Figure 4. Ventral-specific removal of Tsc2 leads to more rapid doubling time, elevated mTORC1 activity, and abnormal growth in the V-SVZ.

(A) Graph illustrating population doublings per day in wild-type dorsal and ventral cultures. Ventral cells exhibit slightly increased doubling times as compared with dorsal, consistent with previous findings (Delgado et al, 2016). N = 3 mice counted three times. Paired t test, P = 0.0018. (B) Graph illustrating doublings per day in Tsc2 ^fl/fl dorsal and ventral cultures treated with Ad:CMV-Cre. When tuberin is lost, ventral cells double twice as fast as their dorsal counterparts do. N = 4 mice, counted four times. Paired t test, P = 0.0001. (C) Graph showing the median fluorescence intensity of p-4EBP1 T37/46 in wild-type and Tsc2^fl/fl dorsal and ventral cultures (treated with Ad:CMV-Cre). High signaling is observed as compared with dorsal in wild-type ventral cultures. Upon Tsc2 removal, both dorsal and ventral cultures exhibit higher p-4EBP1 T37/46 than wild-type but dorsal–ventral differences are maintained. Repeated measures ANOVA with Holm–Sidak’s multiple comparisons test, P = 0.0005. N = 3 mice per condition. (D–G) 10-μm P7 brain sections stained for DRAQ5 (nuclei, blue), GFAP (green), and p-S6 S240/244 (red). (D) Representative confocal images of V-SVZ subregions are shown for Tsc2 ^fl/fl control mouse. (E) Emx1-Cre; Tsc2 ^fl/fl animals do not exhibit tumor growth. (F, G) Representative confocal images for Nkx2.1-Cre; Tsc2 ^fl/fl reveal GFAP+ cellular protrusions in the ventral V-SVZ (F). (G) A larger tumor-like structure is apparent in the third ventricle (G). (H) Phenotypic summary of all mouse models. All images: scale bar = 200 μm and insets = 20 μm. For all graphs, bars represent mean ± SD.