Fig. 5

γ-secretase activity regulates Syt7 protein levels. a, b Western blots of protein samples from neuronal cultures treated or not with 10 µM GSI from 10 to 14DIV. The 46 kDa Syt7 band decreases dramatically when γ-secretase is inhibited. γ-secretase inhibition does not impair expression of VAMP2, Syt1, and Syntaxin1A. c, d Scatter plots of the western-blot quantification of samples from neuronal culture treated or not with GSI. Syt7 expression is decreased by half in treated condition as seen in a, while the expression of VAMP2, Syt1, and Syntaxin1A is stable under GSI condition as seen in b. e Schemes of APP proteolytic metabolism in WT and PSKO conditions. Full-length (FL) APP is first cleaved by BACE producing βCTF, a transmembrane stub, further degraded by PS (γ-secretase) into Aβ and APP IntraCellular Domain (AICD). In absence of PS, βCTF cannot be catabolized and thus accumulates. f Confocal image of the hippocampus depicting the GCs layer dissected with a laser to prepare RNA samples, and RT-qPCR analysis of the samples indicates that mRNA level of Syt7 is not impaired in absence of PS. g Schemes of the two lentiviruses (LV) used to rescue AICD expression in PSKO GCs controlled by light. C1ql2 promoter restricts the expression of Cre to GCs where the PS floxed gene is deleted. The Cre also removes the Lox-Stop-Lox sequence allowing the Cre-ON LV to express AICD and ChIEF. h Strategy to selectively study Mf/CA3 synapses that are presynaptically PSKO, yet express AICD. In PS “floxed” conditional knock-out mice, double-infected GCs do not express PS (Cre deletes PSfl gene), yet express AICD (Cre dependently), and ChIEF (bicistronic construct) allowing the control of their activity by light. GCs infected by a single virus do not respond to light. i Facilitation of EPSCs amplitude measured along trains of 10 stimuli at 20 Hz in WT or PSKO-expressing AICD. The impaired facilitation of PSKO is not rescued by expression of AICD. Two-way ANOVA, n = 8 in WT, 11 in PSKO, p = 0.017. Errors bars represent s.e.m