title: Evidence for cell density affecting C2C12 myogenesis: possible regulation of myogenesis by cell-cell communication.
abstract: BACKGROUND
  Community effect is a phenomenon caused by cell-cell communication during myogenesis. In myogenic C2C12 cells in vitro, the confluent phase is needed for myogenesis induction.
  
  
  METHODS
  To examine the cell-density effect, growth kinetics and myogenic differentiation were investigated in cells plated at four different cell densities.
  
  
  RESULTS
  We found that expression of a myogenic differentiation marker was high in a density-dependent manner. At high density, where cell-cell contact was obvious, contact inhibition after the proliferation stage was accompanied by microarray findings demonstrating upregulation of negative regulating cell-cycle markers, including CDKI p21 and the muscle differentiation markers MyoD and myogenin. Interestingly, developmentally regulated protein expression (drebrin) protein expression was also upregulated in a density-dependent manner.
  
  
  CONCLUSIONS
  These results suggest that contact inhibition after the proliferation stage may induce growth arrest via cell-cell communication through the expression of CDKI p21 and may be responsible for progressing cell fusion.
authors.affiliation: Course of Health Sciences, Gunma University Graduate School of Health Sciences, Showa, Maebashi, Gunma, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Tanaka
authors.forename: Kaori
authors.initials: K
authors.lastname: Sato
authors.forename: Tomomi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Toshio
authors.initials: T
authors.lastname: Fukuda
authors.forename: Kenji
authors.initials: K
authors.lastname: Hanamura
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kojima
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Shirao
authors.forename: Takashi
authors.initials: T
authors.lastname: Yanagawa
authors.forename: Hideomi
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002452:Cell Count / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D051379:Mice; D024510:Muscle Development / Q000502:physiology*