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Joseph Arboleda-Velasquez, Alexandra James, Vincent Primo, Mark Graham, Patricia D'Amore; Notch signaling misregulation in retinal pericytes exposed to high glucose. Invest. Ophthalmol. Vis. Sci. 2013;54(15):277. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetes is the leading cause of new cases of blindness in adults ages 20-74 years. Clinical and experimental observations indicate that pericytes are central to the integrity and function of the retinal vasculature; pericyte loss in background diabetic retinopathy is temporally associated with endothelial dysfunction and disease progression. The Notch signaling pathway plays a crucial role in the regulation of cell fate decisions in metazoans. Depending on how the Notch signals integrate with other signaling pathways and cellular elements in a specific tissue, they can influence differentiation, proliferation or apoptotic events in a broad spectrum of tissues, including the vasculature. We investigated whether culture conditions that mimic a diabetic environment affect Notch signaling in retinal pericytes.
Primary cultures of bovine retinal pericytes were transfected with a Notch signaling-sensitive TP1-luciferase reporter using nucleofection technology 24 hr prior to co-culture with cells expressing the Notch ligand Delta 1 (DLL1) in high/normal glucose conditions. Changes in Notch-related gene/protein expression in pericytes exposed to high/normal glucose were measured using qPCR and western blot. The possible role of Fringe, a known modulator of Notch activity, was investigated by transfecting pericytes with a mammalian Fringe expressing vector.
We found a dose-dependent increase in Notch signaling in retinal pericytes (p=0.01) cultured in high glucose, reaching a 2-fold increase between 5 mM and 20 mM glucose while controlling for osmolarity using mannitol. Consistent with this observation, exposure to high glucose was associated with increased expression of Notch 3, Jagged 1, Fringe, and the Notch-downstream target Heyl in pericytes (p<0.05). In overexpression studies, Fringe enhanced Notch signaling in pericytes exposed to high glucose (p<0.05).
We identified Notch signaling misregulation in pericytes exposed to high glucose. Notch signaling misregulation is associated with changes in the expression of key members of the Notch pathway and may contribute to the microangiopathy that characterizes background diabetic retinopathy.
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