Linking Notch signaling to ischemic stroke

Using a hitherto uncharacterized knockout mouse model of Notch 3, a Notch signaling receptor paralogue highly expressed in vascular SMCs, we uncover a striking susceptibility to ischemic stroke upon challenge. Cellular and molecular analyses of vascular SMCs derived from these animals associate Notch 3 activity to the expression of specific gene targets, whereas genetic rescue experiments unambiguously link Notch 3 function in vessels to the ischemic phenotype. Microarray Studies. Biotinylated cRNA samples from freshly sorted brain SMCs (four Notch 3 +/− mice and five Notch 3 −/− mice) were fragmented before hybridization (15 μg each) onto mouse 430 2.0 Affymetrix chips. The chips were washed, stained by using strepavidin-phycoerytrin, and scanned the next day as described in ref. 24. For data normalization, all probe sets were scaled to a target intensity of 150. Microarray data analysis was performed by using Rosetta Resolver. All cells were from 10- to 12-week-old male mice. Gene Ontology Analyses. PANTHER software was used to define over- and underrepresented functions in the list of signature genes found by microarray analysis (25). P values were calculated by using binomial statistics.