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This Article Full Text Full Text (PDF) Supplemental Videos All Versions of this Article: 296/2/L220    most recent 90474.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Zhu, B. Articles by Stevens, T. Search for Related Content PubMed PubMed Citation Articles by Zhu, B. Articles by Stevens, T.

Type 5 phosphodiesterase expression is a critical determinant of the endothelial cell angiogenic phenotype

Departments of ¹Pharmacology, ²Cell Biology and Neuroscience, ³Center for Lung Biology, University of South Alabama, Mobile, Alabama

Submitted 5 September 2008 ; accepted in final form 20 November 2008

Type 5 phosphodiesterase (PDE5) inhibitors increase endothelial cell cGMP and promote angiogenesis. However, not all endothelial cell phenotypes express PDE5. Indeed, whereas conduit endothelial cells express PDE5, microvascular endothelial cells do not express this enzyme, and they are rapidly angiogenic. These findings bring into question whether PDE5 activity is a critical determinant of the endothelial cell angiogenic potential. To address this question, human full-length PDE5A1 was stably expressed in pulmonary microvascular endothelial cells. hPDE5A1 expression reduced the basal and atrial natriuretic peptide (ANP)-stimulated cGMP concentrations in these cells. hPDE5A1-expressing cells displayed attenuated network formation on Matrigel in vitro and also produced fewer blood vessels in Matrigel plug assays in vivo; the inhibitory actions of hPDE5A1 were reversed using sildenafil. To examine whether endogenous PDE5 activity suppresses endothelial cell angiogenic potential, small interfering RNA (siRNA) constructs were stably expressed in pulmonary artery endothelial cells. siRNA selectively decreased PDE5 expression and increased basal and ANP-stimulated cGMP concentrations in these conduit cells. PDE5 downregulation increased network formation on Matrigel in vitro and increased blood vessel formation in Matrigel plug assays in vivo. Collectively, our results indicate that PDE5 activity is an essential determinant of angiogenesis and suggest that PDE5 downregulation in microvascular endothelium imparts a stable, enhanced angiogenic potential to this cell type.

vasculogenesis; migration; proliferation; nitric oxide; sildenafil