Arteriosclerosis, Thrombosis, and Vascular Biology | ANGPT2 Gene Expression Correlates with Schlemm's Canal Area Expansion

This study successfully generated an Angpt2-miR-145 mouse model carrying the rs76020419 (G>T) mutation, demonstrating that this mutation elevates ANGPT2 expression while expanding Schlemm's canal area, suggesting its protective role in glaucoma. The model provides a critical tool for future investigations into ANGPT2's function in intraocular pressure regulation and retinal neurodegeneration.

 

Literature Overview
This article titled 'A Glaucoma-Protective Human SNP in the Angpt2 Locus', published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology, reviews functional validation of rs76020419 (G>T), a human SNP located in the miR-145 binding site of ANGPT2's 3'UTR region. This mutation has been genetically associated with reduced intraocular pressure and lower risk of primary open-angle glaucoma in GWAS studies, and functions as an eQTL in the GTEx database correlating with ANGPT2 upregulation. The research team employed CRISPR/Cas9 technology to develop a murine model carrying this SNP for evaluating ANGPT2 expression and Schlemm's canal morphological changes across ocular and systemic tissues.

Background Knowledge
Glaucoma represents a leading cause of global blindness affecting approximately 60 million individuals. Maintaining aqueous humor homeostasis through balanced production and drainage remains crucial for intraocular pressure (IOP) regulation, with Schlemm's canal (SC) and trabecular meshwork (TM) serving as primary drainage pathways. Prior studies identified functional loss of ANGPT1 and TEK genes in congenital glaucoma, with ANGPT2 demonstrating partial compensatory activity in Angpt1-deficient contexts. miR-145, an established ANGPT2 suppressor, has its binding site disrupted by rs76020419 (G>T), causing ANGPT2 overexpression that may increase SC caliber and reduce IOP. This study establishes the first in vivo mouse model carrying this protective SNP, filling a critical research gap and providing direct evidence for ANGPT2's protective role in SC homeostasis and glaucoma prevention.

 

 

Research Methods and Experiments
The research team introduced rs76020419 (G>T) mutation into C57BL/6 mice using CRISPR/Cas9 genome editing technology to construct the Angpt2-miR-145 mouse model. ANGPT2 protein expression levels were quantified across plasma, eye, lung, and kidney tissues through qPCR and ELISA analysis. Immunofluorescence staining combined with confocal microscopy was employed to evaluate Schlemm's canal area changes, while Tonolab rebound tonometry measured intraocular pressure. Fluorescent angiography assessed vascular leakage to confirm model stability.

Key Conclusions and Perspectives

• Mice carrying the rs76020419 [T] allele showed significant ANGPT2 protein elevation in plasma and ocular, pulmonary, renal tissues.
• Mutant mice exhibited substantially increased Schlemm's canal cross-sectional area compared to wild-type (WT) controls.
• Significant intraocular pressure reduction in mutant mice suggests enhanced aqueous drainage through expanded SC caliber.
• Absence of retinal vascular leakage in fluorescent angiography indicates preserved vascular stability despite mutation.
• This study provides in vivo evidence confirming miR-145 regulation of ANGPT2 expression and its functional impact on SC development.

Research Significance and Prospects
The findings establish a functional relationship between elevated ANGPT2 expression and structural modifications in Schlemm's canal, supporting its potential as a genetic protective factor against glaucoma. Future investigations should integrate multiple IOP elevation models to comprehensively evaluate this mutation's protective effects against high intraocular pressure and retinal neurodegeneration, laying groundwork for therapeutic strategies targeting ANGPT2 or miR-145 in glaucoma treatment.

 

 

Conclusion
This study represents the first validation in a murine model of human ANGPT2 gene rs76020419 (G>T) mutation's effects on intraocular pressure and Schlemm's canal morphology. Using CRISPR/Cas9 editing, the research team successfully generated mutant mice showing ANGPT2 upregulation across multiple tissues. The observed Schlemm's canal expansion and reduced IOP provide definitive in vivo evidence for miR-145 regulation of ANGPT2 expression. This model establishes critical infrastructure for investigating ANGPT2's protective mechanisms in glaucoma and related neurodegenerative diseases, while identifying novel molecular targets for genetic therapies.

 

Naoki Kiyota, Tuncer Onay, Phoebe Leeaw, Janey L Wiggs, and Susan E Quaggin. A Glaucoma-Protective Human SNP in the Angpt2 Locus Increased ANGPT2 Expression and Schlemm’s Canal Area in Mice. Arteriosclerosis, thrombosis, and vascular biology.