Proteases acting on mutant huntingtin generate cleaved products that differentially build up cytoplasmic and nuclear inclusions.
Proteolytic processing of mutant huntingtin (mhtt) is regarded as a key event in the pathogenesis of Huntington's disease (HD). Mhtt fragments containing a polyglutamine expansion form intracellular inclusions and are more cytotoxic than full-length mhtt. Here, we report that two distinct mhtt fragments, termed cp-A and cp-B, differentially build up nuclear and cytoplasmic inclusions in HD brain and in a cellular model for HD. Cp-A is released by cleavage of htt in a 10 amino acid domain and is the major fragment that aggregates in the nucleus. Furthermore, we provide evidence that cp-A and cp-B are most likely generated by aspartic endopeptidases acting in concert with the proteasome to ensure the normal turnover of htt. These proteolytic processes are thus potential targets for therapeutic intervention in HD.
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, B.P.163, 67404 Illkirch Cédex, CU de Strasbourg, France. astrid.lunkes@embo.org
Astrid
A
Lunkes
Katrin S
KS
Lindenberg
Léa
L
Ben-Haïem
Chantal
C
Weber
Didier
D
Devys
G Bernhard
GB
Landwehrmeyer
Jean-Louis
JL
Mandel
Yvon
Y
Trottier
D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D010450:Endopeptidases