Huntingtin bodies sequester vesicle-associated proteins by a polyproline-dependent interaction.
Polyglutamine expansion in the N terminus of huntingtin (htt) causes selective neuronal dysfunction and cell death by unknown mechanisms. Truncated htt expressed in vitro produced htt immunoreactive cytoplasmic bodies (htt bodies). The fibrillar core of the mutant htt body resisted protease treatment and contained cathepsin D, ubiquitin, and heat shock protein (HSP) 40. The shell of the htt body was composed of globules 14-34 nm in diameter and was protease sensitive. HSP70, proteasome, dynamin, and the htt binding partners htt interacting protein 1 (HIP1), SH3-containing Grb2-like protein (SH3GL3), and 14.7K-interacting protein were reduced in their normal location and redistributed to the shell. Removal of a series of prolines adjacent to the polyglutamine region in htt blocked formation of the shell of the htt body and redistribution of dynamin, HIP1, SH3GL3, and proteasome to it. Internalization of transferrin was impaired in cells that formed htt bodies. In cortical neurons of Huntington's disease patients with early stage pathology, dynamin immunoreactivity accumulated in cytoplasmic bodies. Results suggest that accumulation of a nonfibrillar form of mutant htt in the cytoplasm contributes to neuronal dysfunction by sequestering proteins involved in vesicle trafficking.
Qin
Zheng-Hong
ZH
Laboratory of Cellular Neurobiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA. zhqin5@hotmail.com
Wang
Yumei
Y
Sapp
Ellen
E
Cuiffo
Benjamin
B
Wanker
Erich
E
Hayden
Michael R
MR
Kegel
Kimberly B
KB
Aronin
Neil
N
DiFiglia
Marian
M
D000818:Animals; D002460:Cell Line; D002540:Cerebral Cortex / Q000166:cytology; D034281:Dynamins / Q000032:analysis / Q000276:immunology; D010450:Endopeptidases / Q000494:pharmacology; D000939:Epitopes / Q000032:analysis; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000473:pathology*; D007150:Immunohistochemistry; D051379:Mice; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000737:chemistry* / Q000276:immunology; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure*; D009687:Nuclear Proteins / Q000032:analysis* / Q000737:chemistry* / Q000276:immunology; D010455:Peptides / Q000502:physiology*; D010588:Phagosomes / Q000737:chemistry* / Q000648:ultrastructure; D017434:Protein Structure, Tertiary; D014168:Transferrin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000032:analysis
D000939:Epitopes; C086055:HTT protein, human; C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D014168:Transferrin; D033921:Vesicular Transport Proteins; C011083:polyproline; C097188:polyglutamine; D010450:Endopeptidases; D034281:Dynamins