Severe neurological phenotypes of Q129 DRPLA transgenic mice serendipitously created by en masse expansion of CAG repeats in Q76 DRPLA mice.
We herein provide a thorough description of new transgenic mouse models for dentatorubral-pallidoluysian atrophy (DRPLA) harboring a single copy of the full-length human mutant DRPLA gene with 76 and 129 CAG repeats. The Q129 mouse line was unexpectedly obtained by en masse expansion based on the somatic instability of 76 CAG repeats in vivo. The mRNA expression levels of both Q76 and Q129 transgenes were each 80% of that of the endogenous mouse gene, whereas only the Q129 mice exhibited devastating progressive neurological phenotypes similar to those of juvenile-onset DRPLA patients. Electrophysiological studies of the Q129 mice demonstrated age-dependent and region-specific presynaptic dysfunction in the globus pallidus and cerebellum. Progressive shrinkage of distal dendrites of Purkinje cells and decreased currents through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and gamma-aminobutyrate type A receptors in CA1 neurons were also observed. Neuropathological studies of the Q129 mice revealed progressive brain atrophy, but no obvious neuronal loss, associated with massive neuronal intranuclear accumulation (NIA) of mutant proteins with expanded polyglutamine stretches starting on postnatal day 4, whereas NIA in the Q76 mice appeared later with regional specificity to the vulnerable regions of DRPLA. Expression profile analyses demonstrated age-dependent down-regulation of genes, including those relevant to synaptic functions and CREB-dependent genes. These results suggest that neuronal dysfunction without neuronal death is the essential pathophysiologic process and that the age-dependent NIA is associated with nuclear dysfunction including transcriptional dysregulations. Thus, our Q129 mice should be highly valuable for investigating the mechanisms of disease pathogenesis and therapeutic interventions.
Sato
Toshiya
T
Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, Japan.
Miura
Masami
M
Yamada
Mitsunori
M
Yoshida
Takayuki
T
Wood
Jonathan D
JD
Yazawa
Ikuru
I
Masuda
Masao
M
Suzuki
Takeo
T
Shin
Ryong-Moon
RM
Yau
Hau-Jie
HJ
Liu
Fu-Chin
FC
Shimohata
Takayoshi
T
Onodera
Osamu
O
Ross
Christopher A
CA
Katsuki
Motoya
M
Takahashi
Hitoshi
H
Kano
Masanobu
M
Aosaki
Toshihiko
T
Tsuji
Shoji
S
D000367:Age Factors; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020191:Myoclonic Epilepsies, Progressive / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D009435:Synaptic Transmission; D019680:Trinucleotide Repeat Expansion
D009419:Nerve Tissue Proteins; C095278:atrophin-1