Fig. 4: UBAP1 depletion induces progressive neuronal apoptosis and aberrant mTORC1 activation in mouse brains.

a Representative coronal sections showing progressive accumulation of polyubiquitinated proteins in Ubap1 Nes-cKO brains compared to controls. Scale bar: 50 μm. Quantification of relative fluorescence intensity of ubiquitin in Ubap1 Nes-cKO cortex. E12.5 n = 4, E14.5 n = 4, E16.5 n = 4 brain sections form 3 independent mouse brains. b Immunofluorescence staining of Cleaved-caspase 3 (CC3, red) in the cortex of Ctrl and Ubap1 Nes-cKO mice at the indicated embryonic stage. Scale bar: 20 μm. Quantification of CC3⁺ cells in the cortex of Ubap1 Nes-cKO mouse brains. E14.5 n = 6, E16.5 n = 6 brain sections form more than 3 independent mouse brains. c 2D-SIM microscopy reveals increased lysosome size in Ubap1 Nex-cKO primary cortical neurons. Lysosomes were labeled with Lysotracker. Scale bar: 5 μm. Ctrl n = 454, Nex-cKO n = 444 lysosomes in 20 independent neurons. d Diagram illustrating the regions of analyzed by Transmission Electron Microscopy (TEM) in mouse brains. e Representative TEM images of autophagosomes (arrowheads) and autolysosomes (arrows) in the cortex of E16.5 Ubap1 Nes-cKO mouse brains. Scale bar: 500 nm. The number of autophagosome and autolysosome is quantified on the right. Ctrl n = 8, Nes-cKO n = 8 micrographs. f–i Immunoblot analysis of cortical lysates from E14.5 (f, g) or E16.5 (h, i) Ubap1 Nes-cKO and control mice, and probed with the indicated antibodies. Relative protein expression levels are quantified on the right. Ctrl and Nes-cKO n = 3 individual mouse brains. All data represent the mean ± SEM; One-way ANOVA followed by Tukey’s multiple comparisons test (a), Student’s t test (b, e–i), Mann–Whitney test (c); ns p > 0.05, *p < 0.05, **p < 0.01, ^#p < 0.0001. Exact p-values and test statistics are provided as a Source Data file.