Senataxin, the yeast Sen1p orthologue: characterization of a unique protein in which recessive mutations cause ataxia and dominant mutations cause motor neuron disease.
A severe recessive cerebellar ataxia, Ataxia-Oculomotor Apraxia 2 (AOA2) and a juvenile onset form of dominant amyotrophic lateral sclerosis (ALS4) result from mutations of the Senataxin (SETX) gene. To begin characterization this disease protein, we developed a specific antibody to the DNA/RNA helicase domain of SETX. In murine brain, SETX concentrates in several regions, including cerebellum, hippocampus and olfactory bulb with a general neuronal expression profile, colocalizing with NeuN. In cultured cells, we found that SETX was cytoplasmically diffuse, but in the nucleus, SETX was punctate, colocalizing with fibrillarin, a marker of the nucleolus. In differentiated non-cycling cells, nuclear SETX was not restricted to the nucleolus but was diffuse within the nucleoplasm, suggesting cell-cycle-dependent localization. SETX missense mutations cluster within the N-terminus and helicase domains. Flag tagging at the N-terminus caused protein mislocation to the nucleoplasm and failure to export to the cytoplasm, suggesting that the N-terminus may be essential for correct SETX localization. We report here the first characterization of SETX protein, which may provide future insights into a new mechanism leading to neuron death.
Chen
Ying-Zhang
YZ
Department of Pediatrics, Division of Genetics and Developmental Medicine, University of Washington School of Medicine, Seattle, WA 63110, USA.
Hashemi
Sayed H
SH
Anderson
Susan K
SK
Huang
Yongzhao
Y
Moreira
Maria-Ceu
MC
Lynch
David R
DR
Glass
Ian A
IA
Chance
Phillip F
PF
Bennett
Craig L
CL
D000328:Adult; D000818:Animals; D001259:Ataxia / Q000378:metabolism*; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D016472:Motor Neuron Disease / Q000378:metabolism*; D009154:Mutation; D020365:RNA Helicases / Q000502:physiology*
D020365:RNA Helicases