Abstract 10952: Network Analysis Identifies the Orphan Receptor Tyrosine Kinase Ros1 as a Determinant of Glutathione Peroxidase-1 Mediated Vascular Remodeling
Deficiency of the glutathione peroxidase-1 (GPx1) is associated with atherosclerosis and in-stent stenosis (ISS). Using a genome-wide gene expression network approach in human atherectomy samples (n=89) we found that a subnetwork with the proto-oncogene orphan receptor tyrosine kinase Ros1 with GPx1 as its nexus hub was among the most differentially regulated between atherosclerosis and ISS. We hypothesized that Ros1 was a determinant of GPx1 mediated vascular remodeling. We investigated the importance of Ros1 using knockout mice with constitutive deficiency of GPx1 crossed onto atherosclerotic ApoE-KO background. GPx1/ApoE-KO mice had minimal GPx1 activity but a 20-fold increase in Ros1 activity in vascular tissue, as assessed by phosphorylation of Ros1 on immunoblot, not present in ApoE-KO controls. In keeping with this, both proliferation (71%, P<0.01) and migration (90%, P<0.01) were significantly increased in GPx1/ApoE-KO primary aortic smooth muscle cells compared to ApoE-KO control. This increase was abolished by interference RNA directed against Ros1 or broad-spectrum tyrosine kinase inhibition by Genistein. Balloon angioplasty and stenting (BAS) in these mice led to a dramatic increase in both mRNA level (150-fold, P<0.01) and activity of Ros1 (20-fold, P<0.01) that was associated to a time-dependent increase in intracellular reduced glutathione (18-fold, P<0.01), a known mediator of cellular proliferation and inhibitor of apoptosis. Furthermore, while atherosclerosis was increased by 40% (P<0.05) and ISS by 50% (P<0.01) in GPx1/ApoE-KO mice 28 days following BAS, this increase was eliminated by inhibition of Ros1 by Genistein. In 461 patients who underwent BAS, 107 of whom developed ISS, we found single-nucleotide polymorphisms (SNP) in GPx1 and Ros1 to rank 5th and 6th respectively in terms of informative SNPs for the prediction of ISS (P<0.01). Furthermore SNP interaction between Ros1 and GPx1 ranked 18th out of greater than twenty thousand possible SNP pairs evaluated, suggesting an additive risk conferred by SNPs in both genes. Using a network analysis approach we have identified that activation of the proto-oncogene receptor tyrosine kinase Ros1 is a mechanism by which GPx1 deficiency adversely mediates vascular remodeling.
- © 2011 by American Heart Association, Inc.