%0 Journal Article
%T Inactivation of hnRNP K by Expanded Intronic AUUCU Repeat Induces Apoptosis Via Translocation of PKC¦Ä to Mitochondria in Spinocerebellar Ataxia 10
%A Misti C. White equal contributor
%A Rui Gao equal contributor
%A Weidong Xu
%A Santi M. Mandal
%A Jung G. Lim
%A Tapas K. Hazra
%A Maki Wakamiya
%A Sharon F. Edwards
%A Salmo Raskin
%A H¨¦lio A. G. Teive
%A Huda Y. Zoghbi
%A Partha S. Sarkar
%A Tetsuo Ashizawa
%J PLOS Genetics
%D 2010
%I Public Library of Science (PLoS)
%R 10.1371/journal.pgen.1000984
%X We have identified a large expansion of an ATTCT repeat within intron 9 of ATXN10 on chromosome 22q13.31 as the genetic mutation of spinocerebellar ataxia type 10 (SCA10). Our subsequent studies indicated that neither a gain nor a loss of function of ataxin 10 is likely the major pathogenic mechanism of SCA10. Here, using SCA10 cells, and transfected cells and transgenic mouse brain expressing expanded intronic AUUCU repeats as disease models, we show evidence for a key pathogenic molecular mechanism of SCA10. First, we studied the fate of the mutant repeat RNA by in situ hybridization. A Cy3-(AGAAU)10 riboprobe detected expanded AUUCU repeats aggregated in foci in SCA10 cells. Pull-down and co-immunoprecipitation data suggested that expanded AUUCU repeats within the spliced intronic sequence strongly bind to hnRNP K. Co-localization of hnRNP K and the AUUCU repeat aggregates in the transgenic mouse brain and transfected cells confirmed this interaction. To examine the impact of this interaction on hnRNP K function, we performed RT¨CPCR analysis of a splicing-regulatory target of hnRNP K, and found diminished hnRNP K activity in SCA10 cells. Cells expressing expanded AUUCU repeats underwent apoptosis, which accompanied massive translocation of PKC¦Ä to mitochondria and activation of caspase 3. Importantly, siRNA¨Cmediated hnRNP K deficiency also caused the same apoptotic event in otherwise normal cells, and over-expression of hnRNP K rescued cells expressing expanded AUUCU repeats from apoptosis, suggesting that the loss of function of hnRNP K plays a key role in cell death of SCA10. These results suggest that the expanded AUUCU¨Crepeat in the intronic RNA undergoes normal transcription and splicing, but causes apoptosis via an activation cascade involving a loss of hnRNP K activities, massive translocation of PKC¦Ä to mitochondria, and caspase 3 activation.
%U http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000984