Casein kinase 2 interacts with and phosphorylates ataxin-3.
OBJECTIVE
Machado-Joseph disease (MJD)/Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by an expansion of polyglutamine tract near the C-terminus of the MJD1 gene product, ataxin-3. The precise mechanism of the MJD/SCA3 pathogenesis remains unclear. A growing body of evidence demonstrates that phosphorylation plays an important role in the pathogenesis of many neurodegenerative diseases. However, few kinases are known to phosphorylate ataxin-3. The present study is to explore whether ataxin-3 is a substrate of casein kinase 2 (CK2).


METHODS
The interaction between ataxin-3 and CK2 was identified by glutathione S-transferase (GST) pull-down assay and co-immunoprecipition assay. The phosphorylation of ataxin-3 by CK2 was measured by in vitro phosphorylation assays. Results (1) Both wild type and expanded ataxin-3 interacted with CK2alpha and CK2beta in vitro. (2) In 293 cells, both wild type and expanded ataxin-3 interacted with CK2beta, but not CK2alpha. (3) CK2 phosphorylated wild type and expanded ataxin-3.


CONCLUSIONS
Ataxin-3 is a substrate of protein kinase CK2.
Laboratory of Molecular Neuropathology, Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei 230027, China.
Rui-Song
RS
Tao
Er-Kang
EK
Fei
Zheng
Z
Ying
Hong-Feng
HF
Wang
Guang-Hui
GH
Wang
D000067699:Ataxin-3; D047390:Casein Kinase II / Q000378:metabolism*; D002461:Cell Line, Transformed; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D012097:Repressor Proteins / Q000378:metabolism*; D014162:Transfection / Q000379:methods
D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D005982:Glutathione Transferase; D047390:Casein Kinase II; C092341:ATXN3 protein, human; D000067699:Ataxin-3