Nuclear and cytoplasmic free calcium level changes induced by elastin peptides in human endothelial cells

Abstract

The extracellular matrix protein ''elastin'' is the major component of elastic fibers present in the arterial wall. Physiological degradation of elastic fibers, enhanced in vascular pathologies, leads to the presence of circulating elastin peptides (EP). EP have been demonstrated to inf luence cell migration and proliferation. EP also induce, at circulating pathophysiological concentrations (and not below), an endothelium-and NO-dependent vasorelaxation mediated by the 67-kDa subunit of the elastin-laminin receptor. Here, by using the techniques of patch-clamp, spectrof luorimetry and confocal microscopy, we demonstrate that circulating concentrations of EP activate low specificity calcium channels on human umbilical venous endothelial cells, resulting in increase in cytoplasmic and nuclear free calcium concentrations. This action is independent of phosphoinositide metabolism. Furthermore, these effects are inhibited by lactose, an antagonist of the elastin-laminin receptor, and by cytochalasin D, an actin microfilament depolymerizer. These observations suggest that EP-induced signal transduction is mediated by the elastin-laminin receptor via coupling of cytoskeletal actin microfilaments to membrane channels and to the nucleus. Because vascular remodeling and carcinogenesis are accompanied by extracellular matrix modifications involving elastin, the processes here described could play a role in the elastin-laminin receptor-mediated cellular migration, differentiation, proliferation, as in atherogenesis, and metastasis formation.Elastic fibers in arteries, pulmonary alveolar septa, certain ligaments and skin are normally subjected to stretching. In vascular walls, elastic fibers organize into concentric sheets that endow the arteries with resiliency. In physiological conditions, elastin is synthesized only during the late stages of gestation and early infancy. Although elastin is a stable protein (1), a slow and regular elastin degradation mediated by specialized proteases-the elastases-occurs, contributing to the age-dependent increase in vessel stiffness. This process leads to the presence of elastin peptides (EP) in the circulation (10) (2, 3), increased in some vascular pathologies, as for instance arteriosclerosis (3, 4). EP influence cell migration (5) and proliferation (6) and, in adult rats, EP induce, at circulating concentrations (and not below), an endothelium-dependent vasodilation mediated by NO (7). EP act via binding to the 67-kDa subunit of the high affinity elastin-laminin receptor, present on the cell membranes of the vascular endothelial cells and on numerous other cell types, including arterial medial smooth muscle cells (8-11). Moreover, activation of the 67-kDa subunit of the elastin-laminin receptor also produces a variety of biological reactions, as for instance modifying cell migration (12), differentiation (13), proliferation (6), and enhancing metastatic potential of transformed cells (14,15). The presence and density of the 67-kDa subunit on transformed cell membranes was clai...

Elastin-derived peptides enhance angiogenesis by promoting endothelial cell migration and tubulogenesis through upregulation of MT1-MMP

“…Cell responses to EDPs were often attributed to the binding of a VGVAPG hexapeptide sequence, repeated several times in tropoelastin, the soluble precursor form of elastin, to a unique sequence of S-Gal, encoded by the frame shifted exon 5 of β-galactosidase. Previous investigations indicated that the VGV tripeptide could represent the core sequence in EDPs, mediating their potent influence on vascular tone through increased intracellular calcium in endothelial cells (Faury et al, 1995;Faury et al, 1998a;Faury et al, 1998b). Conversely, a type VIII β-turn conformation adopted by elastin peptides with the GXXPG sequence was mainly involved in directing matrix metalloproteinase expression in fibroblasts and fibrosarcoma cells in culture Huet et al, 2002).…”

“…In addition, EDPs, at a concentration averaging that present in the circulation (Kucich et al, 1983;Fülöp et al, 1990), activate low specificity calcium channels in human umbilical venous endothelial cells (HUVECs), leading to an enhancement of cytoplasmic and nuclear-free calcium concentration (Faury et al, 1998a). Such modifications in calcium flux induce an endotheliumdependent vasodilatation that can be suppressed by an inhibitor of nitric oxide production (Faury et al, 1995;Faury et al, 1998a;Faury et al, 1998b).…”

Microfibrils and fibrillin-1 induce integrin-mediated signaling, proliferation and migration in human endothelial cells

“…Human umbilical venous endothelial cells (HUVEC) were isolated using a technique adapted from Jaffe et al (19,29). Cells were harvested from the umbilical vein by a 10-min incubation at 37°C with collagenase 1A and cultured in 0.25 mg/ml human fibronectincoated dishes in medium 199 containing 22% human serum, streptomycin (0.1 mg/ml), penicillin (100 UI/m), and L-glutamine (2 mmol/ l).…”

Atherosclerosis and Matrix Dystrophy

“…Then, NO production induces a short-term vasorelaxation, counterbalancing the hypertensive and vasoconstrictive effect of atherosclerosis. Elastin peptides, circulating degradation products of extracellular matrix, could play a role in altering gene expression or influencing cell motility and differentiation (50).…”