title: Epidermal growth factor and perlecan fragments produced by apoptotic endothelial cells co-ordinately activate ERK1/2-dependent antiapoptotic pathways in mesenchymal stem cells.
abstract: Mounting evidence indicates that mesenchymal stem cells (MSC) are pivotal to vascular repair and neointima formation in various forms of vascular disease. Yet, the mechanisms that allow MSC to resist apoptosis at sites where other cell types, such as endothelial cells (EC), are dying are not well defined. In the present work, we demonstrate that apoptotic EC actively release paracrine mediators which, in turn, inhibit apoptosis of MSC. Serum-free medium conditioned by apoptotic EC increases extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation and inhibits apoptosis (evaluated by Bcl-xL protein levels and poly (ADP-ribose) polymerase cleavage) of human MSC. A C-terminal fragment of perlecan (LG3) released by apoptotic EC is one of the mediators activating this antiapoptotic response in MSC. LG3 interacts with beta1-integrins, which triggers downstream ERK1/2 activation in MSC, albeit to a lesser degree than medium conditioned by apoptotic EC. Hence, other mediators released by apoptotic EC are probably required for induction of the full antiapoptotic phenotype in MSC. Adopting a comparative proteomic strategy, we identified epidermal growth factor (EGF) as a novel mediator of the paracrine component of the endothelial apoptotic program. LG3 and EGF cooperate in triggering beta1-integrin and EGF receptor-dependent antiapoptotic signals in MSC centering on ERK1/2 activation. The present work, providing novel insights into the mechanisms facilitating the survival of MSC in a hostile environment, identifies EGF and LG3 released by apoptotic EC as central antiapoptotic mediators involved in this paracrine response.
authors.affiliation: Centre de recherche, Centre hospitalier de l'Université de Montréal - Hôpital Notre-Dame, Université de Montréal, Montreal, QC, Canada.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Soulez
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sirois
authors.forename: Nathalie
authors.initials: N
authors.lastname: Brassard
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Raymond
authors.forename: Frédéric
authors.initials: F
authors.lastname: Nicodème
authors.forename: Nicolas
authors.initials: N
authors.lastname: Noiseux
authors.forename: Yves
authors.initials: Y
authors.lastname: Durocher
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Pshezhetsky
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Hébert
mesh_terms: D017209:Apoptosis; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*
chemical_list: D019812:Heparan Sulfate Proteoglycans; C071927:perlecan; D004815:Epidermal Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3