<p><b>OBJECTIVE</b>To explore the subcellular
localization of
ataxin-3 and the effect of polyglutamine (polyQ) expansion
mutation on the morphology of
mitochondrion,
golgi apparatus and
endoplasmic reticulum.</p><p><b>
METHODS</b>
Transient transfection was employed to build
cell models expressing wild-type or mutant
ataxin-3 proteins.
Indirect immunofluorescence was applied to identify markers of
organelle membrane. The results were observed under a
laser scanning confocal microscope.</p><p><b>RESULTS</b>No co-
localization was observed for
ataxin-3 protein and mitochondrial marker TOM20, but the percentage of
cells with mitochondrial fragmentation has increased in
cells expressing mutant
ataxin-3 (P<0.05). No co-
localization was observed for
ataxin-3 protein and golgi marker GM130, and mutant
ataxin-3 did not cause golgi fragmentation. Wide type and polyQ-expanded
ataxin-3 both showed partial co-
localization with ER marker
calnexin. The latter showed more overlap with
calnexin, and the overlapping signals were mostly located in the places where aggregates were situated.</p><p><b>CONCLUSION</b>PolyQ-expanded
ataxin-3 protein may indirectly
affect the integrity of
mitochondria, but may cause no effect on the structure and functions of
golgi apparatus.
Endoplasmic reticulum may be another place where extended
ataxin-3 protein can induce cytotoxicity in addition to the nucleus.</p>