Abstract
Purpose :
Notch signaling plays a critical role in vascular development, regulating fundamental processes such as angiogenesis, arterial/venous differentiation, and mural cell investment. However, aberrant Notch signaling can result in severe vascular phenotypes as observed in cerebral arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and has been implicated in pericyte loss during diabetic retinopathy. An interesting question remains regarding the changing requirement for Notch signaling during aging. It is evident that Notch 3 signaling plays an important role in the differentiation of mural cells during development, yet it remains unclear how these interactions are affected during aging and how this affects retinal vascular stability.
Methods :
Two knockin mouse lines were generated expressing human Notch 3 with or without the C455R CADASIL mutation expressed under an SM22-cre in a Notch 3 knockout (N3KO) background and aged to 24 months. Fluorescein angiography was carried out at 6, 12 and 24 months. Immunolabelling was carried out on cryosections and flat-mounted retinas assessing changes in the vascular, glial and neuronal retinal components. Transmission election microscopy (TEM) was used to assess changes in microvascular structure.
Results :
We report that the C455R mutation in Notch 3 causes a significant reduction in retinal vascular stability in an age dependent and dominant negative manner. C455R mutant mice displayed increased vasopermeability and retinal vascular caliber at 24 months (P<0.05). Interestingly, we also report that N3KO mice develop retinal vascular aneurysms at 24 months of age, this phenotype can be rescued through the expression of wild type Notch 3 in mural cells.
Conclusions :
These data have shown for the first time a requirement for Notch 3 in the aging vasculature and that the expression of the C455R mutation results in an increase in vasopermeability in the retina at 24 months. Whereas, mice expressing wild type Notch 3 rescued the phenotype of N3KO mice. These findings may hold importance for retinal vascular diseases such as diabetic retinopathy in which alternations in Notch 3 expression have been reported and warrants further investigation.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.