Aberrant NOTCH1 Signaling in Placentas Complicated by Congenital Heart Defects

Congenital heart defects complicate 1% of all pregnancies and are associated with abnormal placental development, morphology and function. Mutations in NOTCH1 are common in fetuses with congenital heart defects. However, the role of impaired NOTCH1 signaling in the cells of the CHD placenta remains unclear. We hypothesize that placentas from CHD fetuses have impaired NOTCH1 expression and signaling. Under IRB approval, patients were recruited and consented at the Women’s Medical Plaza Clinic at the University of Florida and Cincinnati Children’s Hospital Medical Center. At the time of delivery, placentas were collected from CHD (n=16) and control (n=8) patients and villous samples processed for RNA and protein extraction. Quantitative PCR was performed for NOTCH1 and its downstream signaling molecules HES1 and HEY1. Western blotting was performed for NOTCH1 in which S2 (110kDa) and S3 (65kDa) cleavage products were identified using the same antibody. Student t-test and one way ANOVA were performed to assess statistical significance. NOTCH1 RNA levels were not different between CHD and control placentas, however NOTCH1 protein levels and signaling were disrupted. NOTCH1 S2 cleaved product (110kDa) was significantly lower in the single ventricle (n=6, p=0.03) and conotruncal (n=3, p=0.03) patients compared to the control group (n=8). Furthermore, NOTCH1 S3 cleaved product (65kDa) was significantly lower in all CHD subtypes (n=16, p=0.006) as well as in the single ventricle (n=6, p< 0.05) patients compared to control. HES1 levels were significantly reduced in all CHD subtypes (n=12; p=0.03). HEY1 levels were significantly reduced only in septal defects (p< 0.05 n=3). The reduction in NOTCH1 protein expression and downstream signaling in CHD placentas suggests impaired NOTCH1 pathway activation despite unchanged NOTCH1 transcript levels. These findings suggest that impaired NOTCH1signaling may contribute to CHD associated placental abnormalities in a subtype specific dependent manner Funding: APS Porter Physiology Development Fellowship This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.