GSE172230
Mitochondrial dysfunction induces ALK5-SMAD2-mediated hypovascularization and arteriovenous malformations in mouse retinas
Although mitochondrial activity is critical for angiogenesis, its mechanism is not entirely clear. Here, we investigate the angiogenic functions of three separate nuclear genes that encode for mitochondrial proteins, including mitochondrial transcriptional factor (TFAM), respiratory complex IV component (COX10), and a mitochondrial redox protein thioredoxin 2 (TRX2), which are responsible for distinct mitochondrial functions. We aim to investigate if mitochondrial activities regulate common endothelial cell (EC) signaling pathways during angiogenesis. The silencing of Tfam, Cox10, or Trx2 in an in vitro 3D sprouting assay attenuates EC sprouting, which correlated with reduced EC proliferation but not with ROS generation or EC apoptosis. Mice with an inducible deletion of Tfam, Cox10, or Trx2 exhibit retarded retinal vessel growth without penetration into the deep plexi at early ages (P5-P12). The three mutant mice develop arteriovenous malformations (AVM) with microaneurysm formation in the microvessels at advanced ages (P12-P30); the hypovasculature and microaneurysm phenotypes resemble that of aged human retinas and human primitive retinal vascular abnormalities such as Coats' disease, Leber's military aneurysms and familial exudative vitreoretinopathy. Single-cell RNA-seq analyses of retinal ECs suggest that the three mutant mice have common EC clusters with reduced gene expressions in anion transporters, actin organization, extracellular matrix, and angiogenesis. These EC clusters also have increased gene expressions in endothelial-mesenchymal transition and arterial markers, correlating with enhanced TGFbR signaling in Tfam, Cox10, or Trx2-deficient mice. Importantly, pharmacological blockade by TGFbR inhibitors attenuated retinal vessel growth retardation and AVM formation in all three mutant mice. Our study demonstrates that mitochondrial dysfunction induces TGF-b receptor-mediated arteriovenous malformations and microaneurysm formation in mouse retinas, and provide a novel model and therapeutic intervention for human primitive retinal vascular abnormalities, which are characterized by retinal vascular malformations and are associated with many pathological complications such as diabetes and hypertension that can result in vision loss. Overall design: Single-cell transcriptome profiles of retina endothelial cells with mitochondrial gene KO