title: Wnt/β-catenin signaling mediates osteoblast differentiation triggered by peptide-induced α5β1 integrin priming in mesenchymal skeletal cells.
abstract: The α5β1 integrin is a key fibronectin (FN) receptor that binds to RGD-containing peptides to mediate cell adhesion. We previously reported that α5β1 integrin promotes osteogenic differentiation in mesenchymal skeletal cells (MSCs), but the underlying mechanisms are not fully understood. In this study, we determined the signaling mechanisms induced by α5β1 integrin interaction with its high-affinity ligand CRRETAWAC in murine and human MSCs and in vivo. We show that cyclized CRRETAWAC fully displaced MSC adhesion to FN, whereas related peptides lacking the full RRET sequence produced a partial displacement, indicating that RRET acts as an RGD-like sequence that is required to antagonize FN-mediated cell adhesion. However, all peptides increased focal adhesion kinase phosphorylation, OSE2 transcriptional activity, osteoblast gene expression, and matrix mineralization in MSCs, indicating that peptide-induced α5β1 integrin priming can promote osteogenic differentiation independently of the RRET sequence. Biochemical analyses showed that peptide-induced α5β1 integrin priming transiently increased PI3K/Akt phosphorylation and promoted Wnt/β-catenin transcriptional activity independently of RRET. Consistently, pharmacological inhibition of PI3K activity reduced osteoblast differentiation and abolished Wnt regulatory gene expression induced by α5β1 integrin priming. In vivo, systemic delivery of cyclized GACRETAWACGA linked to (DSS)6 to allow delivery to bone-forming sites for 6 weeks increased serum osteocalcin levels and improved long bone mass and microarchitecture in SAMP-6 senescent osteopenic mice. The results support a mechanism whereby α5β1 integrin priming by high-affinity ligands integrates Wnt/β-catenin signaling to promote osteoblast differentiation independently of cell adhesion, which could be used to improve bone mass and microarchitecture in the aging skeleton.
authors: From UMR-1132 INSERM, 75475 Paris Cedex 10, France, the Université Paris Diderot, Sorbonne Paris Cité, Paris, France, and.
authors: Zuzana
authors: Z
authors: Saidak
authors: From UMR-1132 INSERM, 75475 Paris Cedex 10, France, the Université Paris Diderot, Sorbonne Paris Cité, Paris, France, and.
authors: Carole
authors: C
authors: Le Henaff
authors: From UMR-1132 INSERM, 75475 Paris Cedex 10, France, the Université Paris Diderot, Sorbonne Paris Cité, Paris, France, and.
authors: Sofia
authors: S
authors: Azzi
authors: From UMR-1132 INSERM, 75475 Paris Cedex 10, France, the Université Paris Diderot, Sorbonne Paris Cité, Paris, France, and.
authors: Caroline
authors: C
authors: Marty
authors: the Equipe Théra, Laboratoire de Glycochimie, des Antimicrobiens, et des Agroressources (LG2A)-FRE-CNRS 3517, UFR de Pharmacie, Université de Picardie Jules Verne, 80037 Amiens Cedex 1, France.
authors: Sophie
authors: S
authors: Da Nascimento
authors: the Equipe Théra, Laboratoire de Glycochimie, des Antimicrobiens, et des Agroressources (LG2A)-FRE-CNRS 3517, UFR de Pharmacie, Université de Picardie Jules Verne, 80037 Amiens Cedex 1, France.
authors: Pascal
authors: P
authors: Sonnet
authors: From UMR-1132 INSERM, 75475 Paris Cedex 10, France, the Université Paris Diderot, Sorbonne Paris Cité, Paris, France, and pierre.marie@inserm.fr.
authors: Pierre J
authors: PJ
authors: Marie
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001851:Bone Diseases, Metabolic / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000187:drug effects*; D051176:beta Catenin / Q000378:metabolism
chemical_list: D039081:Integrin alpha5beta1; D009842:Oligopeptides; D051176:beta Catenin; D019869:Phosphatidylinositol 3-Kinases
keywords: Bone; CRRETAWAC; Cell Differentiation; Integrin; Osteoblast; Osteopenic Mice; Wnt Signaling
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