a Treatment of SH-SY5Y cells with the proteasome inhibitor MG132 did not affect Tau degradation mediated by UBE4B/STUB1. b Treatment with chloroquine (CQ), an autophagy inhibitor, affected Tau degradation by UBE4B/STUB1. c Pepstatin A (PEPA) and E64D, autophagy inhibitors, inhibited Tau degradation by UBE4B/STUB1. All western blots were performed three times. d Schematic illustration of autophagy inhibitor injection to the dentate gyrus of Tau-BiFC mice. e Schematic illustration of the work flow for autophagy inhibitor injection and pathological examination in Tau-BiFC mice. f CQ and E64D plus PEPA (E64D + PEPA) increased pTau (S202/T205) levels in the dentate gyrus relative to saline-injected controls. GCL granular cell layer, POL polymorphic layer. g, h Densitometry analysis revealed that chloroquine and ED64 + PEPA significantly increased both pTau (S202/T205) and Tau-BiFC levels in the dentate gyrus relative to saline-injected controls (AAV-UBE4B + AAV-STUB1 (saline control), N = 4; CQ + AAV-UBE4B + AAV-STUB1, N = 4; E64D/PEPEA + AAV-UBE4B + AAV-STUB1, N = 4; N = 4 biologically independent animals). In the box plots the whiskers represent the 5th to 95th percentile range. i
AAV-UBE4B and AAV-STUB1 decreased LC3 levels in the dentate gyrus relative to control. Scale bars (white): 40 μm. j
AAV-UBE4B and AAV-STUB1 decreased p62 levels in the dentate gyrus relative to control. Scale bars (white): 40 μm. k Densitometry analysis revealed that autophagy inhibitors significantly increased LC3 levels in the dentate gyrus relative to control (AAV-Control, N = 4; AAV-UBE4B + AAV-STUB1, N = 4; CQ + AAV-UBE4B + AAV-STUB1, N = 4; E64D/PEPA + AAV-UBE4B + AAV-STUB1, N = 4; N = 4 biologically independent animals). In the box plots the whiskers represent the 5th to 95th percentile range. l Densitometry analysis revealed that autophagy inhibitors significantly increased p62 levels in the dentate gyrus relative to control (AAV-Control, N = 4; AAV-UBE4B + AAV-STUB1, N = 4; CQ + AAV-UBE4B + AAV-STUB1, N = 4; E64D/PEPA + AAV-UBE4B + AAV-STUB1, N = 4; N = 4 biologically independent animals). In the box plots the whiskers represent the 5th to 95th percentile range. Data are presented as means ± s.e.m. Statistical significance was determined with a two-tailed Student’s t-test. Statistical source data. Each exact p value was listed in Statistical source data.