title: The Role of Sdf-1α signaling in Xenopus laevis somite morphogenesis.
abstract: BACKGROUND
  Stromal derived factor-1α (sdf-1α), a chemoattractant chemokine, plays a major role in tumor growth, angiogenesis, metastasis, and in embryogenesis. The sdf-1α signaling pathway has also been shown to be important for somite rotation in zebrafish (Hollway et al., 2007). Given the known similarities and differences between zebrafish and Xenopus laevis somitogenesis, we sought to determine whether the role of sdf-1α is conserved in Xenopus laevis.
  
  
  RESULTS
  Using a morpholino approach, we demonstrate that knockdown of sdf-1α or its receptor, cxcr4, leads to a significant disruption in somite rotation and myotome alignment. We further show that depletion of sdf-1α or cxcr4 leads to the near absence of β-dystroglycan and laminin expression at the intersomitic boundaries. Finally, knockdown of sdf-1α decreases the level of activated RhoA, a small GTPase known to regulate cell shape and movement.
  
  
  CONCLUSIONS
  Our results show that sdf-1α signaling regulates somite cell migration, rotation, and myotome alignment by directly or indirectly regulating dystroglycan expression and RhoA activation. These findings support the conservation of sdf-1α signaling in vertebrate somite morphogenesis; however, the precise mechanism by which this signaling pathway influences somite morphogenesis is different between the fish and the frog.
authors.affiliation: Department of Biology, San Francisco State University, San Francisco, California.
authors.forename: Marisa A
authors.initials: MA
authors.lastname: Leal
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Fickel
authors.forename: Armbien
authors.initials: A
authors.lastname: Sabillo
authors.forename: Julio
authors.initials: J
authors.lastname: Ramirez
authors.forename: Hernando Martínez
authors.initials: HM
authors.lastname: Vergara
authors.forename: Ceazar
authors.initials: C
authors.lastname: Nave
authors.forename: Daniel
authors.initials: D
authors.lastname: Saw
authors.forename: Carmen R
authors.initials: CR
authors.lastname: Domingo
mesh_terms: D000818:Animals; D054377:Chemokine CXCL12 / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000196:embryology*; D009024:Morphogenesis / Q000187:drug effects / Q000502:physiology*; D060172:Morpholinos / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019170:Somites / Q000196:embryology*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D054377:Chemokine CXCL12; D060172:Morpholinos; D029867:Xenopus Proteins; D020742:rhoA GTP-Binding Protein
keywords: RhoA; Xenopus laevis; cxcr4; morphogenesis; muscle; sdf-1α; somite; β-dystroglycan