QBP1 and a tandem repeat of QBP1 also inhibit aggregation of polyglutamine-yellow fluorescent fusion protein in transfected COS-7 cells. Expression of QBP1 potently inhibits polyglutamine-induced cell death. Selective inhibition of pathologic interactions of expanded polyglutamine domains with themselves or other proteins may be a useful strategy for preventing disease onset or for slowing progression of the polyglutamine repeat diseases.
Nagai
Y
Y
Deane Laboratory, Duke University Medical Center, Durham, North Carolina 27710, USA.
Tucker
T
T
Ren
H
H
Kenan
D J
DJ
Henderson
B S
BS
Keene
J D
JD
Strittmatter
W J
WJ
Burke
J R
JR
D000595:Amino Acid Sequence; D000818:Animals; D017104:Bacteriophage M13; D019556:COS Cells; D016923:Cell Death / Q000187:drug effects*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D011506:Proteins / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D008164:Luminescent Proteins; D009842:Oligopeptides; D019151:Peptide Library; D010455:Peptides; D011506:Proteins; D011993:Recombinant Fusion Proteins; C407346:polyglutamine-binding protein 1; D049452:Green Fluorescent Proteins; C097188:polyglutamine; D013879:Thioredoxins