Localization of ataxin-2 within the cerebellar cortex of the rat.
Spinocerebellar ataxia type 2 is caused by a polyglutamine stretch in the protein ataxin-2 that is due to an expansion of a CAG repeat in the spinocerebellar ataxia-2 gene. The function of wild-type ataxin-2 has not been clarified. A widespread distribution of this protein throughout the brain has been reported. We examined the expression of ataxin-2 in cortical cerebellar cells of the adult rat. We performed a single label immunohistochemical study of ataxin-2 and a single label immunofluorescence study of ataxin-2 and zebrin on adjacent sections, to compare the distribution of the observed parasagittal band pattern. We also performed a double label immunofluorescence study of ataxin-2 and one of each parvalbumin, calbindin, and calretinin. Single label studies revealed that between 50% and 70% of the Purkinje cells express ataxin-2. The abundance of ataxin-2 was different between hemisphere and vermis, with a clear prevalence for the former. Furthermore, the distribution of ataxin-2-positive Purkinje cells showed a peculiar alternating parasagittal band pattern. Among the other cortical cerebellar cells only basket and granule cells showed ataxin-2 staining. Our dual label studies showed that about 50% of calbindin and more than 70% of parvalbumin-immunoreactive Purkinje cells were also labeled for ataxin-2. The uneven distribution of ataxin-2 expression in the Purkinje cell layer does not support the hypothesized link between ataxin-2 content and cell vulnerability. The differences in ataxin-2 expression among the cell types of cerebellar cortex, on the other hand, suggest a possible correlation between ataxin-2 content and cell function.
Fusco
F R
FR
Laboratory of Experimental Neurorehabilitation, Santa Lucia Foundation I.R.C.C.S., Rome, Italy. f.fusco@hsantalucia.it
Viscomi
M T
MT
Bernardi
G
G
Molinari
M
M
D000818:Animals; D000067528:Ataxins; D002525:Cerebellar Cortex / Q000737:chemistry* / Q000166:cytology; D007150:Immunohistochemistry; D008297:Male; D009419:Nerve Tissue Proteins / Q000032:analysis; D010455:Peptides / Q000235:genetics; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D011689:Purkinje Cells / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D020754:Spinocerebellar Ataxias / Q000235:genetics; D018911:Trinucleotide Repeats
D000067528:Ataxins; D009419:Nerve Tissue Proteins; D010455:Peptides; D011506:Proteins; C092565:zebrin I; C097188:polyglutamine