Figure 1. Expanded AUUCU transcripts form discrete aggregates.

(A) FISH on SCA10 fibroblasts encoding ∼2,000 ATTCT repeats showing multiple, bright RNA aggregates (arrow) in the nuclei, nuclear boundary and cytoplasm. (B) FISH on normal control fibroblasts hybridized with a Cy3-labeled (AGAAU)₁₀ probe. (C) Schematic drawing of the transgenic constructs including a human α-enolase promoter, 2^nd intron of rabbit β-globin gene, LacZ gene, expanded ∼500 ATTCT repeats cloned within the intron (or normal range of 12 repeats for control), and Bovine Growth Hormone (BGH) polyA sequences. (D) FISH on Sy5y cells ectopically expressing intronic ∼500 AUUCU repeats from the transgenic constructs shown in Figure 1C. Figure showing the nuclear, perinuclear as well as cytoplasmic foci (arrow). (E) Ladder-PCR analysis of mouse genomic DNA showing the presence of expanded ATTCT repeats, lane 1: Positive control from SCA10 patients; Lane 2: Transgenic mouse containing 12 ATTCT repeats, lane 3 & 4: Transgenic mouse encoding ∼500 ATTCT repeats. (F) Southern blot of the XbaI-HindII digested genomic DNA from the transgenic F1 encoding ∼500 ATTCT repeats (lane 2, 3). Lane 1: Wild-type control mouse DNA. Lane 2 and 3: Transgenic mice expressing ∼500 ATTCT repeats. Southern blot shows the presence of ∼500 ATTCT repeats. A DNA fragment (∼500 bp) of the 5′ of the intron 9 of ATXN10 gene was used as the Southern probe. (G) FISH on sagittal sections of the wild type (left panel) and transgenic mouse brain encoding ∼500 AUUCU repeats (right panel). Bars represent 10 mm in this and all other figures.