Preferential recruitment of ataxin-3 independent of expanded polyglutamine: an immunohistochemical study on Marinesco bodies

In an immunohistochemical study of Marinesco bodies-a neuronal intranuclear inclusion often seen in neurons of the substantia nigra of patients with h epatic encephalopathy-it was shown that one of the polyglutamine proteins, ataxin-3, is preferentially recruited into this inclusion, whereas other po lyglutamine proteins (ataxin-2 and TATA box-binding protein) are not. This suggests that recruitment of each of the polyglutamine proteins may be diff erently regulated. Because this nuclear inclusion is thought to be formed i n response to cellular stress, as occurs in hepatic encephalopathy, even in the absence of an expanded CAG/ polyglutamine repeat, recruitment of ataxi n-3 and ubiquitin into Marinesco bodies may represent a cellular response t o noxious external stimuli unrelated to expanded CAG/polyglutamine.