title: Semaphorin 3A is expressed in human osteoarthritic cartilage and antagonizes vascular endothelial growth factor 165-promoted chondrocyte migration: an implication for chondrocyte cloning.
abstract: OBJECTIVE
  Vascular endothelial growth factor 165 (VEGF165) and its receptors, including neuropilin 1 (NRP-1), are overexpressed in human osteoarthritic (OA) articular cartilage, although their functional roles in the cartilage are not fully understood. An axon-guidance molecule, semaphorin 3A (Sema3A), which binds to NRP-1, acts as an antagonist of VEGF signaling in endothelial cells. The aim of this study was to examine the expression of Sema3A and the functions of the VEGF165/Sema3A/NRP-1 axis in OA cartilage.
  
  
  METHODS
  The expression of Sema3A in OA and normal cartilage samples was examined by real-time polymerase chain reaction and immunohistochemical analyses. Functional analyses of VEGF165 and Sema3A were carried out using OA chondrocytes in culture. The migration activity of chondrocytes was examined in a monolayer wound assay. The effects of Sema3A on VEGF165-induced up-regulation of matrix metalloproteinases (MMPs) and intracellular signaling were also studied in cultured chondrocytes.
  
  
  RESULTS
  Sema3A expression was significantly elevated in OA cartilage as compared to normal cartilage. Sema3A immunoreactivity directly correlated with the Mankin score and with chondrocyte cloning. VEGF165 promoted the migration of chondrocytes, and this activity was suppressed by VEGF receptor 2 tyrosine kinase inhibitors. Sema3A antagonized the chondrocyte migration promoted by VEGF165, and the activity was blocked by a selective inhibitor of, or small interfering RNA for, Sema3A. VEGF165-induced overexpression of MMPs and phosphorylation of ERK and focal adhesion kinase in chondrocytes were inhibited by Sema3A.
  
  
  CONCLUSIONS
  Our findings provide the first evidence that Sema3A is overexpressed, with a direct correlation with cloning, in OA cartilage and that it suppresses the VEGF165-promoted migration of chondrocytes. Our findings also suggest that Sema3A plays a role in chondrocyte cloning through inhibition of cell migration in OA cartilage.
authors.affiliation: Department of Pathology, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Okubo
authors.forename: Tokuhiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Fujita
authors.forename: Satsuki
authors.initials: S
authors.lastname: Mochizuki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Niki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Enomoto
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Suda
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Okada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism*; D040121:Semaphorin-3A / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
chemical_list: D040121:Semaphorin-3A; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A