title: SDF-1α/CXCR4 signaling mediates digit tip regeneration promoted by BMP-2.
abstract: Previously we demonstrated that BMP signaling is required for endogenous digit tip regeneration, and that treatment with BMP-2 or -7 induces a regenerative response following amputation at regeneration-incompetent levels (Yu et al., 2010, 2012). Both endogenous regeneration and BMP-induced regeneration are associated with the transient formation of a blastema, however the formation of a regeneration blastema in mammals is poorly understood. In this study, we focus on how blastema cells respond to BMP signaling during neonatal digit regeneration in mice. First, we show that blastema cells retain regenerative properties after expansion in vitro, and when re-introduced into the amputated digit, these cells display directed migration in response to BMP-2. However, in vitro studies demonstrate that BMP-2 alone does not influence blastema cell migration, suggesting a requirement of another pivotal downstream factor for cell recruitment. We show that blastema cell migration is stimulated by the cytokine, SDF-1α, and that SDF-1α is expressed by the wound epidermis as well as endothelial cells of the blastema. Blastema cells express both SDF-1α receptors, CXCR4 and CXCR7, although the migration response is inhibited by the CXCR4-specific antagonist, AMD3100. Mice treated with AMD3100 display a partial inhibition of skeletal regrowth associated with the regeneration response. We provide evidence that BMP-2 regulates Sdf-1α expression in endothelial cells but not cells of the wound epidermis. Finally, we show that SDF-1α-expressing COS1 cells engrafted into a regeneration-incompetent digit amputation wound resulted in a locally enhanced population of CXCR4 positive cells, and induced a partial regenerative response. Taken together, this study provides evidence that one downstream mechanism of BMP signaling during mammalian digit regeneration involves activation of SDF-1α/CXCR4 signaling by endothelial cells to recruit blastema cells.
authors.affiliation: Division of Developmental Biology, Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Jangwoo
authors.initials: J
authors.lastname: Lee
authors.forename: Luis
authors.initials: L
authors.lastname: Marrero
authors.forename: Ling
authors.initials: L
authors.lastname: Yu
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Dawson
authors.forename: Ken
authors.initials: K
authors.lastname: Muneoka
authors.forename: Manjong
authors.initials: M
authors.lastname: Han
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D019556:COS Cells; D002465:Cell Movement / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000378:metabolism*; D002522:Chlorocebus aethiops; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005121:Extremities / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects; D019718:Receptors, CXCR4 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D012038:Regeneration / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D055396:Bone Morphogenetic Protein 2; D054377:Chemokine CXCL12; D019718:Receptors, CXCR4; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2
keywords: BMP-2/7; Blastema cells; Mice; Migration; Regeneration; SDF-1α/CXCR4