Deficits of proteasomes in CD deficient mice. a. α-syn (Snca) mRNA is down-regulated in CD deficient brains compared to wildtype control brains. Ctsb, Ctsl, Ctsf, Ctsh, Atg7, UCHL1, Park2, and Psmb7 mRNA levels are up-regulated. Atg12 and Psmb6 mRNA levels appear to be normal. b. Western blot analyses show an increase of steady state GAPDH, a CMA substrate. n = 3 p25 brain. *p < 0.05 by Student t-test, compared between Ctsd+/+ and Ctsd-/- brains. c. Extracts from Ctsd-/- cortex exhibit reduced proteasome activities compared to Ctsd+/+ as indicated by assays with trypsin-like fluorigenic substrate (VGR-AMC, reaching maximum at 60 min), chymotrypsin-like fluorigenic substrate (Z-GGL-AMC, reaching maximum at 120 min), and peptidylglutamyl peptide-like fluorigenic substrate (Suc-LLVY-AMC, reaching maximum at 120 min). The activities that are inhibitable by the proteasome inhibitor lactacystin were quantified. n = 3 mice each genotype. *p < 0.05 by Student t-test. d. Normal expression of proteins involved in UPS. Western blot analyses of UCHL1, Usp14, Rpt3, α4 and β1 indicate that these UPS factors are expressed normally in Ctsd+/+ and Ctsd-/- cortical extracts. Actin immunoblotting was used as a loading control. n = 3 mice each genotype. e. A diagram regarding onset of relative pathologies.