Submitted to: Cell Cycle
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/12/2006
Publication Date: 9/1/2006
Citation: Hnasko, R.M., Carter, J.M., Medina, F., Lisanti, M. 2006. Pv-1 labels trans-cellular openings in mouse endothelial cells and is negatively regulated by vegf. Cell Cycle. 5(17):2021-28. Interpretive Summary: Blood vessels are lined by endothelial cells and these cells provide a semi-permeable barrier to the movement of substances from the blood into tissues and organs. The barrier properties of blood vessels differ between tissues yet little is know about how permeability is regulated. The importance of understanding blood vessel permeability is underscored by the need to selectively deliver pharmacological agents to desired tissues for the treatment of disease. In this paper we evaluate the biochemistry of the blood vessel protein PV-1 and localize the protein to large pores in endothelial cells that maybe involved in the movement of blood substances and cells. In addition we show PV-1 is associated with the deformation of the cell nucleus suggesting a role in the maintenance of cell nucleus. Moreover, we show that the pharmacological inhibition of vascular growth factor receptors increases the PV-1 protein which results in the cessation of cell growth but not cell death. We provide a novel target protein and identify a cellular model that will be useful in elucidating the mechanism of blood vessel permeability.
Technical Abstract: An N-glycosylated 60-kDa PV-1 protein that binds heparin was detected in mouse lung from a single mRNA transcript. In the absence of disulfide bond reduction PV-1 is detected as a dimer or large molecular weight oligomer. In the lung of Cav-1, but not Cav-2, null mice the amount of PV-1 protein is diminished, with no detectable change in mRNA level. PV-1 does not fractionate with caveolae on a sucrose density gradient, but the Cav-1 protein is detected in fractions following immunoprecipitation with PV-1 antibodies. Both PV-1 and Cav-1 localize to alveolar endothelial cells, but PV-1 is concentrated at the abluminal and Cav-1 at the luminal cell surface with minimal colocalization. In the Cav-1 null lungs, PV-1 is nearly undetectable in endothelial cells, but remains unchanged in pneumocytes and bronchial epithelial cells. Injection of a VEGF-R2 inhibitor increased PV-1 protein in lung of Cav-1 null, but not Cav-2 or wild-type mice. These data indicate that the PV-1 protein is negatively regulated in pulmonary endothelial cells by VEGF-R2 signaling.