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A. Chaudhuri, I. Ahmad; Regulation of Retinal Angiogenesis and Choroidal Neovascularization (CNV) by Notch Signaling. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3435. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The Notch pathway is an evolutionarily conserved signaling mechanism whose classic function is to keep stem cells/progenitors uncommitted. However, Notch pathway is recruited in different contexts to regulate multiple cellular processes during development and beyond. Recent evidence suggests that Notch signaling regulates both physiological and pathological angiogenesis (Roca and Adams, 2007, Gen. Dev. 21:2511-2524). We have begun understanding the role of Notch signaling which plays in normal retinal angiogenesis and during CNV in animal model of age-related macular degeneration (AMD) to determine whether or not the Notch pathway is a valid molecular target for AMD therapy.
We examined the effects of perturbation of Notch signaling on neonatal vascularization and in laser-induced CNV in rats. To decrease Notch signaling animals (postnatal day 3; a day after laser treatment in adult rats) were injected with DAPT (100mg/Kg) intraperitoneally. DAPT inhibits g-secretase required to activate Notch pathway by releasing the Notch intracellular domain upon receptor-ligand interactions. To increase Notch signaling, animals will be injected with soluble Jagged1, one of the Notch ligands. Effects were evaluated after 2 days (neonatal angiogenesis) and 7 days (laser treatment). Whole mount retina was stained for markers for endothelial cells (FITC conjugated Isolectin-B4) and examined using fluorescent microscopy for vascular branching and size of CNV lesion. Endothelial cells were isolated and examined for transcripts corresponding to Notch target genes, Hes1 and Hes5 and tip-cell specific-gene, pdgfb.
Examination of the whole mount retina stained with Isolectin B4 revealed the vascular bed with branch points. The density of the vascular bed was increased in DAPT-treated retina, compared to controls. The branch points were more extensive and the vascular diameter was relatively large in DAPT-treated animals. RT-PCR examination of endothelial cells revealed decreased and increased levels of Hes1/Hes5 and pdgfb transcripts, respectively. CNV lesion could be identified by both fluorescence angiography and Isolectin B4 staining and we are currently examining the effects of DAPT-treatment on lesion size.
Notch signaling is involved in retinal angiogenesis. A comparison of the influence of Notch signaling in physiological and pathological (CNV) angiogenesis will be presented.
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