title: Vascular adaptation to a dysfunctional endothelium as a consequence of Shb deficiency.
abstract: Vascular endothelial growth factor (VEGF)-A regulates angiogenesis, vascular morphology and permeability by signaling through its receptor VEGFR-2. The Shb adapter protein has previously been found to relay certain VEGFR-2 dependent signals and consequently vascular physiology and structure was assessed in Shb knockout mice. X-ray computed tomography of vessels larger than 24 μm diameter (micro-CT) after contrast injection revealed an increased frequency of 48-96 μm arterioles in the hindlimb calf muscle in Shb knockout mice. Intravital microscopy of the cremaster muscle demonstrated a less regular vasculature with fewer branch points and increased vessel tortuosity, changes that led to an increased blood flow velocity. Reduced in vivo angiogenesis was observed in Shb knockout Matrigel™ plugs. Unlike the wild-type situation, VEGF-A did not provoke a dissociation of VE-cadherin from adherens junctions in Shb knockout venules. The reduced angiogenesis and altered properties of junctions had consequences for two patho-physiological responses to arterial occlusion: vascular permeability was reduced in the Shb knockout cremaster muscle after ligation of one supplying artery and heat-induced blood flow determined by Laser-Doppler measurements was decreased in the hindlimb after ligation of the femoral artery. Consequently, the Shb knockout mouse exhibited structural and functional (angiogenesis and vascular permeability) vascular abnormalities that have implications for understanding the function of VEGF-A under physiological conditions.
authors.affiliation: Department of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden.
authors.forename: Gustaf
authors.initials: G
authors.lastname: Christoffersson
authors.forename: Guangxiang
authors.initials: G
authors.lastname: Zang
authors.forename: Zhen W
authors.initials: ZW
authors.lastname: Zhuang
authors.forename: Evelina
authors.initials: E
authors.lastname: Vågesjö
authors.forename: Michael
authors.initials: M
authors.lastname: Simons
authors.forename: Mia
authors.initials: M
authors.lastname: Phillipson
authors.forename: Michael
authors.initials: M
authors.lastname: Welsh
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002199:Capillary Permeability; D004730:Endothelium, Vascular / Q000502:physiology*; D006614:Hindlimb / Q000098:blood supply; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; C085634:Shb protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2