Nogo-B modulates physiological and pathological angiogenesis during development and disease

Abstract

Angiogenesis, i.e., the formation of new blood vessels, is essential for normal development and functional vessel formation in ischemic diseases. During angiogenesis, endothelial cells (ECs) coordinate migration, proliferation, and metabolic fluxes to adapt to branching vessels' increasing energy demands. Nogo-B is a ubiquitously expressed reticulon family protein mainly localized to the endoplasmic reticulum (ER) membrane. Our previous studies have shown that the genetic loss of Nogo-B results in aberrant vascular remodeling and dysregulated endothelial barrier function. The current study aims to examine the role of endothelial Nogo-B in regulating developmental angiogenesis and pathological angiogenesis in retinopathy of prematurity (ROP). We hypothesized that endothelial Nogo-B is required for physiological and pathological angiogenesis, and Nogo-B depletion attenuates pathological angiogenesis. Using tamoxifen-inducible, endothelial cell-specific Nogo-B−/− (Nogo-BiECKO) mice, Nogo-B global knockout mice, and C57Bl/6 (WT) mice, our results show that loss of Nogo-B in ECs significantly delayed Isolectin B4 (IB4)-labeled retinal blood vessel sprouting. Impaired EC proliferation was observed by the staining of and incorporation of 5-ethynyl-2′-deoxyuridine (EdU). Furthermore, using the Oxygen Induced Retinopathy (OIR) model to mimic ROP, we could demonstrate that loss of Nogo-B in EC resulted in reduced neovascularization compared to WT. Mechanistically, using Percoll gradients, ultra-resolution microscopy, proximity ligation assay, and electron-microscopy, we show that Nogo-B is localized in the mitochondria-associated ER membrane (MAM) and regulated MAM remodeling. Using seahorse assay, quantitative RT-PCR, and metabolomics analysis, we determined that loss of Nogo-B altered VEGF-mediated EC glycolysis, which is needed for the energy demand during angiogenesis. These data suggest that Nogo-B regulates glucose metabolism in EC and plays a pivotal role in physiological and pathological angiogenesis. Targeting endothelial Nogo-B may provide a plausible approach to controlling the formation of pathological neovascularization in retinal diseases, such as ROP, diabetic retinopathy, and wet forms of age-related macular degeneration. This work was supported by the National Institutes of Health (R01HL153599) and awards from the American Heart Association award to JY. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.