TBR2-immunopsitive unipolar brush cells are associated with ectopic zebrin II-immunoreactive Purkinje cell clusters in the cerebellum of scrambler mice / 대한해부학회지

Unipolar brush cells (UBCs) are excitatory interneurons with their somata located in the granular layer. Recently, T-brain factor 2 (Tbr2) was shown to be expressed in a subset of UBCs in mouse cerebellum. Scrambler mice exhibit severe cerebellum abnormalities, including the failure of embryonic Purkinje cell dispersal and a complete absence of foliation due to a mutation in the disabled-1 adaptor protein. Since most UBC markers are expressed postnatally, it has proven difficult to identify the relationship between developing Purkinje cell clusters and migrating UBCs. Because scrambler mice closely mimic normal embryonic day 18 cerebellum, we examined whether Tbr2-positive UBCs are associated with Purkinje cell cluster markers such as zebrin II, which is the most studied compartmentation marker in the cerebellum. We investigated the distribution of Tbr2-positive UBCs in this mutant by using anti-Tbr2 immunocytochemistry. The data revealed that Tbr2 immunoreactivity was exclusively present in the nucleus of UBCs in scrambler cerebellum. Based on expression data, a Tbr2-positive UBC map was constructed. In addition, Tbr2-positive UBCs are found associated with ectopic zebrin II-immunoreactive Purkinje cell clusters in scrambler cerebellum. These data suggest that UBCs use Purkinje cell compartmentation to migrate into their final position through interactions with the embryonic array of specific Purkinje cell subtypes.

Differences of Zebrin II Expression Pattern Between Normal Balb/C and Ataxic Pogo Mouse Cerebellum / 대한해부학회지

The purpose of this study is to identify the differences of zebrin II expression between ataxic pogo and normal Balb/C mouse cerebellum. Zebrin II is expressed by subsets of Purkinje cells that form an array of parasagittal bands that extend rostrocaudally throughout the cerebellar cortex, separated by similar bands of Purkinje cells that do not express zebrin II. Zebrin II immunoreactivity was localized in the perikarya of Purkinje cells, and the dendrites. Distribution of zebrin II-immunoreactive Purkinje cells were very similar pattern in pogo and Balb/C mouse cerebellum. But, in the lobule III, distribution of zebrin II expression was different between pogo and Balb/C mouse cerebellum. In lobule III of Balb/c mouse cerebellum, 10~15 zebrin II-immunoreactive Purkinje cells were observed and clustered to form a parasagittal bands. On the other hand, zebrin II expressions of lobule III in pogo mouse cerebellum showed a little different patterns. In lobule III of pogo mouse cerebellum, three bilateral zebrin II immunoreactive parasagittal band were observed. P1 band was almost same with lobule III of Balb/C mouse cerebellum. But, P2 bands were composed of 50~60 Purkinje cells which were immunoreactive with zebrin II. These kind of thickening in zebrin II expression of pogo mouse cerebellum may be due to the genetical difference. Furthermore, these results may provide useful information with further ataxic pogo mice cerebellum studies.