Journal: bioRxiv
Article Title: PS FAD mutants and γ-secretase inhibition accumulate VEGFR2-derived peptide VCTF1 suppressing brain VEGFR2 dimerization, angiogenesis and neuroprotection
doi: 10.64898/2026.05.12.724648
Figure Lengend Snippet: (A) , Wild-type (WT) and KI mice HTRZ for either PS1 FAD mutant M146V (WT/M146V) or I213T (WT/I213T) were infused with vehicle (0.2% BSA in PBS) or VEGF-A (a total of 3.5μg in 100μl of vehicle) through the carotid artery for 15 days using a mini osmotic pump as in Methods. Left: Brain coronal sections (40μm thick) were prepared and immunostained with anti-Col IV antibodies to visualize brain vessels. Enhanced visualization surfaces were generated using Imaris software from representative confocal images of ipsilateral hemispheres. Scale bar: 50μm. Right: Graph shows total vessel length density in WT and PS1 FAD brains quantified using Imaris 9.9 software as in Methods. (B) , WT and HTRZ for PS1 FAD mutants M146V or I213T mice were injected through the carotid artery for 20 minutes with either vehicle or 100ng of VEGF-A in vehicle prepared as in 1A using a catheter as described in Methods. Brain microvessels (MV) were isolated as in Methods, lysed in Triton X-100 buffer, and subjected to immunoprecipitation (IP) with anti-VEGFR2 antibody or control IgG. Left: IPs were analyzed on Western blots (WBs) using anti-endoglin or anti-VEGFR2 antibodies (upper panel). Input samples are shown in lower panel. β-actin: loading control. Right: Graph shows quantification of endoglin co-IPed with VEGFR2, normalized to IPed VEGFR2. (C) , WT mice were infused for 15 days through the carotid artery with vehicle or VEGF-A in vehicle as in 1A using a mini osmotic pump (as in 1A). For RO injection, mice were treated with vehicle (2% DMSO, 30% PEG 300, 5% Tween-80 in ddH2O) or RO in vehicle (5mg/kg body weight) via five injections in tail vein one injection every three days, with first injection administered 1 hour before osmotic pump implantation. Brain coronal sections (40μm) were prepared and immunostained with anti-Col IV antibodies as in 1A. Left: Representative confocal images of ipsilateral hemispheres are shown prepared as in 1A. Scale bar: 50μm. Right: Graph shows total vessel length density quantified using Imaris software as in 1A. (D) , WT adult mice were treated with either 50μl vehicle as in 1C or 1mg/kg RO in vehicle via carotid artery as in Methods. 15-16 hrs later, 50 μl vehicle prepared as in 1A or 100ng VEGF-A in vehicle was administered via carotid artery for 10-20 minutes using a catheter as in 1B. Brain MVs were isolated and extracted as in 1B. Left: p-VEGFR2 (Tyr1054/Tyr1059), VEGFR2, p-ERK1/2 and ERK1/2 are detected on WBs of extracts with specific antibodies in MV extracts. Vinculin: loading control. Right: Graphs show fold change of phosphorylated to total protein ratio. (E) , WT mice and mice HTRZ for PS1 FAD mutant M146V (WT/M146V) or I213T (WT/I213T) were treated with vehicle or VEGF-A via carotid artery for 10-20 minutes using a catheter as in 1D. Brain MVs were isolated and extracted as in 1B. Left: p-VEGFR2 (Tyr1054/Tyr1059), VEGFR2, p-ERK1/2 and ERK1/2 are detected on WBs of extracts with specific antibodies in MV extracts. β-actin: loading control. Right: Graphs show fold change of phosphorylated to total protein ratio. (F) , WT pCECs were prepared and treated as in Methods with vehicle (DMSO) or RO (200nM in DMSO) and then stimulated with either vehicle (PBS) or VEGF-A (20ng in PBS) for 15min. Upper: Cells were co-immunostained with either anti-VEGFR2 antibodies (green) or early endosome marker Rab5 (red) and cell nuclei were stained with Hoechst (blue) as in Methods. Yellow fluorescence in merged images indicates co-localization of VEGFR2 with Rab5. Scale bar 0.5μm. Lower: Graph shows percent of VEGFR2 co-localized with Rab5 in RO-treated WT cells compared to vehicle-treated cells measured with Imaris software. (G) , pCECs from either WT or mice HTRZ for PS1 FAD mutant M146V (WT/M146V) or I213T (WT/I213T), were stimulated with vehicle or VEGF-A in vehicle as in 1F. Upper: Cells were co-stained with anti-VEGFR2 antibodies and early endosome marker Rab5 as in 1F. Cell nuclei were stained with Hoechst (blue) as in 1F. Yellow fluorescence in merged images indicates co-localization of VEGFR2 with Rab5. Scale bar 0.5μm. Lower: Graph shows percent of VEGFR2 co-localized with Rab5 in PS1 FAD WT/M146V or WT/I213T HTRZ mice compared to WT measured with Imaris software. For Figs A-G, data are shown as Mean ± S.E. from at least three independent experiments or as indicated in the dot plots. Statistical analysis was performed using two-way ANOVA followed by Tukey post-hoc test. ns = not significant, *p<0.05, **p<0.01, ***p<0.001.
Article Snippet: Mouse monoclonal anti-Flag tag (M2; F1804) was from Millipore Sigma, anti-GAPDH (2118S) from Cell Signaling Technologies (Beverly, MA), anti-VEGFR2 (OTI12C1) from Origene, anti-endoglin (CD-105; NBP2-22122) and anti-LAMP2 (NBP2-22217) from Novus Biologicals, Inc, anti-Rab5 (D-11) and anti-Rab7 (B-3) from Santa Cruz Biotechnology, Inc. Chicken polyclonal anti-GFAP (ab4674) was from Abcam.
Techniques: Mutagenesis, Generated, Software, Injection, Isolation, Immunoprecipitation, Control, Western Blot, Marker, Staining, Fluorescence
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