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  • Endothelial lipid phosphate phosphatase-3 deficiency that disrupts the endothelial barrier function is a modifier of cardiovascular development.

Endothelial lipid phosphate phosphatase-3 deficiency that disrupts the endothelial barrier function is a modifier of cardiovascular development.

Cardiovascular research (2016-04-30)
Ishita Chatterjee, Jugajyoti Baruah, Erin E Lurie, Kishore K Wary
ABSTRACT

Lipid phosphate phosphatase-3 (LPP3) is expressed at high levels in endothelial cells (ECs). Although LPP3 is known to hydrolyse the phosphate group from lysolipids such as spingosine-1-phosphate and its structural homologues, the function of Lpp3 in ECs is not completely understood. In this study, we investigated how tyrosine-protein kinase receptor (TEK or Tie2) promoter-dependent deletion of Lpp3 alters EC activities. Lpp3(fl/fl) mice were crossed with the tg.Tie2(Cre) transgenic line. Vasculogenesis occurred normally in embryos with Tie2(Cre)-mediated deletion of Lpp3 (called Lpp3(ECKO)), but embryonic lethality occurred in two waves, the first wave between E8.5 and E10.5, while the second between E11.5 and E13.5. Lethality in Lpp3(ECKO) embryos after E11.5 was accompanied by vascular leakage and haemorrhage, which likely resulted in insufficient cardiovascular development. Analyses of haematoxylin- and eosin-stained heart sections from E11.5 Lpp3(ECKO) embryos showed insufficient heart growth associated with decreased trabeculation, reduced growth of the compact wall, and absence of cardiac cushions. Staining followed by microscopic analyses of Lpp3(ECKO) embryos revealed the presence of apoptotic ECs. Furthermore, Lpp3-deficient ECs showed decreased gene expression and protein levels of Cyclin-D1, VE-cadherin, Fibronectin, Klf2, and Klf4. To determine the underlying mechanisms of vascular leakage and barrier disruption, we performed knockdown and rescue experiments in cultured ECs. LPP3 knockdown decreased transendothelial electrical resistance and increased permeability. Re-expression of β-catenin cDNA in LPP3-knockdown ECs partially restored the effect of the LPP3 loss, whereas re-expression of p120ctn cDNA did not. These findings demonstrate the essential roles of LPP3 in the maturation of EC barrier integrity and normal cardiovascular development.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-PPAP2A (AB1) antibody produced in rabbit, IgG fraction of antiserum
Sigma-Aldrich
Anti-β-Catenin antibody produced in rabbit, whole antiserum
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Anti-β-Catenin−Cy3 antibody, Mouse monoclonal, clone 15B8, purified from hybridoma cell culture
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Anti-von Willebrand Factor Antibody, Chemicon®, from rabbit