Figure 6.

UBQLN2 Mutation Impairs Aggregate Clearance In Vivo

(A and B) UBQLN2 interacts with aggregated, but not SDS-soluble, HTT in vivo, as judged by reciprocal IP of HTT and UBQLN2 from the R6/2 transgenic (A) and HdhQ150 knockin (B) Huntington’s disease models.

(C) UBQLN2, but not UBQLN1, translocates to the nucleus in the R6/2 and HdhQ150 models.

(D) UBQLN2 is present in ubiquitylated Huntingtin aggregates from brains of the R6/2 and HdhQ150 mouse models. Aggregated HTT and UBQLN2 were captured with a ubiquitin binding resin (GST-TUBE).

(E) The R6/2 and UBQLN2 mP520T mice were crossed to produce double-mutant animals, and 9-week-old male brains from these were assayed for aggregated HTT by western blot. Quantification of soluble HTT is shown (bottom) (n = 4 per genotype).

(F) Immunofluorescence (IF) of nuclear HTT aggregates in R6/2 and R6/2;mP520T brains shows more inclusion bodies in the double mutant. Quantification is shown (right). Error bars represent SEM. Statistical test was a two-tailed t test.

(G) The Seprion ligand assay independently confirms a significant increase in aggregated HTT in double mutants, compared to R6/2 littermates (n = 8 per genotype).

Error bars represent SEM. See also Figure S7.