title: Fibronectin assembly during early embryo development: A versatile communication system between cells and tissues.
abstract: BACKGROUND
  Fibronectin extracellular matrix is essential for embryogenesis. Its assembly is a cell-mediated process where secreted fibronectin dimers bind to integrin receptors on receiving cells, which actively assemble fibronectin into a fibrillar matrix. During development, paracrine communication between tissues is crucial for coordinating morphogenesis, typically being mediated by growth factors and their receptors. Recent reports of situations where fibronectin is produced by one tissue and assembled by another, with implications on tissue morphogenesis, suggest that fibronectin assembly may also be a paracrine communication event in certain contexts.
  
  
  RESULTS
  Here we addressed which tissues express fibronectin (Fn1) while also localizing assembled fibronectin matrix and determining the mRNA expression and/or protein distribution pattern of integrins α5 and αV, α chains of the major fibronectin assembly receptors, during early chick and mouse development. We found evidence supporting a paracrine system in fibronectin matrix assembly in several tissues, including immature mesenchymal tissues, components of central and peripheral nervous system and developing muscle.
  
  
  CONCLUSIONS
  Thus, similarly to growth factor signaling, fibronectin matrix assembly during early development can be both autocrine and paracrine. We therefore propose that it be considered a cell-cell communication event at the same level and significance as growth factor signaling during embryogenesis.
authors: Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
authors: Patrícia Gomes
authors: PG
authors: de Almeida
authors: Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
authors: Gonçalo G
authors: GG
authors: Pinheiro
authors: Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
authors: Andreia M
authors: AM
authors: Nunes
authors: Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
authors: André B
authors: AB
authors: Gonçalves
authors: Centre for Ecology, Evolution and Environmental Change (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
authors: Sólveig
authors: S
authors: Thorsteinsdóttir
mesh_terms: D000818:Animals; D019898:Autocrine Communication / Q000502:physiology*; D030161:Avian Proteins / Q000378:metabolism*; D002642:Chick Embryo; D004622:Embryo, Mammalian / Q000196:embryology*; D047108:Embryonic Development / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D051379:Mice; D019899:Paracrine Communication / Q000502:physiology*
chemical_list: D030161:Avian Proteins; D005353:Fibronectins
keywords: autocrine signaling; embryogenesis; extracellular matrix; fibronectin; integrin alpha 5; paracrine signaling