title: P2Y2 receptor represses IL-6 expression by valve interstitial cells through Akt: implication for calcific aortic valve disease.
abstract: Calcific aortic valve disease (CAVD) is a disorder characterized by an abnormal mineralization, which may have intricate links with inflammation. Interleukin-6 (IL-6) and its cognate cytokines are widely expressed and exert pleiotropic effects on different tissues. In this study, we examined the expression of the IL-6 family of cytokines in human CAVD by using a transcriptomic approach and we performed in-depth functional assays with valve interstitial cells (VICs) to unravel the process regulating IL-6 expression and its role during the mineralization of the aortic valve. We documented by both microarray and q-PCR analyses an elevated expression of IL-6 in human CAVD, which was correlated with the remodeling process. IL-6 was highly expressed by VICs. We found that following treatment with a phosphate-containing medium the level of IL-6 expressed by VICs increased by several-fold. Phosphate-induced expression of IL-6 relied on reduced PI3K/Akt signaling downstream of the P2Y2 receptor (P2Y2R). In this regard, we found by using transfection experiments that Akt-1 is a negative regulator of the NF-κB pathway. In addition, by using a siRNA targeting IL-6 we found that phosphate-induced mineralization was largely dependent on IL-6 expression. A transfection of Akt-1 rescued the hypermineralizing phenotype of P2Y2R(-/-) mouse VICS (MVICs). Hence, we documented a novel mechanism whereby P2Y2R and Akt modulate the NF-κB pathway and its downstream target IL-6, which is a strong promoter of the mineralization of VICs.
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Diala
authors.initials: D
authors.lastname: El Husseini
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Marie-Chloé
authors.initials: MC
authors.lastname: Boulanger
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Ablajan
authors.initials: A
authors.lastname: Mahmut
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Rihab
authors.initials: R
authors.lastname: Bouchareb
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Laflamme
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Fournier
authors.affiliation: Quebec Heart and Lung Institute/Research Center, Laval University, Québec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Pibarot
authors.affiliation: Quebec Heart and Lung Institute/Research Center, Laval University, Québec, Canada; Department of Molecular Medicine, Laval University, Québec, Canada.
authors.forename: Yohan
authors.initials: Y
authors.lastname: Bossé
authors.affiliation: Laboratoire d'Études Moléculaires des Valvulopathies (LEMV), Groupe de Recherche en Valvulopathies (GRV), Quebec Heart and Lung Institute/Research Center, Department of Surgery, Laval University, Quebec, Canada. Electronic address: patrick.mathieu@chg.ulaval.ca.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mathieu
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002114:Calcinosis / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D000093242:Interleukin-6 Inhibitors
chemical_list: D003470:Culture Media; D015850:Interleukin-6; D016328:NF-kappa B; D010710:Phosphates; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D058473:Receptors, Purinergic P2Y2; D000093242:Interleukin-6 Inhibitors
keywords: Aortic stenosis; Calcific aortic stenosis; Calcific aortic valve disease; IL-6; NF-kappa B; P2Y2 receptor