Pleiotrophin expression and role in physiological angiogenesis in vivo: potential involvement of nucleolinReportar como inadecuado

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Vascular Cell

, 4:4

First Online: 16 March 2012Received: 03 December 2011Accepted: 16 March 2012


BackgroundPleiotrophin PTN is a heparin-binding growth factor with significant roles in tumour growth and angiogenesis. Although implication of endogenous PTN has been studied in several in vivo models of tumour angiogenesis, its role in physiological angiogenesis has not been addressed. In the present work, we studied expression and functional significance of endogenous PTN during angiogenesis in the chicken embryo chorioallantoic membrane CAM.

MethodsUsing molecular, cellular and biochemical assays, we studied the expression pattern of PTN in CAM and human endothelial cells and its possible interaction with nucleolin NCL. CAM cells were transfected with a pCDNA3.1 vector, empty PC or containing full length cDNA for PTN in antisense orientation AS-PTN. Angiogenesis was estimated by measuring total vessel length. In vitro, human endothelial cells migration was studied by using a transwell assay, and down-regulation of NCL was performed by using a proper siRNA.

ResultsEndogenous PTN mRNA and protein levels, as well as protein levels of its receptor protein tyrosine phosphatase beta-zeta RPTPβ-ζ were maximal at early stages, when CAM angiogenesis is active. Application of AS-PTN onto CAM at days of active angiogenesis was not toxic to the tissue and led to dose-dependent decreased expression of endogenous PTN, ERK1-2 activity and angiogenesis. Interestingly, endogenous PTN was also immunolocalized at the endothelial cell nucleus, possibly through interaction with NCL, a protein that has a significant role in the nuclear translocation of many proteins. Down-regulation of NCL by siRNA in human endothelial cells significantly decreased nuclear PTN, verifying this hypothesis. Moreover, it led to abolishment of PTN-induced endothelial cell migration, suggesting, for the first time, that PTN-NCL interaction has a functional significance.

ConclusionsExpression of endogenous PTN correlates with and seems to be involved in angiogenesis of the chicken embryo CAM. Our data suggest that NCL may have a role, increasing the number of growth factors whose angiogenic-tumorigenic activities are mediated by NCL.

Keywordsangiogenesis endothelial cells migration nucleolin pleiotrophin receptor protein tyrosine phosphatase Electronic supplementary materialThe online version of this article doi:10.1186-2045-824X-4-4 contains supplementary material, which is available to authorized users.

Marina Koutsioumpa, Georgia Drosou contributed equally to this work.

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Autor: Marina Koutsioumpa - Georgia Drosou - Constantinos Mikelis - Katerina Theochari - Dionussios Vourtsis - Panagiotis Katsoris


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