Oligomerization of expanded-polyglutamine domain fluorescent fusion proteins in cultured mammalian cells.
Six inherited neurologic diseases, including Huntington's disease, result from the expansion of a CAG domain of the disease genes to produce a domain of more than 40 glutamines in the expressed protein. The mechanism by which expansion of this polyglutamine domain causes disease is unknown. Recent studies demonstrated oligomerization of polyglutamine-domain proteins in mammalian neurons. To study oligomerization of polyglutamine proteins and to identify heterologous protein interactions, varying length polyglutamine-green fluorescent protein fusion proteins were expressed in cultured COS-7 cells. The 19- and 35-glutamine fusion proteins (non-pathologic length) distributed diffusely throughout the cytoplasm. In contrast, 56- and 80-glutamine fusion proteins (pathologic length) formed fibrillar arrays resembling those previously observed in neurons in Huntington's disease and in a transgenic mouse model. These aggregates were intranuclear and intracytoplasmic. Intracytoplasmic aggregates were surrounded by collapsed intermediate filaments. The intermediate filament protein vimentin co-immunoisolated with expanded polyglutamine fusion proteins. This cellular model will expedite investigations into oligomerization of polyglutamine proteins and their interactions with other proteins.
Onodera
O
O
Department of Medicine (Neurology), Duke University Medical Center, Durham, North Carolina 27710, USA.
Burke
J R
JR
Miller
S E
SE
Hester
S
S
Tsuji
S
S
Roses
A D
AD
Strittmatter
W J
WJ
D000818:Animals; D019556:COS Cells; D019281:Dimerization; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000737:chemistry* / Q000648:ultrastructure; D051379:Mice; D010455:Peptides / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000648:ultrastructure
D008164:Luminescent Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C097188:polyglutamine