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Updated: Dec 29, 2025
Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies
Published on: March 12, 2022
Epithelial Membrane Protein 2 (EMP2) Promotes VEGF-Induced Pathological Neovascularization in Murine Oxygen-Induced
Michel Sun1, Madhuri Wadehra1,1, David Casero1
1.
Insights
Removing epithelial membrane protein-2 (EMP2) protected against retinopathy of prematurity in mice. This suggests EMP2 plays a role in retinal neovascularization and may be a therapeutic target.
Area of Science:
- Ophthalmology
- Molecular Biology
- Developmental Biology
Background:
- Retinopathy of prematurity (ROP) is a significant cause of childhood blindness.
- ROP results from abnormal retinal blood vessel growth following premature birth and oxygen exposure.
- Epithelial membrane protein-2 (EMP2) is implicated in regulating vascular endothelial growth factor (VEGF) production.
Purpose of the Study:
- To investigate the role of EMP2 in oxygen-induced retinopathy (OIR), a model for ROP.
- To determine if knockout of the Emp2 gene (Emp2 KO) offers protection against retinal neovascularization in OIR.
- To explore the molecular mechanisms by which EMP2 influences angiogenic signaling in the retina.
Main Methods:
- Eyes from wildtype (WT) and Emp2 KO mice were analyzed at various developmental stages (P7-P21) under normoxia and hyperoxia.
- RNA sequencing was performed on retinal/choroid layers to assess gene expression changes.
- Immunohistochemistry and whole-mount imaging were used to evaluate Emp2, hypoxia-inducible factor 1α (Hif1α), and VEGF expression, as well as neovascularization.
Main Results:
- Emp2 KO mice exhibited significantly reduced pathological neovascularization in the OIR model compared to WT mice.
- A decrease in Hif1α and VEGF expression was observed in Emp2 KO mice during OIR.
- These findings indicate that EMP2 promotes neovascularization by modulating angiogenic signaling pathways.
Conclusions:
- Emp2 knockout provides protection against pathological neovascularization in a mouse model of ROP.
- EMP2 appears to enhance neovascularization by influencing hypoxia-induced VEGF expression in the neuroretina.
- Targeting EMP2 may offer a novel therapeutic strategy for preventing or treating retinopathy of prematurity.
Purpose:
Retinopathy of prematurity (ROP) is a leading cause of childhood blindness. ROP occurs as a consequence of postnatal hyperoxia exposure in premature infants, resulting in vasoproliferation in the retina. The tetraspan protein epithelial membrane protein-2 (EMP2) is highly expressed in the retinal pigment epithelium (RPE) in adults, and it controls vascular endothelial growth factor (VEGF) production in the ARPE-19 cell line. We, therefore, hypothesized that Emp2 knockout (Emp2 KO) protects against neovascularization in murine oxygen-induced retinopathy (OIR).
Methods:
Eyes were obtained from wildtype (WT) and Emp2 KO mouse pups at P7, P12, P17, and P21 after normoxia or hyperoxia (P7-P12) exposure. Following hyperoxia exposure, RNA sequencing was performed using the retina/choroid layers obtained from WT and Emp2 KO at P17. Retinal sections from P7, P12, P17, and P21 were evaluated for Emp2, hypoxia-inducible factor 1α (Hif1α), and VEGF expression. Whole mount images were generated to assess vaso-obliteration at P12 and neovascularization at P17.
Results:
Emp2 KO OIR mice demonstrated a decrease in pathologic neovascularization at P17 compared with WT OIR mice through evaluation of retinal vascular whole mount images. This protection was accompanied by a decrease in Hif1α at P12 and VEGFA expression at P17 in Emp2 KO animals compared with the WT animals in OIR conditions. Collectively, our results suggest that EMP2 enhances the effects of neovascularization through modulation of angiogenic signaling.
Conclusions:
The protection of Emp2 KO mice against pathologic neovascularization through attenuation of HIF and VEGF upregulation in OIR suggests that hypoxia-induced upregulation of EMP2 expression in the neuroretina modulates HIF-mediated neuroretinal VEGF expression.
