Vascular endothelial cells synthesize a plasma membrane protein indistinguishable from the platelet membrane glycoprotein IIa.

Mechanosensing followed by mechanoresponses by cells is well established, but the mechanisms by which mechanical force is converted into biochemical events are poorly understood. Vascular endothelial cells (ECs) exhibit flow- and stretch-dependent responses and are widely used as a model for studying mechanotransduction in mammalian cells. Platelet EC adhesion molecule 1 (PECAM-1) is tyrosine phosphorylated when ECs are exposed to flow or when PECAM-1 is directly pulled, suggesting that it is a mechanochemical converter. We show that PECAM-1 phosphorylation occurs when detergent-extracted EC monolayers are stretched, indicating that this phosphorylation is mechanically triggered and does not require the intact plasma membrane and soluble cytoplasmic components. Using kinase inhibitors and small interfering RNAs, we identify Fyn as the PECAM-1 kinase associated with the model. We further show that stretch- and flow-induced PECAM-1 phosphorylation in intact ECs is abolished when Fyn expression is down-regulated. We suggest that PECAM-1 and Fyn are essential components of a PECAM-1–based mechanosensory complex in ECs.

Download Full-text

A mathematical model of plasma membrane electrophysiology and calcium dynamics in vascular endothelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.00542.2006 ◽

2007 ◽

Vol 293 (1) ◽

pp. C277-C293 ◽

Cited By ~ 46

Author(s):

Haroldo S. Silva ◽

Adam Kapela ◽

Nikolaos M. Tsoukias

Keyword(s):

Mathematical Model ◽

Endothelial Cells ◽

Plasma Membrane ◽

Vascular Tone ◽

Vascular Endothelial Cells ◽

Anion Channel ◽

Ionic Species ◽

Vascular Endothelial ◽

Health And Disease ◽

Vascular Autoregulation

Vascular endothelial cells (ECs) modulate smooth muscle cell (SMC) contractility, assisting in vascular tone regulation. Cytosolic Ca2+ concentration ([Ca2+]i) and membrane potential ( Vm) play important roles in this process by controlling EC-dependent vasoactive signals and intercellular communication. The present mathematical model integrates plasmalemma electrophysiology and Ca2+ dynamics to investigate EC responses to different stimuli and the controversial relationship between [Ca2+]i and Vm. The model contains descriptions for the intracellular balance of major ionic species and the release of Ca2+ from intracellular stores. It also expands previous formulations by including more detailed transmembrane current descriptions. The model reproduces Vm responses to volume-regulated anion channel (VRAC) blockers and extracellular K+ concentration ([K+]o) challenges, predicting 1) that Vm changes upon VRAC blockade are [K+]o dependent and 2) a biphasic response of Vm to increasing [K+]o. Simulations of agonist-induced Ca2+ mobilization replicate experiments under control and Vm hyperpolarization blockade conditions. They show that peak [Ca2+]i is governed by store Ca2+ release while Ca2+ influx (and consequently Vm) impacts more the resting and plateau [Ca2+]i. The Vm sensitivity of rest and plateau [Ca2+]i is dictated by a [Ca2+]i “buffering” system capable of masking the Vm-dependent transmembrane Ca2+ influx. The model predicts plasma membrane Ca2+-ATPase and Ca2+ permeability as main players in this process. The heterogeneous Vm impact on [Ca2+]i may elucidate conflicting reports on how Vm influences EC Ca2+. The present study forms the basis for the development of multicellular EC-SMC models that can assist in understanding vascular autoregulation in health and disease.

Download Full-text

Ectoadenylate Kinase and Plasma Membrane ATP Synthase Activities of Human Vascular Endothelial Cells

Journal of Biological Chemistry ◽

10.1074/jbc.m513042200 ◽

2006 ◽

Vol 281 (30) ◽

pp. 20728-20737 ◽

Cited By ~ 23

Author(s):

Ellen E. Quillen ◽

Gale C. Haslam ◽

Hardeep S. Samra ◽

Darius Amani-Taleshi ◽

Jeffrey A. Knight ◽

...

Keyword(s):

Endothelial Cells ◽

Plasma Membrane ◽

Atp Synthase ◽

Vascular Endothelial Cells ◽

Vascular Endothelial

Download Full-text

Cultured human endothelial cells synthesize a plasma membrane protein complex immunologically related to the platelet glycoprotein IIb/IIIa complex

Blood ◽

10.1182/blood.v67.4.1176.1176 ◽

1986 ◽

Vol 67 (4) ◽

pp. 1176-1180 ◽

Cited By ~ 26

Author(s):

OC Leeksma ◽

J Zandbergen-Spaargaren ◽

JC Giltay ◽

JA van Mourik

Keyword(s):

Endothelial Cells ◽

Plasma Membrane ◽

Endothelial Cell ◽

Membrane Protein ◽

Protein Complex ◽

Platelet Glycoprotein ◽

Plasma Membrane Protein ◽

Human Endothelial Cells ◽

Membrane Protein Complex ◽

Crossed Immunoelectrophoresis

Abstract We have previously demonstrated that endothelial cells synthesize a plasma membrane protein indistinguishable from platelet glycoprotein (GP) IIa. The present study provides evidence for a further analogy between the platelet and the endothelial cell membrane by showing that cultured endothelial cells also synthesize a membrane protein complex immunologically related to the platelet GP IIb/GP IIIa complex. This evidence is based on the following observations: (1) C17, a murine monoclonal antiplatelet GP IIIa antibody, consistently precipitates two proteins, apparent molecular weights, respectively, 115,000 and 125,000 reduced and 95,000 and 135,000 nonreduced, from metabolically (35S- methionine) as well as surface 125I-labeled cultured human endothelial cells; (2) upon crossed immunoelectrophoresis of solubilized endothelial cells against a polyclonal rabbit antiplatelet antiserum and 125I-labeled C17 IgG, a single precipitate of the protein(s) recognized by C17 is observed. As judged by their mobility in 9% polyacrylamide gels, both endothelial proteins appear to have a somewhat larger molecular weight than their platelet counterparts. Patterns obtained by crossed immunoelectrophoresis are also indicative of a difference in electrophoretic behavior of the platelet GP IIb/IIIa complex and the endothelial cell protein complex.

Download Full-text