High level expression of expanded full-length ataxin-3 in vitro causes cell death and formation of intranuclear inclusions in neuronal cells.
Spinocerebellar ataxia type 3 (SCA3) is caused by a CAG/polyglutamine repeat expansion in the SCA3 gene. To analyse the pathogenic mechanisms in SCA3, we have generated ataxin-3-expressing rat mesencephalic CSM14.1 cells. In these cells, a post-mitotic neuronal phenotype is induced by temperature shift. The isolated stable cell lines provided high level expression of non-expanded (Q23) or expanded (Q70) human full-length ataxin-3. CSM14.1 cells expressing the expanded full-length ataxin-3 developed nuclear inclusion bodies, strong indentations of the nuclear envelope and cytoplasmic vacuolation. These ultrastructural alterations were present prior to a significantly decreased viability of neuronally differentiated cells expressing expanded ataxin-3. The observed spontaneous cell death did not correlate with formation of intranuclear inclusions and was not apoptotic by ultrastructural analysis. No increased susceptibility to staurosporine-induced apoptosis was found for the expanded or non-expanded ataxin-3-expressing cell lines. These data show that high level expression of expanded full-length ataxin-3 in a neuron-like cell line generates ultrastructural alterations of SCA3 pathogenesis and results in increased spontaneous non-apoptotic cell death.
Evert
B O
BO
Department of Neurology, University of Tübingen, 72076 Tübingen, Germany, b.evet@uni-bonn.de
Wüllner
U
U
Schulz
J B
JB
Weller
M
M
Groscurth
P
P
Trottier
Y
Y
Brice
A
A
Klockgether
T
T
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis; D000067699:Ataxin-3; D016923:Cell Death; D002460:Cell Line; D006801:Humans; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000096:biosynthesis*; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D009685:Nuclear Envelope / Q000502:physiology; D009687:Nuclear Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis; D012097:Repressor Proteins
D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C092341:ATXN3 protein, human; D000067699:Ataxin-3; C511593:Atxn3 protein, rat