32 research outputs found
Effect of Vascular Cadherin Knockdown on Zebrafish Vasculature during Development
Background: Vascular endothelial cadherin (VE-cad) is essential for endothelial barrier integrity and vascular sprouting. However, the role of this important protein in cardiovascular development is only recently becoming apparent. Methodology/Principal Findings: To characterize the role of VE-cadherin in cardiovascular development, we analyzed cardiovascular development in a zebrafish VE-cad knockdown model. Embryos deficient in VE-cad show profoundly impaired cardiac development despite having apparently normal peripheral vasculature. Initial formation of the heart proceeds normally in knockdown embryos, but subsequent looping morphogenesis is impaired. Consistent with these results, VE-cad knockdown embryos demonstrate impaired cardiac function and early circulatory arrest. Histologic examination of knockdown embryos shows persistent, abnormal separation of the endocardial and myocardial layers. Using transmission electron microscopy, we demonstrate that endocardial junctions form poorly in VE-cad knockdown embryos, with resulting leak across the endothelial layer and reduction in the density of the cardiac jelly. Conclusions: Our results demonstrate a significant role for VE-cadherin in cardiac development independent of its effects on the formation of the peripheral vasculature
Subcellular targeting of oxidants during endothelial cell migration
Endogenous oxidants participate in endothelial cell migration, suggesting that the enzymatic source of oxidants, like other proteins controlling cell migration, requires precise subcellular localization for spatial confinement of signaling effects. We found that the nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase adaptor p47phox and its binding partner TRAF4 were sequestered within nascent, focal complexlike structures in the lamellae of motile endothelial cells. TRAF4 directly associated with the focal contact scaffold Hic-5, and the knockdown of either protein, disruption of the complex, or oxidant scavenging blocked cell migration. An active mutant of TRAF4 activated the NADPH oxidase downstream of the Rho GTPases and p21-activated kinase 1 (PAK1) and oxidatively modified the focal contact phosphatase PTP-PEST. The oxidase also functioned upstream of Rac1 activation, suggesting its participation in a positive feedback loop. Active TRAF4 initiated robust membrane ruffling through Rac1, PAK1, and the oxidase, whereas the knockdown of PTP-PEST increased ruffling independent of oxidase activation. Our data suggest that TRAF4 specifies a molecular address within focal complexes that is targeted for oxidative modification during cell migration
Comprehensive Molecular Characterization of Pheochromocytoma and Paraganglioma
SummaryWe report a comprehensive molecular characterization of pheochromocytomas and paragangliomas (PCCs/PGLs), a rare tumor type. Multi-platform integration revealed that PCCs/PGLs are driven by diverse alterations affecting multiple genes and pathways. Pathogenic germline mutations occurred in eight PCC/PGL susceptibility genes. We identified CSDE1 as a somatically mutated driver gene, complementing four known drivers (HRAS, RET, EPAS1, and NF1). We also discovered fusion genes in PCCs/PGLs, involving MAML3, BRAF, NGFR, and NF1. Integrated analysis classified PCCs/PGLs into four molecularly defined groups: a kinase signaling subtype, a pseudohypoxia subtype, a Wnt-altered subtype, driven by MAML3 and CSDE1, and a cortical admixture subtype. Correlates of metastatic PCCs/PGLs included the MAML3 fusion gene. This integrated molecular characterization provides a comprehensive foundation for developing PCC/PGL precision medicine