Vascular endothelial cells (VECs) play an essential role in regulating the passage
of macromolecules and cells between the blood stream and underlying tissues. The
second messenger 3’, 5’ cyclic adenosine monophosphate (cAMP) regulates numerous
events in VECs, including permeability. Since human VECs express several distinct
cAMP-hydrolyzing phosphodiesterases (PDEs), and these are the only enzymes that
catalyze the inactivation of cAMP, we investigated if selective pharmacological
inhibition of PDEs could impact VEC permeability. Interestingly, we found that PDE4
inhibitors decreased human aortic VEC (HAEC) permeability and PDE4 and PDE3
inhibitors decreased human microvascular VEC (HMVEC) permeability. Consistent with
a role for both protein kinase A (PKA) and exchange protein activated by cAMP (EPAC)
in regulating VEC permeability, selective activators of these enzymes significantly
decreased permeability. Since neither PDE4 nor PDE3 inhibitors significantly increased
cAMP in these cells, our data are consistent with the idea that PDE inhibition causes
small localized increases in “pools” of cAMP that regulate permeability. In order to test
if PDE4 enzymes could act locally on pools of cAMP that regulated permeability, we
selectively isolated the adherens junctional protein VE-cadherin from confluent
monolayers of HAECs or HMVECs, and immunoblotted these isolates for cAMPeffectors
and PDEs. Briefly, we found that each PKA-II, EPAC1, and a PDE4D variant,
but not PDE3 enzymes, each could be isolated in VE-cadherin-based complexes from
these cells. These novel findings identify PKA-II, EPAC1, and PDE4D as members of
VE-cadherin-based signaling complexes in human VECs and are consistent with the idea
that localized cAMP-signaling regulates permeability in these cells. / Thesis (Master, Pathology & Molecular Medicine) -- Queen's University, 2007-09-14 15:52:20.216
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/678 |
| Date | 17 September 2007 |
| Creators | Ovens, Jeffrey David |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 7915699 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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