Figure 3

Cerebellar pathology in R1098Q heterozygous mice. (a) Hematoxylin and eosin (H&E) stained sections of cerebellum of 26 week old WT and heterozygous R1098Q mice. Most noticeable is the ≈ 50% loss in molecular layer width (double headed arrows) and extensive loss of cells in the Purkinje layer.. These changes are quantified in Supplemental Fig. S7. There may also be some loss of PC’s in the granular layer as well, but the disruption of layer organization in the hets made defining the boundaries of the granular layer problematic and rendered quantitation unreliable. (b) Immunostain for αII spectrin reveals its preservation in all cerebellar layers, and highlights the loss of PCs and the severe disruption and fragmentation of PC dendrites in the R1098Q mice. (c) Immunostain for βIII spectrin. This spectrin is primarily (although not exclusively) expressed in PCs in the cerebellum. Its pattern is the same in PC’s as that of αII spectrin, highlighting the major distortions and fragmentation of PC dendritic architecture. (d) Western blot of adult cerebellum for αII and βIII spectrin quantifying the global and selective PC loss in heterozygotes, expressed as a ratio relative to the WT levels. Results from two WT and three R1098Q heterozygotes are shown. While there is no significant reduction in αII spectrin levels (which is expressed in all cells), the βIII spectrin level is reduced to 64 ± 7% of the WT level (p = 0.033), reflecting the selective loss and vulnerability of PC’s to the R1098Q mutation. (Full length blots of the gels used for quantitation are presented in supplemental Fig. S6). Data analyzed by single tail, 2-sample homosedastic T-test. N = 2 for WT; 3 for het.