NR promotes BACE1 ubiquitination and degradation is linked with PGC-1α. (A) BACE1 stable HEK293 cells were infected with adeno-PGC-1α or adeno-PGC-1α-shRNA and scramble shRNA (B). The adeno-GFP viral constructs were used as control. Cells were treated with NR 200 µg and 5 µM lactacystin. After 48 hours of transfection, cell lysate was collected and BACE1 immunoprecipitated using anti-BACE1 antibody, and probed with anti-ubiquitin antibodies (Sigma). (C) Quantification of the square area in the left panel by ImageJ and represented in the graph. This area represents BACE1 proteins at different ubiquitinated levels. Data are mean ± SEM (error bar) of the results from 2 independent experiments. Student t test was performed; * p < 0.05 compared with GFP-lactacystin treated cells. Abbreviations: BACE1, β-secretase; CTL, control; GFP, green fluorescent protein; NR, nicotinamide riboside; PGC-1α, peroxisome proliferator-activated receptor-γ coactivator 1α; SEM, standard error of the mean; WB, Western blot analysis.