Localization of ataxin-2 within the cerebellar cortex of the rat

• Published in: Brain research bulletin 2001-10, Vol.56 (3-4), p.343-347
• Main Authors: FUSCO, Francesca Romana, VISCOMI, Maria Teresa, BERNARDI, Giorgio, MOLINARI, Marco
• Format: Article
• Language: English
• Subjects: Animals; Ataxins; Biological and medical sciences; Cerebellar Cortex - chemistry; Cerebellar Cortex - cytology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Immunohistochemistry; Male; Medical sciences; Nerve Tissue Proteins - analysis; Neurology; Peptides - genetics; Proteins - analysis; Proteins - genetics; Purkinje Cells - chemistry; Rats; Rats, Wistar; Spinocerebellar Ataxias - genetics; Trinucleotide Repeats
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/S0361-9230(01)00601-3

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.