Dataset Information

Endothelial deletion of Sag/Rbx2/Roc2 E3 ubiquitin ligase causes embryonic lethality and blocks tumor angiogenesis.

ABSTRACT: SAG (Sensitive to Apoptosis Gene), also known as RBX2 or ROC2, is a RING protein required for the activity of Cullin-RING ligase (CRL). Our recent study showed that Sag total knockout caused embryonic lethality at E11.5-12.5 days with associated defects in vasculogenesis. Whether Sag is required for de novo vasculogenesis in embryos and angiogenesis in tumors is totally unknown. Here, we report that Sag endothelial deletion also causes embryonic lethality at E15.5 with poor vasculogenesis. Sag deletion in primary endothelial cells (ECs) or knockdown in MS-1 ECs inhibits migration, proliferation and tube formation, with p27 accumulation being responsible for the suppression of migration and proliferation. Furthermore, Sag deletion significantly inhibits angiogenesis in an in vivo Matrigel plug assay, and tumor angiogenesis and tumorigenesis in a B16F10 melanoma model. Finally, MLN4924, an investigational small molecule inhibitor of NEDD8-activating enzyme (NAE) that inhibits CRL, suppresses in vitro migration, proliferation and tube formation, as well as in vivo angiogenesis and tumorigenesis. Taken together, our study, using both genetic and pharmaceutical approaches, demonstrates that Sag is essential for embryonic vasculogenesis and tumor angiogenesis, and provides the proof-of-concept evidence that targeting Sag E3 ubiquitin ligase may have clinical value for anti-angiogenesis therapy of human cancer.

SUBMITTER: Tan M

PROVIDER: S-EPMC4016996 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Endothelial deletion of Sag/Rbx2/Roc2 E3 ubiquitin ligase causes embryonic lethality and blocks tumor angiogenesis.

Tan M M Li H H Sun Y Y

Oncogene 20131111 44

SAG (Sensitive to Apoptosis Gene), also known as RBX2 or ROC2, is a RING protein required for the activity of Cullin-RING ligase (CRL). Our recent study showed that Sag total knockout caused embryonic lethality at E11.5-12.5 days with associated defects in vasculogenesis. Whether Sag is required for de novo vasculogenesis in embryos and angiogenesis in tumors is totally unknown. Here, we report that Sag endothelial deletion also causes embryonic lethality at E15.5 with poor vasculogenesis. Sag d ...[more]

PMID: 24213570

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Project description:Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. While the role of ubiquitin (Ub) ligase PARKIN in mitophagy has been extensively studied, increasing evidence suggests the existence of PARKIN-independent mitophagy in highly metabolically active organs such as the heart. Here, we identify a crucial role for Cullin-RING Ub ligase 5 (CRL5) in basal mitochondrial turnover in cardiomyocytes. CRL5 is a multi-subunit Ub ligase comprised by the catalytic RING box protein RBX2 (also known as SAG), scaffold protein Cullin 5 (CUL5), and a substrate-recognizing receptor. Analysis of the mitochondrial outer membrane-interacting proteome uncovered a robust association of CRLs with mitochondria. Subcellular fractionation, immunostaining, and immunogold electron microscopy established that RBX2 and Cul5, two core components of CRL5, localizes to mitochondria. Depletion of RBX2 inhibited mitochondrial ubiquitination and turnover, impaired mitochondrial membrane potential and respiration, and increased cell death in cardiomyocytes. In vivo, deletion of the Rbx2 gene in adult mouse hearts suppressed mitophagic activity, provoked accumulation of damaged mitochondria in the myocardium, and disrupted myocardial metabolism, leading to rapid development of dilated cardiomyopathy and heart failure. Similarly, ablation of RBX2 in the developing heart resulted in dilated cardiomyopathy and heart failure. Notably, the action of RBX2 in mitochondria is not dependent on PARKIN, and PARKIN gene deletion had no impact on the onset and progression of cardiomyopathy in RBX2-deficient hearts. Furthermore, RBX2 controls the stability of PINK1 in mitochondria. Proteomics and biochemical analyses further revealed a global impact of RBX2 deficiency on the mitochondrial proteome and identified several mitochondrial proteins as its putative substrates. These findings identify RBX2-CRL5 as a mitochondrial Ub ligase that controls mitophagy under physiological conditions in a PARKIN-independent, PINK1-dependent manner, thereby regulating cardiac homeostasis.

Dataset Information

Endothelial deletion of Sag/Rbx2/Roc2 E3 ubiquitin ligase causes embryonic lethality and blocks tumor angiogenesis.

Publications

Endothelial deletion of Sag/Rbx2/Roc2 E3 ubiquitin ligase causes embryonic lethality and blocks tumor angiogenesis.

Similar Datasets

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