Uncoupling of Elastin Complex Receptor during In Vitro Aging Is Related to Modifications in Its Intrinsic Sialidase Activity and the Subsequent Lactosylceramide Production

Abstract

Degradation of elastin leads to the production of elastin-derived peptides (EDP), which exhibit several biological effects, such as cell proliferation or protease secretion. Binding of EDP on the elastin receptor complex (ERC) triggers lactosylceramide (LacCer) production and ERK1/2 activation following ERC Neu-1 subunit activation. The ability for ERC to transduce signals is lost during aging, but the mechanism involved is still unknown. In this study, we characterized an in vitro model of aging by subculturing human dermal fibroblasts. This model was used to understand the loss of EDP biological activities during aging. Our results show that ERC uncoupling does not rely on Neu-1 or PPCA mRNA or protein level changes. Furthermore, we observe that the membrane targeting of these subunits is not affected with aging. However, we evidence that Neu-1 activity and LacCer production are altered. Basal Neu-1 catalytic activity is strongly increased in aged cells. Consequently, EDP fail to promote Neu-1 catalytic activity and LacCer production in these cells. In conclusion, we propose, for the first time, an explanation for ERC uncoupling based on the age-related alterations of Neu-1 activity and LacCer production that may explain the loss of EDP-mediated effects occurring during aging.

The VGVAPG Peptide Regulates the Production of Nitric Oxide Synthases and Reactive Oxygen Species in Mouse Astrocyte Cells In Vitro

“…Our experiments are the first to show that the VGVAPG peptide in a wide range of concentrations (100 pM to 100 µM) increased ROS production in astrocytes. To date, it has been described that EDPs induce ROS production in murine monocyte and human fibroblasts [ 17 , 18 , 27 ]. Gmiński et al [ 19 ] stated that κ-elastin increased both the activity of antioxidant enzymes (SOD, CAT, GSH-Px) and the lipid peroxide concentration within fibroblasts [ 19 ].…”

“…Moreover, ROS increased mRNA expression of elastin in human skin fibroblasts in vitro [ 16 ]. Simultaneously, EDPs have been reported to induce ROS production in monocytes and human fibroblasts, thus accelerating the ROS generation process [ 17 , 18 ]. On the other hand, EDPs also increase the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) or glutathione peroxidase (GSH-Px), with a simultaneous increase in lipid peroxidation in human fibroblasts [ 19 ].…”

“…The Val-Gly-Val-Ala-Pro-Gly (VGVAPG) peptide, repeated several times in the elastin molecule, is the best characterised ligand that binds to EBP with high affinity [ 26 ]. To date, it has been shown that κ-elastin and the VGVAPG peptide do not affect ROS production in human dermal fibroblasts [ 18 ] or increase ROS production in murine monocytes [ 27 ]. Conversely, the VGVAPG peptide reduced ROS production in the neutrophils in control patients and in patients with stable chronic obstructive pulmonary disease (COPD) [ 28 ].…”

Matrix ageing and vascular impacts: focus on elastin fragmentation

“…Recently, our group has demonstrated that ERC uncoupling observed during ageing involves a rise in basal Neu-1 activity to a level too high to be modulated by EDP stimulation. 42 Consequently, EDPmediated lactosylceramide production and Neu-1 sialidase activity are reduced in ageing cells. These results, proposing that age-related ERC uncoupling could originate from its inability to regulate Neu-1 activity and lactosylceramide production, are of crucial importance considering the fact that EDP biological effects could not only vary during ageing, but also that pharmacological approaches targeting this peculiar receptor have to be adapted.…”

The Elastin Receptor Complex: A Unique Matricellular Receptor with High Anti-tumoral Potential

“…EBP possesses two functional binding sites: the elastin site on which EDP binding triggers signaling pathways, and the galactolectin site whom occupancy by galactosugars induces EDP release and dissociation of the complex ( Mecham et al, 1991 ). When EDP bind to EBP, neuraminidase-1 is activated and catalyzes the desialylation of adjacent gangliosides such as GM 3 [ N -acetylneuraminic-α-(2-3)-galactosyl-β-(1-4)-glucosyl-(1-1′)-ceramide] generating lactosylceramide (LacCer) production ( Rusciani et al, 2010 ; Scandolera et al, 2015 ). LacCer is a second messenger able to activate intracellular signals.…”